Compendium 6

Question 1

Main functions of the cardiovascular system

Answer 1

Transports fluids, wastes, gases, hormones around the body
Exchange of materials between blood, cells and extracellular fluid
Plays role in immune response, blood pressure, regulation body temperature

Question 2

What makes up the cardiovascular system

Answer 2

Heart
Blood vessels
Capillary beds
Blood

Question 3

What are the functions of the heart

Answer 3

Generate blood pressure through contractions
Routes blood through either systemic or pulmonary circulation
Ensures one way blood flow
Regulates blood supply to match body’s needs
“2 pumps in 1”
-right side receives blood coming from body (low O2) and pumps through right side into pulmonary circulation towards lungs
- left side received oxygenated blood from lungs, pumped through left side to systemic circulation around body

Question 4

Where is the heart located

Answer 4

Located in thoracic cavity in mediastinum between lungs

Apex= most inferior part
Base= flat part with major blood vessels
Lies slightly obliquely, with apex towards left

2/3 heart lie on left side of midline, which makes left lung smaller than right

Transverse width heart ~ 132mm, transverse width chest ~224mm

Question 5

Explain the pericardium of the heart

Answer 5

Tough, fibrous outer layer that prevents overstretching and overfilling and anchors heart into mediastinum

Serous: thin, transparent, inner layer made of simple squamous epithelium (smooth to allow good flow)

• parietal: lines outer fibrous layer
• visceral: covers whole heart
• fluid in pericardial cavity

Question 6

Explain the walls of the heart

Answer 6

Surrounds each chamber (2 ventricles, 2 atria)
Consist of 3 tissue layers:
1) epicardium: serous membrane, smooth outer surface
2) myocardium: middle layer composed of cardiac muscle cells for contractibility (thickest layer)
3) endocardium: smooth, inner surface of chambers in contact with blood in heart

Also muscles that increase movement and turbulence of blood flow:
Pectinate: muscular ridges and columns on inside walls of atria
Trabeculae: muscular ridges and columns on side walls on ventricles

Question 7

Explain the atria of the heart

Answer 7

Superior
Thinner than ventricles
Right atrium:
-3 major openings receiving deoxygenated blood from body: superior vena cava (top half body), inferior vena cava (bottom half body) and coronary sinus (blood from heart itself)
Left atrium:
-four openings receiving oxygenated blood: left and right pulmonary veins (2 on either side of the heart)

Question 8

Explain ventricles of the heart

Answer 8

Inferior
Atrioventricular canals= openings between atria and respective ventricles
-contain atrioventricular valves
Wall of left ventricle thicker as does most contractions with high pressure in order to pump blood through whole systemic circulation

RV opens to pulmonary trunk and contains trabeculae corneae muscles on inside to increase turbulence and blood flow

LV opens to aorta, is very muscular wall

Interventricular septum is between the two ventricles

Question 9

Explain greater vessels of the heart

Answer 9

Blood flow:
Superior and inferior vena cava –> right atrium
Right ventricle exits through PULMONARY TRUNK which branches into left and right pulmonary arteries
From lungs goes through left and right PULMONARY VEIN to left atrium
Once in left ventricle exits via AORTA into systemic circulation

Question 10

Explain atrioventricular valves of the heart

Answer 10

Ensure blood flows in one direction and helps generate pressure

Between atrium and ventricles there are valves which have leaf-like cusps attached to papillary muscles by strong fibrous tendons called chordae tendineae – allow 1 way flow as when muscles contract, it pulls on tendons and prevents valves opening into atria and therefore prevents backflow

Left atrioventricular/bicuspid/mitral valve has 2 cusps
Right atrioventricular/tricuspid valve has 3 cusps

Blood flows when valve opens from atrium to ventricles

Question 11

Explain how the cusps of valves work in the heart

Answer 11

Cusps filled = valve closed = no backflow
Ventricle fills up which generates greater pressure so greater blood flow through systemic circulation
Cusps empty = valve open = blood exits heart

Question 12

Explain aortic and semilunar valves of the heart

Answer 12

Pulmonary semilunar valves found at base of pulmonary trunk

Aortic semilunar valve found in aorta

Question 13

Explain arteries

Answer 13

Elastic, muscular 
Arterioles =smallest type
Carry blood AWAY from heart
Contain blood under pressure
Two major arteries leaving heart are pulmonary trunk from right ventricle and aorta from left ventricle

Question 14

Explain capillaries

Answer 14

Site of exchange with tissues
Smallest, most request blood vessel
Form capillary beds

Question 15

Explain veins

Answer 15

Take blood to heart
Thinner walls than arteries, contain less elastic tissue, less smooth muscle
Contain valves to prevent backflow
Venules = smallest type, veins get bigger as they go towards the heart
Two major veins entering heart are superior and inferior vena cava into right atrium and pulmonary veins into left atrium

