4.3 Mammals

Question 1

Compare gas exchange systems

Answer 1

Animals have a:
- low sa:v
- large diffusion distance
- more active
- high metabolic demand

Insects:
- large sa:v ratio
- rely on simple diffusion
- low metabolic demand
- less active

Question 2

Describe the respiratory system

Answer 2

Nasal cavity - provides a passage for oxygen to enter lungs and co2 to exit lungs. - provides a moist environment that filters air ensuring inhaled air reaches same temp to body.
Alveoli - large sa for diffusion, surrounded by lots of capillaries, main site of gas exchange(exchange of carbon and oxygen.
Made up of one layer of flattened epithelial cells providing a short diffusion distance. Diffusion gradient maintained hen oxygenated blood is continuously carried away ensuring more oxygen is brought into lungs so the concentration gradient is steep
Trachea - cartilages have elastic tissue providing support to the trachea preventing it from collapsing.

Cilia - allow passage for gas movement.
Goblet cells - secrete mucus
Bronchi - narrow/ cartilage rings

Question 3

Gas exchange in the respiratory system

Answer 3

Oxygen is inhaled by the contraction of the diaphragm and muscles causing volumes to increase and pressure to decrease and air moves into the lungs through the nasal cavity by diffusion down a pressure gradient through the trachea dividing into smaller tubes of bronchi then into smaller bronchioles moving into the capillaries from the alveoli via diffusion where gas exchange happens. Air moves out when the muscles and diaphragm relaxes the volume decreases and pressure increases air diffuses out down a pressure gradient.