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Test info
Average: 16 out of 30
Range: 7 - 25
Corrections due: Friday
Lab notebooks: Thursday
-Daphnia data – on-line
-Fitness test
-Tape/staple sheet
-Discussion questions
-What is your fitness level?
-Do you agree with the findings?
-Why or why not?
Chapter 44: Osmoregulation and Excretion
1. What is osmoregulation?
- How animals regulate solute concentrations &
balance the gain & loss of water
2. What is excretion?
- How animals get rid of nitrogenous waste of metabolism
3. What is the difference between an osmoregulator & an osmoconformer?
- Osmoconformer – does not actively adjust its internal osmolarity
- Isoosmotic to environment
- Marine animals
- Osmoregulator – actively controls osmolarity
- NOT isoosmotic with environment
Figure 44.3 Osmoregulation in marine and freshwater bony fishes
Gain of water and
salt ions from food
and by drinking
seawater
Excretion of
salt ions
from gills
Osmotic water loss
through gills and other parts
of body surface
Excretion of salt ions
and small amounts
of water in scanty
urine from kidneys
(a) Osmoregulation in a saltwater fish
- Hypoosmotic to ocean
- loses LOTS of water at gills
- “Drinks like a fish”
- excretes salt & little urine
Osmotic water gain
through gills and other parts
of body surface
Uptake of
water and some
ions in food
Uptake of
salt ions
by gills
Excretion of
large amounts of
water in dilute
urine from kidneys
(b) Osmoregulation in a freshwater fish
- Hyperosmotic to lake
- gain LOTS of water at gills
- LOTS of dilute urine
Chapter 44: Osmoregulation and Excretion
1.
2.
3.
4.
What is osmoregulation?
What is excretion?
What is the difference between an osmoregulator & an osmoconformer?
What is the biggest issue for land animals?
- Dehydration
- Many adaptations to prevent this
5. What are the different nitrogenous waste products that animals excrete?
- Ammonia
- Urea
- Uric acid
Figure 44.8 Nitrogenous wastes
Nucleic acids
Proteins
Nitrogenous bases
Amino acids
–NH2
Amino groups
Ammonia – very soluble in water
- VERY toxic
- easily passes through membranes
- 1 N at a time
Many reptiles
Most aquatic
Mammals, most
(including
animals, including amphibians, sharks,
birds), insects,
most bony fishes some bony fishes
land snails
O
NH3
Ammonia
O
C
NH2
NH2
Urea
O
HN
C
C
H
C N
C N
N
H
H
Uric acid
C O
Urea
- 100,000X less toxic than –NH3
- -NH3 + CO2 in liver
- helps conserve water
- 2 N at a time
Uric acid- not very soluble in water
- excreted in paste-like form
- little water loss
- stored in amniotic egg
- 4 N at a time
Chapter 44: Osmoregulation and Excretion
1.
2.
3.
4.
5.
6.
What is osmoregulation?
What is excretion?
What is the difference between an osmoregulator & an osmoconformer?
What is the biggest issue for land animals?
What are the different nitrogenous waste products that animals excrete?
What are the 4 main functions of excretory systems?
- Filtration
- Reabsorption
- Secretion
- Excretion
Figure 44.9 Key functions of excretory systems: an overview
Capillary
Filtrate
Excretory
tubule
1 Filtration. The excretory tubule collects a filtrate from the blood.
Water and solutes are forced by blood pressure across the
selectively permeable membranes of a cluster of capillaries and
into the excretory tubule.
2 Reabsorption. The transport epithelium reclaims valuable substances
from the filtrate and returns them to the body fluids.
3 Secretion. Other substances, such as toxins and excess ions, are
extracted from body fluids and added to the contents of the excretory
tubule.
Urine
4
Excretion. The filtrate leaves the system and the body.
Chapter 44: Osmoregulation and Excretion
1.
2.
3.
4.
5.
6.
7.
What is osmoregulation?
What is excretion?
What is the difference between an osmoregulator & an osmoconformer?
What is the biggest issue for land animals?
