Chapter 42 Flashcards
Ventilation
air or water moves through specialized
gas-exchange organ (lungs or gills, etc
Gas exchange
CO2 & O2 diffuse between air or water
& blood at respiratory surface
circulation
dissolved O2 & CO2 are transported
throughout body
Where gas exchange (diffusion) between blood and cells occur
Tissues where cell respiration occurs
How does gas exchange occur between environment and cells
Diffusion since
Oxygen is high in environment; low in tissues
Carbon dioxide is high in tissues; low in environment
Gills
outgrowths of body surface in aquatic animals
Have extremely large surface area for gasses to diffuse across extremely thin epithelium
Invertebrate gills
diverse; can be external or internal
Bony fish gills
Have internal gills on both sides of head
Water must be driven over them
How do fish ventilate gills
by opening & closing their
mouth & operculum (stiff flap over gills)
Ram ventilation
Process where fast swimmers force water through gills by swimming with
mouths open
Countercurrent
exchange system
Flow of blood
through capillaries is
in opposite direction
to flow of water over
gill surface; sets up
What does Countercurrent exchange system create
large pressure differences of oxygen & carbon dioxide in water vs blood
result is efficient exchange of gases over gills!
Insect tracheal system
Contains tracheae-series of tubes extending throughout body; connects to exterior through openings (spiracles)
Trachae allow gas exchange to take
place directly across cells’
plasma membranes; circulatory
system NOT involved
Vertebrate lung process
- Air enters through lungs
- Trachea carries inhaled air to tubes called bronchi; bronchi branch into even narrower tubes (bronchioles)
Bronchi lung structure
Mammal lungs divided into tiny sacs called alveoli that greatly increase surface area for gas
Negative pressure ventilation
Occurs in only mammals
Pumping action achieved by muscle - diaphragm
Inhalation: Diaphragm contracts, ribcage expands as rib muscles contract
Exhalation: Diaphragm relaxes (moves up) as rib muscles relax
Functions of blood
-Transport oxygen & carbon dioxide
– Transport nutrients to cells from digestive system
– Convey hormones to target tissues & organs
– Deliver cells of immune system
– Distribute heat
Structure of blood
- Platelets- cell fragments that minimize blood loss
– White blood cells (WBCs)- part of immune system
– Red blood cells (RBCs) transport oxygen from lungs to body tissues; participate in transporting carbon dioxide from tissues to lungs
Hemoglobin
Oxygen carrying molecule in red blood cells
Consists of four polypeptide chains, each has iron (Fe2+) containing group (heme)
Each hemoglobin can bind up to four O2 molecules
Carbonic anhydrase
Catalyzes the formation bicarbonate ions & hydrogen ions from Co2
Important because it maintains a strong partial pressure gradient favoring the entry of more CO2 into the red blood cells
How is CO2 transportaed in the plasma
It is transported in form of bicarbonate ion, HCO3−
What do protons produced by carbonic anhydrase do?
Induce Bohr shift, or acidity makes hemoglobin more likely to release oxygen
How does Pco2 in blood drop?
when CO2 converted to bicarbonate, maintaining strong partial pressure gradient favoring entry of Co2 into RBCs
How tiny and large animals maximize diffusion
- Tiny animals have small enough volume that diffusion over body surface is adequate to keep them alive
– Larger animals require a circulatory system in order to achieve a large ratio of surface area to volume
What are walls of arteries or areries made of
Smooth muscle tissue since it allows for elasticity of vessels
Aorta
Largest artery; receives blood directly from heart