Renal Urinary

Question 1

Kidney Functions

Answer 1

maintain the chemical consistency of blood
filter many liters of fluid from blood
send toxins, metabolic wastes, and excess water out of the body
main waste products: urea, uric acid, creatinine

Question 2

Organs of the Urinary System

Answer 2

kidneys
ureters
urinary bladder
urethra

Question 3

Kidneys (Location and External Anatomy)

Answer 3

located retroperitoneally
lateral to T12-L3 vertebrae
average kidney is 12 c, tall, 6 cm wide, 3 cm thick
hilum: on concave surface, vessels and nerves enter and exit
fibrous capsule surrounds the kidney: perirenal fat (external to renal capsule) and renal fascia (external to perirenal fat)

Question 4

Kidneys (Frontal Section)

Answer 4

renal cortex
pyramids of renal medulla
renal pelvis: major and minor calyxes

Question 5

Kidneys (Blood Vessels)

Answer 5

aorta
renal arteries
segmental arteries
interlobar arteries
arcuate arteries
cortical radiate arteries
afferent arterioles
glomeruli capillaries
efferent arterioles
peritubularcapillaries (in cortical nephrons) and vasa recta capillaries (in juxtamedullary nephrons)
cortical radiate veins
arcuate veins
interlobar veins
renal veins
inferior vena cava

Question 6

Kidneys (Nerve Supply)

Answer 6

via the renal plexus
an offshoot of the celiac plexus
a network of autonomic fibers

Question 7

Urine Production (Mechanisms)

Answer 7

filtration (glomerular): liquid filtrate of blood leaves kidney capillaries in glomerular capsule
resorption (tubular): most nutrients, water, and essential ions reclaimed through resportion from urine into peritubular capillaries
secretion (tubular): active process of removing undesirable molecules through secretion from peritubular capillaries into urine

Question 8

Nephron

Answer 8

composed of a renal corpuscle and a renal tubule

Question 9

Renal Corpuscle (1)

Answer 9

present only in kidney cortex
first part of nephron where filtration occurs
consists of a tuft of capillaries called a glomerulus which is surrounded by a cup-shaped, hollow glomerular capsule (Bowman’s capsule)
tuft of capillaries is supplied by an afferent arteriole and drained by a efferent arteriole
the endothelium of the flomerulus is fenestrated making the capillaries highly porous, allowing large quantities of fluid and small molecules to pass from the capillaries into the capsular space (interior of glomerular capsule)

Question 10

Renal Corpuscle (2)

Answer 10

parietal layer of glomerular capsule is simple squamous epithelium
visceral layer covers glomerulus (glomerular capillaries) and consists of epithelial cells called podocytes which branch into foot processes
filtrate passes through clefts between foot processes called filtration slits

Question 11

Renal Corpuscle (Filtration Membrane)

Answer 11

filter system between blood in the glomerulus and capsular space
consists of three layers:
1. fenestrated endothelium of the capillary
2. basement membrane formed by the fusion of the basal lamina of the endothelium and podocyte epithelium
3. filtration slits between foot processes of podocyte epithelium which are covered by a thin slit diaphragm
hold back most blood cells and proteins
allows passage of: water, ions, glucose, amino acids, urea

Question 12

Renal Corpuscle (Filtration)

Answer 12

around 20% of fluid leaves the glomerulus and enters the capsular space and is processed into urine
80% remains within the blood of the capillary
filtrate proceeds from renal corpuscle into renal tube

Question 13

Renal Tubule

Answer 13

proximal convoluted tubule
nephron loop (loop of Henle): descending and ascending limbs, thin and thick segments
distal convoluted tubule
collecting ducts: receive urine from several nephrons, play an important rold in conserving body fluids

Question 14

Epithelial Cells of Nephrons

Answer 14

parietal layer of glomerular capsule: simple squamous
visceral layer of glomerular capsule: podocyte, basement membrane, fenestrated endothelium of glomerulus
proximal convoluted tubule in cortex: simple cuboidal cells with microvillli for efficient resorption
nephron loop thin segment in medulla: simple squamous
distal convoluted tubule in cortex: simple cuboidal specialized for selective secretion or resorption of ions
collecting ducts: simple cuboidal which thicken to become simple columnar in papillary ducts

