Transcript Chapter 42: Circulation and Gas Exchange

Circulation and Gas Exchange
Circulation in Animals
Gas Exchange in Animals
Circulation in Animals
 Transport systems necessary to connect body parts
with organs of exchange
 Critical component to maintaining homeostasis
 Gastrovascular cavity in flatworms and cnidarians
 Open vs. closed systems
 Cardiovascular systems accommodate gills and
lungs
Evolution of the Heart
• Fish: two chambers, one atrium, one ventricle
• Amphibians: larval stage-two chambers
adult stage-three chambers, two atria, one ventricle
• Reptiles: three chambers, most partially divided
ventricle
• Birds and Mammals: four chambers, two of each,
complete separation of oxygenated and
deoxygenated blood
AMPHIBIANS
REPTILES (EXCEPT BIRDS)
MAMMALS AND BIRDS
Lung and skin capillaries
Lung capillaries
Lung capillaries
FISHES
Gill capillaries
Artery
Pulmocutaneous
circuit
Gill
circulation
Heart:
ventricle (V)
A
Atrium (A)
Systemic
circulation
Vein
Systemic capillaries
A
V
Left
Right
Systemic
circuit
Systemic capillaries
Right
systemic
aorta
Pulmonary
circuit
A
V
Right
Pulmonary
circuit
Left
Systemic
aorta
V
Left
A
Systemic capillaries
A
V
Right
A
V
Left
Systemic
circuit
Systemic capillaries
Arteries, Veins, and Capillaries
• Arteries-blood away from the heart, smooth
muscles, diameter able to be regulated
• Veins-blood back to the heart, little
elasticity, contain valves
• Capillaries-functional unit of the circulatory
system, all exchanges occur within the
capillaries, arterioles, and venules
Blood Pressure
• Hydostatic force that the blood exerts
against vessel wall
• Greatest in arteries
• Responsible for movement of fluid (plasma)
out of the capillaries (arterioles), returns in
venules (osmosis and diffusion)
• Lowest in veins
Blood: Plasma and Cells
Plasma
• Water-90%
• Electrolytes-inorganic
salts
• Proteinsimmunoglobulins,
fibrinogens
• Nutrients, metabolic
wastes, respiratory gases,
and hormones
Cellular elements-produced
by pluripotent stem cells
• Erythrocytes-red blood
cells (RBC), oxygen
transport, lack nuclei,
mitochondria, 3-4 months
• Platelets-blood clotting,
cell fragments
• Leucocytes-white blood
cells, immunity
Gas Exchange in Animals
• O2 and CO2 exchange between animal and
environment
• Air or dissolved in water is the source of O2
• Respiratory surface: large, moist,
permeable, vascularized
• Body surface, gills, lungs, tracheal systems
• Countercurrent exchange
Mammalian Lungs
• Alveolus-functional unit
• Exchange is through diffusion, dependent
upon partial pressure of O2 and CO2
• POO2= 160 mm Hg
• POCO2=0.23 mm Hg
Oxygen and Carbon Dioxide
Transport
Oxygen Transport
• Utilizes respiratory
pigments: hemocyanin in
some invertebrates,
hemoglobin in most
vertebrates
• Hemoglobin exhibits
cooperativity
• Hb affinity for O2 altered
by pH (Bohr Shift)
CO2 Transport
• Transported in three
forms:
1. Dissolved in plasma
(7%)
2. Bound to Hb (23%)
3. Bicarbonate ion in
the plasma (70%)