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!!
© 2012 Pearson Education, Inc.
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.
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
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)