Transport in Man

Question 1

What are the four main components of blood?

Answer 1

Plasma, red blood cell (erythrocytes), white blood cell (leucocytes), platelets (thrombocyte)

Question 2

What is plasma and state the dissolved substances

Answer 2

Approximately 55% blood’s volume
90% water, 10% dissolved substances

Substances include—
Mineral ions: sodium, potassium, calcium, magnesium, chloride, bicarbonate ions
Soluble food substances: glucose, amino acids
Metabolic waste products: CO2, urea, uric acid, creatinine
Plasma proteins: fibrinogen, prothrombin, antibodies, albumin
Hormones

Question 3

Function of red blood cells (erythrocytes)

Answer 3

Transport oxygen fro the lungs to the organs of the body

Question 4

Structural features of red blood cells

Answer 4

Haemoglobin present: binds reversible with oxygen to form oxyhaemoglobin, transports O2 around the body

Absence of nucleus: more space available for more haemoglobin to be stored and more oxygen to be transported

Biconcave shape: increases SA:V ratio, allowing quick diffusion of oxygen in and out of the cell

Elastic and flexible membrane: allows cells to change its shape while squeezing through small capillaries

Question 5

What is the effect of carbon monoxide on haemoglobin?

Answer 5

Carbon monoxide binds tightly with haemoglobin to form carboxyhaemoglobin
Less haemoglobin is available to bind with oxygen, so less O2 transported in the body

Question 6

What is sickle cell anaemia and what are its symptoms?

Answer 6

Genetic disease: the gene for haemoglobin contains a mutation, producing mutant haemoglobin with a sickle shape

Symptoms include:
Cells getting stuck in blood cells, blocking them
Prevents delivery of oxygens and nutrients to cells and removal of carbon dioxide and waste from cells
May cause organ swelling or severe pain during blood vessel clogging

Question 7

What is red blood cell production regulated by and what is it released by in response to?

Answer 7

Red blood cell production is regulated by the hormone erythropoietin, which kidneys released in response to a decrease in oxygen

Question 8

What is acclimatisation?

Answer 8

In mountainous areas, lower partial pressures of oxygen result in an initial drop of fitness levels
Body responds by producing more red blood cells, thus more haemoglobin is available for the transport of oxygen around the body

Question 9

Traits of leucocytes (white blood cells)

Answer 9

Colourless due to lack of haemoglobin
Irregularly shaped cells with the presence of a nucleus (phagocytes)
Mobile and able to change shape to squeeze through the gaps in capillary walls
Phagocytes are irregular, lymphocytes have a round nucleus

Question 10

What is phagocytosis and what cells are involved?

Answer 10

Phagocytosis is the process where phagocytes engulf and digest bacteria
After phagocytosis (endocytosis), these cells die and form pus

Phagocytosis by phagocytes (white blood cell, type of leucocytes)

Question 11

What do lymphocytes do?

Answer 11

They produce antibodies and have a round nucleus, with a small amount of granular cytoplasm

Question 12

What do antibodies produced by lymphocytes (leucocytes) do?

Answer 12

Antibodies can neutralise toxins produced by bacteria
Antibodies can bind to the surface of bacteria, causing them to rupture
Antibodies can bind to the surface of bacteria, tagging them, allowing phagocytes to recognise them and carry out phagocytosis
Antibodies can cause bacteria to clump together, so that they can be easily ingested by phagocytes

Question 13

What is transplantation?

Answer 13

The replacement of diseased tissue or organs by healthy donor ones

Question 14

What is tissue rejection?

Answer 14

Tissue rejection is when the recipient’s immune system may recognise the transplant organ/tissue as foreign bodies
Lymphocytes may respond by producing antibodies to destroy the transplanted organ

Question 15

How to prevent tissue rejection during transplantation?

Answer 15

1. Tissue/donor matching: ensuring donor tissue is from a donor genetically close to the recipient (close relatives)
2. Using immunosuppressant drugs to inhibit the recipient’s immune system, reducing the chance of tissue rejection but increasing susceptibility to infection

Question 16

Platelets and function and formation of blood clots (thrombocytes)

Answer 16

Not true cells, but fragments of larger bone marrow cells called megakaryocytes

When an injury first occurs, platelets gather and release substances that attract other platelets. The platelets become sticky and form a temporary platelet plug.

