Chpt. 44
Osmoregulation & Excretion
Julianna Diddle
Ethan Coombes
• Where is homeostasis regulated in mamals vs.
reptiles?
–Regulated internally = MAMMALS
--Regulated externally = REPTILES
• What is an osmoconformer?
-An animal that doesn’t actively adjust its internal osmolarity
• What is an osmoregulator?
–An animal that must control its internal osmolarity because its
body fluids are not isoosmotic with the outside environment
-hyperosmotic
-saltwater
-ioosmotic
-hypoosmotic
-freshwater
• What special characteristics do
anhydrobiotic animals have?
–They can lose almost all body water
& survive in a dormant state if their habitats dry up.
• What are the three types of nitrogenous
waste, what is different about them, and
what is an animal that excretes each type?
–Ammonia(NH3)
-most toxic
-Excreted by aquatic animals
–Urea
-low toxicity
-Requires less water to dilute &
can store large quantities
-Mamals, adult amphibians,
sharks, some bony fish, & turtles
--Uric Acid
-Least toxic
-Insoluble
-Can be excreted with little water
loss but energetically expensive
-Insects, land snails, many
• What are the four main steps of the
excretory process?
1.
2.
3.
4.
Filtration
Reabsorption
Secretion
Excretion
Kidney
Renal vein
Renal Artery
Ureters
Urinary Bladder
Urethra
• What is the functional unit of the kidney?
(1,000,000/kidney in humans)
–Nephron
• What is the pathway of filtrate after leaving
the glomerular capsule?
–Proximal tubule, loop of Henle (descending & ascending loops), distal tubule,
collecting duct, renal pelvis, ureter
• What are the two types of nephrons?
1.) Juxtamedullary
Extend into medulla, important
for
water conservation
2.) Cortical
Loop of Henle stays in the cortex
• What is the pathway for blood supplying
each nephron?
–Afferent arteriole, glomerular capillaries, Efferent arteriole,
peritubular capillaries, vasa recta
• Systems that expend energy to create
concentration gradients are –.
–Countercurrent multiplier systems
• What is the hormone that regulates water
balance & increases collecting duct
permeability to water
–Antidiuretic Hormone (ADH)
• What is the condition of increased
urination called?
-Diuresis
• What does the RAAS do?
(Renin-Angiostentin-Aldosterone System)
-Works with the Juxtaglomerular
apparatus (JGA) to drop blood
pressure & blood volume & triggers
JGA to release renin
-Angiostentin II & Aldosterone reduce
renin secretion in response to JGA
• What is the peptide hormone that opposes
RAAS & is released by the atria of the heart
in response to increased blood volume &
pressure?
–Atrial Natriuretic Factor (ANF)
• What is osmoregulation?
–Solute balance & gain or loss of water
• What is excretion?
-Elimination of nitrogenous wastes