Countercurrent Multiplier Systems
-loop of Henle expends energy to actively transport NaCl from filtrate in the upper part of
ascending limp of loop (Expends energy to create concentration gradients)
-animals have long loops of
-Some organisms have adaptations for osmoregulation (control of water balance) allowing
them to survive in hypertonic or hypotonic environments.
-wall maintain he cells water balance.
-the inelastic wall will expand only so much before it exer
Pinocytosis (cellular drinking)
-cell gulps droplets of extracellular fluid (liquid!) into tiny vesicles. The molecules dissolved in
the droplets are needed.
-It is nonspecific in the substances it transports!
-there are memb
-enzymes remove nitrogen in form of ammonia from breakdown products of proteins and nucleic
-can be tolerated only at low concentrations, must need a lot of water (highly soluble)
-common in aquatic species, some lost as a
Neuron Structure and Function
(highly branched extensions that receive signals from other neurons)
(organelles and nucleus)
(extension that transmits signals to other cells, branches)
(region where axon joins cell
-voltage (electrical potential energy, a separation of opposite charges) across a membrane.
-the cytoplasm is negative in charge relative to the extracellular because of unequal amounts of
anions and cations.
-membrane potential favors
-also stimulates release of aldosterone (acts on distal tubules, making them reabsorb more
sodium and water to increase blood volume and pressure)
-drugs block angiotensin are used to treat hypertension (high blood pressure)
Homeostatic Regulation of Kidn
-Osmoregulators lose water by osmosis through gills/other body surfaces but drink large
amounts of seawater and use gills and kidneys to get rid of salts (chloride cells in gills actively
transport Cl- out and Na+ follow passively)
-salts/urea/TAMO in sha
1. Proximal Tubule: reabsorption, NaCl diffuses into cells of transport epithelium, Na+ is
actively transported into interstitial fluid
-drives passive transport of Cl-water follows by osmosis
-salt and water go from interstitial fluid to
-form network of dead-end tubules connected to external openings, cilia projecting into tubule
-beating of cilia draws water and solutes from the interstitial fluid through flame bulb, releasing
filtrate into tubule network