1.2.2 Gas Exchange and Transport/2.1.4 Thermoregulation

Question 1

Recall how the alveoli allow effective gas exchange in lungs

Answer 1

• large surface area
• most surface for diffusion
• short diffusion pathway e.g. thin walls
• closely associated with capillaries

Question 2

Recall why single celled organisms do not require specialised areas for gas exchange

Answer 2

SA:V ratio is sufficient for diffusion of required gases and other substances

Question 3

Recall how countercurrent exchange is useful to fish for gas exchange?

Answer 3

counter current enables gas exchange over the entire surface area of the lamella = efficient

• flow of blood is counter to water current
• higher oxygen in water, lower in blood = concentration gradient

Question 4

define homeostasis

Answer 4

Involves a stimulus-response model in which change in the condition of the external or internal environment is detected and appropriate responses occur via negative feedback

Question 5

What are the structural thermoregulatory mechanisms that allow endotherms to maintain their internal body temperature?

Answer 5

Structural:

1. Brown adipose tissue
2. Increased number of mitochondria per cell
3. Insulation

Question 6

What are the behavioral thermoregulatory mechanisms that allow endotherms to maintain their internal body temp?

Answer 6

Behavioral:

1. Kleptothermy: animals share heat by huddling
2. Hibernation
3. Aestivation: ‘summer hibernation’; inactivity and lowered metabolic rate in response to high temps and arid conditions
4. Torpor: involuntary hibernation for short periods of time (lower body temp, breathing rate, heart rate and metabolic rate)

Question 7

What are the physiological thermoregulatory mechanisms that allow endotherms to maintain their internal body temp?

Answer 7

Physiological:

1. Vasomotor Control: vasoconstriction or vasodilation
2. Evaporative Heat Loss; sweating or panting
3. Countercurrent Heat Exchange: circulatory adaptation that allow heat to be transferred from blood vessels containing warmer blood to those containing cooler blood.
4. Thermogenesis: conversion of chemical energy into kinetic energy (heat)

Question 8

What are the homeostatic thermoregulatory mechanisms that allow endotherms to maintain their internal body temp?

Answer 8

Homeostatic:

1. Thyroid hormones
2. Insulin