Term
What is the most abundant end product of metabolism?
How is it transported in the blood? |
|
Definition
CO2
Transported
- in dissolved state (10%)
- as bicarbonate (70%)
- in combination w/ hemoglobin (carbaminohemoglobin)& small amount carried by plasma protein (23%) |
|
|
Term
| General Functions of the Cardiovascular System |
|
Definition
- a system of transport between each site of regulation
- maintenance of homeostasis
- transport of nutrients and other vital substances to cells
- transport of waste products away from cells
- regulation of body temp
- endocrine fxn (transport system for hormones) |
|
|
Term
| How does the cardiovascular system regulate core body temperature? |
|
Definition
| by varying skin temp with changes in ambient temperature by changing blood flow to the skin thereby facilitating regulation of core temperature |
|
|
Term
|
Definition
| a chemical substance that is released by a specific cell type into the blood and has a physiologic control effect on other cells of the body. |
|
|
Term
| What are the 3 types of blood vessels and what do they do? |
|
Definition
distributing vessels
- carry blood away from heart
exchange vessels
- exchange nutrients b/w the cardiovascular system and tissues
collecting vessels
- carry blood back to the heart from the tissues |
|
|
Term
| Describe distributing vessels (what they do, examples, how much of the blood is in them, their composition) |
|
Definition
- carry blood away from heart
- aorta, arteries, and arterioles
- hold 15% of the blood
- thick walled and composed of multiple cell layers |
|
|
Term
| Describe exchange vessels (what they do, examples, how much of the blood is in them, their composition) |
|
Definition
- exchange nutrients b/w cardiovascular system and the tissues
- predominantly capillaries (some gas exchange occurs in arterioles and venules)
- one cell layer thick (the endothelial cell layer)
- hold 5% of total blood volume |
|
|
Term
| Describe collecting vessels (what they do, examples, how much of the blood is in them, their composition) |
|
Definition
- carry blood back to the heart from the tissues (also called capacitance vessels b/c can hold a lot of blood)
- vena cava, veins, & venules
- hold 80% of total blood volume |
|
|
Term
What is the formula for the formation of carbonic acid?
What is it maintained by? |
|
Definition
H2O + CO2 <-> H2CO3 <-> H+ + HCO3-
maintained by carbonic anhydrase |
|
|
Term
| If you are running and become hot, how will the cardiovascular system control your temperature? |
|
Definition
| release heat by vasodilation |
|
|
Term
| Explain how Baro Receptors maintain homeostasis |
|
Definition
| Sudden fall in BP sensed by carotid artery/ aortic arch -> Baro receptors -> vagal tone -> sympathetic drive -> increases BP |
|
|
Term
Explain how the cardiovascular system regulates endocrine fxn using insulin as a model.
What type of feedback mechanism is this? |
|
Definition
meal -> increase glucose in blood -> release of insulin from endocrine pancreas -> increase uptake by cells -> blood glucose decreased -> decreased insulin
negative feedback mechanism |
|
|
Term
| Name 3 things that can upset the cardiovascular series. |
|
Definition
Patent ductus arteriosus
fossa ovalis
ventricular septal defect |
|
|
Term
| 100% of the blood in the systemic circulation must go through _________. |
|
Definition
| the pulmonary circulation |
|
|
Term
| At any one time what percent of the blood is in the pulmonary circulation? systemic circulation? |
|
Definition
Pulmonary 25%
Systemic 75% |
|
|
Term
define hydrostatic blood pressure
how is it determined |
|
Definition
the force exerted upon the blood vessel wall by the blood present in the vessel
determined by the volume of blood present & the compliance of the blood vessel |
|
|
Term
the pulmonary circulation is a _______ pressure system?
systemic circulation?
(high or low) |
|
Definition
Pulmonary = low
Systemic = high |
|
|
Term
The central circulation includes ___________________.
The systemic circulation includes _________________. |
|
Definition
Central
- heart and pulmonary circulation
Systemic
- systemic blood vessels (from aorta to vena cava) |
|
|
Term
|
Definition
| the rapid movement of blood over a long distance from a region of high hydrostatic pressure to a region of low hydrostatic pressure. |
|
|
Term
| What is the major mechanism by which blood flows from the aorta to the vena cava? |
|
Definition
|
|
Term
| What is the major mechanism by which blood flows from the pulmonary artery to the pulmonary vein? |
|
Definition
|
|
Term
| What are teh 2 major modes of transport within the cardiovascular system? |
|
Definition
bulk flow (based on hydrostatic pressure)
diffusion (based on concentration gradient) |
|
|
Term
| What is the major mechanism by which blood flows from the capillaries to the tissues? |
|
Definition
|
|
Term
| What is the major mechanism by which blood flows from the tissues to the capillaries? |
|
Definition
|
|
Term
| What provides the energy for cardiac contraction? |
|
Definition
from oxidative metabolism of fatty acids
(to a lesser extent nutrients such as lactic acid or glucose)
ATP is the chemical energy |
|
|
Term
| Why do fatty acids provide the energy for cardiac contraction and not glucose? |
|
Definition
because beta oxidation of fatty acids provides ~150 molecules of ATP
Glucose gives a net yield of only 38 ATP/glucose molecule
- glycolysis only has a net yield of 2 ATP/molecule of glucose
- citric acid cycle yields only 2 ATP/glucose
- oxidative phosphorylation yields 34 ATP/glucose |
|
|
Term
| The efficiency of the heart is |
|
Definition
work output/chemical energy expenditure
(during energy production, a certain percentage of chemical energy is converted to the work of contraction and a certain percentage is used in the production of heat)
The less heat produced during metabolism, the more efficient the heart is. |
|
|
Term
| What is normal cardiac efficiency? |
|
Definition
20-25%
a failing heart may be 5-10% |
|
|
Term
| _________ is an electrical stimulus that is necessary for mechanical contraction. |
