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Anatomy and Phyisology > Urinary system > Flashcards

Urinary system Flashcards

1
Q

12 functions of the kidneys

A

regulates blood ionic composition, blood pH, blood volume, blood pressure, blood glucose, total water volume and total solute concentration in water, ion concentrations in ECF, produces hormones, ensures long-term acid-base balance, exercise metabolic wastes, produces erythropoietin, and activates vitamin D

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2
Q

organs of the urinary system

A

kidneys, ureter, bladder, and urethra

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3
Q

where are the kidneys located?

A

retroperitoneal and between T12 and L5 (superior lumbar region)

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4
Q

what sits above each kidney?

A

adrenal (suprarenal) glands

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5
Q

medial and lateral surfaces of kidneys

A

convex lateral surface and concave medial surface

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6
Q

concave medial surface of kidneys

A

contains renal hilum which leads to the internal space

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7
Q

what enters and exits at the hilium?

A

renal vessels, lymphatics, ureters, and nerves

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8
Q

three layers surrounding the kidneys

A

renal fascia, adipose fat capsule, and renal capsule

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9
Q

renal fascia

A

outer layer of dense irregular fibrous CT surrounding kidneys that anchors these to the abdominal wall

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10
Q

perirenal fat capsule/ adipose capsule

A

fatty cushion surrounding kidneys; holds the kidneys in place and provides protection

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11
Q

fibrous capsule/ renal capsule

A

transparent smooth irregular CT capsule that prevents the spread of infection to kidneys

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12
Q

3 regions of internal kidney

A

renal cortex, renal medulla, and renal pelvis

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13
Q

renal cortex

A

outer layer that is granular appearing

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14
Q

renal medulla

A

deep to cortex layer; composed of cone-shaped medullary pyramids, base, papilla, lobes, and renal columns

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15
Q

what face of pyramid faces the cortex?

A

the broad base

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16
Q

papilla

A

the tip of the pyramid that points internally

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17
Q

renal columns

A

inward extensions of cortical tissue that separate renal pyraminds

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18
Q

lobe

A

medullary pyramid and its surrounding cortical tissue; there are about eight lobes per kidney

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19
Q

renal pelvis

A

funnel shaped tube that is continuous with ureter; contains minor and major calcyes

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20
Q

minor calcyes

A

cup-shaped areas that collect urine draining from pyramidal papillae

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21
Q

major calyces

A

areas that collect urine from minor calyces; empties into renal pelvis

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22
Q

urine flow beginning in kidneys

A

renal pyramid, minor calyx, major calyx, renal pelvis, and ureter

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23
Q

how much cardiac output do kidneys receive each minute?

A

about 1/4 of flow from renal arteries; about 1200 mL

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24
Q

arterial flow of blood to kidneys

A

renal, segmental, interlobal, arcuate, cortical radiate, afferent arteriole, glomerular capillaries, and efferent arteriole

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25
Q

venous flow of blood from kidneys

A

cortical radiate, arcuate, interlobar, and renal veins

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26
Q

nephrons simple and 2 main parts

A

the structural and functional units that form urine; renal corpuscle and renal tubule are the two main parts

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27
Q

how many nephrons per kidney

A

about 1 million

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28
Q

2 parts of the renal corpuscle

A

glomerulus and glomerular capsule

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29
Q

glomerulus

A

fenestrated capillaries that allow for efficient filtrate formation

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30
Q

filtrate

A

plasma-derived fluid that renal tubules process to form urine; basically blood plasma minus proteins

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31
Q

another name for glomerular capsule

A

bowman’s capsule

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32
Q

glomerular capsule

A

cup-shaped, hollow structure that surrounds glomerulus; contains parietal and visceral layer, as well as podocytes, foot processes, and filtration slits

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33
Q

parietal layer cell type in glomerular capsule

A

simple squamous epithelium

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34
Q

visceral layer in glomerular capsule

A

clings to capillaries and has branching epithelial podocytes that terminate in foot processes

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35
Q

filtration slits

A

found in glomerular capsule between foot processes and allow filtrate to pass into the capsular space

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36
Q

foot processes

A

extend from the podocytes and wrap themselves around the glomerulus to form the filtration slits

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37
Q

podocytes

A

slits in which fluid that leaves the glomerulus under high pressures passes through and fills up the capsular space

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38
Q

proximal convoluted tubule

A

where everything leaves from the renal corpuscle; simple cuboidal epithelium that is rich in microvilli and mitochondria

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39
Q

where are juxtaglomerular cells found?

A

sandwiched between the loop of henle and the afferent arteriole

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40
Q

function of macula densa and juxtaglomerular cells together

A

help to regulate blood pressure in the kidneys

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41
Q

function of juxtaglomerular cells

A

help to produce, store, and release renin

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42
Q

renin

A

an enzyme (sorta hormone) that is involved in blood pressure regulation

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43
Q

where does the basement membrane of the capillary sit?

