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The Cardiac System
The heart, blood vessels and regulation
68
Biochemistry
Undergraduate 1
03/02/2013

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Cards

Term
Why do complex organisms require a cardiovascular system?
Definition
They cannot rely on simple diffusion alone to provide the cells with enough nutrition
Term
What are the three functions of the CVS?
Definition
Homeostasis, Flow of blood and the transport of hormones
Term
What are the two circulatory systems?
Definition
Systemic and pulmonary
Term
What is the sytemic system responsible for?
Definition
Pumping blood round the body
Term
WHat is the pulmonary system responsible for?
Definition
Pumping blood to and from the lungs
Term
Which system pumps blood at a high pressure?
Definition
Systemic
Term
Which system pumps blood at a low pressure?
Definition
Pulmonary
Term
What are the four blood vessels fo the CVS?
Definition
Arteries, Arterioles, Capillaries and Veins
Term
Which blood vessel has a high pressure?
Definition
Arteries
Term
Which blood vessel has the highest resistance?
Definition
Arterioles
Term
Which blood vessel has the lowest pressure?
Definition
Veins
Term
Which blood vessel has the thinest diffusion distance?
Definition
Capiilaries
Term
How is flow through a system generated?
Definition
From a high pressure to a low pressure
Term
What creates blood pressure?
Definition
The pumping mechanism of the heart
Term
In which blood vessel is the greatest fall in pressure?
Definition
In the arterioles
Term
Why does there need to be a sudden drop in blood pressure?
Definition
So that the capillaries do not burst under a high blood pressure
Term
What is systolic blood pressure?
Definition
The maximum blood pressure of the system at that time
Term
What is diastolic blood pressure?
Definition
The minimum blood pressure of the system at that time
Term
What is the pressure gradient equation?
Definition
PD = P1 - P2
Term
In the pressure gradient equation what does PD stand for?
Definition
Pressure gradient
Term
In the pressure gradient equation what does P1 stand for?
Definition
Pressure at the artey end
Term
In the pressure gradient equation what does P2 stand for?
Definition
Pressure at the venous end
Term
State Darcys law?
Definition
Q = P/R
Term
In Darcy's Law what does Q stand for?
Definition
Flow
Term
In Darcy's Law what does P stand for?
Definition
Pressure gradient
Term
In Darcy's Law what does R stand for?
Definition
Resistance
Term
State Poiseuilles Law?
Definition
Q = (DP X Pi X r4)/8Ln
Term
In Poiseuilles Law what does Q stand for?
Definition
Flow
Term
In Poiseuilles Law what does DP stand for?
Definition
Pressure gradient
Term
In Poiseuilles Law what does r stand for?
Definition
Radius of the blood vessel
Term
In Poiseuilles Law what does L stand for?
Definition
Length of the blood vessel
Term
In Poiseuilles Law what does n (eta) stand for?
Definition
Viscosity of blood
Term
What and why is the most important factor in Poiseuilles Law?
Definition
Radius because it changes the most and is affected by the power of four
Term
What is the blood velocity equation?
Definition
V = Flow/ Cross Sectional Area
Term
In which blood vessel is velocity at its lowest?
Definition
In the capillaries
Term
In which blood vessel is cross sectional area at its highest?
Definition
In the capillaries
Term
Which side of the heart is recieving from pulmonary and delivering to systemic?
Definition
The left
Term
Which side of the heart is recieving from systemic and delivering to pulmonary?
Definition
The right
Term
What is stroke volume?
Definition
The volume of blood pumped by one ventricle
Term
What is the average stroke volume?
Definition
75ml
Term
What is cardiac output?
Definition
The total volume of blood pumped out by the heart in one minute
Term
How do you work out cardiac output?
Definition
CO = HR/ SV per min
Term
What does CO mean in the cardaic output equation?
Definition
Cardiac output
Term
What does HR mean in the cardaic output equation?
Definition
Heart rate
Term
What does SV mean in the cardaic output equation?
Definition
Stroke volume
Term
What is venous return?
Definition
The amount of blood returning to the heart in one minute
Term
Under steady condition Venous return equals what?
Definition
Cardiac output
Term
What are the two types of valves?
Definition
Semi-lunar and atrioventricular
Term
What produces the sounds of the heart?
Definition
The closing of the valves
Term
What causes the first sound produced by the heart?
Definition
The AV valves closing
Term
What causes the second sound produced by the heart?
Definition
The SL valves closing
Term
What does myogenic mean?
Definition
Causes it's own contractions due to pacemakers independant of the brain
Term
What are the two types of mycoytes?
Definition
Conductive and Contractive
Term
Outline the electronic mechanism of a heart contraction?
Definition
1. SAN send a wave of excitation across the atria causing them to contract
2. SAN impulse reaches AVN which causes another wave of excitation to travel down the bundle of HIS to the purkinje branches and finally up the purkinje fibres of the ventricle walls causing them to contract
3. There is a phase of no electronic activity where the heart refils
Term
How does the SAN impulse not spread to the ventricles?
Definition
There is a band of unconductive tissue that seperates the atriums from the ventricles
Term
Outline the action potential mechanism of a pacemaker signal?
Definition
1. -60mV Na+ voltage gated ion channels open
2. -40mV Ca2+ voltage gated ion channels open
3. 18mV Na+ and Ca2+ voltage gated ion channels shut and K+ voltage gated ion channels open
4. -60mV K+ voltage gated ion channels close
Term
Which is the fastest pacemaker?
Definition
The SAN
Term
How does the SAN control the pace of the AVN?
Definition
How fast and frequent the signal is sent by the SAN directly effects how fast and frequent the signal of the AVN is sent
Term
What is trigger calcium?
Definition
The decrease in Ca2+ ions after the plateu of the action potential that causes the voltage to drop due to the Ca2+ ion acting as a releaser of Ca2+ from the sarcoplasmic reticulum
Term
How does a cardiac contraction differ from a skeletal contraction?
Definition
No refractory period in cardiac and no tetany
Term
What is an electrocardiogram?
Definition
A machine that measures the electrical activity of the pacemakers in the heart
Term
What does the P wave show?
Definition
Atrial depolarisation
Term
What does teh QRS complex show?
Definition
Ventrical depolarisation
Term
What does the T wave show?
Definition
Ventrical repolarisation
Term
WHy is atrial repolarisation not shown on an ECG?
Definition
It is masked by the intensity of the QRS complex
Term
Outline the mechanism of the cardiac cycle?
Definition
1. Ventricles fill
2. Atrial contraction
3. Ventrcile contraction
4. Ventricle ejection
5. Ventricle relaxation
Term
What is a phonocardiogram?
Definition
A machine that records the pressure in the different chambers of the heart
Term
What is considered normal blood pressure?
Definition
120mmHg/80mmHg
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