|
Definition
an action potential
(the resting membrane goes from very neg to very pos due to movement of ions across the membrane) |
|
|
Term
define electrophysiology
how does it relate to cardiology |
|
Definition
the study of how action potentials are generated in the cell and how action potentials move from cell to cell
the electrical behavior of single cells in the heart can be investigated by placing microelectrodes into the interior and measuring changes in membrane potential |
|
|
Term
|
Definition
| the electrocardiograph is a sensitive voltmeter that registers changes in electrical potential on the body surface that results from electrical currents in the heart |
|
|
Term
|
Definition
|
|
Term
| define perfusion pressure |
|
Definition
the pressure difference across circulation (perfusion pressure = Pa - Pv)
it is the pressure difference that drives bulk flow |
|
|
Term
| Systolic Pressure vs. Diastolic pressure |
|
Definition
Systolic
- the peak pressure in the major arteries that occurs during ventricular systole (contraction)
Diastolic
- the lowest pressure in the major arteries that occurs during ventricular diastole (relaxation) |
|
|
Term
|
Definition
the average pressure b/w systolic and diastolic
0.6(diastolic) + 0.4(systolic) = mean pressure |
|
|
Term
| Amount of time spent in systole vs. amount of time spent in diastole |
|
Definition
Systole = 40%
Diastole = 60% |
|
|
Term
| What provide points of contact b/w the intracellular fluid of adjacent cells? |
|
Definition
| gap junctions (nexi) in the intercalated discs |
|
|
Term
| Cardiac tissue behaves as a _______________. |
|
Definition
|
|
Term
| Why do the atria act as a separate functional syncytium from the ventricular syncytium? |
|
Definition
| because the atria are separated from the ventricles by a fibrous band. |
|
|
Term
| __________ is the mechanism by which an action potential causes muscle contraction. |
|
Definition
| Excitation-Contraction Coupling |
|
|
Term
| Describe the cardiac circuitry |
|
Definition
2 pumps in series (left heart and right heart)
systemic circuit is in parallel (why blood is diverted from legs to gut after eating)
systemic capillary beds are in series (all blood from 1st bed must go through the 2nd |
|
|
Term
| Describe the major differences in excitation of cardiac muscle vs. skeletal muscle |
|
Definition
cardiac muscle has automaticity and rhythmicity
spontaneous depolarization of pacemaker cells
SLOW CALCIUM CHANNELS ONLY (don't want fast depolarization, want heart to fill before contraction)
the mechanics of contraction are the same, just longer duration
- cardiac muscle releases 10x more calcium -
cardiac muscle has a much longer refractory period |
|
|
Term
| What controls the movement of the action potential across the AV node? |
|
Definition
|
|
Term
| What is the 2 unique characteristics of pacemaker cells? |
|
Definition
| they display automaticity and rhythmicity |
|
|
Term
| Working muscle cells vs pacemaker cells |
|
Definition
Working Muscle Cells
- responsible for contraction and heart pumping
- make up the majority of the myocardium
Pacemaker Cells
- responsible for initiating action potentials
- spontaneously depolarize and the action potential spreads throughout the syncytium
- control heart rate |
|
|
Term
|
Definition
Sinoatrial node
AV node/ Bundle of His |
|
|
Term
What sets the heart rate under normal conditions?
What if that is damaged? |
|
Definition
SA node
The AV node will take over but has a lower intrinsic rate of firing so the heart rate will be much slower |
|
|
Term
| Describe the role of sodium in the pacemaker potential. |
|
Definition
Pacemaker cells have Na+ chanesl taht are closed during the action potential.
The channels spontaneously open after the action potential is over.
The opening of these channels allows Na+ to move into the cell causing a gradual depolarization towards threshold. |
|
|
Term
| what is the rate of SA node firing in the horse, dog, cow, and cat. |
|
Definition
horse: 40 times/min
large dog: 80 times/min
cow: 60 times/ min
cat: 160 times/min |
|
|
Term
| What is the rate of firing of the AV node in a horse, dog, cow, and cat? |
|
Definition
horse: 22 times/min
dog: 50 times/min
cow: 40 times/min
cat: 90 times/min |
|
|
Term
| Describe the role of potassium in the pacemaker potential |
|
Definition
At the end of an action potential in pacemaker cells, K+ permeability is high because many K+ channels are open.
K+ channels begin to close and the permeability decreases.
As less K+ leaves the cell, the resting membrane potential becomes less negative thereby driving the membrane potential towards threshold. |
|
|
Term
| Describe the role of Ca++ in the pacemaker potential. |
|
Definition
Ca++ gives small contribution
late in the pacemaker potential (just before cell reaches threshold) slow Ca++ channels begin to open
the entry of Ca++ into the cell aids in reaching threshold and initiation of an action potential |
|
|
Term
| Pacemaker cells have no _______ channels. |
|
Definition
|
|
Term
| Describe the pacemaker potential in general terms. |
|
Definition
| gradual change in movement of ions across membrane that creates a gradual change towards threshold |
|
|
Term
| Explain the effect of the ANS on the heart |
|
Definition
Innervation by ANS is not required for the heart to pump.
It modulates the rate (chronotropic effects) and strength (inotropic effects) of heart contraction. |
|
|
Term
parasympathetic effect on the heart
sympathetic effect on the heart |
|
Definition
parasympathetic (acetylcholine)
- decreases heart rate
sympathetic (norepinephrine)
- increases heart rate and strength of contraction |
|
|
Term
| What is different about the membrane potential in working muscle cells vs. pacemaker cells? |
|
Definition
| The membrane potential is stable in working muscle cells. |
|
|
Term
| Name the 2 main reasons for the pacemaker potential. |
|
Definition
leaky slow Na+ channels
decreased permeability to K+ |
|
|
Term
What maintains the negative resting membrane potential of cardiac cells?
