Physiology

Question 1

What is the cardiac cycle of the heart?

Answer 1

A series of alternating contractions and relaxations of the hearts atria and ventricles in order to pump blood throughout the body.

Question 2

Fluid in the body moves from an area of high to low pressure. How does this apply to the heart?

Answer 2

The pressure will increase inside one of the heart chambers and will increase pressure, valves will open and blood will flow to the area of lower pressure.

Question 3

The rate of heart beat is set by the electrical conduction system of the heart. What part of the heart sets this?

a. Pukingje fibres.
b. Bundle branches.
c. SA Node

Answer 3

The SA node of the right atrium sets the rate of your heart beat.

Question 4

Is the systole the contraction or relaxtion of the heart?

Answer 4

Contraction

Relaxtion is the diastole

Question 5

The cardiac cycle has three phases. What are they?

Answer 5

Ventricular Filling.
Ventricular Systole
Isovolumetric relaxtion

Question 6

In phase 1 of the cardiac cycle (Ventricular filling), the ventricles are end of the diastole and will contain the maximum amount of blood. What is this called?

Answer 6

End Diastolic volume

Question 7

An ECG has P, Q, R,S, T Waves. What does the P Wave represent?

Answer 7

The P Wave is when the atria depolarise.

Question 8

In phase 2 of the cardiac cycle, ventricular systole we hear the noise of ‘lub’. What does this represent?

Answer 8

It is when the AV valves close.

Question 9

In Phase 2 of the cardiac cycle, ventricular systole, how is it represented on an ECG?

Answer 9

It is the QRS Wave on an ECG which shows the atria relax and the ventricles depolarise.

Question 10

What is the end systolic volume?

Answer 10

When there is a small amount of blood that remains in ventricles at the end of systole.

Question 11

The second heart sound of the cardiac cycle is a ‘dub’. What phase does this happen and what does it represent?

Answer 11

The dub occurs in Phase 3 - isovolumetric relaxation and represents the closing the Semilunar valves.

Question 12

The T wave on an ECG is what phase of the cardiac cycle?

Answer 12

Phase 3 - isovolumetric relaxation.

This is early diastole where ventricles repolarise, causing them to relax.

Question 13

Sometimes we can hear a 3rd heart sound. When would you hear this?

Answer 13

When blood rapidly empties into ventricles causing turbulent flow of the blood.

Question 14

What is cardiac output and how we do we calculate it?

Answer 14

It is the volume of blood pumped out of each ventricle in 1minute.
Heart rate x Stroke volume = Cardiac Output

Question 15

Venous return and blood pressure are 2 of the 5 factors which influence cardiac output. What are the other three?

Answer 15

Blood volume - amount of blood in CV system.
Heart rate - number of times heart beats in 1min
Stroke volume - amount of blood pushed out of a ventricle each time it contracts.

Question 16

Venous return is the amount of blood returning through the veins to the right atrium of the heart.
Venous return is aided by three functions, what are they?

Answer 16

Respiratory pump - pressure changes in thoracic cavity by breathing.
Valves - preventing backflow.
Muscular pump - skeletal muscles compresses veins and pushes blood back to the heart.

Question 17

What is the amount of blood pumped out of the ventricle with each heart beat?

Answer 17

Stroke Volume

Question 18

Stroke volume is calculated by:

Answer 18

End diastolic volume - end systolic volume = SV

Question 19

Stroke volume is affected by three factors. What are they?

Answer 19

Pre-load - blood volume / venous return.
After-load - vasodilation / constriction
Contractility - hormones / potassium / sodium

Question 20

True or false - Preload is how much the ventricle wall is stretched.

Answer 20

True - and is increased if blood volume and venous return increases.
Therefore will increase stroke volume.

Question 21

Pressure inside the left ventricle must be greater than inside the aorta to ensure the ventricle can eject the blood into the aorta. What is this called?

Answer 21

Afterload.

Question 22

Stroke volume is increased by blood volume and exercise, what are three other factors that influence SV?

Answer 22

Sympathetic stimulation
Vasodilation
Increased EDV - end diastolic volume.

Question 23

What is cardiac output?

Answer 23

The volume of blood pumped out by each ventricle in a minute.

Question 24

How do we calculate cardiac output?

Answer 24

Heart rate x stroke volume = cardiac output.

Question 25

On average, how much blood is pumped into the systemic circuit from the left ventricle every minute?

Answer 25

About 5.25L of blood is pumped from the left ventricle every minute.

Question 26

What two factors affect heart rate?

Answer 26

Para & Sympathetic nervous stimulation.

Question 27

Afterload is the amount of pressure a ventricle needs to overcome. If afterload is increased, what is the effect on stroke volume and cardiac output?

