Chapter 20 Urinary System

1
Chapter 20 Urinary System

• FUNCTIONS
• Removes metabolic wastes

• Erythropoietin secretion
• Renin secretion

• Activates vitamin D

• Maintains electrolyte balance and pH
• Maintains blood volume

• Bean shaped Kidneys with adrenals on top
• Size of a clenched fist

• Located ________________ posterior upper
  abdominal wall
• Protected by ______________

retroperitoneal
renal fat pad
2
KidneyGross Anatomy
label
fibrous connective

• Renal Capsule - ________________
• tissue

• Renal Cortex

• Renal Medulla made up of renal
• __________ renal _________

columns
pyramids

• Minor calyces
• Major calyces

• Renal pelvis

bladder
urethra

• Urine flows out of the ureter to the _________
  to the _________ and out of the body.

ureter
nerves
blood vessels

• Hilum - where ______________ , _______
  _________enters

3
Kidney Blood Flow
Interlobular artery
interlobular vein
Interlobular vein
Interlobular artery
glomerulus
arcuate artery
arcuate vein
arcuate ?artery
efferent arteriole
?arcuate vein
Interlobar vein
interlobar artery
Renal artery
peritubular capillaries
afferent arteriole
renal vein
vasa recta
Segmental artery
4
Nephron
renal corpuscle
proximal convoluted tubule
distal convoluted tubule

• Functional microscopic unit of the kidney

descending limb of Henle

• Structure - label (Path)

• Cortical and juxtamedullary

Loop of Henle

• Associated structure - Juxtaglomerular Apparatus

collecting duct
ascending limb of Henle

• structure of
• juxtaglomerular cells contain renal
  barorecepters

• macula densa cells sense concentration of Na,
  K and Cl-

distal convoluted tubule

• point of contact between the _______ ________
  _____ _________ ______

afferent arteriole
renin

• controls the secretion of ________ - label

5
Urine Formation

• Glomerular Filtration
• substances move from blood to glomerular capsule

• Tubular Reabsorption
• substances move from renal tubules into blood of
  peritubular capillaries
• glucose, water, urea, proteins, creatine
• amino, lactic, citric, and uric acids
• phosphate, sulfate, calcium, potassium, and
  sodium ions

• Tubular Secretion
• substances move from blood of peritubular
  capillaries into renal tubules
• drugs and ions

6
Glomerular Filtration Rate (GFR)

• Fenestrated capillaries filter water dissolved
  materials from blood.

• Filtrate is then collected in Bowman's capsule

• Note the difference between the
• afferent efferent arterioles in diameter
• Filtration is due to hydrostatic pressure
• ____mm glomerular BP
• ____ mm plasma colloid osmotic pressure
• ____mm capsular hydrostatic pressure
• ____mm Net outward pressure (GFR)

60
-32
-18
10

• Kidneys filter about 180 L per/day

• Autoregulation of Filtration Rate (GFR)
• Sympathetic control of the afferent arteriole
• Exercise __BP_________ afferent arteriole to
  avoid ________ to nephron.
• What will happen if BP goes down?
• Myogenic Mechanism high BP stretches afferent
  arteriole smooth muscle
• causing a reflexive ___________ thus ___ GFR. ..
  Opposite for low BP

constricts
damage
constriction
7
Control of Glomerular Filtration Rate (GFR)

• When the macula densa cells sense a high
  osmolarity (high cons. of Na Cl-) in the DCT
  they release vasoconstrictor chemicals which
  causes ___________of the afferent arteriole thus
  lower the ______.

constriction
GFR

• During low BP and osmolarity the juxtaglomerular
  cells containing renal barorecepters
  release______.

