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physio > the kidneys > Flashcards

the kidneys Flashcards

1
Q

what is the most important function of the kidney

A

homeostatic regulation of the water and ion content of the blood (known as salt and water balance or fluid and electrolyte balance)

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2
Q

kidney functions can be divided into six general areas

A
  1. regulation of ECF volume and BP: decreased ECF lead to decreased BP
  2. regulation of osmolarity: maintain around 290 mOsM
  3. maintain ion balance: balance dietary intake with urinary loss
  4. homeostatic regulation of pH: by removing H+ and conserving bicarbonate ions
  5. production of hormones: synthesize erythropoietin for RBC synthesis
  6. excretion of wastes: remove waste products like creatinine, urea, and uric acid
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3
Q

urine production starts when

A

water and solutes move from plasma into the nephrons of the kidneys

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4
Q

nephrons

A

modify the fluid, when then becomes urine and moves into the ureters (tube that links a kidney to the bladder)

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5
Q

each kidney has a ureter that transports

A

urine to the urinary bladder

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6
Q

the bladder stores urine until it is expelled through the

A

urethra

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7
Q

women are more prone to urinary tract infections due to

A

the shorter urethra and proximity to bacteria from large intestine

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8
Q

what is the most common cause of UTIs

A

the bacterium e. coli found in the large intestine

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9
Q

the kidneys are responsible for urine formation and are located on

A

either side of the spine about the level of 11th and 12th ribs just above the waist. they are outside the abdominal cavity (retroperitoneal)

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10
Q

the concave surface of each kidney faces the

A

spine, where renal blood vessels, nerves, lymphatics, and ureters emerge

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11
Q

renal arteries

A

branching from the abdominal aorta, supply blood to the kidneys, while renal veins carry blood from the kidneys to the inferior vena cava (deoxygenated)

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12
Q

the kidneys receive how much of the cardiac output

A

20-25% highlighting the important of their high blood flow for renal function

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13
Q

the kidney’s interior is organized into two layers

A

an outer cortex and an inner medulla

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14
Q

nephrons

A

the functional units of the kidney, are microscopic tubules that form these layers

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15
Q

80% of nephrons are

A

entirely within the cortex (known as cortical nephrons)

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16
Q

the remaining 20% of the nephrons

A

extend into the medulla (juxtamedullary nephrons)

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17
Q

each kidney contain about how many nephrons

A

1 million

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18
Q

blood enter the kidney through

A

the renal artery, flows into smaller arteries then into arterioles in the cortex

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19
Q

the arrangement of blood vessels in the kidney forms

A

a portal system, consisting of two capillary beds inseries

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20
Q

gout

A

is a metabolic disease marked by high uric acid levels in the blood, causing inflammation and severe pain (in feet, ankles, and knees)

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21
Q

uric acid crystal (from gout) can also form

A

kidney stones in the renal pelvis

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22
Q

blood exits the glomerulus via

A

an efferent (away) arteriole and enters the pertubular capillaries, which surround the tubule

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23
Q

in juxtamedullary nephrons, the peritubular capillaries that extend into the medulla are called

A

vasa recta

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24
Q

peritubular capillaries converge to form

A

venules and small veins, which send blood out of the kidney through the renal vein

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25
Q

the renal portal system filters

A

fluid out of the blood into the nephron lumen at the glomerular capillaries and reabsorbs fluid from the tubule lumen back into the blood at the peritubular capillaries

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26
Q

the kidney tubule is composed of

A

a single layer of epithelial cells with apical surfaces folded into microvilli and the basal side resting on a basement membrane

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27
Q

cell to cell junctions in the tubule are mostly

A

tight but some allow selective ion permeability

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28
Q

where does the nephron start?

A

with bowman’s capsule, a hollow structure surrounding the glomerulus. the endothelium of the glomerulus is fused to bowman’s capsule, allowing fluid to pass directly into the tubule lumen

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29
Q

the renal corpuscle

A

is the combination of the glomerulus and bowman’s capsule

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30
Q

filtered fluid flow from bowman’s capsule into the proximal tubule then into the loop of Henle (a hairpin shaped segment divided into two limbs)

A

the two limbs has a descending limp and an ascending limb with thin and thick segments

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31
Q

fluid then moves into the distal tubule, which drains into a larger tube called

A

the collecting duct. the distal tubule and collecting duct together form the distal nephron.

32
Q

collecting ducts pass through

A

the cortex and the medulla, draining into the renal pelvis. from there urine flows into the ureter for excretion

33
Q

the nephron twists and fold, with the ascending limp of the loop of Henle passes between

A

afferent and efferent arterioles forming the juxtaglomerular apparatus. this allow form paracrine communication, crucial for kidney auto regulation.

34
Q

what are the three basic processes occurring in the nephron:

A

filtration, reabsorption, and secretion

35
Q

filtration involves the movement of fluid from the blood into the

A

lumen of the nephrons an occurs only in the renal corpuscle

36
Q

the filtered fluid enters the lumen of the nephron and is consider part of the body’s

A

external environment (substances in the filtrate are destines for excretion unless it’s reabsorbed)

37
Q

reabsorption move substances from the lumen of the tubule back into the blood in the

A

peritubular capillaries

38
Q

secretion selectively removes molecules from the blood and assed them to the

A

filtered fluids in the tubule lumen

39
Q

secretion is more selective than

A

glomerular filtration and typically involved membrane proteins to transport molecules across the tubule epithelium

40
Q

in the proximal tubule 70% of the filtrate volume is reabsorbed, the primary function

