Physiology Chapter 19 (Ch. 7 Has 1St 10)

Front 1

urinary system is composed of

Back 1

the kidneys and accessory structures

Front 2

renal physiology

Back 2

the study of kidney function

Front 3

what makes up the bulk of the paired kidneys?

Back 3

the nephrons which are hollow tubules which modify the composition of the fluid as it passes through

Front 4

micturition

Back 4

urination
the process by which urine is excreted

Front 5

how can you tell if a patient has a urinary tract infection

Back 5

urine sample will have red and white blood cells

Front 6

renal arteries and renal veins

Back 6

branch off the abdominal aorta and supply blood to the kidneys
-carry blood from the kidneys to the inferior vena cava

Front 7

what is the functional unit of the kidney

Back 7

the nephron
-1 million in the kidney

Front 8

the kidney is divided into

Back 8

an outer cortex
an inner medulla

Front 9

where are the afferent arterioles and glomeruli found? cortex or medulla?

Back 9

cortex

Front 10

each nephron has ___ arterioles and ___ sets of what

Back 10

2 arterioles and 2 sets of capillaries

Front 11

how blood goes thru the kidney

Back 11

enters the kidney thru the renal artery
to smaller arteries
to arterioles in the cortex
to a portal system
from afferent arteriole
to glomerulus
to efferent arteriole
to a set of peritubular capillaries
finally renal capillaries join to form venules and small veins

Front 12

what is the function of the renal portal system?

Back 12

first to filter fluid out of the blood and into the lumen of the nephron at the glomerular capillaries
then reabsorb fluid from the tubule back into the blood at the peritubular capillaries

Front 13

renal corpuscle is composed of

Back 13

glomerulus and Bowman's capsule

Front 14

tubular elements of the kidney

Back 14

nephron begins in Bowman's capsule
-filtered fluid flows into proximal tubule
-to loop of henle
-descending and ascending limbs
-to distal tubule
-to collecting duct
-drain to the renal pelvis
-finally, filtered and modified fluid (urine) flows into the ureter on its way to excretion

Front 15

what are the 3 processes of the nephron

Back 15

filtration
reabsorption
secretion

Front 16

filtration is

Back 16

the movement of fluid from blood into the lumen of the nephron
-takes place only in the renal corpuscle (glomerulus and Bowman's capsule)

Front 17

what happens once filtrate leaves bowman's capsule

Back 17

it is modified by reabsorption and secretion

Front 18

reabsorption is

Back 18

the process of moving substances in the filtrate from the lumen of the tubule back into the blood flowing thru peritubular capillaries

Front 19

secretion is

Back 19

removes selected molecules from the blood and adds them to the filtrate in the tubule lumen

Front 20

what is the primary function of the proximal tubule?

Back 20

the bulk reabsorption of isosmotic fluid

Front 21

what is the primary site for creating dilute urine

Back 21

the loop of henle

Front 22

once in the loop of henle the filtrate is ___ osmotic

Back 22

hyposmotic relative to plasma meaning when it leaves it is around 100 mOsM and its volume has fallen from 54 L/day to 18 L/day (at this time, 90% of the volume originally filtered into Bowman's capsule has been reabsorbed into the capillaries)

Front 23

secretion v. excretion

Back 23

secretion in the nephron occurs from the plasma to tubule lumen
-excretion is out of the body, removal of a substance from the body

Front 24

amount of solute excreted =

Back 24

amount filtered - amount reabsorbed + amount secreted

Front 25

what other organs beside kidneys carry out excretory processes?