A

on the visceral layer of the glomerular capsule

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44
Q

proximal convoluted tubule

A

cuboidal cells with dense microvilli that form brush borders on apical side; basal side is in contact with capillaries; large mitochondria; function in reabsorption and secretion; are confined to cortex

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45
Q

another name for nephron loop

A

the loop of henle

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46
Q

nephron loop

A

U-shaped structure consisting of descending and ascending limbs

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47
Q

descending limb

A

continuous with the proximal tubule; consists of simple squamous epithelium

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48
Q

ascending limb

A

thicker than descending limb; cuboidal or columnar cells

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49
Q

what does the ascending limb connect with?

A

the distal convoluted tubule

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50
Q

distal convoluted tubule

A

cuboidal cells with very few microvilli; function more in secretion than reabsorption; are confined to cortex

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51
Q

two types of cells in collecting ducts

A

principal and intercalated cells

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52
Q

principal cells

A

sparse with short microvilli; function to maintain water and Na+ balance

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53
Q

intercalated cells

A

cuboidal cells with abundant microvilli; A and B types; function to maintain acid-base balance of blood

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54
Q

collecting ducts

A

receive filtrate from many nephrons; run through medullary pyramids; ducts fuse together to deliver urine through papillae into minor calyces

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55
Q

2 types of nephrons

A

cortical and juxtamedullary

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56
Q

cortical nephrons

A

make up 85% of nephrons; are found almost entirely in the cortex layer

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57
Q

juxtamedullary nephrons

A

long nephron loops that deeply invade the medulla; important in the production of concentrated urine

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58
Q

what are juxtamedullary nephrons associated with?

A

vasa recta

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59
Q

what enters and what leaves the glomerulus?

A

afferent arteriole enters and efferent arteriole leaves

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60
Q

what does the afferent arteriole arise from?

A

the cortical radiate arteries

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61
Q

what do efferent arterioles feed into?

A

either peritubular capillaries or vasa recta

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62
Q

why is blood pressure in glomerulus high?

A

because afferent arterioles are larger in diameter

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63
Q

peritubular capillaries

A

low-pressure, porous capillaries that are adapted for absorption of water and solutes; cling to adjacent renal tubules in cortex; arise from efferent arteries and empty into venules

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64
Q

vasa recta

A

long, thin-walled vessels parallel to long nephron loops of juxtamedullary nephrons; arise from efferent arterioles serving juxtamedullary nephrons; function in the formation of concentrated urine

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65
Q

juxtaglomerular complex

A

accompany each nephron; important for regulating the rate of filtrate formation and blood pressure; includes the distal portion of ascending limb and afferent (sometimes efferent) arteriole

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66
Q

three cells in juxtaglomerular complex

A

macula densa, granular cells, and extraglomerular mesangial cells

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67
Q

another name for granular cells

A

juxtaglomerular cells

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68
Q

macula densa cells

A

tall, closely packed cells of the ascending limb; contain chemoreceptors that sense NaCl content of filtrate

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69
Q

granular cells

A

enlarged, smooth muscle cells of the arteriole; act as a mechanoreceptor to sense blood pressure in the afferent arteriole; contain secretory granules that contain the enzyme renin

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70
Q

extraglomerular mesangial cells

A

located between arteriole and tubule cells; interconnected with gap junctions; may pass signals between macula densa and granular cells

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71
Q

how much fluid is processed and formed by kidneys each day?

A

180 L processed (60x entire plasma volume) but only 1.5 L of urine is formed

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72
Q

three processes that are involved in urine formation and adjustment of blood composition

A

glomerular filtration, tubular reabsorption, and tubular secretion

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73
Q

glomerular filtration simple

A

produces cell and protein free filtrate

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74
Q

tubular reabsorption simple

A

selectively return 99% of substance from filtrate to blood in renal tubules and collecting ducts

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75
Q

tubular secretion

A

selectively moves substances from blood to filtrate in renal tubules and collecting ducts

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76
Q

glomerular filtration

A

a passive process in which hydrostatic pressure forces fluids and solutes through filtration membrane into glomerular capsule; no reabsorption into capillaries occurs

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77
Q

the filtration membrane

A

a porous membrane between blood and the interior of glomerular capsule that allows water and solutes smaller than plasma proteins to pass; consists of three layers

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78
Q

3 layers of filtration membrane

A

fenestrated endothelium of glomerular capillaries; fused basement membrane; and foot processes of podocytes with filtration slits (repels macromolecules)

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79
Q

how does the filtration membrane work for macromolecules?

A

macromolecules stuck in filtration membrane are engulfed by glomerular mesangial cells

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80
Q

what can pass through the filtration membrane?

A

molecules smaller than three nm; water, glucose, amino acids, and nitrogenous waste

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81
Q

why do plasma proteins remain in blood and aren’t filtered?

