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11.3 The Kidney & Osmoregulation
Essential Idea: All animals excrete nitrogenous
waste products and some animals also balance
water and solute concentrations.
Nature of Science: Curiosity
about particular phenomena—
investigations were carried out
to determine how desert
animals prevent water loss in
their wastes.
http://www.bio.miami.edu/tom/courses/protected/ECK/CH14/figure-14-17.jpg
By Darren Aherne
11.3 The Kidney & Osmoregulation Essential Idea: All animals excrete nitrogenous waste
products and some animals also balance water and solute concentrations.
Assessment Statement
Guidance
11.3 U1 Animals are either osmoregulators or
osmoconformers.
11.3 U2 The Malpighian tubule system in insects and the
kidney carry out osmoregulation and removal of
nitrogenous wastes.
11.3 U3 The composition of blood in the renal artery is
different from that in the renal vein.
11.3 U4 The ultrastructure of the glomerulus and
Bowman’s capsule facilitate ultrafiltration.
11.3 U5 The proximal convoluted tubule selectively
reabsorbs useful substances by active transport.
11.3 U6 The loop of Henle maintains hypertonic
conditions in the medulla.
11.3 U7 ADH controls reabsorption of water in the
collecting duct.
11.3 U8 The length of the loop of Henle is positively
correlated with the need for water conservation
ADH will be used in preference to
vasopressin.
11.3 The Kidney & Osmoregulation Essential Idea: All animals excrete nitrogenous waste
products and some animals also balance water and solute concentrations.
Assessment Statement
Guidance
11.3 U9 The type of nitrogenous waste in
animals is correlated with evolutionary
history and habitat.
11.3 A1
Application: Consequences of
dehydration and overhydration.
11.3 A2
Application: Treatment of kidney failure
by hemodialysis or kidney transplant.
11.3 A3
Application: Blood cells, glucose,
proteins and drugs are detected in
urinary tests.
11.3 S1
Skill: Drawing and labelling a diagram of
the human kidney.
11.3 S 2 Skill: Annotation of diagrams of the
nephron.
The diagram of the nephron should include glomerulus,
Bowman’s capsule, proximal convoluted tubule, loop of
Henle, distal convoluted tubule; the relationship
between the nephron and the collecting duct should be
included.
Osmosis recap
1.4U1 and 9.1U5
11.3 U1 Animals are either osmoregulators or osmoconformers.
• Osmolarity means how much solutes are dissolved in a
solution.
• Osmoregulators: maintain homeostasis for osmolaritythey keep their internal solute concentrations within a
narrow range.
– Terrestrial animals, freshwater fish, marine mammals
• Osmoconformers: Let their osmolarity match that of the
solutes in environment.
– Jellyfish, sea stars
11.3.U9 The type of nitrogenous waste in animals is
correlated with evolutionary history and habitat.
11.U9 The type of nitrogenous waste in animals is correlated
Nitrogenous wastes
Nitrogenous
wastes
to are
are poisonous
with evolutionary history and habitat.
poisonous
toThey
animals
mustand must
animals.
Where does nitrogenous waste come from?
• Breakdown of proteins (amino acids)
• Breakdown of nucleic acids
be excreted!
Forms ammonia (NH4)
Ammonia is toxic & must
be excreted
Animal lives in terrestrial
environment (needs to
conserve water)
Convert NH4 to urea
(mammals)
- costs energy
Convert NH4 to uric
acid (birds)
- costs even more
energy
Animal lives in water
environment (no need
to conserve water)
Excrete NH4 directly
11.3 U2 The Malpighian tubule system in insects and the kidney
carry out osmoregulation and removal of nitrogenous wastes.
• Animals need to maintain homeostasis.
-Osmolarity & the removal of nitrogenous wastes
is maintained by the Malpighian tubule system in
arthropods (insects).
• Nitrogenous wastes in insects is uric acid.
• Uric acid & ions are moved into Malpighian
tubules by active transport.
• Uric acid is excreted with feces.
Insects conserve water, and don’t pee
11.3.U3 The composition of blood in the renal artery is
different from that in the renal vein.
• Kidneys function: to remove wastes, also for
osmoregulation (the amount of water in the
blood).
• Blood enters the kidney through the renal
artery
• Unneeded substances are removed:
– Toxins & products of metabolism, urea and other
nitrogenous wastes
– Non-excretory products: excess water, excess salt
• Blood exits the kidney through the renal vein
11.3 S1 Skill: Drawing and labeling a
diagram of the human kidney.
From I-Biology.net
11.U4 The ultrastructure of the glomerulus and
Bowman’s capsule facilitate ultrafiltration.
• Ultrafiltration occurs in the renal capsule
• The capillary wall and basement membrane
have pores (fenestrated)
• High pressure forces water and blood contents
(except blood cells) across capillary wall
11.3.U4 The Ultrastructure of the glomerulus and
Bowman’s capsule facilitate ultrafiltration
• Small molecules filter through fenestrations
into basement membrane
• Large molecules (proteins) remain in the
blood
11.3.U5 The proximal convoluted tubule selectively
reabsorbs useful substance by active transport
• High surface area
• Movement across membrane requires ATP
11.3.U6 The loop of Henle maintains hypertonic
conditions in the medulla
From I-Biology.net
11.3.U7 ADH controls reabsorption of water
• Anti diuretic hormone
• A diuretic increases urine production
(more water in urine)
• Increase in ADH means small volume of
concentrated urine is produced
• Controlled by
hypothalamus
Osmoregulation uses negative feedback to keep the solute concentration of blood at
the right level.
http://diabetesdietssolution.com/tag/dihybrid-cross-college-of-the-siskiyous-home
From I-Biology.net
11.3.U8 The length of the loop of Henle is positively
correlated with the need for water conservation
• Loop of Henle function is recovery of water
and salts from urine
• The longer the loop the more water and salt
can be recovered
From I-Biology.net
11.3.A2 Treatment of kidney failure by
hemodialysis or kidney transplant
• Kidneys can fail, as a result of diabetes or
chronic high blood pressure
• A donor kidney may be transplanted
Dialysis works in the place of a non-functioning kidney
• Blood from a vein is pumped through semipermeable membrane that allows small
waste molecules to pass through but not larger molecules like proteins & cells
• The tube passes through dialysis fluid which creates a concentration gradient
• Filtered blood is returned to the body through a vein.
How does this use
countercurrent exchange?
http://www.gujaratkidneyfoundation.com/images/dialysis.jpg
11.3.A3 Blood cells, glucose, proteins and
drugs are detected in urinary test
View this animation about kidney function:
http://www.biologymad.com/resources/kidney.swf
View this video by Craig Savage:
Introduction to the Kidney
https://www.youtube.com/watch?v=Z6L8TZaou6k