Question 16

Describe walls of veins and arteries

Answer 16

TUNICA INTIMA: endothelium (touches blood)
TUNICA MEDIA: smooth muscle cells involved in vasoconstriction and vasodilation
TUNICA EXTERNAL/ADVENTITIA: connective tissue, goes from dense and becomes looser when it move further from media layer and towards surrounding vessels so they can merge

Question 17

Explain walls of capillaries

Answer 17

Walls contain simple squamous endothelial cells, basement membrane, delicate connective tissue layer (not all have this)

Question 18

List functions of blood

Answer 18

Transport wastes, gases, nutrients, process molecules, hormones, enzymes
Regulation pH and osmosis (~7.4) 
Maintenance body temp 
Protection against foreign substances
Clot formation

Question 19

Explain composition of blood

Answer 19

Connective tissue
Formed elements: platelets, white blood cells, red blood cells
Plasma: proteins, water, other solutes

Platelets needed for blood clotting and sealing holes in blood vessels

Question 20

Describe red blood cells

Answer 20

No nucleus
Bi-concave shape to increase SA and O2 carrying capacity
Do not live for long

Question 21

Explain pulmonary circulation

Answer 21

Deoxygenated blood enters right atrium and moves to right ventricle then exits ventricle through pulmonary trunk to either left or right pulmonary artery then to left or right lung where gas exchange occurs

Deposit CO2, obtains O2
O2 goes from high conc in lungs to low conc. in blood

Oxygenated blood then flows through left or right pulmonary vein to left atrium

Question 22

Explain systemic circulation

Answer 22

Oxygenated blood enters left atrium and flows through bicuspid valve to left ventricle which contracts and pushes blood out of heart via aorta which branches into ascending aorta, aortic arch and descending aorta

Blood is then delivered to all cells and tissue in body for gas/nutrient/fluid exchange

Blood exits capillary beds and moves towards veins travelling back to heart and re enters right atrium through vena cava

Question 23

List the blood flow through the heart

Answer 23

1) deoxygenated blood enters right atrium via superior or inferior vena cabs
2) flows through tricuspid valve into right ventricle
3) as right ventricle contracts, blood flows through pulmonary semi lunar valve into pulmonary trunk
4) trunk divides into left and right pulmonary arteries to travel to lungs
5) oxygenated blood re enters left and right pulmonary veins and travels to left atrium
6) flows through bicuspid valve to left ventricle
7) left ventricle contracts moving blood through aortic semilunar valve in aorta and then exits to body

Question 24

How does the heart get its own blood supply

Answer 24

Blood would continue from aorta to coronary arteries which travel to heart tissue
Blood is now is coronary circulation
Travels through coronary sinus and cardiac veins then towards right atrium

Question 25

What forces the movement of blood through the circulatory system

Answer 25

Moves from areas of high pressure to areas of low pressure

Question 26

What is the cardiac cycle

Answer 26

Repetitive contraction (systole) and relaxation (diastole) of heart chambers moving blood through the heart and body

Relax=fill up, contract=pump

Question 27

What is cardiac output

Answer 27

The amount of blood leaving the heart each minute

CO= HR x SV

HR= number of beats per minute
SV= amount of blood pushed out of heart with each contraction (usually around 70mls/beat)

Question 28

How do you calculate the % increase of cardiac output after exercise

Answer 28

Increase CO in L/min divide CO at rest in L/min x 100

Question 29

What is pulse

Answer 29

Pressure caused by the ejection of blood from left ventricle which travels along arteries in body to create pulse points

Pulse points- facial, neck, near elbow, wrist, underarm, very top inner thigh, near ankles
Pulse points cause when large arteries are closer to the skin or close to/on top of a bone

Question 30

How can other parts of the body control the cardiovascular system

Answer 30

Nervous system- maintains blood pressure and flow through cardiac centre

Hormonal- adrenaline increase heart rate, vasoconstriction, stroke volume in response to stress or exercise

Question 31

Explain how the heart beats itself

Answer 31

Heart generated own action potential to contract

1) action potential in sinoatrial node
2) spreads across atrium towards atrioventricular node
3) passes through AV node and AV bundle
4) passes fibrous skeleton towards interventricular septum
5) each AV bundle divides into left and right branches so continues to travel down heart and then towards side of heart to reach purkinjie fibres (conducting cells of heart located in wall)
6) now ventricles told to contract

Question 32

Heart diseases

Answer 32

Arrhythmia: heart skips beats, require medical attention

Cardiomyopathy: heart muscle gradually weakens, need to adopt lifestyle changes

Coronary heart disease: coronary arteries become clogged and narrow over time, needs medical attention