Transport in Humans

Question 1

Define diffusion

Answer 1

The random movement of molecules from a high concentration to low concentration

Question 2

When dye is dropped into water it diffuses. What happens when it has completely diffused?

Answer 2

• Equilibrium is reached - There is no net movement

Question 3

What are the five factors that affect the rate of diffusion?

Answer 3

• Temperature - Concentration gradient - Surface area - Volume - Distance

Question 4

How do you work out the Surface area/Volume ratio?

Answer 4

Surface area ÷ Volume

Question 5

What is the function of the circulatory system?

Answer 5

To transport substances around the body

Question 6

What three things does the circulatory system need to do its job?

Answer 6

1. A liquid to transport substances in (The blood) 2. A pump to move the liquid (The heart) 3. Pipes to direct the liquid and move it (Blood vessels)

Question 7

State all the parts in the circulatory system

Answer 7

Question 8

Define metabolic rate

Answer 8

The rate of chemical reactions in the body

Question 9

What is blood made up of and what are the percentages?

Answer 9

Plasma 55%, Red blood cells 45%, White blood cells and platelets 1%

Question 10

What is plasma?

Answer 10

• A straw coloured liquid - Contains a range of dissolved and suspended molecules

Question 11

What are platelets?

Answer 11

• Small cell fragments which help to form clots preventing blood loss and infection

Question 12

What are red blood cells function?

Answer 12

To transport oxygen

Question 13

What shape are red blood cells and how does this increase the rate of diffusion?

Answer 13

Shape = Biconcave - This increases their Surface Area/Volume ratio - More efficient diffusion of oxygen

Question 14

What do red blood cells contain and what happens when it combines with oxygen?

Answer 14

• Contains haemoglobin - Combines to form oxyhaemoglobin

Question 15

What do red blood cells not have and why?

Answer 15

-They don’t have a nucleus - So more haemoglobin can be in each cell and therefore more oxygen can be transported (oxyhaemoglobin)

Question 16

What is the function of the heart?

Answer 16

To pump blood around the body

Question 17

State the cardiac cycle

Answer 17

1. Right Atrium receives deoxygenated blood from the body through the vena cava
2. Moves through the right ventricle which is taken by the pulmonary artery to the lungs
3. Left atrium receives oxygenated blood from the lungs through the pulmonary vein
4. Oxygenated blood then moves through left ventricle which pumps it out round the whole body

Question 18

What do valves do?

Answer 18

Prevent blood flowing in the wrong direction

Question 19

What are the features of an artery?

Answer 19

Thick outer wall, small lumen, thick layer of muscles and elastic fibres

Question 20

What are the features of a vein?

Answer 20

Thin outer wall, large lumen, thin layer of muscle and elastic fibres

Question 21

What are the features of a capillary?

Answer 21

Very small lumen, Wall made of a single layer of cells

Question 22

What do arteries transport?

Answer 22

Carry blood away from the heart to all regions of the body

Question 23

What do veins transport?

Answer 23

Carry blood from organs back to the heart

Question 24

What do capillaries transport?

Answer 24

Carry blood through organs

Question 25

What does a a thick outer wall mean on a artery?

Answer 25

Blood flows at high pressure

Question 26

What does a thin outer wall mean on a vein?

Answer 26

Blood flows at a low pressure

Question 27

What does a wall made of a single layer of cells mean on a capillary?

Answer 27

Short diffusion distance therefore speeds up diffusion

Question 28

What does a small lumen mean on a artery?

Answer 28

Helps maintain the high pressure flow

Question 29

What does a large lumen mean on a vein?

Answer 29

Helps the blood flow easily and prevents further drop in pressure

Question 30

What does a very small lumen mean on a capillary?

Answer 30

Short diffusion distance therefore speeds up diffusion

Question 31

What does a thick layer of muscles and elastic fibres mean on an artery?

Answer 31

Helps the artery expand without being damaged by high pressure

Question 32

What does a thin layer of muscles and elastic fibres mean on a vein?

Answer 32

The pressure is low therefore doesn’t need as thick muscles and elastic fibres as an artery

Question 33

What is heart rate controlled by?

Answer 33

Nerve impulses from the medulla

Question 34

What happens when you start exercising?

Answer 34

1. Muscles produce more CO2 in aerobic respiration 2. Sensors in aorta detect this increase 3. They send nerve impulses to the medulla 4. Accelerator nerve increases heart rate and makes the heart beat with more force 5. More blood is supplied to the muscles due to increased aerobic respiration

Question 35

What happens when you stop exercising?

Answer 35

1. CO2 production returns to normal 2. The decelerator nerve decreases heart rate and reduces the force of contraction 3. Blood pressure returns to normal

Question 36

Why does the left ventricle have a thicker wall than the right ventricle?

Answer 36

• Left ventricle is under more pressure as it has to pump blood around the whole body
• Right ventricle is under less pressure as it only has to pump blood to the lungs.