Chapter 19 The Kidneys

Front 1

the urinary system and kidneys function

Back 1

regulate extra cellular fluid volume, blood pressure, and osmolarity; maintain ion balance; regulate pH; excrete wastes and foreign substances; and participate in endocrine pathways

Front 2

the urinary system

Back 2

is composed of 2 kidneys (produces urine), 2 ureters, a bladder and a urethra

Front 3

each kidney

Back 3

has about 1 million nephrons

Front 4

Renal cortex

Back 4

outer renal area; the outermost layer of kidney

Front 5

renal medulla

Back 5

inner layer of kidney

Front 6

renal blood flow goes from

Back 6

afferent arteriole to glomerulus to efferent arteriole to peritubular capillaries

Front 7

vasa recta

Back 7

____ capillaries dip into the medulla

Front 8

fluid filters from the glomerulus into the

Back 8

bowman's capsule

Front 9

after bowman's capsule, it flows

Back 9

through the proximal tubule, loop of henle, distal tubule and collecting duct, and then drains into the renal pelvis.

Front 10

proximal tubule

Back 10

responsible for reabsorption of ions, h20 and organic molecules

Front 11

urine

Back 11

flows through the ureter to the urinary bladder

Front 12

filtration

Back 12

is the movement of fluid from plasma into the bowman's capsule

Front 13

reabsorption

Back 13

is the movement of filtered materials from tubule to blood.

Front 14

secretion

Back 14

is the movement of selected molecules from blood to tubule

Front 15

average urine volume

Back 15

1.5 L / day

Front 16

osmolarity

Back 16

varies between 50 and 1200 mOsM

Front 17

the amount of a solute excreted equals

Back 17

the amount filtered minus the amount reabsorbed plus the amount secreted

Front 18

filtered solutes

Back 18

must pass first through glomerular capillary endothelium, then through a basal lamina, and finally through bowman's capsule epithelium before reaching the lumen of bowman's capsule

Front 19

filtration allows

Back 19

most components of plasma to enter the tubule but excludes blood cells and most plasma proteins

Front 20

the bowman's capsule epithelim has

Back 20

specialized cells called podocytes

Front 21

podocytes

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speciallized cells in bowman's capsule epithelium that wrap arount the glomerular capillaries and create filtration slits

Front 22

mesangial cells

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are associated with the glomerular capillaries

Front 23

one-fifth of renal plasma flow filters into the

Back 23

tubule lumen

Front 24

the percentage of total plasma volume that filters is

Back 24

the filtration fraction

Front 25

hydrostatic pressure in glomerular capillaries average

Back 25

55 mmHg, favoring filtration

Front 26

opposing filtration are

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colloid osmotic pressure of 30 mmHg and hydrostatic capsule fluid pressure averageing 15mmHg.

Front 27

the net driving force is

Back 27

10mmHg, favoring filtration

Front 28

the GFR (glomerular filtration rate)

Back 28

is the amount of fluid that filters into the bowman's capsule per unit time

Front 29

average GFR

Back 29

is 125mL/min or 180 L/day

Front 30

hydrostatic pressure in glomerular capillaries

Back 30

can be altered by changing resistance in the afferent and efferent arterioles

Front 31

auto regulation of glomerular filtration

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is accomplished by a myogenic response of vascular smooth muscle in response to pressure changes and by tubuloglomerular feedback

Front 32

when fluid flow through the distal tubule increases....

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the macula densa cells send a paracrine signal to the afferent arteriole, which constricts

Front 33

reflex control of GFT is mediated through

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systemic signals, such as hormones, and through the autonomic nervous system

Front 34

most reabsorption takes place in

Back 34

proximal tubule

Front 35

finely regulated reabsorption takes place in

Back 35

the more distal segments of the nephron

Front 36

the active transport of Na+ and other solutes creates

Back 36

concentration gradients for passive reabsorption of urea and other solutes

Front 37

most reabsorption involves

Back 37

transepithelial transport, but some solutes and water are absorbed by the paracellular pathway

Front 38

glucose, amino acids, ions, and various organic metabolites are reabsorbed by

Back 38

Na+ linked secondary active transport

Front 39

most renal transport is mediated by

Back 39

membrane proteins and exhibits saturation, specificity, and competition.

Front 40

the transport maximum Tm

Back 40

is the transport rate at saturation

Front 41

the renal threshold

Back 41

is the plasma concentration at which a substance first appears in the urine

Front 42

pertubular capillaries reabsorb

Back 42

fluid along their entire length

Front 43

secretion enhances excretion

Back 43

by removing solutes from the peritubular capillaries

Front 44

K+, H+ and a variety of organic compounds are

Back 44

secreted

Front 45

molecules that compete for renal carriers

Back 45

slow the secretion of a molecule

Front 46

the excretion rate of a solute depends on

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1. its filtered load 2. whether it is reabsorbed or secreted as it passes through the nephron

Front 47

clearance

Back 47

describes how many milliliters of plasma passing through the kidneys have been totally cleared of a solute in a given period time

Front 48

inulin clearance

Back 48

is equal to GFR

Front 49

in clinical settings, creatinine is used to

Back 49

measure GFR

Front 50

clearance can by used to determine how

Back 50

the nephron handles a solute filtered into it

Front 51

the external sphincter of the bladder is

Back 51

skeletal muscle that is tonically contracted except during urination

Front 52

micturation

Back 52

is a simple spinal reflex subject to conscious and unconscious control

Front 53

increase parasympathetic motor neurons

Back 53

cause contraction of the smooth muscle in the bladder wall

Front 54

somatic motor neurons

Back 54

leading to the external sphincter are simultaneously inhibited.