What is the normal resting membrane potential? |
|
Definition
- permeability to K+ which moves out of the4 cell
- decreased permeavility to Na+
- Na-K ATPase moves Na+ out of cell and K+ in at a ratio of 3:2
normal RMP is -60 to -90 mV |
|
|
Term
| What are the phases of the cardiac action potential? |
|
Definition
Phase IV
- resting membrane potential (-60 to -90 mV)
- permeability to K+
- decreased permeability to Na+
- Na-K ATPase moves 3 Na+ out for every 2 K+ in
Phase 0
- rapid depolarization
- action potential from neighboring cell or pacemaker causes decrease in K+ permeability and big increase in perm to Na+ through FAST Na+ channels
Phase I
- rapid repolarization
- fast Na+ channels close quickly causing a decrease in membrane potl
- repolarization interrupted by opening of slow Ca++ channels
Phase II
- plateau phase
- created by closing of K+ channels and opening of Ca++ channels (decreased exit of K+ and increasing entry of Ca++ keeps membrane in depolarized state for 200 ms)
Phase III
- repolarization
- closure of Ca++ channels and opening of K+ channels
- activity of Na-K ATPase tends to restore resting membrane potl |
|
|
Term
|
Definition
resting membrane potl -60 to -90 mV
maintained by:
- permeability to K+ which moves out
- decreased permeability to Na+
- Na-K ATPase moves Na+ out and K+ in at rate of 3:2 |
|
|
Term
|
Definition
Rapid depolarization
action potl from neighboring cell or pacemaker causes
- decrease in permeability to K+
- big increase in Na+ permeability through FAST Na+ channels |
|
|
Term
|
Definition
rapid repolarization
fast closure of Na+ channels causes temp decrease in mem potl
repolarization interrupted by opening of Ca++ channels |
|
|
Term
|
Definition
plateau phase
caused by closing of K+ channels and opening of Ca++ channels
(decreased K+ exit and increased Ca++ entry keeps in depolarized state for 200 ms) |
|
|
Term
|
Definition
repolarization
- closure of Ca++ channels
- opening of K+ channels
- results in repolarization
- activity of Na-K ATPase tends to restore resting mem potl |
|
|
Term
What causes the absolute refractory period in cardiac cells?
When is the relative refractory period? |
|
Definition
inactivation of Na+ channels (lasts 200-250 ms)
relative refractory is when mem reaches -50 mV (cell can respond to stronger stimulus than norm, such as sympathetic stimulation) |
|
|
Term
| What is the importance of a long refractory period in the heart? |
|
Definition
guarantees a period of relaxation and allows filling of the heart with blood b/w cardiac contractions
prevents tetanus from occurring |
|
|
Term
| What is the route of conduction of an action potential through the myocardium? |
|
Definition
| SA node -> Atrial cells -> AV node -> Bundle of His -> Bundle Branches -> Purkinje fibers -> ventricles |
|
|
Term
| What is the only conduction pathway between the atria and ventricles? |
|
Definition
|
|
Term
| A failing heart produces more ______ and less ______. |
|
Definition
|
|
Term
| Electrophysiology vs Electrocardiology |
|
Definition
Electrophysiology is the study of the ion movement
Electrocardiology is the study of voltage changes |
|
|
Term
| What does regular exercise result in? |
|
Definition
|
|
Term
If you are sleeping, what part of the nervous system is dominating?
What about if you are about to take an anatomy test? |
|
Definition
Sleeping = parasympathetic
Anatomy Test = sympathetic |
|
|
Term
| The plateau phase is primarily created by __________. |
|
Definition
|
|
Term
| What is the importance of a low conduction velocity at the AV node? |
|
Definition
| allows time for filling of ventricles |
|
|
Term
| Sympahetic Stimulation of SA node |
|
Definition
increased Na+ permeability
decreased K+ permeability
increased rate of firing
increased heart rate |
|
|
Term
| Parasympathetic Stimulation of SA node |
|
Definition
decreased Na+ perm
increased K+ perm
decreased rate of firing
decreased HR |
|
|
Term
| Sympathetic Stimulation of AV node |
|
Definition
increased conduction velocity
- lets stimulus get through faster
increased rate of spontaneous depolarization
decreases relative refractory period
- increased rate of depolarization
- increased HR |
|
|
Term
| Parasympathetic Stimulation of AV node |
|
Definition
decreased conduction velocity
decreased rate of spontaneous depolarization
increases relative refractory period
- decreased rate of depolarization
- decreased HR |
|
|
Term
| Sympathetic effect vs. parasympathetic effect on ventricular muscle |
|
Definition
Sympathetic
- strong innervation
- increased Ca++ influx -> increased cross bridges -> increased force of contraction
Parasympathetic
- no innervation
- no effect |
|
|
Term
| Arrhythmias reflect disturbances of ______ or ________. |
|
Definition
| disturbances of impulse propagation (conduction blocks and reentrant rhythms) or impulse initiation (abnormal pacemakers) |
|
|
Term
|
Definition
AV block (1st, 2nd or 3rd degree)
reentrant rhythms
- when the ventricular muscle is refractory and cannot conduct the impulse
- rhythms occur when an impulse re-enters a portion of myocardium that was already depolarized by the same original simulus
- conditions of reentry include pathway around the circuit is long, a decreased conduction velocity, or a decreased refractory period |
|
|
Term
