The Heart

Question 1

Explain the double circulatory system of the heart.

Answer 1

Pulmonary ventilation is where the right hand side of the heart sends deoxygenated blood from the heart to the lungs, via the pulmonary artery.
Systematic ventilation is where the left hand side of the heart sends oxygenated blood from the heart to the rest of the body, via the aorta.

Question 2

Why is it advantageous for the human body to have a double circulatory system?

Answer 2

Having two seperate pumps allows the left hand side to generate much more pressure to transport oxygenated blood around the body fast enough to maintain a high metabollic rate.

Question 3

Where are the coronary arteries found and what is their function?

Answer 3

They are found on the surface of the heart, and they trabsport oxygenated blood to 5he cardiac muscles that make up the walls of the heart. This allows the cells to have a high rate of aerobic respiration for muscle contraction.

Question 4

Describe the structure and functions of the atria

Answer 4

Thinnly walled upper chambers of each side of the heart.
They recieve blood from the Vena Cava/pulmonary vein and contract to move blood throigh the atrioventricular valves into the ventricles

Question 5

Describe the structure and function of the venticles

Answer 5

They are lower chambers of the heart with very thick muscular walls. The right ventricle pumps deoxygenated blood through the pulmonary artery to the lungs. The left ventricle pumps oxygenated blood through the aorta to the rest of ten body.

Question 6

What is the septum?

Answer 6

A wall of muscle that separates the right and left chambers of the heart.

Question 7

What are the roles of the atrioventricular and semilunar valves?

Answer 7

Atrioventricular valves prevent backflow from the venticles to the atrium
Semilunar valves orevent backflow from the arteries to the ventricles

Question 8

What are the tendinous cords?

Answer 8

They are innelastic connective tissues that are attatched to the AV valves and prevent them from inverting.

Question 9

Why are muscles of the left ventricle much thicker than those of the right ventricle?

Answer 9

So they can contract with more force to generate a higher pressure so it can pump blood furtehr, aroun dthe rest of the body

Question 10

What is the cardiac cycle?

Answer 10

One complete sequence of the contraction and relaxation of cardiac muscles in the heart, which pumps blood around the body

Question 11

How does blood move?

Answer 11

From areas of high pressure to areas of low pressure

Question 12

State the three stages of the cardiac cycle

Answer 12

Diastole, atrial systole, ventricular systole.

Question 13

Describe ethe stages of diastole during the cardiac cycle

Answer 13

Hesrt muscles relax and both atria fill with blood from the vena cava or pulmonary vein
Pressure is higher in the arteries than the ventricles so the semilunar valves are closed to lrevent backflow

Question 14

Describe atrial systole of the cardiac cycle

Answer 14

As blood fills the atria. The atrial muscles contract to decrease the volume and therefore increase the pressure. This forces the AV valves to open, blood moves into the ventricles down a pressure gradient.

Question 15

Describe the ventricular systole of the cardiac cycle

Answer 15

Ventricular muscles contract, the volume decreases and the pressure increases.
AV valves close to prevent backflow as pressure is higher in ventricles than atrium.
Blood is pushed upwards towards arteries at the top of the heart, forcing SL valves to open. Blood foows down pressure gradient into aorta/pulmonary arteries

Question 16

Are cardiac muscles myogenic or neurogenic? Explain why

Answer 16

Myogenic, as the contractions arise from within the cardiac muscles themselves, instead of from impulses semt from the nervous system.

Question 17

Where does the initial stimulation for muscle contractions in the heart start?

Answer 17

In the sinoatrial nodes (SAN) in the right atrium.

Question 18

Explain how the cardiac cycle is controlled

Answer 18

A wave of electrocal impulses are sent from the SAN and spread across both atria, causing them to contract.
The impulse reaches the Atriaventricular nodes and is delayed, allowing the atria to fully empty into the ventricles.
After the delay, the impulse spreads to the bundle of hiss in the ventricles.
The impulse is transmitted to the base of the ventricles where it then passes up the purkyne fibres, causing the ventricles to contract from the base upwards.

Question 19

What is stroke volume and what is it measured in?

Answer 19

Stroke volume is the volume of blood pumped out of the ventricle during each cardiac cyle
Measured in cm3

Question 20

What is cardiac output?

Answer 20

The total volume of blood pumped out of one ventricle in one minute

Question 21

What is the equation for cardiac output?

Answer 21

Stroke volume x heart rate

Question 22

What is the advantage of increasing cardiac output during exercise?

Answer 22

More oxygenated blood is pumped around the body, more oxygen and glucose is transported to cells, faster rate of aerobic respiration, more ATP produced for muscle contractions.

