Term
| when does aortic and arterial pressure drop? |
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Definition
in diastole/early systole
the minimum pressure is the diastolic pressure(DP) |
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Term
| with regards to arterial blood pressure, the opening of which valve causes the pressure to rise in aortic and arterial pressure? |
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Definition
the opening of the aortic valve causing the > in pressure
the maximum pressure is the systolic pressure (SP) |
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Term
| how is pulse pressure measured? what is the normal blood pressure? |
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Definition
pulse pressure = SP -DP
normal blood pressure 120/80 mmHg |
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Term
| with regards to arterial blood pressure the dicrotic notch is caused by the closure of which valve? |
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Definition
the aortic valve.
when measuring blood pressure in the arm, we are measuring the BP in the brachial artery in the arm. |
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Term
| hypertension means high blood pressure. what are the normal ranges for blood pressure, the hypertension range and severe hypertension range? |
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Definition
normal ~ 120/80 mm Hg
hypertension 140-159/90-99 mm Hg
severe hypertension >159/>99 mm Hg |
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Term
| hypertension is associated with o........, high c........, s......., g........ predispositon |
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Definition
obesity, cholesterol, smoking, genetic
it is also associated with atherosclerosic which is the build up of fatty deposits in walls of arteries. this narrows the lumen.
with age we get < elasticity in artery thus > blood pressure |
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Term
true or false?
the heart does not need input from the CNS to contract? |
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Definition
this is true. unlike skeletal muscles that are neurogenic, the heart is myogenic thus signals to contract originate from the heart muscle itself
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Term
| due to which feature is the heart able to generate signals on a periodic basis? |
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Definition
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Term
| name the two types of cells the heart is made out of. which one is contractile? which one generates electrical impulses? |
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Definition
the heart is made up of myocardial cells. these are contractile muscle.
the pacemaker cells are not contractile and generate electrical impulses. |
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Term
| where are pacemaker cells contrated (clue:2 regions) |
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Definition
they are concentrated in the sinoatrial node in the upper right atrium and the atrioventricular node; the AV node near the tricuspid valve.
heart contraction is driven by the SA node and conduction fibres spread these electrical signals rapidly throughout the heart muscle. |
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Term
true or false?
the atria and ventricles contract simultaneously? |
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Definition
false!
first the atria contract, then after a slight delay, the ventricles contract. |
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Term
| which pathway results in simultaneous contraction of right and left atria? |
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Definition
the interatrial pathway.
this is rapid and begins at the SA Node > Right atrium > Left atrium |
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Term
| the internodal pathway spreads excitation from which node to which? |
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Definition
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Term
| name the only pathway from atria to ventricles. |
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Definition
the AV Node Transmission
here there is slow conduction and AV Node delay of 0.1 second. this causes the atria to contract before the ventricles. |
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Term
| in pacemake potentials there is no s......... resting membrane p........... as it slowly d....... to reach a threshold. then the a......... p.......... is triggered and repeated again. |
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Definition
| steady, potential, depolarises, action potential |
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Term
| generation of pacemaker potentials involves the movent of which three ions? |
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Definition
Na+ K+ and Ca2+
the concentrations of these ions are similar to other cells |
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Term
| what causes the slow depolaristion in pacemaker potentials? |
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Definition
| this is caused by funny channels that control the movement of K+ and Na+ ions |
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Term
| the cardiac action potential is mainly due to the movemnt of which ions? |
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Definition
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Term
| slow depolarisation occurs when K+ channels close but when which channels are open causing the slow efflux of K and the influx of Na? |
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Definition
funny channels. LOL
just before threshold Ca2+ channels open and there is a slow influx of calcium ions. at threshold there is a rapid influx of Ca2+
at repolarisation Ca2+ influx < and K+ efflux >
we are now back to slow depolarisation stage again |
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Term
the cardiac cycle happens 100,000 times a day
36.4 x 106 times a year
3000 x 106 in a lifetime |
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Definition
| unless you get killed by a bus or shot then it will be a little shorter for you |
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Term
| before rapid depolarisation which voltage gated calcium channels are open? |
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Definition
T-type
during rapid deplarisation the L-type voltage gated calciumchannels are in use. |
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Term
| cardiac output is the volume of blood pumped out of each ventricle in one minute. it is the same for both ventricles. how is Cardiac Output worked out? |
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Definition
CO = HR X SV
HR is in beats per minute
and Stroke Volume is in cm3
avg HR 72 bpm
avg SV 70 cm3
CO = 5L per minute |
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Term
| in autonomic input to the heart, from the medulla oblongata the vagus nerve (parasympathetic) uses which neurotransmitter to the SA and AV nodes? |
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Definition
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Term
| the SA, AV and Ventricular myocardium are sympathetically stimmulated by the cardiac nerve from the medula oblongata using which neurotransmitter? |
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Definition
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Term
| what is the difference and similarties between sympathetic and parasympathetic? |
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Definition
| both of them are part of the autonomic nervous system where you dont have to think about the actions as your body does them for you. sympathetic speeds up reactions for example dilates your pupils so more light can get in and > HR whereas parasympathetic returns the body to normal eg constricting pupils of the eye and < HR. |
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Term
the sympathetic nervous system uses the neurotransmitter...............