A

maintains colloid osmotic pressure; this prevents loss of water to capsular space and proteins in filtrate indicate membrane problem

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82
Q

pressures that affect filtration

A

outward and inward pressures

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83
Q

outward pressures

A

forces that promote filtrate formation; associated with hydrostatic pressure in glomerular capillaries; average is 55 mm Hg

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84
Q

hydrostatic pressure in glomerular capillaries

A

is an outward pressure; is essentially glomerular blood pressure which pushes water and solutes out of blood

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85
Q

inward pressures

A

forces that inhibit filtrate formation; are hydrostatic pressure in capsular space and colloid osmotic pressure in capillaries

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86
Q

hydrostatic pressure in capsular space

A

filtrate pressure in capsule; 15 mm Hg

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87
Q

colloid osmotic pressure in capillaries

A

pull of proteins in blood; 30 mm Hg

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88
Q

net filtration pressure

A

sum of all forces that is responsible for filtrate formation; outward pressures - inward pressures (HPgc) - (HPcs + OP gc); 10 mm Hg

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89
Q

what is the main factor determining glomerular filtration rate

A

net filtration pressure

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90
Q

how is glomerular filtration different?

A

capillaries are long and extensive; mesangial cells can alter surface area; membrane in thin and porous; and glomerular capillary blood pressure is very high

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91
Q

glomerular filtration rate

A

the volume of filtrate formed per minute by both kidneys; average is 120-125 mL per minute

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92
Q

3 things GFR is directly proportional to

A

net filtration pressure, total surface area available for filtration; and filtration membrane permeability

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93
Q

what is the primary net filtration pressure?

A

glomerular hydrostatic pressure

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94
Q

how is total surface area controlled?

A

mesangial cells control this by contracting and relaxing

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95
Q

why is constant GFR important?

A

it allows kidneys to make filtrate and maintain extracellular homeostasis

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96
Q

what is the goal of local intrinsic controls

A

aka renal autoregulation; to maintain GFR in kidneys (important when MAP is in a range of 80-180 mm Hg)

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97
Q

how does GFR affect systemic blood pressure?

A

increased GFR causes increased urine output which lowers blood pressure (and vise versa)

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98
Q

what is the goal of extrinsic controls?

A

to maintain systemic blood pressure; nervous system and endocrine mechanisms are the main controls for this

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99
Q

2 types of renal autoregulation

A

myogenic mechanism and tubuloglomerular feedback mechanism

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100
Q

myogenic mechanism

A

local smooth muscle contracts when stretched; increased blood pressure causes muscle to stretch, leading to constriction of afferent arterioles that restricts blood flow into the glomerulus (and vise versa)

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101
Q

function of myogenic mechanism

A

helps to maintain normal GFR despite normal fluctuations in blood pressure

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102
Q

tubuloglomerular feedback mechanism

A

flow-dependent mechanism that is directed by macula densa cells that respond to filtrate’s NaCl concentration

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103
Q

how does tubuloglomerular feedback mechanism work

A

is GFR increase, filtrate flow rate also increases; this leads to decreased reabsorption time, causing high NaCl levels in filtrate; feedback mechanism causes constriction of afferent arteriole, which lowers NFP and GFR

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104
Q

what is the purpose of extrinsic controls?

A

to regulate GFR to maintain systemic blood pressure; these controls will override renal intrinsic controls if blood volume needs to be increased

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105
Q

sympathetic nervous system and renal system at rest

A

renal blood vessels and dilated and renal autoregulation mechanisms prevail

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106
Q

what happens to nervous and renal system under low blood pressure?

A

norepinephrine is released, causing systemic and afferent arteriole vasoconstriction, causing blood volume and pressure to increase

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107
Q

where is norepinephrine released from?

A

the adrenal medulla

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108
Q

purpose of renin

A

converts angiotensin into its active form

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109
Q

three effects of renin

A

constricts afferent arteriole, enhances reabsorption of Na+/Cl- in PCT, and stimulates adrenal cortex to release aldosterone

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110
Q

what is the main mechanism for increasing blood pressure?

A

renin-angiotensin-aldosterone mechanism

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111
Q

renin-angiotensin-aldosterone mechanism

A

the main mechanism for increasing blood pressure; there are three pathways for the release of renin by granular cells

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112
Q

three pathways for the release of renin by granular cells

A

direct stimulation of granular cells by SNS; stimulation of activated macula densa cells when filtrate NaCl concentration is low; and reduced stretch of granular cells

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113
Q

the renin-angiotensin system

A

a hormone system that regulates blood pressure and fluid and electrolyte balance, as well as systemic vascular resistance

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114
Q

when can the renin-angiotensin system be activated?

A

when there is a loss of blood volume or pressure and a decrease in filtration of NaCl concentration or a decreased filtrate flow rate

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115
Q

when is there a loss of blood volume or pressure?

A

dehydration or a hemorrhage

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116
Q

what is the loss of blood pressure interpreted by?

A

baroreceptors in the carotid sinus

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117
Q

when do juxtaglomerular cells release renin?

A

when blood flow to the juxtaglomerular appartus decreases

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118
Q

what does ANG II act as?

A

it acts of an endocrine, autocrine, paracrine, and intracrine hormone, as well as a potent vasoconstrictor peptide

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119
Q

how does ANG II act as a vasoconstrictor?

