B13 Transport in Humans T17

Question 1

Why do large multicellular organisms need a transport system?

Why do single celled organisms not need it?

Answer 1

low SA:V, diffusion is too slow to supply all their needs

single celled organisms have a large SA:V, so diffusion is fast enough

Question 2

roles of the blood

Answer 2

• defend againt pathogens
• control body temperature (homeostasis)
• helps maintain cell pH

Question 3

(4 points)

What is the blood made up of

Answer 3

1. plasma
2. red blood cells
3. white blood cells
4. platelets

Question 4

Description of plasma
Explain its function

Answer 4

liquid part of blood, mainly water
carries:
- blood cells around body
- dissolved nutrients (glucose, amino acids, fatty acids and glycerol)
- hormones carbon dioxide
- urea
- heat

Question 5

Description of red blood cells
Explain its function

Answer 5

biconcave disk-like cells, no nucleus, filled with haemoglobin, flexible to fit in narrow blood vessels
haemoglobin transports oxygen to lungs, and unloads it in respiring tissues

Question 6

How are red blood cells specialised to carry oxygen?

Answer 6

biconcave - large SA:V to pass oxygen through
cytoplasm - large amounts of haemglobin to transport oxygen
no nucleus - fits more haemoglobin
(flexible to fit in narrow blood vessels)

Question 7

Where are products of digestion transported from and to?

(glucose, amino acids, fatty acids and glycerol)

Answer 7

from small intestine to respiring tissue

Question 8

Where is oxygen transported from and to?

Answer 8

from alveoli to respiring tissue

Question 9

Where is carbon dioxide transported from and to?

Answer 9

respiring tissue to lungs

Question 10

Where is urea transported from and to?

Answer 10

liver to nephron

Question 11

What are the 2 types of white blood cells

Answer 11

1. lymphocytes - makes antibodies
2. phagocytes - englufs bacteria

Question 12

What do phagocytes look like?

Answer 12

multi-lobed nucleus
granular cytoplasm

Question 13

How do phagocytes work?

Answer 13

Phagocytes carry out phagocytosis by engulfing and digesting pathogens
Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells
Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it
This is a non-specific immune response

Question 14

What do lymphocytes look like?

Answer 14

arge round nucleus which takes up nearly the whole cell
clear, non-granular cytoplasm

Question 15

How do lymphocytes work

(What do they also produce)

Answer 15

Antibodies are Y-shaped proteins with a shape that is specific (complementary) to the antigens on the surface of the pathogen
This is a specific type of immune response as the antibodies produced will only fit one type of antigen on a pathogen

also produce antitoxins to neutralise toxins released by pathogens

Question 16

(TA)

Description of platelets
Function of platelets

Answer 16

smallest cells, no nucleus, made in bone marrow
release chemicals to make blood clots

Question 17

(TA)

How do platelets work

Answer 17

1) When the skin is broken (i.e. there is a wound) platelets arrive to stop the bleeding
2) A series of reactions (the clotting cascade) occur within the blood plasma
3) Platelets release chemicals that cause fibrinogen proteins to form a mesh of insoluble
fibrin across the wound, trapping red blood cells and therefore forming a clot.
4) The clot eventually develops into a scab to protect the wound from bacteria entering

Question 18

(TA)

How do vaccinations work

Answer 18

Vaccinations involve making an individual immune to a certain disease. By immunising a large
proportion of the population, the spread of the pathogen is reduced as there are less people to
catch the disease from (called herd immunity).
Vaccines contain either a dead or inactivated form of the pathogen. When injected, they
stimulate the immune system to the white blood cells to produce the correct complementary
antibody to combat it, but since it is dead or inactivated it does not cause any symptoms

Question 19

What are memory cells

Answer 19

Some of these white blood cells remain in the body as memory cells. If this person is then
exposed to the actual pathogen, these memory cells will produce antibodies much faster in a
greater quantity, so the pathogen can be destroyed before symptoms are felt.

Question 20

Advantages of vaccines

Answer 20

• They have eradicated many diseases so far
  (e.g smallpox) and reduced the occurrence of
  many (e.g rubella).
• Epidemics (lots of cases in an area) can be
  prevented through herd immunity.

Question 21

Disadvantages of vaccines

Answer 21

• They are not always effective in providing
  immunity.
• Bad reactions (such as fevers) can occur in
  response to vaccines (although very rare).

Question 22

Why do mammals need a double circulatory system?

Answer 22

the metabolic rate is higher and so need a
faster system

Question 23

How heart works

Answer 23

Process:
1. Blood flows into the right atrium through the vena cava, and left atrium through the pulmonary
vein.
2. The atria contract forcing the blood into the ventricles.
3. The ventricles then contract, pushing the blood in the right ventricle into the pulmonary artery
to be taken to the lungs, and blood in the left ventricle to the aorta to be taken around the body.
4. As this happens, valves close to make sure the blood does not flow backwards.

Question 24

Order of circulatory system
deoxygenated blood -> oxygenated blood from lungs

Question 25

Adaptations of the heart

Answer 25

• muscular wall of left ventricle is thicker - blood needs to be pumped all around the body - whereas right ventricle only going to lungs and back
• 4 chambers that separate the oxygenated blood from the deoxygenated blood: 2 atria above
  and 2 ventricles below
• Valves to make sure blood does not flow backwards
• Coronary arteries cover the heart to provide its own oxygenated blood supply

Question 26

how the heart rate changes during exercise and under the influence of adrenaline

Question 27

how factors may increase the risk of developing coronary heart disease

Question 28

how the structure of an artery is adapted to transport blood

Answer 28

away from heart
high pressure to pump blood around body

Question 29

how the structure of a capillary is adapted to transport blood

Answer 29

as arteries get further from heart, get narrow and branch into capillaries
lots of thin capillaries - large SA:V for quick diffusion
1 cell thick cell wall - short diffusion distance
exchange of oxygen and glucose diffuse out of capillaries into cells - respiration
carbon dioxide diffuses into capillaries from cells as waste product of aerobic respiration

Question 30

how the structure of a vein is adapted to transport blood

Answer 30

capillaries join together to form veins going INTO heart
lowest pressure - blood moving slowly -> veins need largest lumen (space for blood to flow)
valves to stop blood flowing wrong way
lowest pressure is consistent - so thinner than artery walls and little elastic or muscle