chapter 9 - transport in animals

Question 1

*describe what the circulatory system is

Answer 1

a system of blood vessels with a pump and valves to ensure one-way flow of blood.

Question 2

*describe the single circulation of a fish

Answer 2

• the blood goes through the heart once for each complete circuit.
• it is the simplest circulatory system of all vertebrates.
• the heart consists of 1 atrium and 1 ventricle.
• the ventricle sends blood to the gills, where it is oxygenated, the blood then flows to all parts of the body, and then returns back to the heart.

Question 3

*describe the double circulation of a mammal

Answer 3

• the blood passes through the heart twice during one complete circuit.

Question 4

what is the name given to the 2 circulations in double circulation?

Answer 4

• through the lungs: pulmonary circulation

- through the body: systemic circulation

Question 5

*what are the advantages of double circulation? explain

Answer 5

• blood travelling through the small capillaries in the lungs loses a lot of its pressure.
• blood cannot travel as fast.
• by returning the blood to the heart after going through the lungs its pressure can be raised again before sending it to the body.

Question 6

*What blood vessels carry blood away from the heart?

Answer 6

arteries

Question 7

*what blood vessels carry blood towards the heart?

Answer 7

veins

Question 8

*what name is given to the valves that separate the atrium from the ventricle?

Answer 8

atrioventricular valves

Question 9

*what name is given to the valves in the pulmonary artery and aorta?

Answer 9

semi-lunar valves

Question 10

*what name is given to the valve that separates the left atrium from the left ventricle?

Answer 10

bicuspid valve

OR mitral valve

Question 11

*what name is given to the valve in the pulmonary? artery

Answer 11

pulmonary valve

Question 12

*what name is given to the valve in the aorta?

Answer 12

aortic valve

Question 13

*explain the relative thickness of the muscle wall of the left and right ventricles

Answer 13

the left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body, whereas the right ventricle is pumping blood at lower pressure to only one organ (the lungs).

Question 14

*explain the relative thickness of the muscle wall of the atria compared to that of the ventricles

Answer 14

the ventricles have thicker muscle walls than the atria as they are pumping blood out of the heart and so need to generate a higher pressure.

Question 15

*explain the function of the septum

Answer 15

the septum is a wall of muscle that separates the 2 sides of the heart and so prevents mixing of oxygenated and deoxygenated blood.

Question 16

what side of the heart receives oxygenated blood?

Answer 16

left

from the lungs and pumps it to the body

Question 17

what side of the heart receives deoxygenated blood?

Answer 17

right

from the body and pumps it to the lungs

Question 18

*describe the functioning of the heart in terms of the contraction of muscles of the atria and ventricles and the action of valves

Answer 18

1- deoxygenated blood coming from the body flows into the RA via the vena cava.
2-the RA contracts, so blood is pushed through the tricuspid valve into the RV.
3- walls of the RV contract, an blood is pushed into the pulmonary artery through the pulmonary valve.
4- blood travels to the lungs where it is oxygenated.
5- oxygenated blood returns from the lungs into the LA via the pulmonary vein.
6- it passes through the bicuspid valve into the left ventricle.
7- thick muscle wall of the LV contract to push the blood into the aorta through the aortic valve and all the way around the body.

Question 19

explain why pressure of the blood going to the lungs should be lower

Answer 19

the blood is going directly to capillaries which would burst under high pressure.
low pressure means that the blood flows slower to give time for diffusion of gases to occur.

Question 20

*state ways in which heart activity may be monitored

Answer 20

• ECG
• pulse rate
• listening to heart sounds (sound of valves closing)

Question 21

*investigate state the effect of physical activity on the heart

Answer 21

• record pulse rate at rest for a minute
• immediately after the do some exercise, record the pulse rate every minute until it returns to the resting rate.
• the experiment will show that an increase in physical activity increases pulse rate and heart rate may take several minutes to return to normal.

Question 22

*explain the effect of physical activity on the heart

Answer 22

• muscle respire faster, demanding more oxygen and glucose.
• increased respiration also means more carbon dioxide, which needs to be removed.
• blood carries oxygen, glucose and carbon dioxide, so the heart rate needs to increase to satisfy the demand.
• if the muscles don’t receive enough oxygen, they start respiring anaerobically, producing lactic acid.
• leads to oxygen debt which needs to be repaid following exercise, so the heart still continues to beat faster.

