lecture 7_excretion and osmoregulation
DESCRIPTION
Biology 11 Lecture Excretion and OsmoregulationTRANSCRIPT
Lecture 7. Excretion and Osmoregulation
• maintenance of the volume and composition of extracellular fluid
• removes metabolic wastes from the bloodstream
Osmoregulation
• maintenance of proper internal salt and water concentrations in a cell or in the body of a living organism
• active regulation of internal osmotic pressure
Fig. 30.2
Fig. 30.3
• anhydrobiosis, dormant state when habitats dry up– tardigrades or water bears
Animal Nitrogenous
Wastes
Excretory Organelle
Contractile vacuole• Tiny, spherical, intracellular vacuole found in
protozoa• Expels excess water gained by osmosis
Excretory Organelle
Contractile vacuole
Protonephridia• branching network of
dead-end tubules• found in flatworms,
rotifers, some annelids, larval mollusks, and lancelets
• closed system
Excretory Organs
Metanephridia
Excretory Organs
• Found in annelids, molluscs, and other phyla• Made of tubules that are open at both ends• Surrounded by a network of blood vessels that
assists in reclamation of water and valuable materials such as salts, sugars and amino acids
Metanephridia
Excretory Organs
Excretory Organs
Antennal gland• Found in crustaceans
Malpighian tubules
Excretory Organs
• Found in insects
Kidneys
Excretory Organs
Fig. 30.9a
Fig. 30.9b
Nephron• Basic functional
unit of the excretory organ in vertebrates
Physiological Processes in the Formation of Urine
Regulation of Excretion
juxtaglomerular apparatus (JGA)
renin-angiotensin-aldosterone system (RAAS)
Low homeostatis
(blood protein) (from liver)
Antidiuretic hormone(promotes water conservation in liver)
• atrial natriuretic factor (ANF), hormone that opposes the RAAS– released by the walls of the atria in response to an
increase in blood volume and pressure– inhibits the release of renin from the JGA– inhibits NaCl reabsorption by the collecting ducts– reduces aldosterone release from the adrenal
glands– these actions lower blood pressure and volume