Transcript PowerPoint to accompany

PowerPoint Lecture Outlines
to accompany
Hole’s Human
Anatomy and Physiology
Tenth Edition
Shier w Butler w Lewis
Chapter
20
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
20-1
Chapter 20
Urinary System
20-2
Location of Kidneys
20-3
Kidneys
20-4
Renal Blood Vessels
20-5
Renal Blood Vessels
20-6
Glomerular Capsule
20-7
Nephron and Associated Blood
Vessels
20-8
Renal Cortex and Renal
Medulla
20-9
Juxtaglomerular Apparatus
20-10
• Juxtaglomerular apparatus
• DCT- contains cells called the macula densa
• Afferent arteriole- contains juxtaglomerular
cells-release renin-in response to SNS and
baroreceptors
• Cells of the macula densa- responds to
Na+, k, and Cl ions
– Angiotensin II and Aldosterone- conserves Na
and retains water by osmosis, therefore
increasing BP and Blood Volume.
– Vasoconstriction of both afferent and efferent,
contributing to autoregulation of GFR.
Types of Nephrons
• cortical nephrons
• 80% of nephrons
• juxtamedullary nephrons
•20% of nephrons
• regulate water balance
20-11
Blood Supply of Nephron
The capillary loop of the
vasa recta is closely
associated with the
nephron loop of the
juxtamedullary
nephron
20-12
Summary of Blood Flow
Through Kidney and Nephron
20-13
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
20-14
Glomerular Filtration
Glomerular filtrate passes through the fenestrae of
the capillary endothelium
20-15
Glomerular Filtrate and
Urine Composition
20-16
Net Filtration Pressure = force favoring filtration – forces opposing filtration
(glomerular capillary
( capsular hydrostatic pressure
hydrostatic pressure)
and glomerular capillary
osmotic pressure )
• GFR is directly
proportional to the net
filtration pressure
• Sympathetic impulses
constricts the afferent
and GFR occurs
• Constriction of the
efferent, blood backs
up and causes GFR
• Vasodilation does the
opposite
20-17
Amounts of Glomerular Filtrate and
Urine
average amounts over a 24 hour period
• 25% of CO is received by
the kidneys, 20% of
plasma is filtered through
the capillaries
• GFR=
125ml/min=180L/24hrs
• Most fluid is reabsorbed,
with .6-2.5 L excreted as
urine
20-18
Control of Filtration Rate
• Increased sympathetic
impulses decrease GFR
by causing afferent
arterioles to constrict
• Renin-angiotensin
system (shown)
• Autoregulation
20-19
Control of Filtration Rate
• 1. Sympathetic- If BP and BV , resulting in
GFR and UO.( constriction of the afferent)
• 2. Renin-angiotensin system
• 3. ANP- stimulates NA excretion, and increasing
GFR
Tubular Reabsorption
20-20
Tubular Reabsorption of Water
and Ions
20-21
Sodium and Water Filtration,
Reabsorption, and Excretion
20-22
Tubular Secretion
20-23
Secretion of Ions
In distal convoluted tubules, potassium ions or hydrogen
ions may be passively secreted in response to active
reabsorption of sodium ions
20-24
Countercurrent Mechanism
• helps maintain the NaCl concentration gradient in the
medullary interstitial fluid
20-25
Countercurrent Mechanism of
Vasa Recta
• fluid in ascending limb
becomes hypotonic as
solute is reabsorbed
• fluid in descending limb
becomes hypertonic as it
loses water by osmosis
20-26
Effect of ADH on
Renal Tubules
• without ADH, DCT and collecting duct are impermeable to water
• with ADH, DCT and collecting duct become permeable to water
• with ADH, water is reabsorbed by osmosis into hypertonic medullary
interstitial fluid
20-27
Urea and Uric Acid Excretion
Urea
• product of amino acid
catabolism
• plasma concentration
reflects the amount or
protein in diet
• enters renal tubules
through glomerular
filtration
• 50% reabsorbed
• rest is excreted
Uric Acid
• product of nucleic acid
metabolism
• enters renal tubules
through glomerular
filtration
• 100% reabsorbed
• 10% secreted and
excreted
20-28
Renal Clearance
• the rate at which a chemical is removed from the plasma
• tests of renal clearance
• inulin clearance test
• creatinine clearance test
• paraminohipparic acid test
• tests of renal clearance used to calculate glomerular filtration
rate
20-29
Elimination of Urine
• nephrons
• collecting ducts
• renal papillae
• minor and major calyces
• renal pelvis
• ureters
• urinary bladder
• urethra
• outside world
20-30
Ureters
• 25 cm long
• extend downward posterior
to the parietal peritoneum
• parallel to vertebral
column
• in pelvic cavity, join
urinary bladder
• wall of ureter
• mucous coat
• muscular coat
• fibrous coat
20-31
Location of Male and Female
Urinary Bladders
20-32
Urinary Bladder
Longitudinal section and posterior view of
male urinary bladder
20-33
Cross Section of Urethra
20-34
Male and Female Urethras
20-35
Micturition
• 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
20-36
Life-Span Changes
• kidneys appear scarred and grainy
• kidney cells die
• by age 80, kidneys have lost a third of their mass
• kidney shrinkage due to loss of glomeruli
• proteinuria may develop
• renal tubules thicken
• harder for kidneys to clear certain substances
• bladder, ureters, and urethra lose elasticity
• bladder holds less urine
20-37
Clinical Application
Glomerulonephritis
• inflammation of glomeruli
• may be acute or chronic
• acute glomerulonephritis usually occurs as an immune reaction
to a Streptococcus infection
• antigen-antibody complexes deposited in glomeruli and cause
inflammation
• most patients recover from acute glomerulonephritis
• chronic glomerulonephritis is a progressive disease and often
involves diseases other than that caused by Streptococcus
• renal failure may result from chronic glomerulonephritis
20-38