What are the different nitrogenous waste products that animals excrete?
What are the 4 main functions of excretory systems?
How have excretory systems evolved?
- Protonephridia – Planaria
- Metanephridia – Earthworm
- Malpighian tubules – insects
- Kidney - us
Figure 44.10 Protonephridia: the flame-bulb system of a planarian
Nucleus
of cap cell
Cilia
Interstitial fluid
filters through
membrane where
cap cell and tubule
cell interdigitate
(interlock)
Tubule cell
Flame
bulb
Protonephridia
(tubules)
Tubule
Nephridiopore
in body wall
Figure 44.11 Metanephridia of an earthworm
Coelom
Capillary
network
Bladder
Collecting
tubule
Nephridiopore
Nephrostome
Metanephridia
Figure 44.12 Malpighian tubules of insects
Digestive tract
Rectum
Intestine
Midgut
(stomach)
Salt, water, and
nitrogenous
wastes
Hindgut
Malpighian
tubules
Feces and urine
Anus
Malpighian
tubule
Rectum
Reabsorption of H2O,
ions, and valuable
organic molecules
HEMOLYMPH
Chapter 44: Osmoregulation and Excretion
1.
2.
3.
4.
5.
6.
7.
8.
What is osmoregulation?
What is excretion?
What is the difference between an osmoregulator & an osmoconformer?
What is the biggest issue for land animals?
What are the different nitrogenous waste products that animals excrete?
What are the 4 main functions of excretory systems?
How have excretory systems evolved?
What is the structure and function of the kidney?
Figure 44.13 The mammalian excretory system
Posterior vena cava
Renal artery and vein
Aorta
Renal
medulla
Renal
cortex
Kidney
Ureter
Urinary bladder
Urethra
Renal
pelvis
(a) Excretory organs and major
associated blood vessels
JuxtaCortical
medullary nephron
nephron
Ureter
(b) Kidney structure
Afferent
arteriole
from renal Glomerulus
artery
Bowman’s capsule
Proximal tubule
Renal
cortex
Collecting
duct
To
renal
pelvis
(c) Nephron
Peritubular capillaries
20 µm
Renal
medulla
Section of kidney from a rat
SEM
Efferent
arteriole from
glomerulus
Branch of
renal vein
Descending
Loop
limb
of
Ascending
Henle
limb
(d) Filtrate and
blood flow
Distal
tubule
Collecting
duct
Vasa
recta
Chapter 44: Osmoregulation and Excretion
1.
2.
3.
4.
5.
6.
7.
8.
9.
What is osmoregulation?
What is excretion?
What is the difference between an osmoregulator & an osmoconformer?
What is the biggest issue for land animals?
What are the different nitrogenous waste products that animals excrete?
What are the 4 main functions of excretory systems?
How have excretory systems evolved?
What is the structure and function of the kidney?
What is the structure & function of the nephron?
Chapter 44: Osmoregulation and Excretion
1.
2.
3.
4.
5.
6.
7.
8.
9.
What is osmoregulation?
What is excretion?
What is the difference between an osmoregulator & an osmoconformer?
What is the biggest issue for land animals?
What are the different nitrogenous waste products that animals excrete?
What are the 4 main functions of excretory systems?
How have excretory systems evolved?
What is the structure and function of the kidney?
What is the structure & function of the nephron?
- Glomerulus – filtration due to BP
- Proximal tubule – secretion & reabsorption
- Loop of Henle
- Descending – reabsorption
- Ascending – reabsorption
- Distal tubule – secretion & reabsorption
- Collecting duct - reabsorption
Figure 44.14 The nephron and collecting duct: regional functions
of the transport epithelium
1 Proximal tubule
NaCl Nutrients
HCO3
H2O
K+
H+
NH3
4 Distal tubule
NaCl
H2O
HCO3
K+
H+
CORTEX
Filtrate
H2O
Salts (NaCl and others)
