The Kidney Flashcards
What is the functional unit of the kidney?
The nephron, which is the tube system spanning the renal cortex and medulla of the kidney; there are approximately 1 million nephrons in the human kidney; it consists of a tubule and associated vascular component
What are renal pyramids?
divisions of the medulla in larger mammals
What is the function of the renal pelvis?
Drainage system in the centre of the kidney; connecting ducts fuse to form the renal pelvis
What is the function of teh nephron and what are the three basic processes?
Responsible for the formation of urine; 1. glomerular filtration; tubular reabsorption; tubular secretion
What is glomerular filtration?
First step in urine filtration; separates the plasma fraction of the blood; the driving force of separation is hydrostatic pressure; small plasma solutes, such as waste products or useful molecules pass through, but no cells enter the ultrafiltrate; also, unless blood pressure is very high, very few proteins will travel into the ultrafiltrate
What are the forces are involved in glomerular filtration?
Glomerular capillary blood pressure (higher pressure in the blood, so it wants to move out into the nephron); plasma colloid osmotic pressure (high concentration of proteins wants to pull water back into the blood??); Bowman’s capsule hydrostatic pressure (fluid in the glomerulus pushes back on the fluid trying to exit the capillaries);
What is the purpose of the proximal convoluted tubule?
Reabsorption of 65% of filtered water, 67% of filtered sodium, and glucose and amino acids; secretion of protons for acid/base regulation, and organic molecules
How does glucose go from the primary urine into the blood?
Through the proximal convoluted tubule; there exists glucose/sodium symporter which helps glucose diffuse into blood (lower glucose conc in blood than primary urine)
What is renal threshold?
The point where proximal convoluted tubule glucose-sodium symporters are saturated, and no more glucose can be reabsorbed into the blood, so it starts to appear in the urine
What is the purpose of the distal convoluted tubule?
To regulate Na and K in the blood
How is sodium transport regulated in the DCT?
Controlled by aldosterone
How is permeability to water controlled in the DCT?
Controlled by antidiuretic hormone (ADH)
How does the collecting duct decide whether water should be retained or expelled?
Antidiuretic hormone will be released in the case of the dehydration; if water should be expelled, no hormones will act upon the appropriate receptors and thus water will be expelled
What roll does vasopressin play in the nephron?
Changes the permeability of the nephron to water; if one is dehydrated, the collecting duct must be permeable to water so water can enter into the medulla; if one is hydrated the water should stay in the collecting duct to be excreted, so therefore the collecting duct becomes impermeable to water
What is the danger of ammonium in the body?
Affects intracellular pH; also substitutes for K+ in Na/K ATPase activity; uncouples oxidative phosphorylation by abolshing the proton gradient across the inner mitochondrial membrane; also affects membrane potential; also increases glutamate synthesis, which is a neurotransmitter, and can have several effects on the CNS
How is ammonia excreted in ammonotelic animals?
In invertebrates it diffuses out of the body into surrounding water; NH3 is membrane permeable and NH4 is membrane impermeable…?; in fish, it is excreted out of the gills and a little from the kidneys; not all aquatic animals excrete ammonia
How do urecotelic animals excrete ammonia?
By combining it with bicarbonate into urea; less toxic than ammonia, and less soluble, so it can be excreted using smaller amounts of water
How do uricotelic animals excrete ammonia?
It is formed into uric acid, which precipitates and can be excreted with very little water; non-toxic but it requires a lot of energy; good for animals with limited availability of water
What produces the osmotic gradient?
Loop of henle
Know that the cortical nephron has a short loop of henle and does not go deep into the medulla; contributes only slightly to formation of primary urine
Ye
Know what we focused on is the juxtamedullary nephron
Ye
What is the renal corpuscle?
Glomerulus and glimerular capsule
How does urea contribute to the osmotic gradient?
Build up in the collecting duct and then leaks out and goes into loop of henle (to bring more water in?)
What kind of exchange is the vasa recta?
Countercurrent–maintains osmotic gradient
