Chapter 44

the general process by which animals control solute concentrations and balance water gain and loss

an animal that's isoosmotic with its surroundings; marine vertebrates: drink a lot of salt water and then use gills and kidneys to remove it from their system

controls its internal osmolarity independent of that of its environment; ex: freshwater animals, drink almost no water and excrete large amounts of dilute urine

excretory tubule collects a filtrate from the blood; water and solutes are forced by blood pressure across the selectively permeable membranes of a cluster of capillaries and into the excretory tubule

the transport epithelium reclaims valuable substances from the filtrate and returns them to the body fluids; occurs most in the proximal tubule

other substances, such as toxins and excess ions, are extracted from body fluids and added to the contents of the excretory tubules

the altered filtrate (urine) leaves the system and the body

renal artery; renal vein

functional unit of the kidney; consists of a single long tubule and a ball of capillaries called the glomerulus (surrounded by bowman's capsule)

water and small solutes (ex: salts, glucose, amino acids, vitamins, nitrogenous wastes, & other small molecules) but NOT to blood cells or large molecules like plasma proteins

have loops of Henle that descend deeplu into renal medulla; enable mammals to produce urine that is hyperosmotic to body fluids

blood vessels that surround the afferent and efferent arterioles of the nephron

blood vessels that surroud the loop of Henle in the nephron; each ascending portion lies adjacent to the descending portion of the loop of Henle; there is no direct exchange between the two

results from the body's failure to produce insulin; insulin PROMOTES uptake of glucose, so if there's a failure to produce there will be a lot of glucose in the blood (= hyperglycemia)

results from insulin resistance, a condition in which cells fail to use insulin properly

incrases absorption of water by increasing the number of aquaporins molecules in distal tubules and collecting ducts; released in response to salti/solutiness (increased osmolarity); makes their epithelium MORE permeable to water; made by the hypothalamus but STORED in the posterior pituitary; controlled by negative feedback

increased urination/diluteness of the urine; ADH is called the antidiuretic hormone because it opposes this dilute state

• -the release of ADH and
• -the reabsorption of sodium