Question 23

*describe CHD in terms of the blockage of arteries

Answer 23

• in the lining of the coronary arteries, deposits of a fatty substance (atheroma) are laid down in patches.
• the surface of a patch of atheroma sometimes becomes rough and causes fibrinogen in the plasma to deposit fibrin on it, causing a blood clot (thrombus)
• the patches reduce diameter of the lumen.
• the artery becomes less elastic and cannot stretch to accommodate the blood which is being forced through it.
• partial blockage leads to angina.
• complete blockage leads to a heart attack.

Question 24

*state the possible risk factors of CHD

Answer 24

• diet: atheroma contains cholesterol combined with lipids and proteins. blood cholesterol levels is likely to be higher if the person consumes more saturated fatty acids. an unbalanced diet with too many calories can lead to obesity which makes it more difficult to exercise, and puts more strain on the heart.
• stress: causes hormones which increase blood pressure to be produced, increases rate of atheroma formation.
• smoking: chemical in cigarettes damage lining of the arteries.
• genetic predisposition: CHD can be passed from one generation to another –> genetic
• age: older people are more at risk
• gender: males are more at risk
• no exercise: hear muscles loses its tone —> sluggish blood flow.

Question 25

*discuss the role of the diet in the prevention of coronary heart disease

Answer 25

- maintaining a healthy balanced diet. - less chance of a person becoming obese. - low intake of saturated fats.

Question 26

*discuss the role of the exercise in the prevention of coronary heart disease

Answer 26

- regular vigorous exercise. - increases muscle tone. - efficient blood flow.

Question 27

*describe ways in which CHD may be treated.

Answer 27

- long-term use of low-dose aspirin (salicylic acid) prevents formation of blood clots i n the arteries. - stents - angioplasty - by-pass

Question 28

describe an angioplasty and stent surgery

Answer 28

- a narrow catheter (tube) is inserted into the blocked or narrowed artery. - a wire attached to a tiny deflated balloon is inserted into the catheter. - the balloon is then inflated to widen the atheroma by flatting the atheroma against the wall of the artery. - in some cases a stent is also inserted which pushes against the wall of the artery. the stent could be coted with a drug that slowly releases medication to prevent further blockage.

Question 29

describe a by-pass surgery

Answer 29

- the surgeon removes a section of blood vessel from a different part of the body (ex: leg) - the blood vessel is used to create a new passage for the flow of blood to the cardiac muscle, bypassing the blocked area.

Question 30

describe the structure and function of arteries

Answer 30

- all arteries carry oxygenated blood, except for the pulmonary artery. - carry blood away from the heart. - high blood pressure - thick, strong elastic walls. made of elastic fibers, fibrous tissue and muscle. - lumen is less wide than veins - no valves

Question 31

describe the structure and function of viens

Answer 31

- carry deoxygenated blood, except for the pulmonary vein. - carry blood to the heart. - low/ steady blood pressure - less thick. mainly made of fibrous tissue, no muscle or elastic fibers. - wide lumen - have valves.

Question 32

describe the structure and function of capillaries

Answer 32

- connect arteries and veins. penetrate to all parts of the body parts. - low blood pressure - very thin, permeable walls - very thin lumen - no valves

Question 33

*name the blood vessels that carry blood to and from the heart

Answer 33

- vena cava carry deoxygenated blood to the heart - aorta carries oxygenated blood away from the heart - pulmonary arteries carry deoxygenated blood away from the heart - pulmonary veins carry oxygenated blood to the heart.

Question 34

*name the blood vessels that carry blood to and from the lungs

Answer 34

- pulmonary arteries carry deoxygenated blood to the lungs. | - pulmonary veins carry oxygenated blood away from the lungs.

Question 35

*name the blood vessels that carry blood to and from the kidney

Answer 35

- renal artery carries oxygenated blood to the kidney | - renal vein carries deoxygenated blood away from the kidney.

Question 36

*explain how arteries are adapted for their function

Answer 36

- have thick muscular walls containing elastic fibers to withstand high pressure and maintain it. - have a narrow lumen to maintain high blood pressure.