• Renin-angiotension causes the following
• ___ aldosterone secretion
• Circulatory vasoconstriction ____
• Increased _____ secretion ___ thirst .. All
  leading to ___GFR due to ___BP

renin
ADH

• The heart releases ANP when it is stretched due
  to high BP which will than act on the kidney to
  lose ____ thus _________ BP and GFR.

lowering
Na
8
Tubular Reabsorption
Proximal Convoluted Tubule

• 65 of filtrate reabsorbed into blood 100
  nutrients

• slow flow through convolutions
• brush border (microvilli)

• glucose by facilitated transport
• limited by number of carriers
• renal plasma threshold
• osmotic diuresis

• amino acids by active transport

• Ion and water transport
• Active transport of Na starts a cotransport
  system of ____________ and _______
• What causes Cl- to follow?
• What cause water to follow Na and the negative
  ions?

negative ions
water
9
Tubular Reabsorption

• Loop of Henle - concentrates urine by
  countercurrent mechanism

• Descending limb
• Highly permeable to ______

water

• Increasing cons. of interstitial fluid of the
  medulla causes water to _________ of the tubule
  into interstitial fluid

flow out

• Ascending limb
• impermeable to _______ and _______
• active transport of Na and Cl- to interstitial
  fluid
• maintains concentration gradient for
  concentration of _______

water
urea
urine
10
Distal Convoluted Tubule Collecting Duct

• Distal Convoluted Tubule
• permeability regulated by presence of hormones

• ADH's effect?

• Aldosterone's effect?

• PTH's effect?

• Collecting Duct - about the same as DCT

11
Tubular Secretion

• Movement from the plasma of peritubular
  capillary into the renal tubules

• Maintains ion concentrations in blood by
  eliminating excesses.

• PCT- removes toxins, drugs,urea and wastes
  (penicillin, creatinine, histamines)
• DCT - Active secretion of H K and passive
• NH3 H----gt NH4

12
COMPOSITION OF URINE

• Normal composition - 95 water
• Urea - protein decomposition
• Uric acid - nucleic acid decomposition
• Creatinine - creatine phosphate
• Ions - NH4 PO4-3 SO4-2 NO3- H K
• Specific gravity 1.001 to 1.030
• pH depends on food intake
• pH 4.5 - protein diet
• pH 8 vegetarian
• pH 6 - average

Crystals another

• Abnormal composition
• glucose - diabetic, too sugary diet, glycosuria
• albumin - over exertion, BP to high, blow to
  kidney
• ketone bodies - starvation acidosis, diabetes
• RBC's - urinary tract stones, hematuria
• Hemoglobin - transfusion reaction, burns, renal
  disease
• Bile pigments(yellow foam) -liver disease,
  hepatitis
• WBC's - pyuria, urinary tract inflammation
• Casts - not always abnormal
• RBC's - glomerulonephritis(result of a immune
  complex reaction)
• WBC's pyelonephritis
• fatty - renal damage

13
MOVEMENT OF URINE

• Hydrostatic pressure of 18mm Hg in Bowman's
  capsule to 0 in renal pelvis

• Parasymthetic stimulation of ureter smooth
  muscle---gtperistaltic waves

• 0 pressure in bladder when empty pressure
  builds as it fills

• Pressure goes up quickly when bladder contains
  400 - 500 ml of urine

• Micturition reflex
• bladder distends and stretch receptors stimulated

• micturition center activated in sacral portion
  of spinal cord

• parasympathetic nerve impulses cause detrusor
  muscle to contract
• need to urinate is sensed

• voluntary contraction of external urethral
  sphincter prevents urination

• when decision is made to urinate, external
  urethral sphincter relaxes, detrusor muscle
  contracts, and urine is expelled

14
Ureters Urinary Bladder

• URETERS
• Joins urinary bladder underneath and posteriorly
• Layers
• transitional epithelial
• smooth muscle
• fibrous coat

• Renal calculus - stones
• causes strong peristaltic waves
• uretrorenal reflex - constricts renal arteries

• URINARY BLADDER
• Located against the rectum in male
• Contacts the anterior walls of uterus vagina
  in female
• Trigone
• Histology same as ureters except
• submucosal coat -elastic fibers
• detrusor muscle - bundles of interlacing smooth
  muscle in all directions
• Over active bladder

15
URETHRA

• Urethral glands secrete mucous
• Females more susceptible to cystitis (bladder
  infection) than males
• female urethra - 4cm

• sections of male urethra - 19.5 cm
• prostate
• membranous
• penile

16
References

• Urinalysis - Utah WebPath
• Haemodialysis
• Fluid Balance Regulation
• Kidney Transplant
• Peritoneal dialysis
• Urine Analysis
• Hole's Online Learning Center - try Test Yourself