Chapter 8: transport in mammals

Question 1

Describe the mammalian circulatory system

Answer 1

• closed double circulation

- consisting of a heart, blood vessels and blood

Question 2

what are arteries?

Answer 2

vessels carrying blood away from the heart

Question 3

what are veins?

Answer 3

vessels carrying blood to the heart

Question 4

what are arteries made of?

Answer 4

• inner endotelium called the tunica intima
• tunica media
• tunica externa

Question 5

what is the tunica media?

Answer 5

middle layer of arteries which contains smooth muscle, collagen and elastic fibres

Question 6

what is the tunica externa

Answer 6

outer coating of arteries containing elastic fibres and collagen fibres

Question 7

what is the tunica intima?

Answer 7

inner layer made of squamous epilthelium cells

Question 8

what are the distinctive characteristics of the arteries?

Answer 8

strength and elasticity

Question 9

why do artery walls need to be extremely strong?

Answer 9

-to withstand the blood pressure leaving the heart

Question 10

why do artery walls need to be elasticy

Answer 10

to reduce the likelihood that they will burst because of the high blood pressure

Question 11

what are arterioles?

Answer 11

smaller vessels than the arteries

Question 12

what is the main difference between the arteries and the arterioles?

Answer 12

the arterioles have a greater proportion of smooth muscle so that the muscle can contract and reduce/ increase blood flow

Question 13

what are capillaries?

Answer 13

the smallest of all blood vessels

Question 14

what is the function of capillaries?

Answer 14

to take blood as close as possible to all cells, allowing rapid transfer of substances between cells and blood

Question 15

what are capillary beds?

Answer 15

networks of capillaries

Question 16

what are semi-lunar valves?

Answer 16

half-moon valves that allow blood to move towards the heart, but not away from it

Question 17

how is blood in the veins moved?

Answer 17

-muscles contract and the blood in the veins is pushed up through the valves

Question 18

give another name for red blood cells

Answer 18

erythrocytes

Question 19

what causes the red colour in red blood cells?

Answer 19

haemoglobin

Question 20

what is the main function of haemoglobin?

Answer 20

to transport oxygen from lungs to respiring tissues

Question 21

give 4 adaptations of red blood cells

Answer 21

• bioncave disc shape
• very small diameter
• very flexible (can deform so they can pass through vessels)
• have no nucleus, mitochondria or endoplasmic reticulum

Question 22

what are lymphatics?

Answer 22

tiny, blind-ending vessels that are found in almost all body tissue

Question 23

describe the role of the valves in the lymph vessel walls

Answer 23

• wide enough to allow large protein molecules to pass through
• important because they are too big for capillaries

Question 24

what are lymph nodes?

Answer 24

• involved in the protection against disease
• bacteria is removed by white blood cells as the lymph passes through a node
• some white blood cells in the nodes secrete antibodies

Question 25

describe the structure of a white blood cell

Answer 25

• nucleus
• larger than red blood cells
• spherical or irregular in shape

Question 26

what is the purpose of a phagocyte?

Answer 26

cells that destroy invading microorganisms by phagocytosis

Question 27

give another example of a phagocyte

Answer 27

monocytes

Question 28

how do lymphocytes destroy microorganisms?

Answer 28

-secrete chemicals called antibodies, which attatch to and destroy the invading cells

Question 29

describe the structure of haemoglobin

Answer 29

• four polypeptides
• each polypeptide contains one haem group
• each haem group can combine with one oxygen molecule
• one haemoglobin can carry 8 oxygen molecules

Question 30

what does saturated mean?

Answer 30

a sample of haemoglobin that has combined with the maximum amount of oxygen

Question 31

describe the saturation of oxygen in an actively respiring muscle?

Answer 31

the partial pressure will be about 20-25% saturated

the haemoglobin from the lungs carries lots of oxygen and releases around 75% at the muscles

Question 32

give the first reaction with carbonic anhydrase

Answer 32

C02 + H20 ==> H2CO3

Question 33

give the first reaction in the cytoplasm of red blood cells

Answer 33

H2C03 ==> H+ + HCO3-