Back 25

lungs and intestines

Front 26

filtration of plasma into the kidney tubule is the first step in urine formation

Back 26

the contents usually consist of only water and dissolved solutes
-filtration takes place in the renal corpuscle

Front 27

in filtration what are the 3 filtration barriers before entering the tubule lumen

Back 27

glomerular capillary endothelium, a basal lamina, and the epithelium of Bowman's capsule

Front 28

the first barrier is capillary endothelium

Back 28

large pores that allow most components of the plasma to pass but small enough to keep blood cells from leaving

Front 29

2nd barrier is the acellular layer of ECM called the basal lamina

Back 29

acts as a coarse sieve that excludes most plasma proteins from the flui that filters thru it

Front 30

3rd filtration barrier is the epithelium of Bowman's capsule

Back 30

blank

Front 31

only what percentage of plasma flows thru the kidneys filters into the nephrons?

Back 31

1/5
the remaining 4/5 along with most proteins and blood cells flow into the peritubular capillaries

Front 32

filtration fraction

Back 32

the percentage of total plasma volume that filters into the tubule

Front 33

why does filtration occur?

Back 33

because of the hydrostatic pressure in the capillaries

Front 34

hydrostatic pressure of blood pressure

Back 34

averages 55 mm Hg and favors filtration back into Bowman's capsule

Front 35

colloid osmotic pressure (pi)

Back 35

inside the glomerular capillaries is higher than that of the fluid in the bowman's capsule
gradient due to presence of proteins
-averages 30 mm Hg and favors fluid movement back into the capillaries

Front 36

hydrostatic fluid pressure

Back 36

averages 15 mm Hg and is opposing filtration

Front 37

the 3 pressures that influence glomerular filtration

Back 37

capillary blood pressure
capillary colloid osmotic pressure
capsule fluid pressure

Front 38

the net driving force is ___ , and favors

Back 38

10 mm Hg out into bowman's capsule

Front 39

what is the glomerular filtration rate GFR?

Back 39

the volume of fluid that filters into Bowman's capsule per unit time
average is 125 ml/min or 180 L/day which is incredible considering total plasma volume is only about 3 liters

Front 40

GFR is influenced by

Back 40

the net filtration pressure
-the filtration coefficient

Front 41

filtration coefficient has 2 components

Back 41

surface area of the glomerular capillaries available for filtration and the permeability of the capillary-Bowman's capsule interface

Front 42

the filtration fraction

Back 42

only 20% of volume filters while 80% goes into peritubular capillaries
19% of fluid is reabsorbed meaning less than 1% of filtered fluid is eventually excreted

Front 43

blood pressure provides the hydrostatic pressure that drives GF so what happens when when BP increases

Back 43

surprisingly, GFR is remarkably constant over a wide range of BPs as long as mean arterial blood pressure remains btw 80-180 mm Hg

Front 44

what happens if the overall resistance of the renal arterioles increases?

Back 44

renal blood flow decreases and blood is diverted to other organs

Front 45

vasoconstriction of the afferent arteriole does what to resistance, renal blood flow, cap BP, and GFR?

Back 45

it increases resistance
decreases RBF, Cap BP, and GFR

Front 46

increases resistance in EFFERENT arteriole does what to rbf, cap BP, and GFR?

Back 46

it decreases RBF
but this time it increases cap BP and GFR

Front 47

the effect of increased resistance on GFR depends on where

Back 47

resistance increase in the AFFERENT, hydrostatic pressure decreases on the glomerular side which causes a decrease in GFR
-if resistance is in efferent arteriole, blood "dams up" in front of the constriction and hydrostatic pressure in the glomerular caps increases which increases GFR

Front 48

GFR is subject to autoregulation by several mechanisms

Back 48

myogenic response
tubuloglomerular feedback

Front 49

myogenic response

Back 49

of afferent arterioles...
if bp decreases, arterioles becomes max dilated, consequently when mean bp drops below 80 mm Hg, GFR decreases which helps the body conserve blood volume

Front 50

tubuloglomerular feedback

Back 50

when NaCl delivery past the macula densa increases as a result of increased GFR, the afferent arteriole constricts, increasing resistance and decreasing GFR

Front 51

neural and hormonal signals work in 2 ways

Back 51

changing the resistance in the arterioles and by altering the filtration coefficient

Front 52

where does most of reabsorption take place?

