Lecture 16

Question 1

What are the reactants and products of aerobic respiration?

Answer 1

Reactants: Oxygen and glucose
Products: ATP, CO2, water.

Question 2

What are the issues with respiration?

Answer 2

CO2 is toxic, gasses can only diffuse.

Question 3

What limits respiration?

Answer 3

S.A. and thickness of respiratory surface, metabolic demands.

Question 4

Why do endotherms need to respire more?

Answer 4

They have a greater metabolic rate.

Question 5

What are the constraints on respiration?

Answer 5

Molecular weight of gasses, solubility and temperature.

Question 6

Which animals can diffuse gasses across their entire membrane?

Answer 6

Sponges, flatworms, jellyfish etc.

Question 7

What are the components of respiratory systems for?

Answer 7

To provide a large enough S.A. for gas exchange, breathing to maintain a concentration gradient and circulatory systems to transport gasses.

Question 8

Describe the insect respiratory system.

Answer 8

Air diffuses through spiracles into trachea which inflate and deflate to ventilate and pump air into tracheoles. Larger insects use rhythmic body movements to ventilate.

Question 9

What is tidal ventilation?

Answer 9

Gasses exit the same way they enter causing gasses to mix which reduces efficiency.

Question 10

How do insects cope with water loss?

Answer 10

Must balance O2 with water loss by closing spiracles to conserve water and using hairs around spiracles to trap water. Air sacs store air when conserving water or metabolic demands are high.

Question 11

How are vertebrate respiratory systems different to insects?

Answer 11

They are closed systems due to larger S.A.:V ratio.

Question 12

How does partial pressure affect O2 unloading?

Answer 12

Tissues with larger O2 demands have lower partial pressure so more O2 is unloaded by haemoglobin.

Question 13

How does temperature affect haemoglobin affinity?

Answer 13

Increasing temperature decreases haemoglobin affinity for O2 so more O2 is unloaded to active tissues that have a higher temperature.

Question 14

What effect does pH have on haemoglobin affinity?

Answer 14

Lower pH decreases haemoglobin affinity so O2 disassociates at a lower partial pressure (Bohr effect). This is useful as CO2 in respiring muscles reacts with carbonic acid to reduce the pH therefore increasing O2 unloaded to these muscles.

Question 15

How do fetus’ get O2 from mothers blood?

Answer 15

Adults have lower haemoglobin affinity than fetus’.

Question 16

What are the pros and cons of gas exchange in water?

Answer 16

Respiratory surfaces are kept moist but warm, salty water has lower concentrations of O2.

Question 17

Why is ventilation costly in fish?

Answer 17

Water is more dense than air.

Question 18

Describe gills.

Answer 18

Filamentous to increase S.A., large capillary network and have a thin membrane to decrease the diffusion distance.

Question 19

What is counter-current flow?

Answer 19

Blood flows in the opposite direction to the water which increases net movement between water and blood and increases the diffusion rate.

Question 20

Describe respiration in birds.

Answer 20

1. Air down trachea to posterior air sac.
2. posterior air sacs contract and air forced into lungs and gas exchange occurs.
3. Air from lungs to anterior air sacs.
4. anterior air sacs contract and push air out of trachea.

Question 21

What adaptations do birds have which make their respiratory systems efficient enough for high altitude and high metabolic demands of flight?

Answer 21

8-9 air sacs that contract and expand.
Uni-directional flow of air through lungs (no tidal ventilation).
Cross-current flow increases diffusion gradient.
Birds have very thin respiratory surfaces,

Question 22

Describe mammal inhalation.

Answer 22

Intercostal muscles and diaphragm contracts to expand chest volume.

Question 23

Describe mammal exhalation.

Answer 23

Intercostal muscles and diaphragm relax to decrease chest volume.

Question 24

What are the limitations of mammal respiration?

Answer 24

Tidal ventilation and not all air is exhaled from the lungs meaning O2 concentration is lower inside lungs.

Question 25

How do marine mammals specialise their respiration?

Answer 25

Store O2 in muscles, extract O2 more efficently, temporarily cut off circulation to some parts of the body.

Question 26

How is breathing homeostatically controlled?

Answer 26

Rise in CO2 levels is detected by chemoreceptors which signal medulla which then signals diaphragm to increase breating rate.