Circulation and gas exchange

Goals

1. To become familiar with the structure and function of the mammalian circulatory and respiratory systems

2. To understand how these systems allow the organism to overcome the problems of multicellularity

Outline

Comparitive gas exchange systems

skin

gills

tracheal systems

lungs

mammals

birds

Structure (of human respriatory system)

[see book for this]

Function

air is drawn into our lungs by negative pressure as the diaphragm contracts

the rib cage is rigid, but may also expand

note: our lungs move air in and out, while birds have a flow-through system

Control

the breathing center is in the brain stem (specifically the pons and medulla oblongata)

chemoreceptors monitor blood pH and regulates breathing rate and depth

Gas transport

CO₂

mostly in solution (as bicarb)

plasma is buffered

some is carried on hemoglobin

O₂

each hemoglobin (Hb) carries 4 O₂

the affinity of Hb for O₂ drops as P_O2 decreases, which means O₂ is dropped off where it's most needed

a lower pH (i.e., high CO₂) accentuates this, decreasing the affinity of Hb for O₂ even more at low P_O2 ( = the Bohr effect)

 

Vocabulary

click here to go to respiration vocabulary