A

it causes blood vessels to narrow, resulting in increasing blood pressure and secretion of aldosterone

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120
Q

aldosterone role

A

causes the renal tubules to increase the reabsorption of sodium and water into the blood, while at the same time causing the excretion of potassium (to maintain electrolyte balance)

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121
Q

does ANG II have a larger effect on afferent or efferent arterioles?

A

efferent

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122
Q

what is the effect of ANG II vasoconstriction?

A

it causes blood to build up in the glomerulus, increasing glomerular pressure and thus maintaining GFR

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123
Q

what does decreased medullary blood flow through the vasa recta cause?

A

higher concentration of NaCl and urea (higher concentration of urine) in the medulla which facilitate increased absorption of tubular fluid

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124
Q

how does ANG II cause constriction?

A

contraction of smooth muscle cells

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125
Q

what are the overall results of ANG II?

A

reductions in renal blood flow and GFR that preserve ECF and blood pressure

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126
Q

what chemicals can renal cells release?

A

adenosine and prostaglandin E2; these act as paracrines that affect renal arterioles

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127
Q

what is the effect of cells making their own ANG II?

A

reinforces the effects of hormonal ANG II

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128
Q

what is the internal space of the kidney called?

A

the renal sinus

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129
Q

what are heavily modified smooth muscle cells called?

A

juxtaglomerular cells

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130
Q

what is the difference between cells in distal and proximal convoluted tubules?

A

distal cells are thinner and have less microvilli; distal cells also function more for secretion than reabsorption

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131
Q

do principal or intercalated cells have more microvilli?

A

intercalated cells

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132
Q

how is urine delivered into minor calyces?

A

through collecting ducts fusing together to deliver urine through the papillae

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133
Q

what chemicals cause constriction of vessels?

A

norepinephrine and epinephrine

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134
Q

what cells release renin?

A

juxtaglomerular cells

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135
Q

what runs through the medullary pyramind?

A

collecting ducts; gives them their striped apperance

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136
Q

what is the numerical value of pressure for HSGC?

A

55 mm Hg; compared to 26 mm Hg which is normal in capillaries

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137
Q

what is the numerical value of pressure for HSCS?

A

15 mm Hg

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138
Q

what is the numerical value of pressure for COGC?

A

30 mm Hg

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139
Q

what is average NFP?

A

10 mm Hg

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140
Q

tubular reabsorption

A

the process that moves solutes and water out of the filtrate and back into the bloodstream

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141
Q

why is reabsorption ‘re’?

A

because this is the second time that substances are being absorbed; the first time is when they were absorbed in the bloodstream after a meal

142
Q

two routes that substances can follow for tubular reabsorption

A

transcellular and paracellular

143
Q

types of active transport

A

pumps/ATPases; secondary active transport; cotransporter; pinocytosis/endocytosis/exocytosis

144
Q

types of passive transport

A

simple diffusion; channel proteins; carrier protiens

145
Q

first step of tubular reabsorption

A

the passive or active movement of water and dissolved substances from the fluid inside the tubule into the space outside

146
Q

second step of tubular reabsorption

A

water and these substances move through the capillary walls into the bloodstream via passive or active transport

147
Q

transcellular route

A

solute enters apical membrane of tubule cells and exits through basolateral membrane; it then enters blood through endothelium of peritubular capillaries

148
Q

what happens when solutes are saturated in tubular reabsorption (and example)?

A

excess will be excreted in the urine; ex. hyperglycemia leads to high blood glucose levels that exceed Tm, and glucose spills over into urine

149
Q

paracellular route

A

water and solutes move between tubule cells through tight junctions in leaky proximal nephorns

150
Q

what can move via the paracellular route?

A

water, Ca2+, Mg2+, K+, and some Na+ (only in the PCT)

151
Q

what is the site of most reabsorption?

A

the proximal convoluted tubule

152
Q

what is absorbed in the PCT?

A

all nutrients (ex. glucose and amino acids), 65% of Na+ and H20, many ions, almost all uric acid, and about half of urea

153
Q

what can leave in the descending loop?

A

H2O can leave, solutes cannot

154
Q

what can leave in the ascending loop?

A

solutes can, H2O cannot

155
Q

what is the thin segment of ascending loop passive to?

A

Na+ movement

156
Q

symporters in thick segment of ascending loop

A

Na+ - K+ - 2Cl-

157
Q

symporter meaning

A

when two molecules move in the same direction across a membrane

158
Q

antiporter meaning

A

when two molecules move in opposite directions across a membrane

159
Q

antiporters in thick segment of the ascending loop

A

Na+ - H+ (these transport Na+ into the cell)

160
Q

where is reabsorption hormonally regualted?

A

in the DCT and collecting duct

161
Q

what is ADH released by?

A

the posterior pituitary gland

162
Q

ADH

A

antidiuretic hormone

163
Q

role of ADH

A

causes principal cells to insert aquaporins in apical membranes, increasing water reabsorption

164
Q

what do increased ADH levels cause?

A

increase in water reabsorption

165
Q

what does the countercurrent multiplier depend on?

A

filtrate flow in opposite directions, difference in permerabilities b/w loops, and active transport of solutes out of ascending limb

166
Q

what are actively reabsorbed in the thick segment of the ascending limb?