A

is the isosmotic reabsorption of solutes and water

41
Q

the loop of Henle reabsorbs more solute than

A

water making the filtrate hyposmotic and reducing its volume to 18 liters/day

42
Q

the distal tubule and collecting duct fin-tune salt and water balance under

A

hormonal control, determining the final urine volume and osmolarity

43
Q

secretion involves

A

moving solutes from plasma to the tubule lumen while excretion is the removal of substance from the body

44
Q

filtration occurs in the

A

renal corpuscle, while reabsorption and secretion happen along the tubule affecting the final urine composition

45
Q

the amount excreted in the urine is calculated as

A

amount excreted = amount filtered - amount reabsorbed + amount secreted

46
Q

filtration of plasma into the kidney tubule is the initial step in urine formation, producing a filtrate similar to

A

plasma but without plasma proteins

47
Q

blood cells typically remain in the

A

capillary, so the filtrate consists of mainly water and dissolved solutes

48
Q

only about one-fifth of the plasma entering the kidneys filters into the nephrons, the rest

A

including most plasma and blood cells, continues into the peritubular capillaries

49
Q

the filtration fraction is the

A

percentage of renal plasma flow that filters into the tubule

50
Q

filtration in the renal corpuscle involves three barriers:

A

the glomerular capillary endothelium, the basement membrane, and the epithelium of Bowman’s capsule

51
Q

the glomerular capillary endothelium is fenestrated (has windows)

A

allowing most plasma components to pass through while preventing blood cells form leaving. the glycocalyx negatively charges glycoprotein layer, repels negatively charged plasma proteins

52
Q

the basement membrane, an acellular extracellular matrix layer, contains

A

negatively charged glycoproteins and collagen, excluding most plasma proteins

53
Q

the epithelium of Bowman’s capsule consists of podocytes with foot precesses that interlace to form arrow filtration slits,

A

closed by a slit diaphragm containing proteins like nephrin and podocin. Mutation in these proteins can lead to congenital kidney diseases where proteins leak in the urine

54
Q

glomerular mesangial cells support the capillaries, influence

A

filtration by altering the surface area of filtration slits, and secretes cytokines involved in the immune and inflammatory responses. disruptions in the mesangial cell function are linked to kidney diseases

55
Q

diabetic nephropathy begins with increased

A

glomerular filtration, followed by proteinuria, indicating an altered filtration barrier. later stages filtration rates decline due to thickening of the glomerular basal lamina

56
Q

abnormal growth of mesangial cells compresses glomerular capillaries, reducing

A

blood flow and further decreasing glomerular filtration.

57
Q

patients with advanced diabetic nephropathy often require

A

dialysis and eventually may need a kidney transplant

58
Q

filtration across the glomerular capillaries is driven by three main pressures

A

capillary blood pressure, capillary colloid osomotic pressure, and capsule fluid pressure

59
Q

capillary blood pressure (Ph)

A

averages 55 mm Hg and favors filtration into Bowman’s capsule, maintaining a higher pressure than opposing forces along the capillaries.

60
Q

colloid osmotic pressure (pi)

A

inside the glomerular capillaries, averaging 30 mmHg is due to plasma proteins and favors fluid movement back into the capillaries

61
Q

hydrostatic fluid pressure (Pflu) in bowman’s capsule

A

averages 15 mmHg and opposes filtration by creating resistance to fluid movement into the capsule

62
Q

the net driving force for filtration is 10 mmHg which combined with leaky nature of the glomerular capillaries, results in

A

rapid fluid filtration

63
Q

glomerular filtration rate (GFR)

A

is the volume of fluid filtered into Bowman’s capsule per unit time, averaging 125 mL/min or 180 L/day

64
Q

the kidneys filter the entire plasma volume approximately

A

60 times a day, necessitating significant reabsorption to prevent plasma depletion

65
Q

GFR is influenced by net filtration pressure and the filtration coefficient, which depends on the

A

surface area of the glomerular capillaries and the permeability of the filtration slits

66
Q

filtration pressure is primarily determined by

A

renal blood flow and blood pressure

67
Q

the filtration coefficient is comparable to factors influencing gas exchange at the alveoli,

A

such as partial pressure differences, surface area, and permeability of diffusion barrier

68
Q

most reabsorption occurs in the proximal tubule with

A

additional reabsorption in the distal segments of the nephrons

69
Q

regulated reabsorption in the distal nephron

A

allows selective return of ions and water to the plasma to maintain homeostasis

70
Q

the high filtration rate (GFR) services two main purposes

A
  1. main foreign substances are filtered into the tubule and not reabsorbed, aiding rapid clearance from plasma
  2. desirable nutrients like glucose are filtered in large amounts but efficiently reabsorbed by transporters in the proximal tubule
71
Q

the filtrate in the proximal tubule has the same solute concentrations as

A

extracellular fluid, necessitating active transport to create concentration or electrochemical gradients

72
Q

active transport of Na+ from the tubule lumen to the ECF fluid creates a

A

transepithelial electrical gradient, making the lumen more negative than the ECF

73
Q

anions follow the positively charged Na+ out of the lumen, and

A

water follow osmotically due to the resulting concentration gradient

74
Q

the removal of Na+ and anions form the lumen dilutes the

A

luminal fluid and increased the ECF concentration causing water to leave the tubule by osmosis

75
Q

the loss of volume from the lumen increase the concentration of

A

remaining solutes (K+, Ca2+, and urea), leading to higher solute concentration in the filtrate

76
Q

when solute in the kidney tubule are more concentrated than the ECF, they can move out of the tubule if

A

the wall is permeable

77
Q
A

physio (6 decks)

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