Blood clots defend the body by:

1. Preventing the excessive loss of blood from a cut
2. Preventing entry of bacteria into a cut

Question 17

Describe the process of blood clotting

Answer 17

Damaged tissues and platelets will release the enzyme thrombokinase. Together with calcium ions in blood plasma, the thrombokinase will convert inactive prothrombin (in plasma) to active thrombin.
Thrombin will convert soluble fibrinogen to form insoluble fibrin threads, forming a blood clot consisting of a network of fibrin threads that trap blood cells

Question 18

What are the antigens on rbc and antibodies in plasma for each blood type?

Answer 18

A: A-antigen and antibody B
B: B-antigen and antibody A
AB: A-antigen, B-antigen and no antibodies
O: no antigens and A antibody, B antibody

Question 19

What is agglutination and when does it occur?

Answer 19

Agglutination is the clumping of red blood cells

When antigen A/B binds with antibody A/B (respectively), fatal

Question 20

What do the walls of arteries and veins consist of?

Answer 20

Three layers—

Innermost:
Endothelium, minimises resistance to fluid flow

Middle: smooth muscle tissue and elastic fibres
Smooth muscle in the arteries and veins allow vasoconstriction adn vasodialation

Outer: connective tissue like collagen fibres

Question 21

What are arteries and their structure and function?

Answer 21

Blood vessels that carry blood AWAY from the heart, oxygenated except for pulmonary

Thick muscular walls: allow the diameter of the blood vessels to be adjusted, control the blood pressure inside the vessel and regulate blood flow

Numerous elastic fibres: elasticity for blood vessel to stretch and recoil, accommodate blood pressure increases and prevent bursting

Question 22

Size of arteries/veins walls relative to lumen size

Answer 22

The walls of arteries are thicker, walls of veins are thinner, deoxygenated apart from pulmonary
Relative to the lumen size

Question 23

What are veins and their structure and function?

Answer 23

Blood vessels that carry blood towards the heart

Thinner, less muscular and less elastic walls: blood pressure in veins is lower, less muscular tissue needed to support the vessel

Semilunar valves present: prevent blood back flow and allow one directional flow

Veins located between largest muscles of the body: contraction of body muscles (eg leg) help push blood back to the heart, against gravity

Question 24

What are varicose veins?

Answer 24

They occur when semilunar valves cannot function properly, so blood flows backwards and veins bulge and enlarge

Question 25

Do arteries and veins have valves?

Answer 25

All arteries do not have valves apart from aortic valve and pulmonary valve All veins have semi-lunar valves present

Question 26

Differences in arteries and veins (blood pressure, flow of blood)

Answer 26

Artery blood pressure higher Vein blood pressure lower Artery blood flow rapid Vein blood flow sluggish, tendency for back flow

Question 27

Pathway of blood from arteries to veins

Answer 27

Arteries to arterioles to capillaries to venules to veins

Question 28

Structure and function of capillaries

Answer 28

Capillary walls are one cell thick: shorter distance and quicker diffusion of substances between blood and body cells Small gaps between the endothelial cells: causes tissue fluid to leak from the plasma, gaps allow leucocytes to squeeze through but not large molecules Large network of capillaries: large total SA for diffusion, lower blood pressure for more time to diffuse

Question 29

What is tissue fluid and its function?

Answer 29

It is a fluid that bathes the cells of most tissues Tissue fluid functions to provide a medium for diffusion to allow for the exchange of materials between the capillaries and body cells

Question 30

What pushes plasma out of blood?

Answer 30

Hydrostatic pressure: blood pressure against the capillary wall

Question 31

Movement of substances in tissue fluid

Answer 31

Useful (oxygen and glucose and food substances): diffuse from the blood into tissue fluid into body cells Waste (carbon dioxide and urea): diffuse from the cells into tissue fluid into blood

Question 32

What is the main tissue present in the heart?

Answer 32

Cardiac muscle tissue

Question 33

What does the cardiac cycle refer to?

