Transcript Slide 1
All organisms must EXTERNAL ENVIRONMENT
CO2
eliminate waste
O2 respiratory system
Food
Mouth
products!!
Eliminates CO2
ANIMAL
digestive
system
Digestive
eliminates system
solid
wastes
Nutrients
and excess H+.
Respiratory
system
Interstitial
fluid
Heart
Circulatory
system
Body
cells
Urinary
system
Intestine
Anus
Unabsorbed
matter (feces)
Metabolic waste
products (urine)
Functions of
the Excretory
System
-- Maintains
salt/water
balance
-- Eliminates
metabolic
wastes, drugs,
toxins
-- Indirect
regulation of
blood pressure
and pH
Osmoregulation = The Balance of water and
solute levels in body fluids.
Osmoconformers (marine invertebrates)
– have body fluids with a [solute] = to [seawater]
Osmoregulators (land animals, freshwater animals,
saltwater fish)
– have body fluids with [solute] that differ from environment
– must actively regulate water movement
Osmoregulation strategy depends on animal’s habitat!!
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Figure 40.1 Osmoconformity Has Limits
Osmoregulation = Balance of solutes and water
Freshwater fish
Passive water gain
through gills
Salts actively
Taken up by gills
–
gain water by osmosis
(mainly through gills),
–
take in salt by active
transport through their gills
and in food
–
excrete excess water in dilute
urine.
Excretion of dilute urine
from kidneys
FRESH WATER
(hypotonic environment)
Osmoregulation strategy depends on animal’s habitat!!
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Osmoregulation = Balance of solutes and water
Saltwater fish
– lose water by osmosis from the gills and body surface,
– drink seawater, and
– use their gills and kidneys to excrete excess salt.
Passive loss of water through gills
Drinks seawater
SALT WATER
(hypertonic environment)
Salts actively
excreted by gills
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Excretion of
concentrated urine
Osmoregulation = Balance of solutes and water
Land animals
– risk of dehydration
– lose water by evaporation and waste disposal
– gain water by drinking and eating
– conserve water by
– efficient kidneys.
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Disposal of Nitrogenous
and metabolic
wastes
Metabolism produces
toxic by-products.
Nitrogenous wastes =
breakdown products
of proteins and
nucleic acids.
Animals dispose of
nitrogenous wastes in
different ways.
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The Human Urinary System
The urinary
system
– forms and
excretes urine
and
– regulates
water and
solutes in
body fluids.
Nephrons = functional units of
kidneys
–extract a fluid filtrate from the
blood, and
–refine the filtrate to produce
urine.
Animation: Nephron Introduction
DETAILED STRUCTURE OF A NEPHRON
Figure 40.5 The Vertebrate Nephron
Processing of Urine in 4 Stages
Filtration
– Blood enters kidney via renal artery --> various capillary beds
(GLOMERULUS)
– Each capillary bed wraps around nephron
– Blood filtered through capillary bed by force of blood pressure
– Proteins and RBCs remain in blood
– Filtrate contains: Water, salts, glucose, amino acids, urea collected
by Bowman’s capsule
From Bowman’s
Filtration
renal capsule
artery
Nephron tubule
H2O, other small molecules
Reabsorption
Secretion
Excretion
Urine
Interstitial fluid
Capillary
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To renal vein
Processing of Urine in 4 Stages
Reabsorption
– proximal and distal tubules return
– Glucose, salt, and amino acids to blood by active transport
– Water follows by osmosis
Secretion
– Substances in the blood are transported into the urine by active
transport at PCT and DCT
Excretion
From Bowman’s
Filtration
renal capsule
artery
Nephron tubule
H2O, other small molecules
Reabsorption
Secretion
Excretion
Urine
Interstitial fluid
Capillary
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To renal vein
PROXIMAL TUBULE
NaCl Nutrients
HCO3– H2O
K+
H+
NH3
CORTEX
DESCENDING
LIMB
OF LOOP OF
HENLE
Filtrate Contains:
H2O
Salts (NaCl and others)
HCO3–
H+
Urea
Glucose; amino acids
Some drugs
DISTAL TUBULE
H2O
NaCl
K+
H+
ASCENDING
LIMB OF LOOP
OF HENLE
NaCl
H2O
OUTER
MEDULLA
NaCl
COLLECTING
DUCT
Key
Active transport
Passive transport
HCO3–
Urea
NaCl
INNER
MEDULLA
H2O
Kidneys and Acid-Base Balance
pH is regulated by
– Secretion of acidic and basic organic compounds
– reabsorption of HCO3– and
– secretion of H+.
© 2012 Pearson Education, Inc.
Figure 40.8 Concentrating the Urine
Figure 40.9 Renin-Angiotensin-Aldosterone System Helps Regulate GFR
Homeostasis:
Blood pressure,
volume
Acts on:
Effect?
STIMULUS:
Hormone?
Acts on:
Effect?
Gland?
Converted to:
Distal
tubule
Angiotensinogen
JGA
Enzyme
Produced?
Hormonal Control of
Kidneys
Antidiuretic hormone
(ADH)
– Produced by pituitary
gland
Osmoreceptors
in hypothalamus
Thirst
Hypothalamus
Drinking reduces
blood osmolarity
to set point
ADH
Pituitary
gland
– Released in response to
decreased blood volume
– Regulates the permeability
of collecting duct to water
– High ADH; nephrons
reabsorb water from the
urine, returning it to the
blood
H2O reabsorption helps
prevent further
osmolarity
increase
STIMULUS
Increase in solute concentration
In blood; decrease blood
Collecting duct
Volume;
Decreased blood pressure
– Leads to increased blood
volume and blood
pressure
Homeostasis:
Proper blood pressure
Solute levels
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Figure 40.10 ADH Induces Insertion of Aquaporins into Plasma Membranes (Part 1)
Figure 40.10 ADH Induces Insertion of Aquaporins into Plasma Membranes (Part 2)