Question 37

*explain how veins are adapted for their function

Answer 37

- have a large lumen to allow the flow of blood even though its pressure is low. - contain valves to prevent the backflow of blood, as it is under low pressure. - walls are less thick and have no elastic tissue.

Question 38

*explain how capillaries are adapted for their function

Answer 38

- blood pressure is low in capillaries, which gives time for exchange of materials to occur. - have walls that are one cell thick, so substances can easily diffuse across them. - have permeable walls, so blood plasma can leak out and form tissue fluid surrounding cells.

Question 39

*state the function of arterioles, venules and shunt vessels

Answer 39

- shunt vessels link the arterioles with venules. - when we are cold the shunt vessel dilates, and the arteriole constricts, which restricts blood flow, so little heat is lost --> vasoconstriction. - when we are hot the shunt vessel narrows, and the arterioles dilate, which enables more blood flow, so more heat is lost ---> vasodilation.

Question 40

*what is the lymphatic system?

Answer 40

a system of lymphatic vessels (carry the tissue fluid that isn't returned back to the blood plasma ---> lymph) and lymph nodes (swellings in the lymphatic vessels/ small clusters of lymphatic tissues).

Question 41

*describe the function of the lymphatic system in the circulation of body fluids

Answer 41

- it is formed from a series of tubes which flow from tissues back to the heart. - blood pressure in the capillaries forces a fluid (tissue fluid) out of the capillary walls. - the lymphatic system connects with the blood system near to the heart, where the fluid is returned to the blood plasma. - not all of it is returned, some goes into lymphatic vessels, becoming lymph. - some large lymphatic vessels can contract. - presence of valves and muscle contraction are the main things resulting in lymph flow.

Question 42

*describe the function of the lymphatic system in the protection of the body from infection

Answer 42

- lymph nodes form an important part of the body's defense system against infection. - it contains WBCs : lymphocytes are stored there and are released into the lymph to eventually reach the blood system. phagocytes are also present in it. if bacteria aren't ingested by WBCs of the blood, they will be carried in the lymph to lymph nodes and phagocytes there will ingest them.

Question 43

*state the function of red blood cells

Answer 43

- they have a red pigment called hemoglobin in their cytoplasm. - it is a protein combined with iron, which combines with oxygen to form oxyhemoglobin. - blood that contains oxyhemoglobin is oxygenated - oxyhemoglobin is unstable, breaks down in places where oxygen conc. is low. - RBCs transport oxygen in this way.

Question 44

*state the function of white blood cells

Answer 44

- the most numerous types of WBCs are lymphocytes and phagocytes. - phagocytes collect at the site of an infection and engulf harmful bacteria ---> phagocytosis. - lymphocytes

Question 45

*state the function of white blood cells

Answer 45

- the most numerous types of WBCs are lymphocytes and phagocytes. - phagocytes collect at the site of an infection and engulf harmful bacteria ---> phagocytosis. - lymphocytes produce antibodies which attach to antigens of pathogens to mark them out so phagocytes can engulf them.

Question 46

*state the function of platelets

Answer 46

- help to clot blood. - when tissues are damaged and blood vessels are cut, platelets clump together and block the blood flow. - they produce the enzyme thrombin which acts on the soluble plasma protein (fibrinogen) and turns it into insoluble fibrin. - this forms a network/ mesh of fibers across the wound. - RBCs become trapped in this network and form a blood clot. - the clot stops blood flow, and prevents entry of harmful bacteria (pathogens).

Question 47

*state the function of plasma

Answer 47

- plasma contains soluble nutrients, hormones, excretory products (carbon dioxide + urea), and ions which it transports. - also contains the proteins: fibrinogen (needed for blood clotting) and globulin (needed for immunity)

Question 48

*describe the transfer of materials between capillaries and tissue fluid

Answer 48

- the walls of the capillaries are so thin that water, dissolved solutes and dissolved gases easily leak out of them from the plasma into the tissue fluid surrounding the cells. - tissue fluid is similar to plasma in capillaries but contains less proteins. - tissue fluid contains dissolved food and oxygen from the blood.