Physiology exam 4 part 2
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What is diabetes mellitus? Why does it cause frequent
urination, thirst, and dehydration? What causes type 1 diabetes mellitus? Type 2 diabetes mellitus?
- - Blood glucose level is above normal "hyperglycemia" and exceeds renal threshold
- Type 1: pancreas is defective, doesn't make insulin.
- Type 2: cells have become resistant to the effect of insuline due to too much glucose
- -less water is being reabsorbed from the filtrate into the blood "osmotic diuresis"
What components are reabsorbed from the proximal convoluted tubule?
What are the nonreabsorbed filtrate components?
- 1) Most water, Most Nutrients (glucose), Required salts (ions), like sodium and chloride
- 2) Some Water, Much nitrogenous waste, Excess salts (ions)
What kinds of substances are moved from the capillaries into the kidney tubules? How does this occur?
- Hydrogen ions H+, creatinine, and drugs- like penicillin
- active transport and carrier proteins
What happens to substances that are in large concentrations
in the blood?
How can the retention of pencillin be increased?
- too high of concentration may have difficulty leaving blood and entering kidney this way
- penicillin levels in blood can be prolonged by administering it simultaneously with probenecid (competes for the same tubular carrier proteins)
What is in urine?
What happens to the fluid in the collecting ducts?
- Urin contains substances that have undergone glomerular filtration but have not been reabsorbed AND substances that have undergone tubular secretion
- Fluid in the collecting ducts goes to the renal pelvis and is now called "urine"
What happens to most of the water in the filtrate?
Where is water reabsorbed?
What always precedes the reabsorption of water?
How is water reabsorbed?
What are aquaporins?
- Most of the water is reabsorbed into the blood before urine leaves the body
- Water is reabsorbed at all parts of the nephron and the collective duct
- The reabsorption of salt always precedes the reabsorption of water. (water is returned to the blood by the passive process of osmosis)
- Aquaporins are water channels within a plasma membrane protein
Where in the nephron is most of the water reabsorbed? Are the aquaporins open or closed?
- 65% of the water is reabsorbed from the nephron into the blood at the proximal convoluted tubule.
- The aquaporins are always open in the proximal convoluted tubule (water is reabsorbed osmotically into the blood)
What regulates the reabsorption of sodium and
water in the distal convoluted tubule and the collecting duct?
What causes the secretion of adolsterone?
What organ secretes it?
What does aldersterone promote the excreation of?
The reabsorption of?
- Renin is an enzyme that leads to the secretion of adolsterone
- Adolsterone is a hormone secreted by the adrenal glands
What is the juxtaglomerular apparatus?
A region of contact between the afferent arteriole and the distal convoluted tubule (secretes renin, which in turn leads to the secretion of aldosterone by the adrenal glands)
Where is antidiuretic hormone made?
Where is it stored for later use?
- Made by the Hypothalamus
- Stored in the posterior pituitary gland
What does ADH do? What happens if our intake of water is low? High?
- ADH helps open aquaporins in the distal convoluted tubule
- -too low, ADH is secreted through numerous open aquaporins back into blood
- -too high, ADH secretion is reduced to close many aquaporins
What happens at the ascending limb of the loop of Henle?
What collects in the inner medulla?
- Salt (NaCl) passively diffuses out of the lower portion of the ascending limb
- high concentration of solutes
What is a diuretic
Increase the flow of urine
How does ethyl alcohol act as a diuretic? Caffeine? Diuretic
- Inhibits the secretion of ADH
- Caffeine increases the glomerular filtration rate and decreases the tubular reabsorption of sodium
- Diuretic drugs decrease the tubular reabsorption of sodium
What is the normal pH of body fluids? What is alkalosis and
- 7.4 is normal ph of body fluids
- alkalosis is if blood ph rises above 7.45
- acidosis is if blood ph decreases below 7.35
What happens if the H+ ion concentration of the blood rises?
the respiratory center in the medulla oblongata increases the breathing rate
What ion does the kidney excrete to regulate pH? What ion is reabsorbed as need to regulate pH?
Hydrogen ions are excreted and bicarbonate ions are reabsorbed
What happens if blood is to acidic? Basic?
- too acidic hydrogen ions are excreted and bicarbonate ions are reabsorbed
- too basic hydrogen ions are not excreted and bicarbonate ions are not reabsorbed
If the infection is localized in the urethra:
If the infection invades the urinary bladder:
If the kidneys are affected
What is damaged in diabetes insipidus? What hormone is lacking? What affect does this have one urination?
- Hypothalamus or Pituitary Gland
- the aquaporins in the distal convoluted tubule and collecting ducts close so these two portions of the nephron become impermeable to water (persons can urinate themselves to death)
What happens if renal calculi block the renal pelvis or
reverse pressure builds up and destroys the nephrons
What are the first signs of nephron damage?
albumin, white blood cells, or red blood cells in urine
What is uremia?
What are two way that edema can result?
- Uremia is extreme nephrone damage. More than 2/3 are inoperative, urea and other waste substances accumulate in the blood.
- Loss of plasma protein (typically albumin) decreases plasma osmotic pressure, and the accumulation of sodium causes increased blood pressure and fluid retension.
What is dialysis?
the diffusion of dissolved molecules through a semipermeable natural or synthetic membrane that has pore sizes that allow only small molecules to pass through
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