Answer 27

Stroke Volume will decrease. | Cardiac output will also decrease.

Question 28

True or false. | Blood pressure is the pressure exerted by the circulating blood on the blood vessel walls.

Answer 28

True. Refers to systemic arteries at the level of the heart.

Question 29

In order for blood to flow to tissues there has to be a pressure gradient. True or False - blood flow from low pressure to the high pressure outside of the arteries?

Answer 29

False. | Blood flows from an area of high pressure (inside arteries) to the low pressure in the veins.

Question 30

How do you calculate blood pressure?

Answer 30

Cardiac Output x Peripheral resistance = Blood Pressure

Question 31

Will blood pressure increase or decrease if cardiac output is increased?

Answer 31

Blood pressure will increase as the amount of blood pumped out of each ventricle in 1 minute increases.

Question 32

If the resistance inside the blood vessel is increased through blood being viscous. What will this do to blood pressure?

Answer 32

Blood pressure will increase as the peripheral resistance of the vessel increases, therefore, increasing blood pressure.

Question 33

The mean arterial blood pressure (MAP) measures _______ in the arteries over the whole cardiac cycle. a. Rate of contraction b. Pressure c. Volume of blood pumped d. length of artery

Answer 33

The MAP is the average pressure in the arteries over the whole cardiac cycle.

Question 34

Why do we know the mean arterial blood pressure of our arteries?

Answer 34

We calculate the MAP so that we know the tissue perfusion of the blood flow through the tissues - if the MAP is above 60mmHG we will have healthy tissues.

Question 35

What does the systolic blood pressure represent?

Answer 35

Systolic blood pressure is the highest pressure in the arteries created by the contraction of the left ventricle.

Question 36

Does the diastolic pressure represent contraction or relaxtion of the ventricles?

Answer 36

Relaxation of the ventricles.

Question 37

What are considered normal (healthy range) parameters for MAP?

Answer 37

60-100mmHG

Question 38

Is blood pressure lower in the systemic or pulmonary circuit in the body?

Answer 38

BP is lower in the pulmonary circuit -

Question 39

What is the most important force in venous flow of blood through veins?

Answer 39

The pressure gradient that is generated by the heart.

Question 40

Stimulation of the sympathetic nervous system, which will increase stress, will increase BP, what are the two factors that increase BP?

Answer 40

Increased blood viscosity | Increased peripheral resistance

Question 41

Vasodilation is one of four factors which decrease BP, what are the other 3?

Answer 41

Decreased blood volume Decreased heart rate Decreased contractility of the heart.

Question 42

There are two main reasons why it is important for you BP to be within normal ranges, what are they?

Answer 42

Ensures adequate blood supply to the tissues. | Prevents damage to the blood vessels through having an high BP.

Question 43

There are two fast short term corrections that can occur to regulate BP, what are they?

Answer 43

1. Neural mechanisms | 2. Hormonal mechanisms

Question 44

Baroreceptors are found in the wall of blood vessels. What is their role of when BP increases?

Answer 44

When BP increases, it stretches the walls of the blood vessels which stimulate the baroreceptors. This will send a rapid stream of nerve impulses to the brain, altering: Heart rate Contractility Dilation of blood vessels.

Question 45

The kidneys play a role in the long term regulation of BP. This is achieved in two ways, they are:

Answer 45

1. Direct mechanism - variation in blood flow through the kidneys alters rate of urine formation. 2. Indirect mechanism - hormones alter the reabsorption of water in the kidneys.

Question 46

There are five hormones which will be secreted when BP is low to increase it, they are?

Answer 46

``` Aldosteron Antidiuretic hormone Atrial natriuretic peptide Angiotensin 11 Noradrenaline ```

Question 47

What hormone is secreted when BP is high to lower it?

Answer 47

Atrial Natriuretic peptide (ANP)

Question 48

Movement of fluid between the blood and _______ occurs in the capillary bed? a. venules b. veins c. interstitual fluid d. arteriorles

Answer 48

Occurs between the blood and interstitial fluid.

Question 49

The majority of blood is returned to the heart through veins, a small amount is returned to circulation by what ____ vessels. a. venules b. capillary beds c. lympathic d. endocrine

Answer 49

Lymphatic vessels.

Question 50

BP can be measured directly and indirectly. What is the was you would see in the hospital?

Answer 50

Indirect measurement - | Direct measurement is a catheter into the artery with an attached pressure gauge..

Question 51

Korotkoff sounds in BP is first heard when the blood spurts into the constricted artery. Is this the systolic or diastolic reading?

Answer 51

Systolic pressure.