| In each cardiac cycle the left ventricle __________ and the left atrium ____________. |
|
Definition
left ventricle
- takes in a volume of blood from teh pulmoney vein
left atrium
- pumps it into the aorta |
|
|
Term
| In each ardiac cycle the right ventricle _______ and the right atrium _______. |
|
Definition
right ventricle
- takes in an equal volume of blood from the vena cava
right atrium
- pumps it into the pulmonary artery |
|
|
Term
| The cardiac cycle consists of _______. |
|
Definition
| atrial contraction and relaxation and ventricular contraction and relaxation |
|
|
Term
|
Definition
the period of ventricular contraction
Isovolumetric contraction
- both inflow valves (AV) and outflow valves (aortic and pulmonic) are closed so contraction occurs at a constant volume
- produces significatnt pressure buildup in the ventricles and significant kinetic energy in the blood in the heart chamber
Ejection
- as pressure in ventricles exceed perssure in the major arteris, the aortic and pulmonary valves are pushe dopen and the blood rushes into the arteries |
|
|
Term
|
Definition
the amt of blood pumped out of the ventricles per contraction
end diastolic volume - end systolic volume |
|
|
Term
| End systolic volume vs. end diastolic volume |
|
Definition
end systolic volume
- the amt of blood in the ventricles at the end of systole (ventricular contraction)
end diastolic volume
- the amt of blood in the ventricles at the end of diastole (ventricular relaxation) |
|
|
Term
|
Definition
ventricular relaxation
isovolumetric relaxation
- ventricles relax against closed valves so the volume remains the same even though the pressure drops precipitously
rapid ventricular filling
- during relaxatino the pressure in ventricles falls below that in the atria so the AV valves open allowing blood from atria to the ventricles (no contraction of atria)
reduced ventricular filling (diastasis)
- as ventricles fill and atria empty, the preessure differential falls and the rate of filling decreases |
|
|
Term
| What is responsible for ventricular filling? |
|
Definition
| periods of rapid and reduced ventricular filling are responsible for 80-90% of total ventricular filling (the other 10-20% of filling is due to atrial systole) |
|
|
Term
|
Definition
the period of atrial contraction
the heart can function fine at rest w/o atrial systole |
|
|
Term
|
Definition
| the fraction of the end diastolic vollume that is pumped out during ventricular systole |
|
|
Term
| What is the importance of ventricular diastole? |
|
Definition
| it is critical to proper cardiac performance to allow adequate time for ventricular filling & for myocardial perfusion |
|
|
Term
period of myocardial perfusion
What happens if this period is shortened? |
|
Definition
the only time blood flows in coronary arteries isduring diastole
- flow ceases during systole
if period becomes too short, the myocardium can become ischemic |
|
|
Term
|
Definition
1st heart sound (lup)
- closure of AV valves
2nd heart sound (dub)
- closuer of aortic and pulmonic valves |
|
|
Term
Cardiac murmurs occur due to ____________.
They can be caused by what? |
|
Definition
due to turbulence as blood flows through the heart
Caused by:
- narrowing of the valves (stenosis)
- insufficiency of the valves (regurgitation)
- anatomical defects (patent ductus arteriosus, septal defects)
- decreased viscosity of blood (anemia) |
|
|
Term
| Systolic Murmurs occur during ___________ |
|
Definition
systole
(the period of time b/w the lup and dub)
- tricuspid or mitral regurg
- pulmonic or aortic stenosis
- ventricular septal defect |
|
|
Term
tricuspid or mitral regurgitation
what type of murmur is this? |
|
Definition
AV valves are insufficient (they do not close completely so blood shoots back up into the atria during ventricular systole)
systolic murmur b/c it only occurs when the heart is contracting |
|
|
Term
pulmonic or aortic stenosis
What type of murmur is this? |
|
Definition
narrowing of the aortic or pulmonic valves
systolic murmur b/c there is turbulence during systole as blood flows rapidly through the narrowed valve |
|
|
Term
ventricular septal defect
What type of murmur is this? |
|
Definition
congenital defect where the ventricular septum fails to close completely so there is a hole b/w right and left ventricles
heard during systole only and is created by turbulence as blood flows from the left ventricle (high pressure) to the right ventricle (low pressure)
often accompanied by a vibration on the right chest wall
(atrial septal defects also occur and cause systolic murmurs) |
|
|
Term
|
Definition
occur during ventricular diastole (relaxation)
- during the time of ventricular filling
- mitral or tricuspid stenosis
- pulmonic or aortic regurg |
|
|
Term
mitral or tricuspid stenosis
What type of murmur is this? |
|
Definition
narrowing of the mitral or tricuspid valves
creates a turbulence created by blood glowing into the ventricles from the atria during ventricular filling
diastolic murmur |
|
|
Term
pulmonic or aortic regurgitation
What type of murmur is this |
|
Definition
insufficiency of the pulmonic or aortic valves
creates durbulence during diastole b/c of elastic recoil of aorta and pulmonary arteries that moves blood backwards toward the heart
if valve doesn't close properly, allows reflux into the ventricles.
