Kidney Flashcards
What homeostasis regulates and what doesn’t?
Endotherms regulate. Ectotherms do not.
What is the difference between hyper osmotic and hypo osmotic
Hyper osmotic contains less water. Hypo osmotic contains more water.
What are the three important regulatory functions of the kidney?
Removal of nitrogenous waste, osmoregulation- regulation of water content, regulation of salt balance
What nephrons hold high urine concentration? Low urine?
Juxta-medullary is high. Cortical is low.
How does fluid get started flowing in the bowman’s capsule?
The hydrostatic pressure (Blood pressure) forces fluid through glomerular capillaries
What prevents movement of large particles in kidney?
Pores in endothelium, Podocyte pores
Why is blood pressure high in glomerular capillaries?
Low resistance input pathway in large diameter arteries, constriction of the arteriole, high resistance in several small capillaries?
What promotes filtration in kidney?
Glomerular hydrostatic force - 55mm
What opposes filtration in kidney?
Capsular hydrostatic pressure- 15mm, glomerular colloid osmotic -pressure- 30mm
What is the glomerular filtration rate?
125ml filtered in the kidney per minute
What tubules do reabsorption and secretion occur in?
Proximal and distal convoluted tubules.
How do kidneys regulate the concentration of a substance in the blood?
Renal threshold mechanism
What is the countercurrent heat exchange?
Veins and arteries travel very close together. Heat from the arteries is absorbed by the veins, the blood in veins near center are almost as warm as body core.
What is the countercurrent multiplier?
Salt is continuously lost by active transport, salt drops down hairpin loop, is absorbed by other side of hairpin loop, concentration is high in lower areas and not so much in top area.
How is NaCl transported in the hairpin system?
NaCl is actively transported through thick segment, lower to the thin segment, it is facilitated diffusion.
What is the osmotic response in the loop of Henle?
Water leaves by osmosis, drawn by the high concentration of NaCl .
What happens in the collecting duct?
Some urea leaves, maintaining high osmotic pressure in medulla. Water leaves by osmosis.
What nephrons do reptiles have?
Reptiles only have cortical nephrons, can only produce isosmotic urine.
What is the function of a freshwater fish kidney?
Large volume of dulite urine, no loop of Henle. Absorb and loose salts through gills.
What is the function of a salt water fish kidney?
Hypo osmotic kidney- danger of gaining salts and dehydrating. More osmoregulation done In gills than kidneys.
How do mammals respond to dehydration?
Stimulus in rise of osmolarity is received by the hypothalamus, ADH released from posterior pituitary, increase in water collection in collecting duct.
What is the job of ADH?
Binds to receptors and increases permeability in the collecting ducts.
How do mammals respond to over hydration?
Decreases stimulation in hypothalamus, inhibits ADH release, stretch receptors in Aorta and Arteries further inhibit ADH.
