Transport in animals

Question 1

What is the transport medium in open circulatory systems?

Answer 1

Haemolymph

Question 2

What is the body cavity in open circulatory systems called?

Answer 2

Haemocoel

Question 3

Why do animals require transport systems?

Answer 3

Rate of diffusion too low
High metabolic rates
Low SA:V ratios
Molecules (e.g. enzymes and hormones) need to be transported to specific tissues

Question 4

What are internal transport systems for?

Answer 4

To transport nutrients and oxygen around the body

Question 5

What are some examples of organisms with open circulatory systems?

Answer 5

Some invertebrates, such as arthropods (including insects) and molluscs

Question 6

What are some examples of organisms with closed circulatory systems?

Answer 6

All vertebrates and many invertebrates (e.g annelid worms, cephalopods)

Question 7

What is the transport medium in closed circulatory systems?

Answer 7

Blood

Question 8

What are some examples of organisms that have single circulatory systems? (blood passes through heart once per circulation)

Answer 8

Fish, annelid worms

Question 9

What are some organisms that have a double circulatory system? (Blood pumped to lungs and returns to heart carrying oxygen, then to body tissues before returning to heart

Answer 9

Birds and mammals

Question 10

What is circulation to the lungs called?

Answer 10

Pulmonary circulation

Question 11

What is circulation to the respiring tissues called?

Answer 11

Systemic circulation

Question 12

What are the advantages of a closed double circulatory system?

Answer 12

Blood pressure is maintained
Oxygenated and deoxygenated blood does not mix
Lower volumes of transport fluid required
Blood supply to different tissues can be varied depending on demand
Delivery of oxygen and nutrients more efficient

Question 13

What do elastic fibres provide in blood vessels?

Answer 13

Flexibility

Question 14

What is the role of smooth muscle in blood vessels?

Answer 14

To adjust lumen size

Question 15

What is the role of collagen in blood vessels?

Answer 15

Structural support

Question 16

What are the main differences between veins and arteries?

Answer 16

Veins have a larger lumen and arteries have more elastic tissue. Veins have valves typically.

Question 17

What is the typical diameter of an artery?

Answer 17

5000 micrometres

Question 18

What is the typical diameter of a capillary?

Answer 18

10 micrometres

Question 19

What is the typical diameter of a vein?

Answer 19

10,000 micrometres

Question 20

Why do arterioles contain a high proportion of smooth muscle?

Answer 20

The muscle can contract to narrow the lumen (vasoconstriction) or relax to widen the lumen (vasodilation), controlling blood flow

Question 21

What are the key features of capillaries?

Answer 21

Thin walls (single layer of squamous epithelial cells with gaps between them). The walls are permeable to allow diffusion of particles into tissue fluid

Question 22

Why do arteries have a high proportion of elastic tissue?

Answer 22

To stretch and recoil, preventing rupture when the heart pumps

Question 23

Why do veins have wide lumens and valves?

Answer 23

For smooth blood flow at low pressures and prevent backflow of blood

Question 24

Which 2 pressures are the key to tissue fluid formation?

Answer 24

Osmotic and hydrostatic

Question 25

What is hydrostatic pressure?

Answer 25

The pressure exerted by a fluid in confined spaces

Question 26

Why are cells bathed in tissue fluid?

Answer 26

To enable the exchange of materials: oxygen and nutrients enter cells, waste products leave

Question 27

At which end does the hydrostatic pressure outweigh the osmotic?

Answer 27

Arterial

Question 28

At which end does the osmotic pressure outweigh the hydrostatic?

Answer 28

Venous

Question 29

What is oncotic pressure?

Answer 29

A form of osmotic pressure exerted by proteins, notably albumin, in a blood vessel’s plasma

Question 30

What approximate percentage of tissue fluid enters the lymphatic system rather than re-entering the blood?

Answer 30

10%

Question 31

What is the function of lymph?

Answer 31

Important part of the immune system (e.g. phagocytes in lymph notes ingest bacteria)

Question 32

What proportion of blood is plasma and what proportion is cells/platelets?

Answer 32

55% plasma, 45% cells and platelets

Question 33

Why is there less solute in tissue fluid than in blood?

Answer 33

Many substances (e.g. oxygen, glucose, amino acids) diffuse into cells. There are no plasma proteins (e.g. albumin, fibrinogen)

Question 34

What is the difference between lymph and tissue fluid?

Answer 34

Lymph contains less oxygen and nutrients, a greater proportion of fatty acids and a large number of leucocytes

Question 35

How do leucocytes enter the lymphatic system

Answer 35

They (particularly t lymphocytes) are added to the lymphatic system after maturing in the thymus

Question 36

What is the equation for the conversion of haemoglobin into oxyhaemoglobin?

Answer 36

Hb + 4O2 -> Hb(O2)4

Question 37

What percentage of oxygen in the blood is transported by haemoglobin?

Answer 37

98% (2% in solution in plasma)

Question 38

What proportions of carbon dioxide is found dissolved in the plasma, combined with haemoglobin, and as HCO3- ions?

Answer 38

5% in plasma 10-20% combined with haemoglobin 75-85% converted to hydrogen carbonate ions

Question 39

What is the equation for the conversion of carbon dioxide into hydrogen carbonate ions?

Answer 39

CO2 + H2O <> H2CO3 <> HCO3- + H+ | Catalysed by carbonic anhydrase

Question 40

Why is a large proportion of CO2 in the blood converted into HCO3-?

Answer 40

To maintain a steep CO2 concentration gradient between respiring tissues and blood

Question 41

What is the chloride shift?

Answer 41

HCO3- ions move out of erythrocytes and into the plasma, and Cl- ions move into the erythrocytes to replace them Exchange

Question 42

What is the Bohr effect?

Answer 42

Haemoglobin’s oxygen affinity decreases when CO2 is present. Oxygen is released from haemoglobin more easily when carbon dioxide is present

Question 43

What is partial pressure?

Answer 43

The pressure exerted by a particular gas in a mixture

Question 44

Why does fetal haemoglobin have a higher affinity for oxygen than adult haemoglobin?

Answer 44

So that oxygen can be passed from the mother’s haemoglobin to the foetus’s haemoglobin in the placenta

Question 45

What is a slow heart rate called?

Answer 45

Bradycardia

Question 46

What is a fast heart rate called?

Answer 46

Tachycardia