PE anatomy and physiology - cardiovascular system

Cardiovascular system

Describe the process of where blood flows in the heart?

1. Blood enters the heart via the vena cava

2. into the right atrium to the right ventricle via the tricuspid valve

3. out of the semi lunar valve

4. into the pulmonary artery

5. to the lungs

6. into the pulmonary vein

7. into the left atrium

8. into the left ventricle via the bicuspid valve

9. out to the aorta via the semi lunar valve

10. to the body and then to the vena cava again

What does myogenic mean?

generates its own electrical impulse which spreads through the heart muscle causing it to contract.

What is Starling’s law?

1. increased in venous return

2. means that a greater volume of blood enters the heart between contractions

3. which causes the cardiac muscles to stretch

4. which generates a greater force of contraction

5. so it increases ejection fraction/stroke volume

What are the venous return mechanisms?

Smooth muscle in veins

gravity

muscle pump

respiratory pump

pocket valves

suction of the heart

Where is the SA node located?

(top of right) right atrium

Where does the impulse of the heart’s conduction system begin?

SA node

What is the order of the heart’s conduction system?

SA node —> AV node —> bundle of his —> purjinke fibres

What is the function of the SA node?

→ where the cardiac impulse

→ pacemaker of the heart

→ sends the impulse around the atria walls to make them contract

What is the pacemaker of the heart?

SA node

→ small mass of cardiac muscle fibres that generate the pace of the heart

What is the AV node?

Receives the cardiac impulse from the SA node and delays the impulse by 0.1 seconds so the atria can finish contracting and allows the ventricles to fill with blood

→ delays and transfers the cardiac impulse from the upper chambers to the lower chambers of the heart

What is the bundle of His?

Located at the septum of the heart and spreads the impulse down into the ventricles

What is the Purjinke fibres?

located around the the walls of the ventricle and spread the impulse through the ventricles, causing them to contract

How does Muscle pump help with venous return mechanism?

Muscles contract and relax which changes the shape, thus pushes on nearby veins causing them to squeeze and send blood back to the heart

How does respiratory pump help as a venous return mechanism?

Change in pressure compress nearby veins and assist blood returning to the heart

How does suction of the heart help as a venous return mechanism?

As blood approaches the contracting heart, the heart acts as a vacuum and sucks blood back in

What type of exercise does the cardiovascular drift occur?

Sub-maximal

In warm conditions, how many minutes into activity does the cardiovascular drift occur?

10 mins

Where is blood redistributed in order to cool the body?

Skin

Fluid is lost as sweat which makes the blood more…

Viscous

What effect does losing fluid have on venous return stroke volume?

Decreases SV