Back 52

in the proximal tubule

Front 53

why not simply filter and excrete the 1% that needs to be eliminated?

Back 53

1) many foreign substances are filtered into the tubule but not reabsorbed into the blood
2) filtering ions and water into the tubule simplifies their regulation

Front 54

principles governing the tubular reabsorption of solutes and water

Back 54

na+ is reabsorbed by active transport
-electrochemical gradient drives anion reabsorption
-water moves by osmosis, following solute reabsorption
-conc. of other solutes increase as fluid volume in lumen decreases

Front 55

reabsorption involves both transepithelial transport and paracellular pathway

Back 55

TT- substances cross both the apical and basolateral membranes of the tubule epithelial cell
-PP: substances pass thru the junction btw 2 adjacent cells

Front 56

active transport of sodium

Back 56

is the primary driving force for most renal reabsorption.

Front 57

this antiporter plays a huge role in na+ reabs. in the proximal tubule

Back 57

Na+-H+ antiporter

Front 58

secondary active transport: symport with sodium

Back 58

responsible for reabs or glucose, aa, ions

Front 59

sodium reabsorption
in tubule lumen
proximal tubule cell
interstitial fluid

Back 59

high
low
high

Front 60

urea: reabsorption

Back 60

is passive
occurs when water moves by osmosis out of lumen and a filtrate conc of urea increases bc same amount of urea is in smaller volume
-urea diffuses out of the lumen into the ecf

Front 61

most transport in the nephron exhibits 3 char of mediated transport

Back 61

saturation
specificity
competition

Front 62

the filtrate glucose conc. is ___ the plasma glucose conc

Back 62

always equal to

Front 63

is glucose not secreted, excreted, reabs?

Back 63

glucose is not secreted

Front 64

glucose excreted =

Back 64

glucose filtered - glucose reabsorbed

Front 65

filtration of glucose is proportional to

Back 65

the plasma concentration

Front 66

reabsorption of glucose is proportional to plasma conc until the

Back 66

tranport max is reached

Front 67

pressure gradient in the peritubular capillaries is

Back 67

20mmHg favoring absorption of fluid into the caps

Front 68

secretion is

Back 68

the transfer of moelcules from ecf into the lumen of the nephron
-active process because it requires moving substrates against their conc. gradients

Front 69

excretion rate depends on

Back 69

its filtration rate
whether the substance is reabsorbed, secreted, or both as it passes thru the tubule

Front 70

clearance

Back 70

rate at which that solute disappears from the body by excretion or by metabolism

Front 71

inulin

Back 71

100% of it is excreted
neither reabsorbed or secreted

Front 72

all plasma is

Back 72

reabsorbed but no inulin is, thus we say that plasma is totally cleared of inulin

Front 73

for any substance that is freely filtered but neither reab or sec, its clearance =

Back 73

GFR

Front 74

filtered laod of x =

Back 74

x(plasma) x GFR
= excretion rate of x

Front 75

clearance of x =

Back 75

excretion rate of x/x(plasma)

Front 76

creatinine is used to estimate GFR

Back 76

but not perfect because a small amount is secreted into the urine

Front 77

what determines renal handling of solutes?

Back 77

clearance and GFR

Front 78

if filtration is greater than excretion rate

Back 78

there is a net reabsorption

Front 79

if the clearance of x is less than inulin clearance

Back 79

then there is a net reabsorption

Front 80

glucose clearance

Back 80

no glucose is excreted
100% is reabsorbed
clearance = 0

Front 81

urea clearance

Back 81

50% is excreted
50% is reabsorbed
50 ml is cleared

Front 82

penicillin clearance

Back 82

more penecillin was excreted than was filtered
0 penicillin reabsorbed, some penicillin secreted
150 ml penicillin clearance (original 100 ml)