A

Na+ and Cl- (some is passively transported in thin segment)

167
Q

countercurrent multiplier

A

the effect of countercurrent exchange with the active transport mechanisms that reabsorb ions from the tubular fluid back into the interstitial fluid; slowly creates a higher solute concentration of interstitial fluid

168
Q

why does countercurrent multiplier work?

A

because the limbs of nephron loops are not in direct contact but still close enough to influence each other’s exchange with surrounding interstitial fluid

169
Q

what is the constant difference between the two limbs of nephron limbs, as well as the ascending limb and interstitial fluid?

A

200 mOsm

170
Q

what is the vasa recta highly permeable to?

A

water and solutes

171
Q

why does the ascending limb use salty filtrate?

A

to further raise the osmolarity of medullary interstitial fluid

172
Q

what three key players interact with the medullary osmotic gradient

A

the long nephron loops, the vasa recta, and the collecting ducts

173
Q

what act as the countercurrent multipliers?

A

the long nephron loops

174
Q

what preserve the concentration gradient in the medulla?

A

the vasa recta

175
Q

how is varying concentrations of urine produced?

A

the juxtamedullary nephrons create an osmotic gradient within the medulla

176
Q

where is flow of blood countercurrent?

A

the loop of nephron and the vasa recta

177
Q

what is the blood in the vasa recta like relative to the surrounding interstitial fluid

A

isosmotic

178
Q

2 ways that the countercurrent exchanger preserves medullary gradient

A

by preventing rapid removal of salt from interstitial space and by removing reabsorbed water

179
Q

blood volume at the end of the vasa recta

A

is greater than at the beginning

180
Q

movement of water in descending limb (passive or active?)

A

passive

181
Q

movement of solutes in ascending limb (passive or active?)

A

active

182
Q

highest mOsm of filtrate in nephron loop

A

1200 mOsm at bend of loop

183
Q

when is the filtrate the most dilute in nephron loop?

A

as it leaves (100 mOsm); here it is hypoosmotic to the interstitial fluid

184
Q

what happens when you are overhydrated

A

decreased osmolarity of extracellular fluid and ADH production decreases, as well cells swell due to excess H20

185
Q

what happens when you are dehydrated

A

increased osmolarity of extracellular fluid and ADH production increases, as well cells lose water and shrink

186
Q

relationship between gradient and concentration of urine

A

without the gradient, we would not be able to raise urine concentration

187
Q

where is the concentration of urine mainly produced?

A

loop of henle concentrates or diltues by countercurrent multiplication, and then this is finished in the DCT and collecting ducts

188
Q

how much sodium is reabsorbed in the early DCT?

A

5%

189
Q

how much sodium is reabsorbed in the late DCT?

A

3% (final bit of fine tuning occurs here and determines how much sodium will be excreted)

190
Q

early DCT and late DCT

A

have difference in these transporters, as well as the sodium/potassium ATPase that drives reabsorption of calcium and chloride

191
Q

calcium reabsorption

A

similar to that of sodium; 99%. reabsorped

192
Q

phosphate reabsorption

A

similar to glucose and mainly occurs in the PCT

193
Q

reabsorption of magnesium

A

majority occurs in the ascending loop

194
Q

what is the most abundant cation filtrate?

A

sodium

195
Q

how is sodium transported across basolateral membrane of a tubule cell?

A

primary active transport; Na+-K+ ATPase pumps Na+ into interstitial space

196
Q

how does sodium enter into peritubular capillaries?

A

via bulk flow

197
Q

how does sodium enter tubule cell at apical surface

A

via secondary active transport (cotransport) or via facilitated diffusion through channels

198
Q

what is the result of active pumping of sodium at basolateral membrane

A

more Na+ diffusion into the cell due to low intracellular levels inside, and K+ leaks out of the cell; overall results in a net negative charge inside the cell

199
Q

what provides energy and means for reabsorbing almost every other substance?

A

sodium

200
Q

secondary active transport in tubular reabsorption

A

the electrochemical gradient created by pumps at basolateral surface gives the push needed for transport of other substances

201
Q

organic nutrients reabsorption

A

done by secondary active transport (cotransport with Na+); these are glucose, amino acids, some ions, and vitamins

202
Q

how is glucose reabsorbed?

A

Na+-glucose symporter first, then facilitated diffusion, then simple diffusion

203
Q

how is H+ reabsorbed?

A

Na + - H+ antiporter

204
Q

how is HCO3- reabsorbed?

A

CO2 enters cell and makes H2CO3-, breaks down into HCO3- and enters via facilitated diffusion

205
Q

how are Ca, K, Mg, Urea, and water reabsorbed?

A

passive diffusion

206
Q

osmolarity

A

the concentration of a solution; expressed in mOsm/L

207
Q

a higher osmolarity rate says what?

A

that the concentration of solutes is higher per L

208
Q

does osmolarity of the interstitial fluid increase or decrease the deeper into the medulla?

