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BMS 300 > Exam 4--kidney > Flashcards

Exam 4--kidney Flashcards

1
Q

what do the kidneys do?

A
  • remove nitrogenous waste in the form of urea
  • maintain fluid volume in the body
  • excrete or maintain salts as needed
  • contribute importantly to maintaining blood pH
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2
Q

what is the basic functional unit of the renal system

A

nephron

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3
Q

what does the beating of the heart do for the kidneys?

A

produces a hydrostatic pressure that forces the fluid out of the capillaries in the glomeruli

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4
Q

how does the kidney receive blood?

A

renal artery

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5
Q

what drains the kidney?

A

renal vein

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6
Q

how fast do the kidneys receive blood?

A
  • 1200ml/min

- 20-25% of blood flow goes into the kidneys

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7
Q

how is the kidney organized?

A
  • a cortex

- a medulla

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8
Q

where is the blood from the renal artery delivered to?

A

the cortical region of the kidney

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9
Q

what are the different parts of the nephron?

A
  • glomerulus
  • Bowman’s capsule
  • the ascending and descending limb
  • distal convoluted tubule
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10
Q

what does the distal convoluted tubule empty into?

A

the collecting duct, which is not a part of the nephron

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11
Q

where is the glomerulus encapsulated?

A

in bowman’s capsule (glomerular capsule) and it is made up of epithelial cells called podocytes

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12
Q

what is bowman’s capsule made up of?

A

podocytes

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13
Q

what causes the fluid to be forced out of the glomerular capillary?

A

hydrostatic pressure or blood pressure (55mmHg)
-the gaps between the endothelial cells of the capillary are sufficiently large to permit water ions and small molecules such as glucose and amino acids to pass easily from the blood into Bowman’s capsule–the formed elements and plasma proteins are mostly retained in the capillaries

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14
Q

albumin

A

major protein in blood plasma which remains in the glomerular capillary and creates an osmotic pressure (30mmHg) that permits water to reenter the glomerular capillary from Bowman’s capsule

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15
Q

what does the collection of fluid in Bowman’s capsule create?

A

hydrostatic pressure (15mmHg) which forces water out of the capsule

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16
Q

net filtration pressure

A

10mmHg
[55(30+15)]
causes the net movement of fluids and solutes –ions, glucose, amino acids, and urea from the capillary into the capsule

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17
Q

glomerular filtration rate (GFR)

A
  • rate at which fluid moves from the glomerulus into Bowman’s capsule
  • normally this is about 125 ml/minute
18
Q

what does the normal function of the kidney require?

A

that hydrostatic pressure in the glomerulus remain constant

19
Q

myogenic regulation

A
  • relies on the tendency of smooth muscle to contract when stretched
  • increases in systematic blood pressure stretch smooth muscles in the renal arteries and arterioles causing them to contract and restrict the diameter of the artery
  • this reduces the amount of blood flowing into the kidneys
  • thereby reduces blood pressure in the renal arteries to ultimately reduce the pressure in the glomerular capillaries
20
Q

macula densa

A
  • located in the distal convoluted tubule near its junction with the afferent arteriole and Bowman’s capsule help control GFR
  • monitor the osmolality of the filtrate in the nephron and release molecules that regulate the degree of constriction of the afferent arterioles
  • helps maintain a constant GFR
21
Q

dilution of the afferent renal arteries

A

increases blood flow and blood pressure in the glomerulus to increase GFR and vice versa