HCO3–
H+
Urea
Glucose; amino acids
Some drugs
2 Descending limb
of loop of
Henle
3 Thick segment
of ascending
limb
NaCl
H2O
OUTER
MEDULLA
NaCl
3 Thin segment
of ascending
limbs
Key
Active transport
Passive transport
5 Collecting
duct
Urea
NaCl
INNER
MEDULLA
H2O
Chapter 44: Osmoregulation and Excretion
1. What is osmoregulation?
2. What is excretion?
3. What is the difference between an osmoregulator & an osmoconformer?
4. What is the biggest issue for land animals?
5. What are the different nitrogenous waste products that animals excrete?
6. What are the 4 main functions of excretory systems?
7. How have excretory systems evolved?
8. What is the structure and function of the kidney?
9. What is the structure & function of the nephron?
10. What causes the movement of water out of the filtrate?
- Increasing salt concentration within the kidney
Figure 44.15 How the human kidney concentrates urine
Osmolarity of
interstitial
fluid
(mosm/L)
300
100
300
100
CORTEX
H2O
Active
transport
H2O
Passive
transport
H2O
OUTER
MEDULLA
H2O
300
300
400
200
400
400
600
400
600
600
900
700
H2O
H2O
INNER
MEDULLA
900
H2O
1200
1200
1200
Figure 44.15 How the human kidney concentrates urine
Osmolarity of
interstitial
fluid
(mosm/L)
300
100
300
100
CORTEX
H2O
Active
transport
H2O
Passive
transport
H2O
OUTER
MEDULLA
H2O
INNER
MEDULLA
H2O
300
200
400
400
400
600
600
Nacl
400
Nacl
Nacl
Nacl
600
H2O
H2O
300
Nacl
900
Nacl
900
700
Nacl
1200
1200
1200
Figure 44.15 How the human kidney concentrates urine
Osmolarity of
interstitial
fluid
(mosm/L)
300
100
300
100
CORTEX
H2O
Active
transport
H2O
Passive
transport
H2O
OUTER
MEDULLA
H2O
Nacl
400
Nacl
600
INNER
MEDULLA
H2O
200
Nacl
Nacl
H2O
400
400
600
600
H2O
400
Nacl
900
300
H2O
Nacl
H2O
H2O
Nacl
300
700
H2O
H2O
Urea
H2O
Urea
H2O
Urea
900
1200
1200
1200
Chapter 44: Osmoregulation and Excretion
1. What is osmoregulation?
2. What is excretion?
3. What is the difference between an osmoregulator & an osmoconformer?
4. What is the biggest issue for land animals?
5. What are the different nitrogenous waste products that animals excrete?
6. What are the 4 main functions of excretory systems?
7. How have excretory systems evolved?
8. What is the structure and function of the kidney?
9. What is the structure & function of the nephron?
10. What causes the movement of water out of the filtrate?
11. How is blood osmolarity regulation?
- ADH
- RAAS
Figure 44.16 Hormonal control of the kidney by negative feedback
circuits
Osmoreceptors
in hypothalamus
Homeostasis:
Blood pressure,
volume
Thirst
Hypothalamus
Drinking reduces
blood osmolarity
to set point
Increased Na+
and H2O reabsorption in
distal tubules
STIMULUS:
The juxtaglomerular
apparatus (JGA) responds
to low blood volume or
blood pressure (such as due
to dehydration or loss of
blood)
ADH
Increased
permeability
Pituitary
gland
Aldosterone
Distal
tubule
Arteriole
constriction
Adrenal gland
STIMULUS:
The release of ADH is
triggered when osmoreceptor cells in the
hypothalamus detect an
increase in the osmolarity
of the blood
H2O reabsorption helps
prevent further
osmolarity
increase
Angiotensin II
Distal
tubule
Collecting duct
Homeostasis:
Blood osmolarity
(a) Antidiuretic hormone (ADH) enhances fluid retention by making
the kidneys reclaim more water.
Angiotensinogen
JGA
Renin
production
Renin
(b) The renin-angiotensin-aldosterone system (RAAS) leads to an increase
in blood volume and pressure.