Question 15

Nephrons (Classes)

Answer 15

cortical nephones make up 85% of all nephrons

juxtamedullary nephrons make up 15% of all nephrons

Question 16

Cortical Nephrons

Answer 16

located almost entirely within cortex

nephron loops dip only a short distance into the medulla

Question 17

Juxtamedullary Nephrons

Answer 17

have renal corpuscles which lie near the cortex-medulla junction
nephron loops extend deeply into the medulla
thin segments in loops are much longer than those of cortical nephrons
contribute to kidney’s ability to concentrate urine

Question 18

Nephrons (Blood Vessels)

Answer 18

nephrons associate closely with the following capillary beds:
glomeruli capillaries
peritubular capillaries of cortical nephrons
vasa recta of juxtamedullary nephrons

Question 19

Glomeruli Capillaries

Answer 19

fed by afferent arterioles and drained by efferent arteriole
produce filtrate that moves through the renal tubule and becomes urine
glomeruli generate 1 liter of fluid filtrate every 8 minutes:
1 % of filtrate goes into urine
99% of filtrate is reabsorbed and returned to the blood in the peritubular and vasa recta capillary beds
(these ratios will change in relationship to degree of hydration of a person; solute concentration in urine is inversely related to amount of water taken by mouth)

Question 20

Peritubular Capillaries in Renal Cortex

Answer 20

arise from the efferent arterioles of cortical nephrons
lie in the interstitial loose areolar connective tissue in the renal cortex
are adapted for absorption
tubular resportion: low-pressure, porous capillaries readily absorb solutes and water from renal tubule cells as these substances are resorbed from the filtrate
tubular secretion: all molecules secreted by nephrons into urine are from blood of peritubular capillaries

Question 21

Vasa Recta in Renal Medulla

Answer 21

emerge from efferent arterioles of juxta medullary nephrons in deepest part of renal cortex
thin-walled looping vessels which descend into the medulla running alonside the nephron loops
important part of the kidney’s urine concentrating mechanism
desert vertebrates tend to have very well developed vasa recta to conserve their water

Question 22

Antidiuretic Hormone (Vasopressin)

Answer 22

produced by hypothalamus and released by posterior part of pituitary gland
released when the body needs to conserve water

Question 23

Vasopressin Effect on Distal Tubules and Collecting Ducts

Answer 23

the antidiuretic hormone (vasopressin) increases the permeability of distal tubules and collecting ducts allowing water from the filtrate to be resorbed into the surrounding blood capillaries which decreases urine volume
alcohol can significantly reduce the production of the ADH resulting in increased urination

Question 24

Aldosterone Effect on Distal Tubules and Collecting Ducts

Answer 24

aldosterone is a hormone produced by the adrenal cortex that increases the resorption of sodium ions and water and the secretion of potassium in the distal convoluted tubules and the collecting ducts which results in increased blood pressure

Question 25

Pharmacology of Some Diuretics and Caffeine

Answer 25

block the resorption of sodium from distal convoluted tubules which increases urine production and lowers blood pressure

Question 26

Juxtaglomerular Apparatus

Answer 26

a structure that functions in regulating blood pressure an area of specialized contact between terminal end of the ascending limb of nephron loop and afferent arteriole within the apparatus, the structures of both tubule and the arteriole are modified granular cells, macula densa, extraglomerular mesangial cells, mesangial cells between glomerular capillaries

Question 27

Juxtaglomerular Apparatus (Granular Cells)

Answer 27

modified smooth muscle cells with secretory granules contained in the walls of the afferent and efferent arterioles and appear to contain mechanoreceoptors granular cells contain the hormone renin which is secreted in response to falling blood pressure in afferent arterioles which triggers the renin-angiotensin system which increases aldosterone levels

Question 28

Juxtaglomerular Apparatus (Macula Densa)