elastic recoil occurs during diastole when the pressure in the artery exceeds slightly the pressure in the ventricles. |
|
|
Term
|
Definition
occur during diastle and systole
- patent ductus arteriosus |
|
|
Term
patent ductus arteriosus
What type of murmur is this? |
|
Definition
failure of closing of teh ductus arteriosus at birth
blood flows from aorta to pulmonary artery continuously
sometimes called machinery murmur b/c sounds like a washing machine |
|
|
Term
| Name the different murmurs and whether they are systolic, diastolic, or continuous |
|
Definition
Systolic
- tricuspid or mitral regurg
- pulmonic or aortic stenosis
- ventricular septal defect
Diastolic
- mitral or tricuspid stenosis
- pulmonic or aortic regurg
Continuous
- patent ductus arteriosus |
|
|
Term
|
Definition
a measure of cardiac performance
the amount of blood pumped by the ventricles per unit time
CO (ml/min) = HR (beats/min) x SV (ml/beat) |
|
|
Term
| What factors influence cardiac output? |
|
Definition
heart rate
- up to a certain point, an increase in HR will cause an increase in cardiac output
- if so fast that there isn't time for adequate ventricular filling, the cardiac output will fall due to precipitous fall in stroke volume
stroke volume
- an increase in stroke volume causes and increase in cardiac output |
|
|
Term
| What factors influence stroke volume? |
|
Definition
Preload
Afterload
Contractility |
|
|
Term
Preload
How is it measured? |
|
Definition
the ventricular pressure or volume at the end of diasstole
equal to the atrial pressure and to the pressure in the veins returning blood to the heart
measured by use of a central venous cath placed in the jugular and advanced into the vena cava |
|
|
Term
| What does an increase in preload signify? |
|
Definition
| and increase in venous return to the heart & an increase in end diastolic volume |
|
|
Term
| Starling's Law of the Heart |
|
Definition
an increase in preload will cause an increase in the stroke volume
this mechanism keeps a balance b/w the stroke volume of the right ventricle and the stroke volume of the left ventricle |
|
|
Term
|
Definition
forces opposing movement of blood out of the ventricles into the arteries
- the load against which the muscle must work when it contracts
determined by:
- aortic and pulmonary artery pressure (the higher pressure in the arteries, the more contraction of the ventricles that is required to pump blood out of the heart)
- ventricular radius (an increase in ventricular radius creates an increas in wall tension which will tend to increase afterload and therefore decreases stroke volume |
|
|
Term
| What is the major determinant of afterload? |
|
Definition
|
|
Term
| With higher pressure in the arteries, is more or less contraction needed to pump blood out of the heart? |
|
Definition
|
|
Term
| An increase in ventricular radius will do what to stroke volume? |
|
Definition
decrease stroke volume
b/c it creates an increase in wall tension which tends to increase afterload and therefore decrease stroke volume |
|
|
Term
|
Definition
the force of contraction at a given preload
An increase in contractility can bring about an increase in stroke volume without having an increase in end diastolic volume.
When this occurs, the heart empties more completely and the end systolic volume decreases. |
|
|
Term
| How can you bring about an increase in stroke volume w/o an increase in end diastolic volume? |
|
Definition
| by increasing contractility (the force of contraction at a given preload) |
|
|
Term
| What factors affect contractility? |
|
Definition
ANS (symp input increases strength of contraction)
Heart failure (decrease in contractility)
Alterations in plasma electrolytes (Ca++ levels falling results in decreased contractility)
bacteral toxins (decreased contractility due to myocardial depression factor)
Alterations in acid-base balance (acidosis causes myocardial depression and decreased contractility)
Drugs
Hypertrophy (up to a certain amt of hypertrophy will increase contractility, but if it is excessive, it will decrease contractiltiy due to lack of blood supply to the thickened muscle) |
|
|
Term
| What effect does an increase in sympathetic drive have on stroke volume and why? |
|
Definition
it increases contractility and therefore increases stroke volume
Norepi increases Ca++ release which increases the # of crossbridges that are cycling and will increase the strength of contraction. |
|
|
Term
How does heart failure affect the heart?
What causes heart failure? |
|
Definition
causes a decreased pumping ability of the heart and therefore decreases contractility
Causes
- coronary artery dz
- cardiac hypoxia
- myocarditis
- valvular dz
- chronic hypertension
- toxic rxns
- electrolyte imbalances
- genetic defects in cardiac muscle fxn (hypertrophic or dilated cardiomyopathy) |
|
|
Term
| How does a decrease in pH affect the heart? |
|
Definition
| acidosis causes myocardial depression and a decrease in contractility |
|
|
Term
Name some drugs that decrease contractility.
Name some drugs that increase contractility. |
|
Definition
Decrease Contractility
- beta adrenergic antagonists (propanolol)
- barbituates
Increase Contractility
- beta agonists (dopamine, norepi, isproterenol)
- cardiac glycosides (digitalis) |
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Term
| What causes hypertrophy and how does it affect the heart? |
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Definition
it is caused by an increase in pressure resulting in a thickened ventricle
it will increase contractility up to a certain extent
If the hypertrophy is extreme, it will decrease contractility b/c there isn't adequate blood supply to the thickened muscle. It will obstruct outflow to the arteries due to valvular obstruction and this will decrease stroke volume because of an increase in afterload. |
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Term
| What will extreme hypertrophy do to stroke volume and why? |
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Definition
it will decrease stroke volume
b/c it obstructs outflow due to valvular obstruction causing an increase in afterload which will decrease stroke volume |
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Term
Define blood flow.
Define resistance. |
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Definition
Blood flow
- the rate at which blood moves through the vasculature (ml/min)
Resistance
- the impediment to blood flow through the blood vessel
- dependent on properties of the blood vessel and fluid |
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Term
| An increase in arterial pressure w/o a change in venous pressure will do what to blood flow? |
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Definition
| it will increase blood flow |
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Term
| An increase in venous pressure w/o a change in arterial pressure will do what to blood flow? |
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Definition
| it will decrease blood flow |
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Term
An increase in cardiac output will do what to arterial pressure?
