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Define Excretion
The removal from the body of waste products of metabolic pathways
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Draw and label a diagram of the kidney
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Annotate a diagram of a glomerulus and associated nephron to show the function of each part
 - 3) Afferent arteriole: brings blood from renal arteriole to the glomerulus
- 2) Glomerulus: ultrafiltration; a ball of fenestrated capillaries that produces the initial filtrate
- 4) efferent arteriole: connects the glomerulus to the peritubular capillaries; blood more concentrated
- 9) Vasa recta: capillaries that serve the loop of Henle and exchange water with it by countercurrent exchange
- 1) Bowman's capsule: collects filtrate expelled from the glomerulus
- 5) Proximal convoluted tubule- reabsorbs glucose, water, HCO3- and salt from the filtrate; secretes H+ and ammonia for pH balance
- 8) Loop of Henle: (descending) water is reabsorbed, (ascending) salt is reabsorbed (both passively and actively
- 6) Distal convoluted tubule: reabsorbs Na+, Cl-, Ca2+ HCO3- and water; secretes H+ K+ and NH3
- Blood vessels in sequene (3,2,4,9), followed by nephron components in sequence (1,5,8,6,7)
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Explain the process of ultrafiltration, including blood pressure, fenestrated blood capillaries and basement membrane
- Ultrafiltration occurs as high blood pressure (hydrostatic) forces fluid from the glomerulus into the lumen of the Bowman's capsule. Blood pressure is high due to proximity to aorta
- Proteins and blood cells are too large to fit through the fenestrations (pores/openings) in the blood capillaries
- Basement membrane: semi permeable tissue with podocytes that is permeable to water/small molecules but no proteins
- Initial filtrate identical to blood plasm except it lacks proteins and red blood cells.
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Define osmoregulation
control of water balance of the blood, tissue, or cytoplasm of a living organism
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Explain the reabsorption of glucose, water, and salts in the proximal convoluted tubule, including the role of microvilli, osmosis, and active transport
- Active: salt and nutrients, such as glucose, are actively transported into the endothelial cells lining the proximal tubule
- Microvilli of the endothelium increase surface area for transport
- Water and bicarbonate passively follow the salts and nutrients (by diffusion and osmosis)
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Explain the roles of the loop of Henle, medulla, collecting duct, and ADH in maintaining the water balance of the blood
- the medulla is hyperosmotic to the filtrate (has a higher solute concentration by comparison)
- the water moves out of the descending loop Henle by osmosis
- the thin segment of the ascending loop of Henle is permeable to salt, which diffuses out
- the thick limb actively transports salt out to maintain the high solute concentration of the medulla
- the loop of Henle passes through the very hyperosmotic inner medulla, allowing water to be removed from the filtrate by osmosis
- Water leaves the collecting duct by osmosis, concentrating the urine as it passes through the medulla
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Explain the differences in the concentration of proteins, glucose, and urea between blood, plasma, glomerular filtrate, and urine.
- Protein: Proteins are unable to fit through the pores of the glomerular capillaries and are absent from the filtrate (remain in blood)
- Glucose: present in the filtrate, but reabsorbed in the proximal convoluted tubule
- Urea: not reabsorbed, leading the high concentration of urea in the urine (some diffuses out into medulla)
- Glucose: concentration is equal in blood plasma and initial filtrate and should be absent from the urine
- Proteins: found in blood plasma only (do not pass through the basement membrane)
- Urea: concentration is greatest in urine, initially present in filtrate and blood plasma where it is equal
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Explain the presence of glucose in the urine of untreated diabetic patients
- Insulin signals body cells to remove glucose from blood plasma. So in the absence of insulin, glucose is not removed by cells and builds up in the plasma
- High plasma levels of glucose in diabetic patients prevent complete reabsorption of glucose in the proximal tubules
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