Respiratory Systems

Question 1

Gas exchange basic information

Answer 1

• Gases (O2 and CO2) diffuse from regions of high to low partial pressure (pp = pressure exerted by an individual gas in a mixture)
• O2 is delivered from the environment to the cells (to be used in cellular respiration); CO2 (a byproduct of metabolism) is eliminated from cells into the environment

Question 2

O2 Pathway

Answer 2

• Breathing - Pulmonary diffusion - circulatory delivery - tissue diffusion - tissue O2 utilization

Question 3

Respiratory Media

Answer 3

• Animals can use air or water as a source of O2 (= respiratory medium)
  ▪ In a given volume, there is less O2
  available in water than in air
  ▪ Obtaining O2 from water requires greater
  efficiency than air breathing

Question 4

Respiratory Surfaces

Answer 4

• Animals require large, moist respiratory
  surfaces for exchange of gases between their cells and respiratory medium
  ▪ Gas exchange across respiratory surfaces takes place by diffusion
  ▪ Respiratory surfaces vary by animal and
  include outer surface, skin, gills, tracheae, and lungs

Question 5

Tracheal systems

Answer 5

• In insects
• Oxygen enters through spiracles and moves through the body via the tracheal tubes and branching tracheoles
• No connection between the respiratory and circulatory systems

Question 6

Gills (aquatic animals)

Answer 6

• outfoldings of the body that create a
  large surface area for gas exchange
• Secondary lamella = principle sites for gas exchange
• COUNTERCURRENT exchange: VERY efficient (most). Water and blood flow in different directions
  *DRAW graph

Question 7

Bimodal breathing

Answer 7

• In amphibians
• Adult salamander uses its skin and lungs to exchange gases with the environment
• Before maturity, it uses external gills while in a watery environment

Question 8

Bimodal amphibian breathing graph

Answer 8

DRAW graph

Question 9

Lungs

Answer 9

• Organs of the respiratory system in
  reptiles, birds, and mammals (and most adult amphibians…and even some fish!)
  ▪ The circulatory system (open or closed)
  transports gases between lungs and the rest of the body
  ▪ The size and complexity of lungs correlate
  with an animal’s metabolic rate

Question 10

Bird lungs

Answer 10

• CROSS-CURRENT exchange (very efficient, not as much as countercurrent)
• Air passing through the lungs travels at a right angle to blood flow

Question 11

Mammalian lungs

Answer 11

• TIDAL-EXCHANGE (not as efficient as countercurrent and crosscurrent)
• Air passes through the pharynx, larynx,
  trachea, bronchi, and bronchioles to the
  alveoli, where gas exchange takes place
• Alveoli: Type 1 - thin, place of gas exchange, Type 2 - synthesis and secretes surfactant

Question 12

Homeostasis control of breathing

Answer 12

Normal blood pH (7.4) - pH falls b/c of increased CO2 - signals brain - signals rib muscles and diaphragm to increase rate and depth of ventilation, CO2 falls + pH rises