A

increase; this will later facilitate the passive diffusion of water into the interstitial fluid later in the collecting duct

209
Q

how much water has already been reabsorbed in the early DCT?

A

80%; it will reabsorb an additional 10-15%, and 5% each of Na+ and Cl-

210
Q

how does reabsorption of Na+ and Cl- occur in the early DCT?

A

Na+ - Cl- symporter in the apical membranes

211
Q

what stimulates the reabsorption of calcium in the DCT?

A

parathyroid hormone

212
Q

two mechanisms for water reabsorption

A

obligatory and facultative

213
Q

obligatory water reabsorption

A

occurs anywhere the nephron tube is permeable to water; the PCT and descending limb

214
Q

facultative water reabsorption

A

depends on the presence of ADH and ADH-competent principal cells of of terminal DCT and CT

215
Q

where is aldosternone released from?

A

the adrenal cortex

216
Q

what does ANG II act on?

A

AT1 receptors through binding to them

217
Q

where are AT1 receptors located?

A

on luminal and basolateral membranes of proximal and distal nephron segments

218
Q

what does the activation of AT1 receptors do?

A

leads to increased activities of the sodium/hydrogen exchanger, the sodium bicarbonate cotransporter, the sodium-chloride transporter, and the epithelial sodium channel

219
Q

what does aldosterone bind to increase sodium reabsorption?

A

through binding to the cytoplasmic mineralocorticoid receptor

220
Q

what does ANG II stimulate?

A

the release of aldosterone, the release of ADH, Na+/H+ exchangers, and the secretion of potassium back into the tubules

221
Q

ADH and salt

A

ADH acts on the CNS to increase an individual’s appetite for salt and the sensation of thirst

222
Q

where does tubular secretion mainly occur?

A

in the PCT

223
Q

substances involved in tubular secretion?

A

K+, H+, NH4+, creatinine, organic acids, and bases (as well as those synthesised in the tubule cells such as HCO3-)

224
Q

NH4+

A

ammonium (ammonia with an extra hydrogen atom)

225
Q

why is tubular secretion important?

A

allows for the disposal of harmful substances that are bound to plasma proteins and were passively reabsorbed, rids body of excess K+, and controlling blood pH by altering amounts of H+ and HCO3-

226
Q

aldosterone effect

A

causes sodium to be absorbed and potassium to be excreted into the lumen by principal cells

227
Q

what cells secrete H+?

A

intercalated cells

228
Q

how is H+ secreted?

A

CO2 + H20 forms H2CO3 > H+ + HCO3-; H+ is removed by a proton pump back into the tubule

229
Q

what happens to H+ once it enters back into the tubule? (buffering)

A

it bonds with NH3 to form NH4+ or bonds with HPO42- to form H2PO4-

230
Q

four major fluid compartments of the body

A

intracellular, extracellular, interstitial, and intravascular

231
Q

intracellular component

A

aka cytosol; all fluid contained inside the cells and normally is in osmotic equilibrium

232
Q

extracellular compartment

A

the intersital, intravascular and transcellular compartments

233
Q

interstitial compartment

A

surrounds tissue cells and is not static (refreshed by capillaries and lymphatic system)

234
Q

intravascular compartment

A

blood (includes intracellular fluid inside blood cells and blood plasma)

235
Q

what fluid compartment holds the most fluid?

A

intracellular (28 L in males and 22 L in females)

236
Q

flow of how renin is converted along the line?

A

prorenin is converted to renin by granular cells; angiotensinogen released by the liver is converted to angiotensin I (by plasma renin); angiotensin I is converted to II by angiotensin-converting enzyme

237
Q

ACE

A

angiotensin-converting enzyme

238
Q

where is ACE found?

A

on the surface of vascular endothelial cells, predominantly those of the lungs

239
Q

ions found in electrolytes

A

sodium, potassium, calcium, magnesium, bicarbonate, chloride, hydrogen phosphate, and sulfate

240
Q

osmolality

A

number of solute particles in one kg of H20

241
Q

two types of countercurrent mechanisms

A

countercurrent multiplier and countercurrent exchanger

242
Q

how do the two countercurrent mechanisms work together?

A

they establish and maintain medullary osmotic gradient from renal cortex through medulla

243
Q

range of mOsm

A

300 - 1200

244
Q

what countercurrent mechanism makes gradient and what preserves it?

A

multiplier makes, exchanger preserves

245
Q

where does aldosterone function?

A

collecting ducts (principal cells) and DCT

246
Q

what does aldosterone promote synthesis of?

A

Na+/K+ channels on apical side, and Na+-K- ATPases

247
Q

why does little Na+ leave the body?

A

because of Na+/K- channels as a result of aldosterone

248
Q

atrial natriuretic peptide

A

reduces blood Na+, resulting in decreased blood volume and pressure

249
Q

from where and why is atrial natriuretic peptide released?

A

from cardiac atrial cells when blood volume or pressure is elevated

250
Q

parathyroid hormone

A

acts on DCT to increase Ca+ reabsorption; osteoclasts will break down bone in response to this

251
Q

ADH negative feedback loop

A

decreased osmolarity of plasma and interstitial fluid detected by osmoreceptors in the hypothalamus activates the posterior pituitary gland to cause principal cells to be more permeable to water

252
Q

another word for urination

A

Micturition

253
Q

what happens when your bladder is at rest?

