Cardiovascular system Anatomy & Physiology

Question 1

What is the main purpose of the CV system?

Answer 1

Ensures a continuous flow of blood to all cells to supply oxygen and nutrients and to extract tissue waste

Question 2

Where does the heart lay?

Answer 2

Lies obliquely in the thoracic cavity in the mediastinum slight more to the left of the chest.

Question 3

What is the mediastinum?

Answer 3

is the space in the thorax which lies between the lungs.

Question 4

The heart has how many chambers and valves?

Answer 4

4 chambers and 4 valves

Question 5

What are the two types of circulation?

Answer 5

The Systemic Circulation

The Pulmonary Circulation

Question 6

What is The Pericardium?

Answer 6

(Outer layer - protecting the heart)

Question 7

What is The Myocardium?

Answer 7

Inner layer responsible for the heart’s electrical signals
When an impulse is initiated contraction occurs.
Left ventricle thickest as it pumps blood around the body.

Question 8

What is The Endocardium?

Answer 8

Lines the chambers and valves of the Heart, smooth membrane to ensure smooth flow of blood.

Question 9

Briefly talk about the myocardium?

• specialised
• structure

Answer 9

This consists of specialised cells called cardiac myocytes

Large mitochondria, therefore have a high resistance to fatigue

Contracts as a result of an electrical impulse

Question 10

Explain how the myocardium works?

Answer 10

Plasma membranes of adjacent cardiac cells are interlocked by intercalated discs, (tightly bound together, double membrane) which allow ions to pass from one cell to another to allow electrical current to move across the heart.
Plasma membranes of adjacent cardiac cells are interlocked by intercalated discs, (tightly bound together, double membrane) which allow ions to pass from one cell to another to allow electrical current to move across the heart.

The myocardial muscle contracts as a result of an electrical impulse which takes place momentarily before the contraction happens.
This impulse is generated by the exchange of ions (molecule with an electrical charge) including sodium and potassium across cell membranes of the myocytes and an influx of calcium.

So sodium and potassium as well as calcium are very important in the contraction of cardiac myocardial cells.

Question 11

MYOCARDIUM
Automaticity?
Excitability?
Conductivity?
Contractility?

Answer 11

The ability to initiate a response spontaneously.

The ability to respond to a stimulus

The ability to transmit an impulse from one cell to another through the discs.

The ability to contract after an electrical stimulus

Question 12

What is the SA node?

• where is it situated
• what is it a collection of
• depolarise/ repolarise
• how many bpm

Answer 12

situated in the right atrium
Collection of unstable/excitable cells. The instability leads them to discharge an electrical impulse (DEPOLARISE) regularly between 60 to 90 times a minute.
Then followed by recovery (REPOLARISATION). In 0.1 seconds impulse travels to

Question 13

What is the AV node?

• where is it situated
• what does it generate
• how many bpm

Answer 13

2nd pacemaker if SA node fault) - situated at the atrial septum and close to the atrioventricular valves, generates electrical impulses from the atria through to the ventricles. 0.1 seconds 40-60 beats per minute.

Question 14

What is the Atrioventricular bundle also known as?

Answer 14

Bundle of his

Question 15

What is the bundle of his?

Answer 15

mass of fibrous ring separating the atria and ventricles, dividing into the left and right bundle branches.

Question 16

Within the ventricular myocardium the branches break up into fine fibres called the ….?

Answer 16

Purkinje fibres.

Question 17

How does the bundle of his work?

Answer 17

Electrical impulses are transmitted from the AV node to the apex of the myocardium causing ventricular contraction (upwards and outwards) to pump blood into the pulmonary artery and aorta.

Question 18

When looking at an ECG, what does the:

P stand for

QRS?

T?

Answer 18

P - impulses from the SA node. (atrial depolarisation)

QRS - impulses from the AV node, through the bundle and Purkinje fibres. (ventricular depolarisation)

T - relaxation of the ventricle muscle (ventricular repolarisation)

Question 19

What are arteries?

What are arterioles?

What are capillaries?

What do veins do?