22
Q

juxtaglomerular cells

A
  • modified smooth muscle cells
  • regulate blood pressure both in the kidney and systematically
  • regulates blood flow to the glomerulus
  • located mostly on the afferent arterole
  • release renin
23
Q

renin

A
  • released by the juxtaglomerular cells
  • an enzyme that leads to vasoconstriction through the production of angiotensin 2
  • causes constriction of the efferent arteriole to increase hydrostatic pressure in the glomerulus
  • increases the release of aldosterone from the adrenal cortex–increases Na+ resorption from the distal convoluted tubule and increases blood volume
24
Q

where does bowman’s capsule lead to

A

the proximal convoluted tubule

25
Q

proximal convoluted tubule

A
  • return of water, glucose, amino acids, and ions from the nephron begin returning
  • this is called resorbtion
  • about 65% of the Na+ and water is resorbed here
  • lined by a simple epithelium–apical in the lumen and basilar adjacent to basal lamina
26
Q

how does sodium move into the proximal convoluted tubule

A
  • diffuses down its concentration gradient from the filtrate into the epithelial cells of the convoluted tubule (Na channels)
  • moves into epithelial cells by a cotransporter
27
Q

Na+ driven cotransporters

A

when a transport protein on the apical surface of the epithelial cells binds a Na+ ion and a molecule of glucose at the same time which leads to a conformational change in the shape of the molecule so that the Na+ and the glucose are both transported across the epithelial cell membrane into the epithelial cell
-amino acids are also cotransported this way

28
Q

paratubular capillaries

A
  • surround the proximal convoluted tubule
  • after the amino acids and glucose diffuse out through the basilar membranes into the interstitial space they then diffuse into the paratubular capillaries
  • ion concentrations are low because much of the solutes were forced out of the capillaries in the glomerulus
29
Q

Na/K ATPase

A

-pump the Na+ out of the epithelial cells across the basilar membrane into the interstitial fluid

30
Q

proximal convoluted tubule–

A

the descending limb

31
Q

the descending limb

A
  • the epithelial cells contain many aquaporins

- the apical membrane is nearly devoid of ion channels making the membrane nearly impervious to the movement of ions

32
Q

medulla of the kidney

A
  • an ionic gradient is established
  • the ionic concentration increases as it dips into the medulla because water leaves the descending limb and enters the interstitial space
33
Q

hairpin turn

A

-the ionic concentration in the filtrate reaches about 1200 milliosmoles

34
Q

the ascending limb

A
  • impermeable to water
  • permits ions to cross
  • the ionic concentration of the filtrate falls as it ascends the tubule
35
Q

what are the two hormones the distal convoluted tubule is affected by

A
  • aldosterone

- antidiuretic hormone (ADH)

36
Q

aldosterone

A
  • produced by adrenal cortex regulates the resorbtion of Na+
  • affects epithelial cells in the distal convoluted tubule–it induces Na+ channel production and insertion in the apical region of the tubular epithelial cells
  • increases the synthesis of Na/K Pase in the basolateral membrane
  • pump Na+ out of the epithelial cells of the distal convoluted tubule and into the interstitial space
  • the net effect is to transfer Na+ from the tubule into the paratubular capillaries
  • steroid hormone
37
Q

ADH

A
  • the permeability of the collecting ducts to water is under the control of ADH
  • released from the posterier pituitary and regulates the incorporation of aquaporins into the epithelial cells in the distal convoluted tubule and in the collecting ducts
  • little ADH=little water leaves the collecting ducts=dilute urine
  • great deal of ADH=water leaves the collecting ducts and consequently concentrates the ions that remain in the collecting ducts–concentrated urine is produced
38
Q

cortico-medullary gradient

A
  • extends from the cortex into the medulla of the kidney
  • 1200milliosmoles deep in the medulla
  • maintained by the loop of henle and the vasa recta which leads to the movement of ions, h2o, and urea into the ascending and descending help establish the gradient
  • can’t be maintained without the vasa recta
39
Q

vasa recta

A
  • extension of the tubular capillaries that extend deep into the medulla
  • is little hydrostatic pressure and the blood moves very smoothly
  • osmolality in the vasa recta is nearly the same as the interstitial fluid
40
Q

urea

A
  • as urine moves through the deep medullary regions, urea reaches equilibrium with the interstitial fluid
  • water leaves the tubule through aquaporins and the remaining ions are destined to enter the bladder
  • remains in the tubule until it reaches the deep medullary regions where the tubular epithelial cells are permeable to urea

BMS 300 (5 decks)

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