Lecture 22: GU System Flashcards
Describe the basic structure, function, and comparative anatomy of the nephron and its relationship to the blood vascular system
Functional unit of kidney is kidney tubule/ nephron
Functions:
-Filtration
-Selective reabsorption
-Secretion
Location: retroperitoneum
Close relationship btw aorta and kidneys b/c BP is driving force behind urination. Kidneys flank dorsal aorta.
Primitive nephron: dilute urine and N secreted form of ammonia-large nephron.
Marine teleost: ammonia is not excreted and less water filtered. Small nephron.
Glomeruli primitive nephron: supplied by arterial branches coming directly off dorsal aorta. Filtration occurs in coelom
Describe the 3 types of kidneys found in the phylogeny and ontogeny of living vertebrates
Pronephros: diffferentiate about 22 day gestation. Pronephric is non-functional and tubules are solid cords. But, it is req’d for rest of excretory system to develop. ONLY functional in larvae of fishes/amphibians and adults-primitive. Duct extends to cloaca. Pronephric duct becomes mesonephric duct. Purpose is to establish mesonephric duct. Degrades after.
Mesonephros: Functional kidney in most vertebrates. Filtration occurs btw glomerulus and the corpuscle now. Glomeruli still coming directly from aorta. Filtrate bypasses the coelom abd goes directly into the nephron. Renal corpuscle formed -bowman capsule. W/o pronephric duct growing caudally, mesonephric tubules will not form.
Metanephros: formation of final kidney. 5 week gestation. Metanephric tubules will not form w/o mesonephric duct.
Describe and compare the comparative anatomy of the urinary system in select vertebrates
Amphibians: primitive nephron. N eliminated-ammonia in larvae(pronephros) and urea in adults(mesonephros). Cloaca =well-developed.
Reptile: reduction in size renal corpuscle. Salt gland in orbit-not crying. Lizards/turtles excrete Uric acid. Crocodiles: eliminate N via ammonia.
Amniotes: mesonephros-larval; metanephros-adult. Cloaca is a primitve vertebrate feature. No urinary bladder
MAmmals: adult kidney is made up of metanephric nephrons. This incorporates the loop of henle- osmotic gradient responsible for most of the water reabsorption.
