Circulatory System

Question 1

Describe the conduction system of the heart?

Answer 1

1. Diastole, Cardiac Muscle Relaxes, Blood enters the atria via the vena cava and pulmonary vein. NO IMPULSE.
2. Atrial Systole, Atria muscle contracts as blood is forced from the atria to ventricles. SA NODE TO AV.
   Ventricular Systole, Ventricles contract, forcing blood from the ventricles through the aorta and pulmonary artery. BUNDLE OF HIS TO PURKINJE FIBRES.

Question 2

Where does the CCC get its information from?

Answer 2

The medulla oblongata in the brain.

Question 3

What are the neural control mechanisms?

Answer 3

Chemoreceptors- in muscles, aorta and carotid arteries to inform of Chemical changes in blood- la, C02.
Proprioceptors- muscles, tendons, ligaments, detect changes in motor activity.
Baroreceptors- located in blood vessel walls to inform CCC of an increase in blood pressure.

Question 4

What are the intrinsic control mechanisms?

Answer 4

1. TEMPERATURE CHANGES will lead to a decrease in blood viscosity and an increased speed of nerve impulse transition.
2. VENOUS RETURN CHANGES will lead to an increase in stretch in the ventricular walls, force of ventricular contraction and stroke volume.

Question 5

What are the hormonal control mechanisms?

Answer 5

ADRENELINE AND NORADRENALINE are released from the adrenal glands increasing ventricular contractions force, and therefore stroke volume.

Question 6

What is the Frank Starling Mechanism (Starling’s Law) ?

Answer 6

Shows us how stroke volume is dependant on venous return. A greater volume of blood returning to the heart leads to a GREATER STRETCH of the ventricular walls and therefore stroke volume per beat.

Question 7

How do you calculate cardiac output (Q)?

Answer 7

Q = SV * HR

Question 8

Average values for untrained performer?

Answer 8

HR- 72 BPM SV- 70ML/ BEAT Q- 5L/MIN

Question 9

Average values for trained performer?

Answer 9

HR- 50BPM SV-100ML/ BEAT Q- 20-30L/MIN

Question 10

Define Venous Return?

Answer 10

The volume of blood returned to the heart via the right atrium, largely against the force of gravity.

Question 11

What are venous control mechanisms and expand on their function?

Answer 11

1. Pocket valves. 3. Gravity 5. Skeletal Muscle
2. Smooth muscle. 4. Respiratory Pump
   If insufficient force= blood pooling= need for ACTIVE COOL DOWN.

Question 12

Define Vascular Shunt Mechanism? What is it controlled by?

Answer 12

The redistribution of Q during exercise.
The VCC- it stimulates the sympathetic nervous system to either vasodilate or vasoconstrict the pre-capillary sphincters.

Question 13

What are the control mechanisms of the VCC?

Answer 13

Baroreceptors- in muscles, aorta and arteries. Inform VCC of changes in systolic blood pressure.
Chemoreceptors- in muscles, aorta and arteries. Inform VCC of increase in la and C02 and a decrease in pH.