UNIT 2 (Chapter 42 Circulation and Gas Exchange (42.4 Blood components…
Circulation and Gas Exchange
Blood components function in exchange, transport, and defense
Gas exchange occurs across specialized respiratory surfaces
Patterns of blood pressure and flow reflect the structure and arrangement of blood vessels
Breathing ventilates the lungs.
Coordinated cycles of heart contraction drive circulation in mammals.
Adaptations for gas exchange include pigments that bind and transport gases.
Circulation systems link exchange surfaces with cells throughout the body.
Osmoregulation and Excretion
Diverse excretory systems are variations on a tubular theme.
Most excretory systems carry out
The nephron is organized for stepwise processing of blood filtrate.
An animal's nitrogenous wastes reflect its phylogeny and habitat.
Protein and nucleic acid metabolism generates
Most aquatic animals excrete ammonia.
Mammals and most adult amphibians convert ammonia to the less
, which is excrete with minimal loss of water.
Insects and many reptiles, including birds, convert ammonia to
a mostly insoluble was excrete in a paste-like urine
The kind of nitrogenous waste excrete depends on an animal's evolutionary history and habitat.
The amount excreted is coupled to the animal's energy budget and dietary protein intake.
Hormonal circuits link kidney function, water balance, and blood pressure.
Osmoregulation balances the uptake and loss of water and solutes.
Cells balance water gain and loss through
Controlled movements of solutes between internal fluids and external environment and the movement of water.
Water-conserving excretory organs help terrestrial animals avoid desiccation, which can be life-threatening.
Animals that live in temporary waters may enter a dormant state callled
when their habitats dry up.
Isoosmotic with their marine environment and do not regulate their
They control water uptake and loss in a hypoosmotic or hyperosmotic environment, respectly.
Transport epithelia contain specialized epithelial cells that control the solute movements required for waste disposal and osmoregulation.