What will it do to blood flow? |
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Definition
increase arterial pressure
increase blood flow |
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Term
| What are the determinants of pressure? |
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Definition
cardiac output
blood volume
compliance
peripheral vascular resistance
total peripheral resistance
total pulmonary resistance |
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Term
| How does volume expansion affect blood pressure? |
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Definition
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Term
| ________ is how much the pressure changes with a given change in volume. |
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Definition
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Term
| How will a vessel with a high compliance respond when a change in volume occurs? |
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Definition
| it will have a small increase in pressure when a relatively large change in volume occurs |
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Term
| How will a vessel with low compliance respond to a change in volume? |
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Definition
| it will display a large increase in pressure when a relatively low change in volume occurs |
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Term
| Veins are capable of storing _______ amts of blood with a ______ increase in pressure b/c they have a _______ compliance. |
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Definition
store large amts of blood
small increase in pressure
have a high compliance |
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Term
| A relatively small increase in volume will cause a much larger increase in pressure in _______. (artery or vein?) |
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Definition
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Term
| What is peripheral vascular resistance? |
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Definition
the impediment to flow in the peripheral vasculature
can't be measure directly
- cauculated it from perfusion pressure and flow
resistance = change in pressure/flow |
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Term
| What is total peripheral resistance? |
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Definition
the resistance of the entire systemic circulation
TPR = (mean aortic pressure - vena caval pressure)/cardiac output |
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Term
| What are the determinants of resistance? |
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Definition
Radius (the most impt determinant)
- a 2 fold increase in radius will cause a 16 fold decrease in resistance
Length
- the longer the length of the vessel, the greater the resistance
Viscosity of blood
- the more viscous the blood, the greater the resistance
- viscosity is dependent on the red cell mass |
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Term
| What does Poiseuille's Law do? |
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Definition
| it relates blood flow to factors that determine resistance |
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Term
| If the left side of the heart isn't pumping well, what happens? |
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Definition
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Term
| A failing heart has ________ due to weakness in the muscle. |
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Definition
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Term
| How is the ejection fraction calculated? |
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Definition
| (the amount of blood that goes out per beat)/(the amount of blood after filling) |
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Term
| If you increase the heart rate, what do you do to the stroke volume? |
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Definition
| you decrease stroke volume by decreasing the time of diastole |
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Term
| What causes a physiologic murmur? |
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Definition
| a decrease in blood viscosity (anemia) |
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Term
| _______ is how much blood is returning to the heart. |
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Definition
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Term
| _____________ is how the heart maintains the right ventricular output (lower pressure) equal to left ventricular output(higher pressure). |
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Definition
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Term
| Right heart failure results in _________. |
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Definition
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Term
| An increased contractility will have what effect on the end systolic volume? |
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Definition
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Term
Is an increase in preload good or bad?
What about an increase in afterload? |
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Definition
Increased preload = good (up to a certain point, after that it will increase afterload)
Increased afterload = bad
- because it increases the amount of work the heart has to do |
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Term
| What results in an increased afterload? |
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Definition
a dog with heartworms
- pulmonary hypertenstion
- increased afterload to right heart
- results in heart failure |
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Term
| physiologic hypertrophy vs. pathophysiologic |
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Definition
physiologic
- increase muscle mass but coronary circulation grows with it
pathophysiologic
- chronic increase in afterload
- aortic or pulmonary stenosis
- AV node insufficiency |
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Term
| What is the equation for blood flow? |
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Definition
| flow = perfusion pressure/ resistance |
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Term
1) Increased resistance will have what effect on blood flow?
2) Increased perfusion pressure?
3) Increased arterial pressure?
4) Increased venous pressure? |
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Definition
1) decrease
2) increase
3) increase
4) decrease |
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Term
| What is the biggest component in resistance? |
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Definition
| the diameter of the blood vessel |
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Term
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Definition
| the difference between systolic pressure and diastolic pressure |
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Term
| What effect does increasing stroke volume have on pulse pressure? |
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Definition
| increase stroke volume -> increase systolic pressure -> increase pulse pressure |
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Term
| What effect does decreasing stroke volume have on pulse pressure? |
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Definition
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Term
| What effect does increasing the heart rate have on pulse pressure |
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Definition
up to a point it increases pulse pressure
at very high HR (no time for ventricular filling) it will decrease pulse pressure |
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Term
| What diseases cause alterations in pulse pressure? |
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Definition
patent ductus arteriosus
- decrease in diastolic pressure
- increase in pulse pressure
aortic regurg
- decrease in diastolic pressure
- increase in pulse pressure
hypovolemic shock
- decrease systolic pressure
- decrease in pulse pressure |
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Term
What effect does a patent ductus arteriosus have on pulse pressure?
Aortic regurg?
Hypovolemic shock? |
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Definition
PDA
- decrease in diastolic pressure b/c blood flowing both ways in diastole
- increase in pulse pressure
Aortic Regurg
- decrease in diastolic pressure b/c blood is shooting back up into the ventricle
- increase in pulse pressure
Hypovolemic Shock
- decrease in systolic pressure
- decrease in pulse pressure |
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Term
| What affect does aging have on pulse pressure and why? |
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Definition
With aging, the compliance or distensibility of the arteris decreases.
A decrease in compliance causes an increase in pulse pressure |
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Term
| A decrease in compliance has what effect on pulse pressure. |
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Definition
| causes an increase in pulse pressure |
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Term
| The largest drop in pressure throughout the vasculature occurs at ________ |
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Definition
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Term
Where in the vasculature is the flow pulsatile?
