12) Transport in animals

Question 1

Septum

Answer 1

-Separates right side of heart from left side
-to prevent mixing of oxygenated and deoxygenated blood

Question 2

Valve

Answer 2

Allows blood to flow in one direction and prevent is backflow

Question 3

Explain how blood coming from the body reaches the lungs

Answer 3

1. Blood coming from the body enters heart through vena cava into right atrium
2. Right atrium contracts, pressure of blood increases in right atrium
3. Atrioventricular valve (tricuspid) opens
4. Blood is forced from right atrium into right ventricle
   5.Right ventricle contracts, right atrium relax, and pressure in right ventricle increases.
5. Atrioventricular valve closes to prevent backflow of blood, semilunar valve open
6. Blood is forced out of heart through pulmonary artery to lungs

Question 4

Explain how blood coming from lungs reaches the body

Answer 4

1. Blood entering from lung, through pulmonary vein into the left atrium.
2. Left atrium contracts, so blood pressure in left atrium increases
3. Atrioventricular (bicuspid) valve opens
4. Blood is forced from left atrium into left ventricle
5. Left ventricle contracts, left atrium relaxes, and pressure of blood in left ventricle increase
6. Atrioventricular valve closes to prevent backflow of blood, semilunar valve opens to allow the blood to be forced out of heart through aorta to body

Question 5

Double circulatory system

Answer 5

Blood enters the heart twice in one complete circuit (pulmonary and systemic circuits)

Question 6

Advantages of having a double circulatory system

Answer 6

1. To pump blood under 2 different pressures
   - High pressure to the body, for longer distance, to allow sufficient blood supply of oxygen and glucose to all body cells
   - Low pressure to avoid damage to lungs
2. To prevent mixing of oxygenated and deoxygenated blood
   - To maintain steep concentration gradient for faster gas exchange

Question 7

Single circulation

Answer 7

Blood enters the heart once in one circulation

Question 8

Disadvantages of single circulation

Answer 8

1. Rapid fall in blood velocity and pressure
   -Insufficient supply of oxygen and nutrients to body cells
2. Pressure too low for kidney function

Question 9

Diastole

Answer 9

1. Atrium : relaxed
2. Ventricle : relaxed
3. Atrioventricular valve : Open
4. Semilunar : Closed

(filling of heart 0.4S)

Question 10

Atrial systole

Answer 10

1. Atrium : Contract
2. Ventricle : Relax
3. Atrioventricular valve : open
4. Semilunar valve: Closed

( Emptying of blood in atria into ventricles, 0.1S)

Question 11

Ventricular systole

Answer 11

Atrium : Relaxed
Ventricle : Contracts
Atrioventricular valve : Closed
Semilunar valve : Open

(0.3s)

Question 12

Why does left ventricle has thicker muscle walls

Answer 12

1. To pump the blood with higher pressure so it can travel longer distances to all body cells
2. To be able to overcome the resistance in arteries

Question 13

Pace maker

Answer 13

Bundle of nerves in right atrium
1. Regulates the rate of heart beats according to body demand
2. Ensures atria contract before ventricles, to empty blood into ventricles

Question 14

Ways to monitor heart acticity

Answer 14

1. Use ECG
2. Listen to the heart sound using stethoscope ( Listen to lub dub sound which is due closing of heart valves)

Question 15

Artery function

Answer 15

Carry blood away from heart under high pressure
(all carry oxygenated blood except pulmonary and umbilical)

Question 16

Describe features of arteries

Answer 16

1. Thick outer wall:
   - To withstand high blood pressure and prevent it from bursting
2. Narrow lumen:
   - to maintain high blood pressure
3. Smooth muscle:
   - Contracts and relax to adjust the volume of blood transported to different body parts
4. Elastic fibres:
   - Stretch and recoil to maintain blood pressure

Question 17

Function of vein

Answer 17

Transport blood back to heart under low pressure

Question 18

Describe features of veins

Answer 18

1. Thin wall:
   - for low blood pressure flow
2. Wide lumen:
   - for no resistance to blood flow
3. Semilunar valves :
   - Prevent back flow of blood

Question 19

Why blood flowing in veins is under low pressure

Answer 19

As they receive blood coming from capillaries, so blood had already lost its pressure. It also has a wide lumen

Question 20

How blood flow in veins

Answer 20

Veins are embedded between muscles, so when muscles contract they squeeze the vein and push blood up in vein
Semilunar valves prevent back flow of blood

Question 21

Function of capillary

Answer 21

Allow exchange of substances between blood and cells
by diffusion of gases and reabsorption of useful substances into blood (e.g. glucose)

Question 22

Describe features of capillaries

Answer 22

1. Wall is one cell thick (thin):
   -for shorter diffusion distance
2. Pores in wall:
   -To allow filtration of small molecules from blood
3. Large number of branching capillaries:
   -For larger surface area to reach every cell
4. Lumen almost same size of RBC:
   -So RBC can move slowly for efficient gas exchange

Question 23

Components of blood

Answer 23

1. plasma 55%
2. 45% blood cells

Question 24

Plasma consists of

Answer 24

90% water
10% dissolved substances (e.g. glucose, amino acids vitamins, minerals and urea) AND plasma proteins (e.g. enzymes, hormones, antibodies and fibrinogen)

Question 25

Blood cells

Answer 25

1. White blood cells 2. Red blood cells 3. Platelets

Question 26

Platelets

Answer 26

Platelets needed for blood clotting -When platelets become in contact with cut, they become sticky - release thrombin enzyme - catalyse the conversion of soluble fibrinogen into insoluble fibrin - fibrin forms mesh - mesh traps blood cells, forming a clot - clot dries and becomes a scab - this prevents more blood loss and entry of pathogens