B1 The cardiovascular system

Question 1

What is the cardiovascular system and what is it’s function?

Answer 1

It consists of the heart, blood vessels and blood. The function is to transport important substances around the body eg oxygen, glucose.

Question 2

The heart is part of a double circulatory system meaning?

Answer 2

Blood passes through the heart twice per cycle.

Question 3

What is pulmonary circulation?

Answer 3

The blood passes through the heart and is pumped to the lungs returning back to the heart.

Question 4

What is systematic circulation?

Answer 4

The blood then passes through the heart a second time (blood is repressurised) and pumped around the body organs before returning to the heart.

Question 5

What is mass flow? Give an example.

Answer 5

Blood moves around the body due to pressure difference between the pressure in the heart (high) and the pressure in the blood vessels (low).

Question 6

Heart structure

Answer 6

The heart is a pump made of cardiac muscle (myogenic) - will beat/contract without any nervous stimulation. Muscle cells- are able to depolarise/generate own electrical pulses.
The heart has 4 chambers: seperated by muscular wall called septum, each side consists of upper chamber (atrium) and lower chamber (ventricle).

Question 7

Describe the route that blood flows through the heart and around the body.

Answer 7

1) deoxygenated blood returns from the body in the vena cava and enters the right atrium.
2) the blood then passes via atrioventricular valve (tricuspid) into the right ventricle and out, via semilunar valve, into the pulmonary artery.
3) The blood now passes through the lungs and returns to the left atrium via the pulmonary vein.
4) the blood passes through a second AV valve (bicuspid) into left ventricle and then through semi lunar valve into the aorta and then body tissues.

Question 8

Suggest the purpose of the valves in the heart

Answer 8

To prevent back flow of blood/ ensures that blood flows in one direction/ smooth flow of blood and maintains high blood pressure.

Question 9

Role of the atrioventricular valves

Answer 9

• Left AV valve prevents back flow to left atria/ ensures blood pumped to aorta/ body.
• Right AV valve prevents back flow from right ventricle to right atria/ ensures blood is pumped to the lungs.

Question 10

Role of semi-lunar valves

Answer 10

These are at the base of the arteries leaving the heart, they prevent blood from returning to the ventricle during diastole (heart at rest).

Question 11

Characteristics of arteries (blood vessel)

Answer 11

• Transports blood from heart to organs (blood under high pressure).
• Thick walls made of fibrous proteins to resist damage due to high pressure of the blood, many muscle tissue (strengthening) and elastin fibres to withstand the high pressure generated by left ventricle during contraction.
• endothelium- reduced friction and gives a smooth flow
• narrow lumen- maintains pressure

Question 12

Characteristics of capillaries

Answer 12

• wall has endothelial layer, one cell thick
• it’s involved in exchange of materials between blood and the tissue sells (site of diffusion)
• diameter very small + large number of capillaries- this creates greater friction and high surface area, reducing blood pressure and blood flow
  -very thin walls- increased rate of diffusion
• wall spaces- gaps between cells of the endothelial cells which allow rapid formation of tissue fluid and WBC to pass tissue spaces.

Question 13

Characteristics of veins

Answer 13

• veins carry blood back to the heart from the tissue. (Blood is under low pressure) the vein wall doesn’t need to be thick.
• large lumens- to give low resistance
• thinner muscle layer- no need for vaso constriction as all blood going back to heart
• thinner elastic layer- as pressure is very low and wall does not need to stretch/ recoil
• semilunar valves- the residual blood pressure is very low, blood is moved along the vein when skeletal muscles contract.

Question 14

Pressure changes in the arteries

Answer 14

Flow is fast and pressure is high and flunctuating due to the contraction of the left ventricle.

Question 15

Pressure changes in the capillaries

Answer 15

Increased cross-sectional area causes increased friction which reduces blood pressure and flow changes from pulsar to smooth and speed of flow decreases.

Question 16

Pressure in the veins

Answer 16

Pressure is low and flow is smooth and non-pulsar.

Question 17

The chart shows the change in speed of flow and pressure of blood from the start of the aorta into the capillaries. Describe and explain the changes in the speed of flow of the blood in shown in the chart. (3 marks)

Answer 17

It shows a slow decrease in speed until it reaches the arterioles then a rapid decrease as there is an increase in cross sectional area of blood vessels leading to more friction in smaller blood vessels.

Question 18

Explain how the structures of the walls and arteries and arterioles are related to their functions. (6 marks)

Answer 18

The arteries have many muscle and elastin fibres to withstand high pressure generated by the left ventricle during contraction and recoiling. The muscle also reduces diameter of lumen. It has a smooth epithelium layer which reduces friction and has less resistance.

Question 19

Pressure changes in a graph

Answer 19

A- closed (Av): pressure in ventricle rises above that in atria

B- open (SL): pressure in ventricle rises above that in aorta

C- closed (SL): pressure in ventricle falls below that in aorta

D- open (AV): pressure in atrium rises above that in ventricles

Question 20

What is blood composed of?

Answer 20

-Redblood cells
- white blood cells
- platelets: cell fragments that aid in clotting

Question 21

What are the risks of blood transfusion (donating blood) ?

Answer 21

• Transfusing the wrong blood group
• infection
• reaction to the blood product

Question 22

When a unit of blood has been donated, before it has been transfused what does it undergo?

Answer 22

• testing of blood for risk of infection
• testing for blood grouping
• taken to processing facility where wbc are removed and get split into rbc, platelets and plasma.

Question 23

What causes the different blood group types (A,B,AB,O)?

Answer 23

Variations in the antigens on RBC membranes.

