Title: Anatomy and Physiology by Rod R Seeley 6th edition chapter 26 power-point
1 Anatomy and Physiology, Sixth Edition
Rod R. SeeleyIdaho State University Trent D.
StephensIdaho State University Philip
TatePhoenix College
Chapter 26 Lecture Outline
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2Chapter 26
3Urinary System Functions
- Filtering of blood
- Regulation of
- blood volume
- concentration of blood solutes
- pH of extracellular fluid
- blood cell synthesis
- Synthesis of Vitamin D
4Urinary System Anatomy
5Location and External Anatomyof Kidneys
- External Anatomy
- Renal capsule
- Surrounds each kidney
- Perirenal fat
- Engulfs renal capsule and acts as cushioning
- Renal fascia
- Anchors kidneys to abdominal wall
- Hilum
- Renal artery and nerves enter and renal vein and
ureter exit kidneys
- Location
- Lie behind peritoneum on posterior abdominal wall
on either side of vertebral column - Lumbar vertebrae and rib cage partially protect
- Right kidney slightly lower than left
6Internal Anatomy of Kidneys
- Cortex Outer area
- Renal columns
- Medulla Inner area
- Renal pyramids
- Calyces
- Major Converge to form pelvis
- Minor Papillae extend
- Nephron Functional unit of kidney
- Juxtamedullary
- Cortical
7The Nephron
8Histology of the Nephron
9Internal Anatomy of Kidneys
- Renal corpuscle
- Bowmans capsule
- Parietal layer
- Visceral layer
- Glomerulus
- Network of capillaries
- Arterioles
- Afferent
- Blood to glomerulus
- Efferent
- Drains
- Tubules
- Proximal (convoluted) tubule
- Loops of Henle
- Descending limb
- Ascending limb
- Distal (convoluted) tubules
- Collecting ducts
10Renal Corpuscle
11Kidney Blood Flow
12Ureters and Urinary Bladder
- Urethra
- Transports urine from bladder to outside of body
- Difference in length between males and females
- Sphincters
- Internal urinary
- External urinary
- Ureters
- Tubes through which urine flows from kidneys to
urinary bladder - Urinary bladder
- Stores urine
13Ureters and Urinary Bladder
14Urine Formation
15Filtration
- Filtration
- Renal filtrate
- Plasma minus blood cells and blood proteins
- Most (99) reabsorbed
- Filtration membrane
- Fenestrated endothelium, basement membrane and
pores formed by podocytes
- Filtration pressure
- Responsible for filtrate formation
- Glomerular capillary pressure (GCP) minus capsule
pressure (CP) minus colloid osmotic pressure
(COP) - Changes caused by glomerular capillary pressure
16Filtration Pressure
17Tubular Reabsorption
- Substances transported
- Active transport moves Na across nephron wall
- Other ions and molecules moved by cotransport
- Passive transport moves water, urea,
lipid-soluble, nonpolar compounds
- Reabsorption
- Passive transport
- Active transport
- Cotransport
- Specialization of tubule segments
18Reabsorption in Proximal Nephron
19Reabsorption in Loop of Henle
20Reabsorption in Loop of Henle
21Tubular Secretion
- Substances enter proximal or distal tubules and
collecting ducts - H, K and some substances not produced in body
are secreted by countertransport mechanisms
22Secretion of Hydrogen and Potassium
23Urine Production
- In ascending limb of loop of Henle
- Na, Cl-, K transported out of filtrate
- Water remains
- In distal tubules and collecting ducts
- Water movement out regulated by ADH
- If absent, water not reabsorbed and dilute urine
produced - If ADH present, water moves out, concentrated
urine produced
- In Proximal tubules
- Na and other substances removed
- Water follows passively
- Filtrate volume reduced
- In descending limb of loop of Henle
- Water exits passively, solute enters
- Filtrate volume reduced 15
24Filtrate and Medullary Concentration Gradient
25Medullary Concentration and Urea Cycling
26Urine Concentration Mechanism
- When large volume of water consumed
- Eliminate excess without losing large amounts of
electrolytes - Response is kidneys produce large volume of
dilute urine
- When drinking water not available
- Kidneys produce small volume of concentrated
urine - Removes waste and prevents rapid dehydration
27Urine Concentrating Mechanism
28Hormonal Mechanisms
- ADH
- Secreted by posterior pituitary
- Increases water permeability in distal tubules
and collecting ducts - Aldosterone
- Produced in adrenal cortex
- Affects Na and Cl- transport in nephron and
collecting ducts
- Renin
- Produced by kidneys, causes production of
angiotensin II - Atrial natriuretic hormone
- Produced by heart when blood pressure increases
- Inhibits ADH production
- Reduces ability of kidney to concentrate urine
29Effect of ADH on Nephron
30Aldosterone Effect on Distal Tubule
31Autoregulation and Sympathetic Stimulation
- Autoregulation
- Involves changes in degree of constriction in
afferent arterioles - As systemic BP increased, afferent arterioles
constrict and prevent increase in renal blood flow
- Sympathetic stimulation
- Constricts small arteries and afferent
arterioles - Decreases renal blood flow
32Clearance and Tubular Load
- Plasma clearance
- Volume of plasma cleared of a specific substance
each minute - Used to estimate GFR
- Used to calculate renal plasma flow
- Used to determine which drugs or other substances
excreted by kidney
- Tubular load
- Total amount of substance that passes through
filtration membrane into nephrons each minute - Normally glucose is almost completed reabsorbed
33Tubular Maximum
- Tubular maximum
- Maximum rate at which a substance can be actively
absorbed - Each substance has its own tubular maximum
34Urine Flow and Micturition Reflex
- Urine flow
- Hydrostatic pressure forces urine through nephron
- Peristalsis moves urine through ureters
- Micturition reflex
- Stretch of urinary bladder stimulates reflex
causing bladder to contract, inhibiting urinary
sphincters - Higher brain centers can stimulate or inhibit
reflex
35Micturition Reflex
36Effects of Aging on Kidneys
- Gradual decrease in size of kidney
- Decrease in kidney size leads to decrease in
renal blood flow - Decrease in number of functional nephrons
- Decrease in renin secretion and vitamin D
synthesis - Decline in ability of nephron to secrete and
absorb
37Kidney Dialysis