Question 23

What unit is cardiac output measured in?

Answer 23

dm3min-1

Question 24

Why do mammals require a circulatory system?

Answer 24

So cells can recieve oxygen and glucose fast enough to maintain a high metabollic rate

Question 25

What is mass transport?

Answer 25

The movement of substances from one area to another due to the differences in pressure

Question 26

What is the difference between pulmonary and systematic circulation?

Answer 26

Pulmonary circulation is the mass transport of blood around the lungs Systematic circulation is the mass transport of blood around the body

Question 27

Describe mass flow around the kidneys

Answer 27

The renal artery transports oxygenated blood to the kidneys The renal vein transports deoxygenated blood away from the kidneys

Question 28

Describe mass flow around the liver

Answer 28

The hepatic artery carries oxygenated blood to the liver The hepatic vein carries deoxygenated blood away from the liver The hepatic portal vein transports deoxygenated blood from the small intestine to the liver

Question 29

What are blood vessels and name the three main blood vessels in mammals

Answer 29

Blood vessels are tubes with spaces in the centre called a lumen, where blood flows and is transported. Capillaries, veins, arteries

Question 30

What is the function of capillaries?

Answer 30

They branch of from arterioles and create a network of tubes in tissues where materials are exchanged between blood and cells

Question 31

State and explain 5 adaptations of capillaries

Answer 31

- Contain pores, highly permeable - low blood pressure so blood flows slower, allowing more time for the exchange of materials. - walls consist of single endothelial cells, which provide a short diffusion pathway for diffusion lf oxygen - numerous and branched to provide large SA for diffusion. - narrow lumen which pushes red blood cells against walls to decrease diffusion pathway for oxygen

Question 32

What is the function of arteries?

Answer 32

Arteries carry oxigenated blood away from the heart (exept for the oulmonary artery) and branch into smaller vessels called arterioles

Question 33

Describe 4 characteristics of arteries and why they are necessary

Answer 33

No valves, as blood is constantly at high pressure so unlikely to flow backwards Thick muscular walls, controlls volume of blood into tissues by contracting (which constricts arterioles) and relaxing (which causes arterioles to dialate) Thick vessel wall withstands high pressure, stops vessel bursting under high pressure Thick elastic tissue allows vessel to stretch and recoil to maintain high pressure and smooth blood when surges are send from contractions of the heart

Question 34

What is the function of veins?

Answer 34

Carry deoxygenated blood (exept pulmonary vein) towards the heart

Question 35

What is the name for very small veins, and very small arteries?

Answer 35

Small veins are called venules Small arteries are called arterioles

Question 36

Describe 4 characteristics of veins and why they are necessary

Answer 36

Have valves to prevent backflow of blood due to low pressure. Overall thickness of the vessel wall is small, allowing veins to be compressed and flattened which can aid blood flow Thinner muscular walls (than arteries) as they carry blood away from tissues so dont need to contoll volume lf blood into tissue Thinner elastic tissue (than arteries) as pressure is low and there are no syrges of blood from the heart to smoothe

Question 37

Give two examples of prgans that carry blood

Answer 37

Arteries and veins

Question 38

What is a risk factor?

Answer 38

A factor that increases the probability of developing a disease. They are a correlation not necessarily a causation

Question 39

Explain what coronaty heart desease is

Answer 39

Layers of fatty materials (called atheroma) build up in the coronary arteries. This causes them to narrow and restrict blood flow So less oxygen is transported to the cardiac muscle cells of the heart. Further atheroma can cause thrombosis (blood clots), which can lead to heart attacks

Question 40

State 4 unavoidable risk factors for coronary heart disease

Answer 40

Gender (males more likely to develop disease) Advancing age Ethnicity Family history of the disease

Question 41

State and explain 3 risk factors for coronary heart disease that are a result of lifestyle

Answer 41

Smoking- nicotine increases heart rate and acts as a vasoconstrictor, norrowing the lumen of the artery and increasing blood pressure, increasinh risks of thrombosis Diet- High levels of salt or cholesterol in the blood that result from diets high in cholesterol and saturated fats can lead to atheroma High blood pressure (caused by diets, prolonged stress or lack of excersise) damages the arteries endothelium tissue, which can cause atheroma

Question 42

Hat unique properties do carduac muscles have?

Answer 42

They are myogenic- so contractions can be stimulated from within the muscles rather than from the brain Contain large amounts of mitochondria for ATP production, for a higher rate of aerobic respiration

Question 43

What are the units for cardiac output?

Answer 43

litres min-1 / dm3 min-1