Where is the flow nonpulsatile? |
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Definition
Pulsatile
- aorta & arteries
- arterioles
Nonpulsatile
- capillaries
- venous system |
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Term
| Describe the flow of blood throughout the vasculature |
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Definition
Aorta and arteries
- flow rate is extremely fast
- flow and pressure is pulsatile
Arterioles
- flow rate slows down considerably
- pressure and flow are pulsatile but much less magnitude
Capillaries
- flow rate is extremely slow
- flow and pressure become nonpulsatile
Venous system
- flow rate increases significantly
- pressure and flow nonpulsatile |
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Term
| What 4 factors facilitate venous return to the heart |
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Definition
skeletal muscle pump
- large muscle groups of limbs compress bessels when they contract forcing blood towards the heart
one way valves
- veins have one way valves that prevent back-flow of blood towards the periphery
intrathoracic pressure
- intrathoracic pressure becomes negative during respiration sucking blood towards the thorax
venomotor tone
- venous smooth muscle displays rhythmic contractions that serve as a venous pump to move blood towards the heart |
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Term
| What insures unidirectional movement of blood in the venous system? |
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Definition
| one-way valves and skeletal muscle pump |
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Term
Define microcirculation
What does it include? |
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Definition
the portion of the cardiovascular system that is involve in the exchange of substances b/w the blood and tissues.
includes
- capillaries
- arterioles
- venules |
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Term
Capillaries are ________ in diameter.
They offer ________ resistance to flow than arterioles. |
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Definition
smallest in diameter
offer less resistance to flow than arterioles b/c large number of them with large cross-sectional area |
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Term
| What is responsible for the blood-brain barrier? |
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Definition
| the pores between endothelial cells are so small that they allow only water and electrolytes can pass through |
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Term
| Where are fenestrated capillaries found? |
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Definition
in the liver
pores are so large that even plasma protein can pass |
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Term
| What is the most abundant type of blood vessel? |
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Definition
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Term
| structure of capillaries vs. arterioles |
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Definition
capillaries
- single layer of endothelial cells and a basement membrane with clefts or fenestrae b/w cells to allow exchange of materials
arterioles
- endothelial cell layer
- thick tunica media (circular smooth muscle layer) |
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Term
| What does the "gateway to the microcirculation" refer to? |
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Definition
arterioles
b/c of large amt of smooth muscle, they can change dramatically in diameter to control movement of blood into a given capillary bed |
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Term
| "resistance vessels" refer to ___________ |
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Definition
arteriols
b/c they have the greatest resistance to flow and causes the biggest pressure drop as the blood goes through the circulation |
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Term
| Where in the circulation does flow go from pulsatile to a constant pattern? |
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Definition
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Term
| What are precapillary sphincters? |
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Definition
terminal arterial with very thick smooth muscle
they can contract and close down a capillary bed completely |
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Term
| What are the modes of transportation in the microcirculation? |
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Definition
bulk transport
- process by which blood moves from the arterioles to the capillaries
diffusion
- how water moves out of the capillary
filtration
- bulk transport across the capillary bed driven by hydrostatic pressure (pressure is higher in capillary bed than the interstitium)
- occurs at the beginning of the capillary bed
reabsorption
- osmotic pressure difference across the capillary wall b/c the presence of protein inside the capillary is too large to get out of the vasculature
- favors the movement of water into the vasculature |
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Term
| What are the 4 factors that determine the movement of fluids in the microcirculation? |
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Definition
hydrostatic pressure in the capillaries
plasma oncotic pressure
oncotic pressure in the interstitium
hydrostatic pressure in the interstitium |
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Term
Hydrostatic pressure in the microcirculation is __________.
It is dependent on ____________. |
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Definition
pressure exerted on the vessel wall
due to the volume of blood |
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Term
What is the driving force of filtration?
reabsorption? |
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Definition
Filtration
- hydrostatic pressure
Reabsorption
- more protein inside the vessel than in the interstitium which drives osmotic pressure |
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Term
What favors filtration?
Reabsorption?
(parts of the starling's hypothesis equation) |
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Definition
Filtration
- capillary hydrostatic pressure
- interstitial oncotic pressure
Reabsorption
- interstitial hydrostatic pressure
- plasma oncotic pressure |
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Term
| Where are stretch receptors located? |
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Definition
- atrial volume receptors
- aortic arch baroreceptor
- carotid sinus baroreceptor |
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Term
| Decreased baroreceptor activity results in _________ |
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Definition
increase in heart rate
increase in contractility
increase in cardiac output
in addition, most blood vessels will become constricted (brings BP back to normal, impt in shock) |
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Term
| atrial volume receptor reflex senses change in stretch due to ___________ |
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Definition
a change in volume
- a decrease in stretch will decreaase firing, and this causes release of vasopressin or ADH (which increases H2O retention)
- causes an increase in sympathetic drive to restore BP to normal
- increased renal constriction causes release of renin and will acto to retain Na+ and cause vasoconstriction |
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Term
| Long term mechanisms for BP are driven by ________. |
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Definition
hormones
renin-angiotensin-aldosterone system
epi/norepi-adrenal medulla |
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Term
| Renin-Angiotensin-Aldosterone System |
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Definition
decreased renal perfusion results in release of renin
renin converts angiotensinogen -> angiotensin I
in circulation, angiotensin I -> angiotensin II (which causes release of aldosterone
aldosterone reduces excretion of Na+ resulting in increased water retention |
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Term
| Describe the effect of epi/norepi on BP |
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Definition
| cause an increase in cardiac output and vasoconstriction |
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Term
| The blood flow through any organ or tissue is determined by _________. |
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Definition
perfusion pressure and resistance
(all organs have the same perfusion pressure so the vascular resistance determines the blood flow) |
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Term
| Extrinsic control of blood flow to an organ is primarily ___________. |
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Definition
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Term
| What is the most impt local control mechanism for blood flow? |
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Definition
metabolic control of blood flow
allows the organ to match blood supply with metabolic needs |
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Term
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Definition
| increase in tissue metabolic rate results in iccumulation of waste products and release of local vasodilators (NO, K+, prostaglandins) |
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Term
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Definition
| a temp increase above normal in the flow of blood to a tissue after a period when blood flow was restricted |
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Term
local control of blood flow:
autoregulation is impt in ___________ |
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Definition
| coronary and skeltal muscle beds where constant blood supply is critical to the maintenace of life |
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Term
| 4 primary categories of shock in the etiologic system |
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Definition
hypovolemic
- decreased blood volume
cardiogenic
- inability of heart to pump blood to maintain adequate arterial pressure
- due to decreased cardiac output
- caused by myocarditis, arrhythmiad, congestive heart failure, acute valvular insufficiency, or cardiac tamponade
obstructive
- a group of lesions that restric cardiac ejection into the arterial tree
- include valvular stenosis and aortic lesions
distributive
- an expansion of vascular space due to regional or generalized loss of vascular tone
- principal causes are neurogenic, anaphylactic, septic, and endotoxic shock
- loss of vascular tone results in decreased mean circulatory filling pressure, cardiac output, and tissue diffusion |
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Term
| What form of shock is characterized generalized loss of venular and arteriolar tone? |
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Definition
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Term
| What are the different types of distributive shock? |
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Definition
neurogenic
- due to nervous sys dysfunction
anaphylactic
- due to anaphylactic rxn
septic
- due to presence of pathogenic bacteria in the blood stream
endotoxic
- a type of septic shock due to gram neg bacteria (endotoxin) in the blood |
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Term
| Describe the stages of shock. |
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Definition
Stage I
- nonprogressive stage
- compensatory mechanisms will eventually caude complete recover w/o medical intervention.
