8. TRANSPORT IN MAMMALS

Question 1

How is the mammalian cardiovascular system a closed system

Answer 1

blood always remains within vessels

Question 2

Why is the mammalian cardiovascular system called a double circulatory system

Answer 2

blood flows twice through the heart in one complete circuit.

Question 3

The function of arteries

Answer 3

to transport blood swiftly and at high pressure to the tissues

Question 4

Layers of the arteries

Answer 4

• tunica intima (squamous epithelium) (minimises friction with moving blood)
• tunica media (elastic fibres, collagen fibres, smooth muscle)
• tunica externa (collagen fibres and some elastic fibres)

Question 5

Arteries near the heart contain more _____ and arteries away from the heart contain less elastic tissue and more _____ in the tunica media

Answer 5

more elastic tissue

smooth muscle

Question 6

The distinctive characteristics of an artery

Answer 6

strength and elasticity

Question 7

Role of elastic fibres in artery

Answer 7

• allow the wall to stretch as pulses of blood at high pressure surge through, making the artery wider and reducing the pressure
• allow the wall to recoil inwards as the pressure drops, making it narrower and raising the pressure
• reduces the likelihood of artery bursting

Question 8

What is a pulse

Answer 8

The stretching of the arteries due to the high pressure of the blood passing through it with each surge of blood from the heart

Question 9

Significance of arterioles

Answer 9

• control the volume of blood entering capillaries and thus tissues
• reduce the pressure of blood going into the capillary (preventing oedemas)

Question 10

The function of the capillaries

Answer 10

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

Question 11

What places do capillaries not form a capillary bed

Answer 11

• cornea

- cartilage

Question 12

What allows some components of the blood to seep through into the spaces between the cells in all the tissues of the body

Answer 12

tiny gaps between the individual cells that form the endothelium

Question 13

Functions of veins

Answer 13

to return blood to the heart

Question 14

Movement of blood in veins

Answer 14

• pressure in veins is produced by the contraction of skeletal muscles close to it
• semilunar valves prevent backflow of blood away from heart

Question 15

Role of plasma proteins in blood

Answer 15

• regulate osmotic potential
• regulate pH
• some, such as fibrinogen, have a role in blood clotting

Question 16

Function of haemoglobin in red blood cells

Answer 16

to transport oxygen from lungs to respiring tissues

Question 17

First site of red blood cell production

Answer 17

liver of foetus, while in the uterus

Question 18

Why do red blood cells not live long

Answer 18

• membranes become more and more fragile

- eventually rupture in some ‘tight spot’ usually the spleen

Question 19

Plan an experiment for a haemoglobin dissociation curve

Answer 19

page 168

Question 20

Adaptations in people living at high altitudes to the low-oxygen environment

Answer 20

• more red blood cells
• broad chest (providing larger lung capacities)
• larger heart, especially the right side, that pumps to the lungs
• more haemoglobin in blood (increasing the efficiency of oxygen transport from lungs to tissues, compensating for low partial pressures)
• increase in rate and depth of breathing
• increase in heart rate

Question 21

What pushes valves open and shut

Answer 21

pressure differences in the blood

Question 22

Why do the right ventricles need to produce less force

Answer 22

• only have to pump blood to the lungs which are very close to the heart
• if too high a pressure was developed, tissue fluid would accumulate in the lungs, hampering gas exchange

Question 23

Function of the papillary muscles

Answer 23

papillary muscles attached to the valve by tendons prevent the atrioventricular valve from being forced inside-out

Question 24

Diameter of capillaries

Answer 24

7μm

Question 25

Features of capillaries

Answer 25

• small diameter (7μm)
• wall is made of a single layer of squamous epithelium
• form a capillary bed throughout every tissue in the body (except cornea and cartilage)
• spaces between cells

Question 26

Sources of carbon monoxide

Answer 26

• exhaust fumes from cars

- cigarette smoke

Question 27

Explanation of the S shaped curve

Answer 27

• oxygen molecule combines with the iron atoms in the haem group in the haemoglobin molecule
• the whole haemoglobin molecule is slightly distorted
• this makes it easier for successive O2 molecules to bind

Question 28

Problems with haemoglobin and CO

Answer 28

• haemoglobin has a higher affinity for CO than O2

- carboxyhaemoglobin is a very stable compound and CO remains combined with Hb for a long time

Question 29

Symptoms of altitude sickness

Answer 29

• increase in depth and rate of breating

- feeling of dizziness and weakness