A

internal sphincters is passively contracted and external is also contracted (but by skeletal muscle); motor neurons are firing

254
Q

what is the micturition centre?

A

in the sacral spinal cord

255
Q

what happens when your bladder is full?

A

stretch receptors and parasympathetic neurons fire; sphincters relaxes while detrustor muscle contracts

256
Q

what do thiazide type blood pressure drugs do?

A

block symporter for the reabsorption of Na+ and Cl- in the DCT

257
Q

percentage composition of urine

A

95% water and 5% solutes

258
Q

what solutes are found in urine?

A

Na+, K+, PO43-, SO42-, Ca2+, Mg2+, and HCO3-

259
Q

what nitrogenous wastes are found in urine?

A

urea, uric area, and creatinine

260
Q

what nitrogenous waste is most abundant in urine?

A

urea

261
Q

how does urea form?

A

from amino acid breakdown

262
Q

how does uric acid form?

A

from nucleic acid metabolism

263
Q

how does creatinine form?

A

a metabolite of creatine phosphate

264
Q

pH of urine

A

average is 6, range of 4.5 to 8

265
Q

what can cause urine pH to drop?

A

an acidic diet such as protein and whole wheats

266
Q

what can cause urine pH to rise?

A

an alkaline diet; vegetarians, lots of vomiting, or UTI’s

267
Q

specific gravity

A

the ratio of mass of substance to mass of equal volume

268
Q

what is the specific gravity of urine?

A

1.001 to 1.035

269
Q

what indicates pathology of urine?

A

high concentrations of any substance, or abnormal levels of blood proteins, WBC’s and bile pigments

270
Q

what does cloudy urine indicate?

A

UTI

271
Q

urochrome

A

a yellow pigment from hemoglobin breakdown that gives urine its colour

272
Q

what does abnormal urine colour indicate?

A

certain foods, bile pigments, blood, and drugs

273
Q

what happens to urine odor after some time?

A

it develops ammonia as bacteria metabolise the urea

274
Q

diabetes urine odor

A

may have an acetone smell

275
Q

substances that enhance urination

A

alcohol, caffeine, drugs for hyperextension or edema, loop diuretics, and osmotic diuretics

276
Q

why does alcohol increase urination?

A

it is an ADH inhibitor

277
Q

why do caffeine and drugs increase urination?

A

they inhibit Na+ reabsorption

278
Q

why do loop diuretics increase urination?

A

they inhibit medullary gradient formation

279
Q

why do osmotic diuretics increase urination?

A

the substances are not reabsorbed, so water remains in urine

280
Q

where do ureters begin?

A

L2; they are a continuation of the renal pelvis

281
Q

ureters

A

slender tubes tubes that convey urine from kidneys to bladder

282
Q

what happens when bladder pressure increases?

A

the distal ends of the ureters close, preventing backflow of urine

283
Q

three layers of ureter wall

A

mucosa, muscularis, and adventitia

284
Q

mucosa layer of ureter

A

consists of transitional epithelium with an underlying lamina propria

285
Q

muscularis layer of ureter

A

smooth muscle sheets that contact in response to stretch; this layers propels urine into bladder along with peristalsis; inner long layer and middle circular layer

286
Q

adventitia layer of ureters

A

outer fibrous CT

287
Q

where is the bladder located?

A

on pelvic floor posterior to the pubic symphysis

288
Q

male position of bladder

A

prostate is inferior to bladder neck

289
Q

female position of bladder

A

anterior to vagina and uterus

290
Q

trigone

A

smooth triangular area outlined by openings for ureters and urethra; where infections persists

291
Q

3 layers of bladder wall

A

mucosa, muscular layer, and fibrous adventitia

292
Q

mucosa layer of bladder

A

transitional epithelium

293
Q

muscular layer of bladder

A

contains thick detrusor muscle that contains three layers of smooth muscle (inner and outer are long and middle is circular)

294
Q

adventitia layer in bladder

A

fibrous except on superior surface where it is covered by peritoneum

295
Q

bladder when empty

A

collapses and rugae appear

296
Q

fhow much can a pull bladder hold

A

500 mL and becomes 12 cm long (rises superiorly when filling)

297
Q

urethra

A

muscular tube that drains urinary bladder

298
Q

epithelium of urethra

A

mostly pseudostratified columnar but transitional near bladder and stratified squamous near orifice

299
Q

female urethra

A

tightly bound to anterior vaginal wall; external urethral sphincter is anterior to vaginal opening and posterior to clit

300
Q

male urethra

A

carries semen and urine; has three regions

301
Q

three regions of male urethra

A

prostatic urethra, intermediate part of the urethra, and spongy urethra

302
Q

prostatic urethra

A

within prostate

303
Q

intermediate part of the urethra

A

aka membranous urethra; passes through urogenital diaphragm from prostate to beginning of penis

304
Q

spongy urethra

A

passes through penis; opens via external urethral orifice

305
Q

three events of micturition

A

contraction of detrusor by ANS; opening of internal sphincter by ANS; opening of external sphincter by SNS

306
Q

where does active transport energy come from?