Stage II
- progressive stage
- shock becomes progressively worse if left untreated
- requires medical intervention
Stage III
- an irreversible stage
- shock has progressed to the point that medical intervention is ineffictive and death is imminent |
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Term
What parts of the heart have parasympathetic innervation? What effect does it have?
What parts have sympathetic innervation? What effect does it have? |
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Definition
Vagus (parasympathetic)
- innervates SA node & AV node
- decreases HR
- no effect on force of contraction
Sympathetic
- Innervates SA node, AV node, and heart muscle itself (primarily the ventricles)
- increases HR
- increases force of contraction by modulating Ca++ channels |
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Term
| What are the parts of an ECG wave and what do they correspond to in the body? |
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Definition
P wave = SA node (atrial depolarization)
PR interval = time it takes to go through the AV node
QRS = ventricular depolarization
T = repolarization |
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Term
| An ECG looks at the heart from how many directions? |
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Definition
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Term
| In a typical ECG setup, which leg serves as the ground? |
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Definition
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Term
| What is a normal heart rate in a dog, cat, horse, & cow? |
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Definition
dog: 70-160
cat: 160-240
horse: 28-40 (60)
cow: 40-80 |
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Term
| What is a 1st degree heart block? |
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Definition
| the impulse is blocked in the SA node |
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Term
| What is a 2nd degree heart block? |
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Definition
impulse is blocked in the AV node
see P wave but no QRS complex due to vagal tone
will go away with exercise |
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Term
| Which is longer, the period of systole or diastole? |
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Definition
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Term
| isovolumetric contraction results in a big increase in ____________. |
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Definition
kinetic energy
increased pressure, decreased volume of space (b/c contracting), same volume of blood |
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Term
Diastole refers to the time of ventricular _________.
(depolarization/repolarization) |
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Definition
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Term
| Increased contractility is associated with ________ end stroke volume and ________ stroke volume |
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Definition
decreased ESV
increased SV |
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Term
an increase in blood flow is associated with __________ & __________.
Decreased blood flow is associated with ___________ & _________.
Increased blood pressure is associated with __________ & __________.
Decreased blood pressure is associated with ___________ & _________. |
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Definition
Increased blood flow
- increased perfusion pressure
- increased arterial pressure
Decreased blood flow
- increased resistance
- increased venous pressure
Increased BP
- increased volume
- increased compliance (veins)
Decreased BP
- decreased volume
- decreased compliance |
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Term
| What are the components of a pressure wave? |
|
Definition
anacrotic limb
- peak systolic pressure
- during systole
dicrotic limb
- during diastole
dicrotic notch
- where blood flows backwards
diastolic pressure |
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Term
| An arrhythmia is a failure of __________. |
|
Definition
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Term
| What does ADH do in shock? |
|
Definition
it is released from posterior pituitary in response to decreased atrial stretch receptor firing and increased plasma osmolarity
- increases thirst
- increases water retention by the kidneys
- potent vasoconstrictor |
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Term
| Anesthesiologists must deal with what form of shock? How do they prevent this? |
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Definition
Neurogenic shock (a form of distributive shock)
decrease the amt of smelly stuff results in less vasodilation |
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Term
| neurogenic shock refers to |
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Definition
| nervous sys dysfunction with loss of sympathetic tone |
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Term
| What do colloids do compared to crystalloid therapy |
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Definition
| reduce peripheral edema, pulmonary edema, and increase urine production |
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Term
| What are the advantages of colloid therapy? |
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Definition
prevents hemodilution of plasma proteins that occurs with crystalloid therapy
allows reduction of crystaloids to 40-60% original volume |
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Term
| Giving colloids with crystalloids does what? |
|
Definition
crystalloid therapy provides immediate volume expansion
colloid therapy provides long term crystalloid retention in teh vascular compartment |
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Term
|
Definition
osmotically active moliecules
when given IV, draw fluids into teh vascular space
include
- whole blood
- plasma
- albumin
- dextrans
- hetastarch
- gelatins
- cell free hemoglobin solutions |
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Term
Early stages of shock may be characterized by ________.
Later stages are characterized by __________. |
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Definition
early stages = respiratory alkalosis
later stages = metabolic acidosis due to inadequate tissue perfusion |
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