Answer 33

The events that occur during a single heartbeat: The atria are collection chambers that fill up with blood Blood is forced from the atria to the ventricles and out of the heart The systole phase, contraction of walls of chambers of the heart The diastole phase, relaxation of the walls of the chambers of the heart

Question 34

Pathway of blood flow through the heart on the right

Answer 34

Deoxygenated blood from the rest of the body enters (relaxed) right atrium via (superior and inferior) vena cava Wall of right atrium contracts (atrial systole), BP in right atrium higher than right ventricle Tricuspid valve opens Blood forced from right atrium to right ventricle “Lub” sound: backflow of blood from ventricle to atrium prevented by closing tricuspid valve Wall of right ventricle contracts (ventricular systole), BP in right ventricle higher than pulmonary artery Semi-lunar valve in pulmonary artery opens, blood forced into artery to lungs Right ventricle walls relax (ventricular diastole) “Dub” sound: backflow of blood from pulmonary artery into right ventricle prevented by closing semi-lunar valve

Question 35

Pathway of blood through the heart on the left

Answer 35

Oxygenated blood from the lungs is transported into (relaxed) left atrium via pulmonary vein Walls of left atrium contract (atrial systole), BP in left atrium higher than left ventricle Bicuspid valve opened Blood forced into left ventricle “Lub” sound: backflow of blood from left ventricle to left atrium prevented by closing bicuspid valve Walls of left ventricle contract (ventricular systole), BP in left ventricle higher than in aorta Semi-lunar valve in the aorta opens, blood forced into aorta to rest of the body Left ventricle walls relax (ventricular diastole) “Dub” sound: semi-lunar valve in the aorta closed to prevent backflow of blood from aorta to left ventricle

Question 36

What are the function of coronary arteries?

Answer 36

They supply oxygenated blood and glucose to the heart muscle, since heart muscles require a constant supply of glucose and oxygen, the raw materials of respiration Heart muscles have a high energy demand, due to the muscular contractions of the heart beating

Question 37

What is coronary heart disease and what are its causes?

Answer 37

Coronary heart disease is when the blood supply and oxygen to the heart is reduced or cut off due to occlusion of the coronary arteries (atherosclerosis) The narrowing of the lumen of the coronary arteries due to fatty deposits increases the blood pressure in the coronary arteries and reduce the amount of blood flow to the heart muscles

Question 38

How can blood supply to the heart muscle is completely cut off, and what does it cause?

Answer 38

Due to a blood clot (thrombosis), a heart attack occurs

Question 39

Causes of coronary heart disease and corresponding preventative measures

Answer 39

Diet high in trans fat and saturated fat (diet low in aforementioned substances, high in polyunsaturated fat) High stress lifestyle (proper stress management) Lack of exercise / sedentary lifestyle (regular physical exercise strengthens heart and maintains elasticity of arterial walls Smoking cigarettes, CO increases chance of thrombosis (don’t)

Question 40

What are angioplasty treatments for coronary heart disease?

Answer 40

Minimally invasive and less effective, restore blood flow Balloon: catheter with angioplasty balloon inserted into artery with fatty deposit Stent: collapsed mesh tube threaded along ballon and inserted into artery with fatty deposit

Question 41

What is coronary bypass

Answer 41

Surgical replacement of damaged or blocked coronary arteries taken from another part of the body

Question 42

Advantages and disadvantages of double circulation

Answer 42

Advantages: Blood entering lungs at lower pressure, blood has sufficient time to be oxygenated Blood pumped into the systemic circulation at high pressure, allowing oxygenated blood to quickly reach tissues Disadvantages: In amphibians, turtles, snakes, lizards, incomplete septum does not separate ventricle into left and right, slight mixing of oxygen erased and deoxygenated blood

Question 43

What is a septum?

Answer 43

A muscular wall that separates the left and right side of the heart, preventing mixing of oxygenated and deoxygenated

Question 44

What are chordae tendineae

Answer 44

Fibrous connective tissue that holds the atrioventricular valves in the correct orientation (bicuspid in left and tricuspid in right)

Question 45

State the relationship between velocity of blood flow and total surface area exposed by blood vessel

Answer 45

The velocity of blood flow is inversely proportional to the total surface area exposed by the blood vessel

Question 45

What is blood pressure?

Answer 45

The force exerted by the blood against the walls of the blood vessel

Question 46

Why does blood pressure increase the closer the blood is to the heart?

Answer 46

The contraction of muscular walls of the heart generates blood pressure