Answer 19

Arteries and smaller branches -

arterioles carry blood away from the heart

Capillaries - enormous network of tiny exchange vessels, allowing nutrients, water and oxygen to diffuse into the tissues and cellular waste - carbon dioxide to diffuse into the bloodstream for excretion.

Small venules - Veins - carry blood back to the heart.

Question 20

What are anastomoses and end arteries?

Answer 20

Arteries that form a link between the main arteries supplying an area e.g. palms of the hands and soles of the feet; the brain the joints and the heart muscle.

If an artery supplying the area is blocked, the anastomotic arteries supplies collateral circulation.

Sole source of blood to a tissue - end-artery if blocked then the tissue will die (retina of the eye, branches (circle of willis) in the brain.

Question 21

What does the lymphatic system do?

Answer 21

Which helps to protect against infection and disease - immunity.

Assists movement of fluid back into the bloodstream - lymph maintaining homeostasis.

Transports plasma proteins back into the bloodstream, production and maturation of lymphocytes

Question 22

What are the three types of blood vessel tissue?

Answer 22

Tunica Adventitia (Outer layer; fibrous tissue protects and supports vessels)

Tunica Media- (Middle layer contains variable smooth muscle)

Tunica Intima- (smooth lining layer only one layer thick, much thinner than arteries.)

Question 23

Arteries:

Why are they so large?
Why are the walls thicker than veins?

Capillaries:
What do they link?
Why do they have large lumen?
Is blood flowing fast or slow?

Veins:

What sort of pressure of blood?
Are walls thin or thick, why?
How do they work?

Answer 23

Arteries - the largest (close to the heart) have more elastic tissue in the tunica media and less smooth - allowing more stretch to absorb the wave of pressure as it beats. Arteries branch many times through the body to smaller arteries then into arterioles where the tunica media contains more smooth muscle - enabling more control to regulate the internal pressure. . Arteriole walls are thicker than venous walls to withstand the high blood pressure in the arterial system.

Capillaries - link the smallest arterioles to the venules -single layer of endothelial cells extensive exchange of materials. In the liver and bone marrow, capillaries are wider and leakier than normal.The Capillaries are called sinusoid wall. Their walls are incomplete and larger lumen than usual (blood flows slowly, allowing much faster exchange of substances between blood and tissue) e.g. in the liver which regulates the composition of blood arriving from the Gastrointestinal Tract.

Veins - low pressure of blood, Venous walls are thinner than arterial wall (have three layers of tissue)
When cut vein collapse, whereas the artery remain open.
Veins (capacitance vessels) because they stretch. Therefore have the capacity to hold large proportion of the body’s blood.
In haemorrhage veins constrict preventing fall in blood pressure.
Some Veins possess valves prevents backflow of blood. (Valves are abundant in the lower limbs)

Question 24

What happens during pulmonary and systemic circulations?

Answer 24

The right side of the heart pumps blood to the lungs (pulmonary circulation) where gaseous exchange occurs, oxygen collected by the blood from the air sacs, and excess carbon dioxide diffuses out into the air sacs for exhalation. The oxygenated blood then returns to the left side of the heart where it pumps to the remainder of the body (systemic circulation) - body cells extract oxygen and nutrients and remove waste.

Question 25

How does deoxygenated blood become oxygenated?

What system is it?

Answer 25

Deoxygenated blood
Superior vena cava and inferior vena cava.
Right Atrium
Right AV valve (tricuspid)
Right ventricle
Pulmonary valve
Pulmonary artery
Lungs
Pulmonary veins (oxygenated blood)

PULMONARY

Question 26

Arteries contain what type of blood?

Veins contain what type of blood?

Answer 26

All arteries contain oxygenated blood except the pulmonary artery which contains deoxygenated blood.

All veins contain deoxygenated blood except the pulmonary vein which contains oxygenated blood.

Question 27

What is the flow for systemic circulation?

(LEFT SIDE)

Answer 27

Oxygenated blood
Left Atrium (oxygenated blood)
Left AV valve (Mitral)
Left ventricle
Aortic valve
Aorta (branches off into many other arteries to supply other organs and systems)
Superior and inferior vena (deoxygenated blood)

Question 28

What is a healthy resting BPM ?

