Cardiovascular System

Question 1

Describe the conduction system?

Answer 1

1. The SA node generates the electrical impulse and fires it through the atria walls causing them to contract.
2. The AV nose collects the impulse and delays it for 0.1 seconds to allow the atria to stop contracting.
3. Bundle of his splits the impulse into two ready to be distributed to each separate ventricle
4. The bundle branches carry the impulse to the base of each ventricle.
5. The purkyne fibres the distribute the impulse through the ventricle causing them to contract.
6. Once the electrical impulse journey is complete the atria and ventricle relax and the heart re-fills with blood.

Question 2

What is the diastole phase?

Answer 2

This is the relaxation phase where the cardiac muscle fills with blood, firstly the atria then the ventricles

Question 3

What is the systole phase?

Answer 3

This is the contraction phase of the cardiac muscle, firstly the atria then the ventricles

Question 4

What is the cardiac cycle?

Answer 4

This is the process of cardiac muscle contraction and the movement of blood through its chambers.

Question 5

Describe the cardiac cycle?

Answer 5

1. Diastole phase:

• the atria and ventricles relax, they expand drawing blood into the atria
• the pressure in the atria increases opening the AV valves
• blood passively enters the ventricles
• SL valves are closed to prevent blood from leaving the heart

2. Atrial systole phase:

• the atria contracts forcing remaining blood into the ventricles

3. Ventricular systole:

• the ventricles contract increasing the pressure closing the AV valves to prevent back flow into the atria
• SL valves are forced open as blood is ejected from the ventricles into the aorta and pulmonary artery.

Question 6

What are the components of 3-2-1?

Answer 6

3-neutral control:

• chemoreceptors- (located in the blood)- inform the CCC of chemical changes in blood stream such as increased levels of CO2 and lactic acid
• Proprioceptors- (located in muscles,tendons & ligaments)- informs the CCC of motor activity

-baroreceptors- (located in blood vessel walls)-inform the CCC of increased blood pressure

2-intrinsic control

-temperature changes affect the viscosity and thickness of the blood and speed of nerve impulses

• venous return changes will affect the stretch the of the ventricular walls, force of ventricular contraction= stroke volume

1- Hormonal control

• adrenaline and noradrenaline are released from the adrenal gland increasing the force of ventricular contraction (SV) and distribution of electrical activity through out the heart therefore the HR

Question 7

Based on the information provided how does the CCC cause either increase or decrease heart rate?

Answer 7

If an increase in heart rate is required the sympathetic nervous system is actioned, releasing adrenaline/ noradrenaline and sending stimulation to to the SA node via the accelerator

If a decrease in heart rate is required the parasympathetic nervousness system is actioned to inhibit these effects via the vagus nerve, lowering the heart rate.

Question 8

What is the sympathetic nervous system?

Answer 8

Part of the autonomic nervous system responsable for increasing HR, specifically during exercise

Question 9

What is the parasympathetic nervous system?

Answer 9

Part of the autonomic nervous system responsible decreasing HR, specifically during recovery.

Question 10

What is the autonomic nervous system (ANS) responsibility?

Answer 10

ANS is responsible for regulating HR and determines the firing rate of the SA node

Question 11

What is the cardiac control centre (CCC) responsable for?

Answer 11

The CCC receives information from the sensory nerves and sends direction through the motor neurones to change HR

Question 12

What is vascular shunt?

Answer 12

It’s the redistribution of cardiac output through our the body during exercise which causes an increases percentage of blood flow to the working muscles.

Question 13

Where do arterioles lead?

Answer 13

They lead to capillary beds which serve to bring the blood in close contact with organ and muscles cells.

Question 14

What is the blood flow to the capillary beds controlled by?

Answer 14

• the pre-capillary sphincters
• they constrict= limits blood flow to blood
• they dilate= maximises blood flow to capillary bed

Question 15

How do the pre capillary sphincters construct or dilate?

Answer 15

This is done increased/ decreased stimulation from the sympathetic nervous system

Question 16

What is the responsibility of the vasomotor control centre?

Answer 16

It controls the redistribution of blood

Question 17

Describe what happens to vascular shunt during exercise?

Answer 17

Pre capillary sphincters:

• dilate @ the working muscles- this is due to decreased stimulation from the sympathetic nervous system.
• constrict @ the vital organs- this is because of an increased stimulation from the sympathetic nervous system- decreasing HR

-arterioles:

@ working muscles they vaso dilate- because of decreased stimulation front the sympathetic nervous system- increasing

@ vital organs- they vasoconstrict- because of increased stimulation from the sympathetic nervous
system- decreasing cardiac output

Question 18

What is frank sterling’s mechanism?

Answer 18

Increased venous return ( return of blood to the heart) causes an increased stroke volume

Question 19

What is the explanation of frank Sterling mechanism?

Answer 19

-increased venous return= increased amount of deoxygenated blood to the heart

-causing the atrial and ventricular walls to contract

• this increases the force of the ventricular contractions meaning an increased volume of blood is being ejected front the ventricle per beat= stroke volume.

Question 20

Why does frank starling mechanism cause an increase in HR?

Answer 20

Because the SA node impulses increase due to the atrial and ventricular walls stretching which causes an increase in HR

Question 21

What are the mechanics of venous return?

Answer 21

• pocket valves- one way valves which prevent the back flow of blood
• smooth muscle- the layer of smooth muscle in the vein wall which venoconstricts to create venomotor tone which aids the movement of blood
• gravity- blood from the upper body is helped to be returned by gravity
• muscle pump- during exercise skeletal muscle contract compressing the veins located between them, squeezing the blood back to the heart

-respiratory pump- during inspiration and expiration a pressure difference between the thoracic and abdominal cavity is created squeezing blood back to the heart- as exercise increases respiratory rate, respiratory pump is maximised.

Question 22

What is the explanation for the graphs for HR & Cardiac output @ sub -max intensity?

Answer 22

1. An increase takes place because of the production of Adrenaline= anticipatory rise
2. Sudden increase= heart need to beat more to get more oxygen to the working muscles
3. Platue- reached steady state meaning oxygen supply= oxygen demand
4. Sharp/ sudden decrease= heart beats less as muscles aren’t working so they don’t need large amounts of oxygen
5. HR is higher than the rest king rate because active recovery is taking place as oxygen debt is being payed off

Question 23

What is the explanation for cardiac out put/ HR @ maximal intensity?

Answer 23

1,2,4,5= the same as sun max

3= working towards maximal intensity as heart rate won’t increase till exercise is complete

Question 24

What is the explanation for stroke volume at sub maximal intensity?

Answer 24

It’s stops increasing because there’s no more time for the heart to fill up with blood and eject more blood

Question 25

What are slow oxidative muscle fibres?

Answer 25

A type of muscle fibre rich in mitochondria, myoglobin and capillaries which produces a small amount of force over a long time.

Question 26

What are fast glycolytic muscle fibres?

Answer 26

A type of muscle fibre rich in phosphocreatine (energy compound stored in muscle cells and used as fuel) which produces maximal force over a short period of time