A

ATP hydrolysis

307
Q

what type of transport is cotransport?

A

secondary active transport

308
Q

where does paracellular transport mainly occur?

A

PCT

309
Q

what cells insert aquaporins?

A

principal cells

310
Q

what do aquaporins do?

A

increase water reabsorption

311
Q

ATPase

A

brings 3 sodium ions out of cell and 2 potassium in; overall negative charge inside cell remains after this

312
Q

how is blood pH controlled by the urinary system?

A

by altering the amounts of H+ and HCO3-

313
Q

H2PO4-

A

Dihydrogen phosphate (HPO4- + H+)

314
Q

what ions are more abundant inside the cell?

A

K+, Mg+, HPO4-, S042-, and protein anions

315
Q

what ions are more abundant outside the cell?

A

Na+, Cl-, and HCO3-

316
Q

what is released when blood pressure is too high

A

atrial natriuretic peptide which releases Na+ to decrease blood pressure

317
Q

low calcium levels negative feedback loop

A

low calcium levels cause parathyroid glands to release parathyroid hormone, causes osteoclasts to degrade bone matrix to bring more calcium into the bloodstream

318
Q

how are aquaporins formed?

A

by exocytosis done by principal cells

319
Q

what maintains electrolyte balance?

A

renin-angiotensin-aldosterone system

320
Q

is sodium or potassium concentration higher inside the cell?

A

potassium

321
Q

is sodium or potassium concentration higher outside the cell?

A

sodium

322
Q

how does metabolism create water?

A

dehydration synthesis; an extra water molecule is created from two compounds joining

323
Q

review of negative feedback loop

A

stimulus is detected by receptor or sensor; info sent along afferent pathway to the control centre; output is send along efferent pathway to an effector; response of effector reduces stimulus

324
Q

water dissociation theory

A

H20 > H+ and OH-

325
Q

water dissociation in reality

A

H20 + H20 > H3O+ and OH- (this is because protons never really exists alone and in water they bind with water molecules to form hydronium ions

326
Q

hydronium

A

H3O+

327
Q

acids and hydrogen

A

the stronger the acid, the more readily it donates H+; these combine with OH- to form water

328
Q

bases and hydroxyl

A

bases readily donate Oh- ions; these combine with H+ to form water

329
Q

pH scale

A

the measure of the concentration of H+ ions in a solution; 0 -14 (water is 7 which is neutral)

330
Q

buffer systems

A

convert strong acids/bases into weak ones; ex. the carbonic-acid/bicarbonate buffer system

331
Q

the carbonic-acid/bicarbonate buffer system

A

protects your blood plasma from sharp changes of pH; CO2 + H20 > H2CO3 > H + HCO3

332
Q

sodium bicarbonate

A

NaHCO3; used as a buffer; can dissociate to HCO3 to increase pH

333
Q

receptors for decreased blood pH

A

central chemoreceptors in medulla oblongata and peripheral chemoreceptors in aortic and carotid bodies

334
Q

control centre for decreased pH

A

inspiratory area in medulla oblongata

335
Q

effectors for decreased pH

A

diaphragm contracts more forcefully and frequently so more CO2 is exhaled; this causes fewer H+ to form as less H2CO3 forms, decreasing H+ concentration

336
Q

negative feedback loop for decreasing pH levels

A

H+ concentration is high, receptors in medulla oblongata and heart relay info to inspiratory area in medulla oblongata to increase expiration and ultimately decrease H+ levels in blood

337
Q

acid-base balance

A

buffers typically consist of a pair of compounds in a solution, one of which is a weak acid and the other a weak base

338
Q

most abundant buffer in the ECF

A

H2CO3 and HCO3 (associated with Na+)

339
Q

most positively charged electrolyte in ECF

A

sodium

340
Q

amount of sodium in ECF

A

increases blood ECF, determining blood volume and pressure

341
Q

what forms of Na are mostly reabsorbed in the PCT?

A

sodium bicarbonate and sodium chloride

342
Q

when are the most essential substances of the filtrate reabsorbed?

A

the first half of the PCT

343
Q

most important reabsorbed substances

A

glucose, amino acids, phosphate, lactate, and citrate

344
Q

what enables the reabsorption of bicarbonate?

A

sodium/proton exchanger

345
Q

what is fluid entering the late proximal tubule like?

A

it is depleted of the essential substances

346
Q

what is the negatively charged ion initially absorbed with sodium?

A

bicarbonate

347
Q

chloride/formate anion exchangers

A

brings chloride into the cell and formate out

348
Q

gluconeogenesis

A

production of glucose and this occurs in the kidneys

349
Q

what hormone do the kidneys produce?

A

erythropoietin

350
Q

basolateral side of PCT

A

highly infolded plasma membrane

351
Q
A

Anatomy and Phyisology (94 decks)

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