Answer 28

60- 90 BPM

Question 29

What are the 3 stages of the cardiac cycle?

Answer 29

atrial systole, ventricular systole, complete cardiac diastole

Question 30

Explain the Cardiac cycle?

Answer 30

Continually filling with blood increasing pressure to open the AV valves into ventricles.

Also by gravity (70% ventricular filling).

The SA node triggers wave of contraction, which slows at the AV node to allow ventricular filling.

The AV node triggers an impulse through the ventricles (via the bundle and Purkinje fibres) resulting in another contraction pumping blood into the pulmonary artery and aorta.

Question 31

What is CO?

Answer 31

SV x HR
Amount of blood ejected from each ventricle every minute.

Question 32

What is SV?

Answer 32

The amount expelled by each contraction is the Stroke volume - which needs to be known to calculate the cardiac output.

Per beat

Question 33

What does stroke volume depend on?

Answer 33

Preload - Blood volume in the heart at the end of diastole (ventricular filling)
Afterload - Resistance the ventricles have to work against.
Contractility - Myocardium strength of contraction

Question 34

What factors can affect HR?

Answer 34

Factors affecting the HR
Autonomic activity
Circulating hormones
Activity and exercise
Gender
Age
Temperature
Emotional states
Baroreceptor reflex

Question 35

How is SV calculated?

Answer 35

Stroke Volume = End Diastolic Volume (EDV) - End Systolic Volume (ESV)

EDV - The amount of blood that is in the Ventricles before they contract
Around - 120mls

ESV - The amount of blood that is in the Ventricles after they have contracted
Around - 50mls

120mls - 50mls = 70mls

Stroke Volume is 70 mls

Question 36

What is blood pressure?

Answer 36

The force / pressure that blood exerts on the walls of blood vessels. Fluctuates with every heartbeat.

Question 37

What is Peripheral resistance?

Answer 37

major factor in BP regulation. Resistance is dependent upon the lumen diameter and is regulated in the smooth muscle of the tunica media. Also length of the tube and viscosity of fluid.

Question 38

What is vasoconstriction?

What is vasodilation?

Answer 38

Vasoconstriction - narrowing of the vessel - increases the BP (increase in sympathetic nerve activity). Peripheral resistance increased.

Vasodilation - enlarged lumen, relaxing of the smooth muscle decreases the BP (decreased sympathetic activity) Peripheral resistance decreased.

Question 39

What are chemoreceptors?

Answer 39

Chemoreceptors - aortic and carotid bodies primarily for respiration - sensitive to rising carbon dioxide and falling oxygen - inputs the CVC increasing sympathetic drive to the heart and blood vessels. Increasing BP and blood flow. (influence output only)

Question 40

What is the short term control of BP?

Answer 40

Baroreceptors - pressure receptors (nerve endings sensitive to stretch) in the aorta and carotid sinuses
Chemoreceptors
Circulating hormones

Question 41

What is the long term control of BP?

Answer 41

Kidneys
Renin - angiotensin - aldosterone system

Question 42

What is a pulse?

What does a pulse do?

Answer 42

Represents the heart rate.
Regularity of the heartbeat (should be equal)

Volume and strength of the beat (compression moderate pressure should stop the flow, giving some indication of BP and vessel wall.
Tension - the artery wall should feel soft and pliant under the fingers.
Average 60-80 bpm.

Question 43

Numbers:

What is
Bradycardia

Tachycardia

Answer 43

< 60 bpm
> 100 bpm

Question 44

What are the affects of ageing on the CV system?

Answer 44

Compliance (stretchability) of the heart fails, increasing the workload.
Declining of cardiovascular function
Cardiac output falls
Conduction pathways less efficient
Cardiac muscle cell numbers decline - hypertrophy (enlargement)
Regulation of blood flow less efficient (vasodilation, vasoconstriction)
Hardening/stiffening of arterial walls, thus increase in BP.
Baroreceptor reflex less brisk, due also neuronal ageing.