3.4 Mass Transport in Animals

Question 1

What is mass transport?

Answer 1

Mass transport is the bulk movement of gases or liquids in one direction at a constant speed, usually via a system of vessels and tubes.

Question 2

What is the function of haemoglobin?

Answer 2

Haemoglobin is responsible for binding oxygen in the lungs and transporting the oxygen to the tissue to be used in aerobic metabolic pathways.

Question 3

Describe cooperative binding.

Answer 3

The binding of the first oxygen molecule results in a conformational change in the structure of the haemoglobin molecule, making it easier for each successive oxygen molecule to bind (increasing its affinity for oxygen). → uncovers the haem group making it more available for successive O2 to bind to

Question 4

What does the oxygen dissociation curve show?

Answer 4

The rate at which oxygen associates, and also dissociates, with haemoglobin at different partial pressures of oxygen.
- low saturation (start of graph) = respiring cells
- high saturation (end of graph)= alveoli

Question 5

What is partial pressure?

Answer 5

The pressure exerted by an individual gas in a mixture- in this case the concentration of oxygen

Question 6

When is haemoglobin considered to be “saturated”?

Answer 6

When all four haem groups have bound to an oxygen molecule.

Question 7

What is the ease at which haemoglobin binds to and dissociates with oxygen called?

Answer 7

Affinity for oxygen

Question 8

Desctibe a low affinity for oxygen

Answer 8

binds to O2 less easily but release more easily

Question 9

Describe a high affinity for oxygen?

Answer 9

• binds easily to oxygen but **release less easily **

Question 10

What is meant by unloading?

Answer 10

haemoglobin releases O2 into the tissues (low affinity)

Question 11

What is meant by loading?

Answer 11

haemoglobin binds with O2 in lungs (high affinity)

Question 12

Why is the dissociation curve S-shaped?

Answer 12

Due to cooperative binding.

Question 13

What is the Bohr effect?

Answer 13

Changes in the oxygen dissociation curve as a result of carbon dioxide levels.

Question 14

What happens when the partial pressure of carbon dioxide in the blood is high?

Answer 14

Haemoglobin’s affinity for oxygen is reduced by decreasing blood pH resulting in a conformational shape change therefore oxygen is given up more readily (increased dissociation/decreased O2 affinity).

Question 15

How does an increase in partial pressure of carbon dioxide affect the graph?

Answer 15

Graph shifts to the right.

Question 16

Describe foetal haemoglobin

Answer 16

• foetal oxyhaemoglobin curve shifts to the LEFT of adults (foetal is more saturated than adult at the dame partial pressure)
• higher affinity of O2 in foetal haemoglobin
• ADV: foetus cant inhale/exhale, only source of O2 is from mothers haem through placenta in blood supply SO must have higher affinity to grab O2 from mother haem

Question 17

What are the effects of altitude on haemoglobin?

Answer 17

• low partial pressure of oxygen at higher altitudes
• oxyhaemoglobin curve shifts to the LEFT
  –therefore species living at higher altitudes have haemoglobin with a higher affinity for oxygen to optimise the amount of oxygen it can bind to

Question 18

What are the effect of faster metabolism organisms on haemoglobin?

Answer 18

• haemoglobin has low affinity for O2, more ready to unload O2 so respiring tissue has constant supply
• oxyhaemoglobin curve shifts to the RIGHT
  ADV: much faster metabolism, so needs more oxygen for respiration to provide energy for contracting muscles (e.g birds wings)

Question 19

Describe the advantage of the Bohr effect during intense exercise?

Answer 19

• haemoglobin has a **lower affinity ** of oxygen, therefore unloads more easily
• for aerobic respiration at the muscles (respiring tissues)

Question 20

What is meant by a closed, double circulatory system?

Answer 20

• closed: blood remains within the blood vessels
• double circulatory system: blood passes through the heart twice in each circuit, one circuit delivers blood to the lungs, one circuit delivers blood to the body)

Question 21

What issues arise from less plasma in blood?

Answer 21

• viscosity: heart has to pump harder to push the blood around
• increases blood pressure and strain on the heart

Question 22

Heart is…

Answer 22

• a hollow muscle which pumps blood, cardiac muscle is specialised for repeated contraction w/out rest

Question 23

Arteries are…

Answer 23

• blood vessels which carry blood AWAY from the heart
• walls contain lots of muscle & elastic muscle and narrow tissue to maintain high blood pressure

Question 24

Arterioles are…

Answer 24

• small arteries which branch from longer arteries and connect to capilarries