Answer 28

at the end of nephron loop adjacent to granular cells tall, closely packed epithelial cells act as chemoreceptors and monitor solute concentration in the filtrate when solute concentrations fall below a certain level, the cells of the macula densa signal granular cells to secrete renin

Question 29

Juxtaglomerular Apparatus (Extraglomerular Mesangial Cells)

Answer 29

interact with macula densa and granular cells to help regulate blood pressure

Question 30

Juxtaglomerular Apparatus (Mesangial Cells Between Glomerular Capillaries)

Answer 30

located around base of the glomerulus | these cells have contractile properties which help regulate blood flow within the gomerulus

Question 31

Urine Movement

Answer 31

``` capsular space of renal corpuscle proximal convoluted tubule nephron loop distal convoluted tubule collecting duct renal calyzes renal pelvis ureter ```

Question 32

Ureters

Answer 32

carry urine from the kidneys to the urinary bladder | enters into posteriolateral corner of bladder and run medially in bladder wall before opening into bladder's interior

Question 33

Ureters (Histology)

Answer 33

mucosa: transitional epithelium on fibroelastic lamina propria muscularis: inner longitudinal and outer circular layer of smooth muscle; in inferior (lower) 1/3rd of ureter there is a 3rd layer (external longitudinal layer) adventitia: connective tissue

Question 34

Urinary Bladder (Layers)

Answer 34

three layers: 1. mucosa with transitional epithelium 2. thick muscular layer - detrusor muscle: contraction of this muscle squeezes urine from the bladder during urination 3. fibrous adventitia

Question 35

Trigone

Answer 35

a triangular region in the posterior wall of the bladder which is defined by the openings of the two ureters and urethra

Question 36

Urinary Bladder

Answer 36

a collapsible muscular sac that stores and expels urine empty bladder - lies entirely within the pelvis full bladder expands into the abdominal cavity and becomes spherical and the mucosa rugae flatten out a full adult bladder can hold 500 ml of urine

Question 37

Urinary Tract Epithelium

Answer 37

ureters: transitional epithelium bladder: transitional epithelium proximal urethra: transitional epithelium mid-urethra (males): stratified and pseudostratified columnar distal urethra: stratified squamous epithelium

Question 38

Prostate Gland (Males)

Answer 38

lies directly inferior to the bladder | surrounds the urethra

Question 39

Urethra

Answer 39

in females: 3-4 cm long in males: 20 cm in length with three regions 1. prostatic urethra: passes through the prostate gland 2. membranous urethra: passes through the urogenital diaphragm 3. spongy (penile) urethra: passes through the length of the penis

Question 40

Urethra (Sphincters)

Answer 40

internal urethral sphincter: involuntary smooth muscle keeps urethra closed when urine not being passed external urethral sphincter: surrounds urethra within the sheet of muscle called the urogenital diaphragm; this skeletal muscle sphincter inhibits urination until person is ready to urinate; voluntarily relaxed which enables urination

Question 41

Micturition

Answer 41

1. bladder fills and stretch receptors in the bladder wall send message via visceral afferent impulses to spinal cord and then via ascending tract up to pontine micturition center 2. micturition response initiated and sent down descending tracts to spinal cord 3. parasympathetic efferent extend from spinal cord and stimulate contraction of the detrusor muscle and opening of internal urethral sphincter 4. sympathetic efferents to the bladder are inhibited 5. somatic motor efferents to the external urethral sphincter are inhibited which causes the voluntary muscle of this sphincter to relax to allow urine to exit the urethra

Question 42

Disorders of the Urinary System

Answer 42

urinary tract infections: more common in females, burning sensation during mictruition renal calculi: kidney stones bladder cancer: 3% of cancers, more common in men kidney cancer: arises from epithelial cells of urine tubules

Question 43

Urinary System Throughout Life

Answer 43

kidney and bladder function declines with advancing age nephrons decrease in size and number tubules less efficient at secretion and reabsorption filtration declines recognition of desire to urinate is delayed loss of muscle tone in the bladder