the parasympathetic nervous system uses the neurotransmitter.............. |
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Definition
noradrnaline
acetylcholine |
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Term
which branch of the autonomic nervous system would have the following effects?
- > action potential frequency at SA node
- > HR
- <AV Node delay so ventricular contraction starts sooner
- > contractile force of cardiac muslce
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Definition
sympathetic
the parasympathetic input has all the opposite affects |
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Term
| which hormone enhances sympathetic input? |
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Definition
| adrenaline aka epinephrine |
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Term
| stroke volume is affected by 3 main factors. one of them is Ventricular contractility, name the other two |
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Definition
end-diastolic volume (EDV) and afterload
EDV - the volume of blood in the heart at the end of diastole, affects the degree of stretching of cardiac muscle and stops blood from pooling
afterload is the back-pressure in the arteries |
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Term
| ventricular contractility AKA ventricular force, is cntrolled by two main things. what are they? |
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Definition
nervous and chemical factors
- Sympathetic input (nervous) gives increased force
- adrenaline (chemical) which has similar effects
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Term
Starling's Law of the Heart: when the rate at which blood flows into the heart from the veins changes.....
what happens? |
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Definition
...the heart automatically adjusts its output to match the inflow.
similarly, if an > in EDV occurs, the force of ventricular contraction rises, producing > in SV and CO.
stretching of muscle fibres increases contraction force. |
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Term
Fact: As EDV increases, the SV increases to compensate
what increases the contraction force of the ventricles?
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Definition
the stretching of muscle fibres.
eg, if there is an increase in EDV the walls of the ventricles will be stretched thus following starling's law the heart will adjust and increased ventricular contraction to match the increased in EDV. |
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Term
weak heart leads to reduced blood circulation due to coronary artery disease, myocardial infarction or infection.
what happens to the pumping pressure to systemic circulation? |
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Definition
it decreases leading to > EDV so the heart is enlargened.
water retention causes swelling of legs/ankles. can also lead to congestion of blood in pulmonary circulation leading to pulmonary oedema leading to right heart failure |
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Term
| name a drug that can treat congestive heart failure. How does it work? |
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Definition
Digitalis - it works by increasing the force of contraction.
used when hearts pumping functionis weakened, it makes the heart contract harder. it can also slow fast heart rhythms (tachycardia) |
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Term
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Definition
| Blood cholesterol-lowering agents |
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Term
| what do ACE (angiotensin converting enzyme) inhibitors do? |
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Definition
| they stop production of angiotensin II, a hormone that constricts blood vessels and so it used to control high BP. Also used for persons with heart failure, where the heart is unable to pump enough blood to supply the body's needs |
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Term
true or false
Angiotensin II receptor antagonists work on the same system as ACE inhibitors and prevent the hormone angiotensin II frm acting on cells |
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Definition
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Term
| Digitalis used to make the heart contract hearder works by inhibiting whihc active pump? |
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Definition
the Sodium/ Potassium pump
because the pump actively pumps 3Na out for every 2 K in, inhibiting its action causes intracellular Na to rise.
the Na is then exchanged for Ca2+ at the Na/Ca exchange system and the increased Calcium results in increased contractility of heart muscle via interaction of Ca2+ with Troponin (calcium binding protein) |
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