Question 24

What are antigens?

Answer 24

They are proteins which are produced by the immune system that bind to antigens.

Question 25

What is agglutination?

Answer 25

When an antibody binds to the antigens on red blood cells, it causes them to clump together. This only happens when the blood cells are not compatible with the body system I.e wring blood group do they’re rejected.

Question 26

Rhesus system

Answer 26

85% human pop have the rhesus antigen on their RBC surface and are rhesus positive (Rh+). Ppl who lack this antigen are Rh-

Question 27

A patient has blood group A, what are the antibodies and antigens?

Answer 27

• antibodies: anti B
• antigen: A

Question 28

A patient has blood group AB- what are the antibodies and antigens?

Answer 28

-Antibodies: neither
- Antigens: AB

Question 29

A patient has blood group O+ what are the antibodies and antigens?

Answer 29

• antibodies: anti A, anti B
• antigen: Rh

Question 30

Universal donor

Answer 30

A person of blood group O can donate blood to anyone w blood groups ABO.

Question 31

Universal recipient

Answer 31

A person of blood group AB can receive a blood transfusion or organ transplant from any blood type. This the rarest blood type.

Question 32

How does the heart control and coordinate the regular contraction of the atria and ventricles? Describe how?

Answer 32

• wave of depolarisation from sinoatrial node (SAN) spreads over both atria causing the atria to both contract (atrial systole).
• Layer of connective tissue stops wave of depolarisation
  passing down through walls of ventricles.
• 0.1 second delay at atrioventricular node (AVN) = allows atria to finish contracting (systole).
• electrical impulse passes down septum through bundle of his to the apex (bottom) of the ventricles.
• wave of depolarisation spreads up through the ventricle walls (purkinje fibres) = ventricular systole.

Question 33

How to calculate cardiac output?

Answer 33

Cardiac output (cm3) = stroke vol (cm3) x heart rate (dm3 min-1)

Question 34

What is cardiovascular disease?

Answer 34

Cardiovascular disease is a group of diseases which can affect the heart or blood vessels. It can damage arteries in organs such as the heart, brain, kidneys and eyes.

Question 35

What does cardiovascular disease include and how can it affect your body?

Answer 35

Cardiovascular disease includes heart or blood vessel issues, including things such as narrowing of the blood vessels in your heart, other organs or throughout your body. Heart and blood vessel problems present at birth, heart valves that aren’t working right, irregular heart rhythms. A person can either physically experience the disease (symptomatic) or not feel anything at all (asymptomatic).

Question 36

Risk factors/causes of cardiovascular disease.

Answer 36

• Genetics- A family history of CVD can increase chances of suffering
  CVD.
• Smoking- increases risk of cardiovascular disease as nicotine can
  affect heart rate, platelet, red blood cell and plasma cholesterol levels.
• Age- as you get older the risk of CVD increases.
• High blood pressure- pressure of the blood in your arteries and other
  blood vessels too high, if pressure is not controlled then it can affect
  your heart or other organs including kidneys and brain.
• High blood cholesterol- extra cholesterol can build up in the walls of the
  arteries which leads to the narrowing of the arteries and can decrease
  blood flow to the heart, brain, kidneys and other parts of the body.
• Diabetes- causes sugar to build up in the blood and your body will not
  make enough insulin.
• Family history of heart disease
• Being overweight or obese/ diet- can lead to high blood pressure and
  diabetes as well as heart disease. Consuming high levels of saturated f
  at, salt, limited intake of healthy fats and vitamins can increase risk of
  CVD.

Question 37

What is atherosclerosis?

Answer 37

Atherosclerosis causes coronary artery disease and peripheral artery disease. Atherosclerosis is a condition that develops when a substance called plaque builds up in the walls of the arteries. This build-up narrows the arteries, making it harder for blood to flow through. If a blood clot forms, it can block the blood flow. This can cause such things as a heart attack or stroke.

Question 38

Treatments for cardiovascular disease

Answer 38

-Statins eg. Atorvastatin, simvastatin. Statins work by blocking the formation of cholesterol and increasing the number of low-density lipoprotein receptors in the liver. This helps remove LDL cholesterol from your blood. Not all statins are suitable for everyone so several different types will be needed to test.
-Beta blockers eg. Atenolol, bisoprolol, metoprolol They work by blocking the effects of a particular hormone in the body which slows down your heartbeat and improves blood flow as well as lowering blood pressure. Can cause side effects such as tiredness, cold hands and feet, slow heartbeat. Can also cause sleep disturbances.
-Calcium channel blockers. These work to decrease blood pressure by relaxing the muscles that make up the walls of your arteries. Not suitable with history of heart disease, liver disease or circulation problems. Side effects include headaches and facial flushing.
-Heart transplant. When the heart is severely damaged and medicine is not effective or when there is heart failure it will be the final option to ensure survival of the patient. Rejection of the donor heart which can be immediately after surgery or years later. Failure to pump

Question 39

Effect of caffeine on heart rate

Answer 39

• Caffeine makes your heart beat faster by increasing the electrical activity of the sino-atrial node.
• It affects the ventricles leading to increase in the rate of contraction and relaxation of each heartbeat.
• A larger volume of blood can be pumped out every time the heart beats.

Question 40

What is the P wave

Answer 40

The first part of the trace shows the depolarisation of the atria when they begin to contract and therefore represents atrial systole.

Question 41

what is the QRS wave?

Answer 41

Shows the spread of depolarisation through the ventricles when they begin to contract and therefore represents ventricular systole.

Question 42

T wave

Answer 42

Represents relaxation and repolarisation of the ventricle muscle during ventricular diastole.