3.1.2 Transport in Animals

Question 1

Multicellular organisms

Answer 1

High metabolic demand

SA:V low

Question 2

Open circulatory system (insects)

Answer 2

Blood NOT inside vessels

Low metabolism

Question 3

Closed circulatory system (fish and mammals)

Answer 3

Blood within the vessels

Pumped by heart

Higher metabolism

Question 4

Single circulatory system (fish)

Answer 4

One circuit

Low metabolic rate still sufficient

Question 5

Double circulatory system (mammals)

Answer 5

Pulmonary (lungs)
Systemic (body)

Higher metabolism
Higher pressure

Question 6

Arteries

Answer 6

Narrow lumen
Thick elastic layer
Thick muscle layer 
Thin outer layer
High elasticity

Question 7

Veins

Answer 7

Wide lumen
Thin elastic layer
Thin muscle layer
Thick tough outer layer
Low elasticity

Question 8

Transporting O2 and CO2; erythrocytes

Answer 8

Biconcave shape
High surface area
Haemoglobin

O2 binds loosely to iron containing haem group

Hb + 4O2 Hb(O2)4

Question 9

Transporting O2 and CO2 in the blood

Answer 9

See diagram

Question 10

The blood

Answer 10

Transports:O2,CO2,digested food, hormones,platelets, antibodies

Maintain:steady body temp,buffer - minimise pH changes

Question 11

Blood plasma

Answer 11

Glucose, amino acids, mineral ions, hormones, plasma proteins, red and white bc, platelets

55% of blood volume

Question 12

Tissue fluid

Answer 12

Everything except large plasma proteins

Plasma proteins have oncotic effect so H2O has a tendency to more into the blood from fluid

Question 13

Oncotic pressure

Answer 13

The tendency of H2O to move into the blood

Around -3.3kPa

Question 14

Hydrostatic pressure

Answer 14

Blood under pressure from surge of blood when the heart contracts

Around 4.6kPa

When h.s pressure high: H2O moves out

When h.s pressure low: H2O moves in

Question 15

Lymph

Answer 15

Blood plasma ultrafiltrated into tissue fluid.

Tissue fluid drains into lymph

Question 16

The cardiac cycle

Answer 16

DEOXYGENATED
RA in vena cava - AV valve open - RV - RA contract - AV closes - RV contract - semilunar valve - pulmonary artery - lungs

OXYGENATED
LA in pulmonary vein - LA contracts - LV contracts - semilunar - aorta - body

Question 17

Transporting O2/CO2

Answer 17

CO2
—> 5% in plasma as H2CO3

—> 10% in cell as carbamino-haemoglobin (CO2+HbNH2)

—> 85% in plasma as HCO3-

i) CO2+H2O–>H2CO3
ii) H2CO3–>H++HCO3-

For CO2=opposite

Question 18

How heart action is initiated and coordinated

Answer 18

• Electrical excitation starts at SAN - atria contract
(A layer of non-conducting tissue prevents it passing directly to ventricles)

• AVN picks it up and imposed delay before stimulating bundle of His (purkyne fibres)
• branches at apex where conduction begins = efficient emptying

Question 19

ECGs

Answer 19

See book

Question 20

Positive cooperativity

Answer 20

Once one oxygen binds to haem group, the molecule changes shape, making is easier for the next oxygen molecules to bind

Question 21

What does the oxygen dissociation curve show?

Answer 21

Shows the affinity of haemoglobin for oxygen

Question 22

Oxygen dissociation curve

Answer 22

Small change in partial pressure of oxygen in surroundings makes significant difference to saturation of the haemoglobin with oxygen

Question 23

Pattern of oxygen dissociation curve as partial pressure of oxygen increases

Answer 23

• at low pO2: few haem groups bound to oxygen, so haemoglobin doesn’t carry as much
• at higher pO2: more haem groups bound to oxygen, making is easier for oxygen to be picked up
• haemoglobin becomes saturated at v high pO2 as all haem groups become bound

Question 24

Effect of CO2 on oxygen dissociation curve

BOHR SHIFT

Answer 24

As pCO2 rises, haemoglobin gives up oxygen more easily
As a result:
• active tissues w high pCO2, haemoglobin gives up O2 more easily
• lunge w low pCO2, oxygen binds to the haemoglobin molecules easily

Question 25

Transporting carbon dioxide

Answer 25

• 5% dissolved in blood plasma
• 10-20% A’s carbaminohaemoglobin
• 75-85% hydrogen carbonate ions in cytoplasm of red blood cells

CO2+H2OH2CO3H++HCO3-