Upload
arlene-wells
View
226
Download
0
Tags:
Embed Size (px)
Citation preview
Excretory (Urinary) System
Chapter 44Chapter 44Chapter 44Chapter 44
Urinary ComponentsFunctions of Urinary System1. Kidney Functions2. Urine transport3. Urine storage.4. Excretion
Kidney - Internal Anatomy
Kidney Functions1. Regulate blood ionic composition.
2. Regulate blood pH.
3. Regulate blood volume.
4. Regulate blood pressure.
5. Maintain blood osmolarity.
6. Production of hormones.
7. Regulation of blood glucose levels.
8. Excretion of wastes and foreign substances.
Corticalnephron
Juxtamedullarynephron
Collectingduct
(c) Nephron types
Torenalpelvis
Renalmedulla
Renalcortex
Animation: Nephron IntroductionAnimation: Nephron Introduction
Nephron
1. Glomerular Filtration
2. Tubular Reabsorption
3. Tubular Secretion
Fig. 44-14dAfferent arteriolefrom renal artery
Efferentarteriole fromglomerulus
SEM
Branch ofrenal vein
Descendinglimb
Ascendinglimb
Loop ofHenle
(d) Filtrate and blood flow
Vasarecta
Collectingduct
Distaltubule
Peritubular capillaries
Proximal tubule
Bowman’s capsuleGlomerulus
10 µm
1. Glomerular Filtration
2. Tubular Reabsorption
3. Tubular Secretion
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
From Blood Filtrate to Urine: A Closer Look
Proximal Tubule
• Reabsorption of ions, water, and nutrients takes place in the proximal tubule
• Molecules are transported actively and passively from the filtrate into the interstitial fluid and then capillaries
• Some toxic materials are secreted into the filtrate
• The filtrate volume decreasesAnimation: Bowman’s Capsule and Proximal TubuleAnimation: Bowman’s Capsule and Proximal Tubule
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Descending Limb of the Loop of Henle
• Reabsorption of water continues through channels formed by aquaporin proteins
• Movement is driven by the high osmolarity of the interstitial fluid, which is hyperosmotic to the filtrate
• The filtrate becomes increasingly concentrated
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Ascending Limb of the Loop of Henle
• In the ascending limb of the loop of Henle, salt but not water is able to diffuse from the tubule into the interstitial fluid
• The filtrate becomes increasingly dilute
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Distal Tubule
• The distal tubule regulates the K+ and NaCl concentrations of body fluids
• The controlled movement of ions contributes to pH regulation
Animation: Loop of Henle and Distal TubuleAnimation: Loop of Henle and Distal Tubule
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Collecting Duct
• The collecting duct carries filtrate through the medulla to the renal pelvis
• Water is lost as well as some salt and urea, and the filtrate becomes more concentrated
• Urine is hyperosmotic to body fluids
Animation: Collecting DuctAnimation: Collecting Duct
Fig. 44-15
Key
ActivetransportPassivetransport
INNERMEDULLA
OUTERMEDULLA
H2O
CORTEX
Filtrate
Loop ofHenle
H2O K+HCO3–
H+ NH3
Proximal tubule
NaCl Nutrients
Distal tubule
K+ H+
HCO3–
H2O
H2O
NaCl
NaCl
NaCl
NaCl
Urea
Collectingduct
NaCl
Composition of Filtrate