Download BIO132 Chapter 26 The Urinary System Lecture Outline

BIO132 Chapter 26 The Urinary System Lecture Outline
Urinary system
Components
Kidneys
Urinary tract
Ureters
Urinary bladder
Urethra
Functions
1. excretion
2. elimination
3. plasma regulation
4. other kidney functions
a. gluconeogenesis
b. renin
c. erythropoietin
d. calcitriol
Kidneys
Retroperitoneal
Adrenal glands
Connective tissues:
1. Renal capsule
2. Adipose capsule
3. Renal facia
Renal ptosis
Hilum
Renal sinus
Layers
1. Cortex
Nephrons
2. Medulla
Renal pyramids
Collection tubules
Papilla
Renal lobes = Renal pyramid + Renal columns
Flow: Nephrons → Collecting ducts → Papillary
ducts → Minor calyx → Major calyx →
Renal pelvis → Ureter
Pyelonephritis
Renal plexus
ANS: Sympathetic
-rate of urine formation
-renin
Nephron
1. Renal corpuscle
Glomerular capsule
Glomerulus
2. Renal tubule
Proximal convoluted tubule (PCT)
Nephron loop
Distal convoluted tubule (DCT)
Capillary beds
1. Glomerulus
2. Peritubular capillaries
afferent arteriole → capillary bed → efferent
Amy Warenda Czura, Ph.D.
arteriole (no venule)
Types
1. Cortical nephrons
2. Juxtamedullary nephrons
Renal corpuscle
1. Glomerular capsule
Parietal epithelium
2. Glomerulus
Fenestrated capillaries
Podocytes: visceral epithelium
Filtration slits
Glomerulonephritis
Renal tubule
1. PCT
Simple cuboidal epithelium
Microvilli
-reabsorption: nutrients, ions, water
2. Nephron loop
Simple squamous epithelium
-reabsorption: water
3. DCT
Simple cuboidal epithelium
a. secretion
b. reabsorb Na+, Ca2+
c. H2O
d. JGA
Juxtaglomerular Apparatus (JGA)
Cells
1. Macula densa
2. Juxtaglomerular cells
Secretions
1. Renin
2. Erythropoietin
Collecting system = Collecting duct + Papillary duct
many nephrons → 1 collecting duct →many
collecting ducts → 1 papillary duct (urine
complete)
Polycystic kidney disease (PKD)
Renal physiology
Waste removal
Filtrate
Urine
Wastes:
1. Urea
2. Creatinine
3. Uric acid
4. Urobilin
Dialysis
Urine production
1. Glomerular filtration
Filtration membrane
A. Fenestrate endothelium (glomerulus)
B. Podocytes (visceral epithelium)
C. Basal lamina
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SCCC BIO132 Chapter 26 Handout
Filtration
a. surface area
b. high BP
c. permeability
Glomerular filtration rate (GFR)
Regulation
1. Autoregulation
↑ GFR or ↓ GFR
arteriole dilation
arteriole constriction
2. Hormonal regulation
A. Renin
angiotensin→Angiotensin II
1. arteriole constriction
2. Aldosterone
↓ Na+ loss
3. thirst
4. ADH
↓ H2O loss
B. Natriuretic peptides
↑ GFR ↓ blood volume
3. Nervous regulation (ANS)
Sympathetic
↓ GFR
2. Tubular reabsorption
Carrier proteins
Renal threshold
Glycosuria
A. PCT reabsorption
1. organic nutrients
facilitated diffusion, cotransport
2. ions
diffusion
3. ions
ion pumps
4. water
osmosis
B. Nephron loop reabsorption
Countercurrent multiplication
Ascending limb: ions
Descending limb: water
C. DCT reabsorption
1. Aldosterone
Na+ uptake
K+ loss
2. Parathyroid hormone & Calcitriol
Ca2+ uptake
3. ADH
H2O uptake
3. Tubular secretion
a. wastes & drugs
b. K+
c. H+
Bicarbonate ion
Water volume
Obligatory reabsorption: PCT, descending loop
Amy Warenda Czura, Ph.D.
Facultative reabsorption: DCT, collecting ducts
ADH
aquaporins
Diuretics
Osmotic diuretics
Hypertension & Edema meds
Alcohol
Diabetes insipidus
Anuria
Nephrolithiasis
Calculi
Lithotripter
Ureters
Wall
1. Mucosa
transitional epithelium
2. Muscularis
3. Adventitia
Bladder
Wall
Rugae
1. Mucosa
transitional epithelium
2. Muscularis
Detrusor muscle
Internal urethral sphincter
3. Adventitia
Urethra
pseudostratified columnar epithelium
External urethral sphincter
Micturition reflex
1. stretch receptors
2. detrusor muscle contracts
3. relax external urethral sphincter
4. internal urethral sphincter relaxes
5. urination
Incontinence
Age related changes
↓ functional nephrons
↓ GFR
↓ ADH sensitivity
↑ incontinence
↑ urinary retention
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SCCC BIO132 Chapter 26 Handout
Amy Warenda Czura, Ph.D.
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SCCC BIO132 Chapter 26 Handout
Regulation of Filtration
Three levels of regulation to maintain constant Glomerular Filtration Rate:
1. Autoregulation
-functions to maintain constant GFR with normal BP fluctuations in systemic arteriole
pressure
A. Reduced blood flow/ BP triggers:
-dilation of afferent arteriole
-dilation of glomerular capillaries
-constriction of efferent arteriole
All functions to increase pressure at the glomerulus to increase GFR
B. High blood flow / BP triggers:
- constriction of afferent arteriole
- constriction of glomerular capillaries
-dilation of efferent arteriole
All functions to decrease pressure at the glomerulus to decrease GFR
2. Hormonal Regulation
-extrinsic regulation aimed at maintaining systemic blood pressure
A. Renin:
Enzyme released by juxtaglomerular apparatus in response to:
-decline in BP at kidney
-decline in osmotic concentration of filtrate
-direct sympathetic stimulation
Renin activates angiotensin in blood to form Angiotensin II which triggers:
-arteriole constriction to elevate BP
-secretion of aldosterone from adrenal glands (aldosterone promotes
sodium reabsorption in kidney tubules)
-thirst
-release of ADH from pituitary (ADH promotes water uptake in tubules)
Effect: ↑ blood volume, ↓ urine production
B. Natriuretic Peptides:
Hormones released in response to stretching in heart or aorta (↑blood volume)
Triggers:
-dilation of afferent arteriole, constriction of efferent arteriole:
Effect: ↑ GFR, ↑ urine production, ↓ blood volume
3. Autonomic Nervous System Regulation
Sympathetic causes vasoconstriction = ↓ GFR, ↓ urine production
(Prolonged sympathetic stimulation can cause hypoxia of kidneys and waste
accumulation in blood)
Amy Warenda Czura, Ph.D.
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SCCC BIO132 Chapter 26 Handout