Chapter 44
2005-2006
Living in the world organisms had a choice: regulate their internal environment
▪ maintain relatively constant internal conditions conform to the external environment
▪ allow internal conditions to fluctuate along with external changes
mammals internally regulate
reptiles fluctuate with external conditions
Control of solute concentrations and balancing water gain and loss.
Based upon osmosis. Osmolarity = total solute
concentration expressed as molarity. -Hyperosmotic -Isoosmotic -Hypoosmotic * Water moves from a hypoosmotic
solution to a hyperosmotic solution- H to L!
Osmoconformer- isoosmotic with surrounding. – All are marine animals.
Osmoregulator- controls internal environment independent of external.
Stenohaline- can be either of above- can’t tolerate substantial changes in external osmolarity.
Euryhaline- can be either of above- can survive large external changes in osmolarity.
Keeping the balance animal body needs to coordinate
many systems all at once▪ temperature▪ blood sugar levels▪ energy production▪ water balance & waste disposal▪ nutrients▪ ion balance▪ cell growth
maintaining a “steady state” condition
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Osmoregulation solute balance & gain or loss of water
Excretion elimination of nitrogenous wastes
Thermoregulation maintain temperature within tolerable range
Most invertebrates are osmoconformers Must move solutes to keep homeostasis
Most marine vertebrates are osmoregulators
Ocean strongly dehydrating Fish balance by drinking seawater Use gills and kidneys to get rid of salt Chloride cells in gills Retain water in kidneys
Sharks are not hypoosmotic because tissue: High amounts of urea- a N waste TMAO- organic molecule protects from urea
damage Together these maintain an osmolarity close to
seawater Sharks are often considered osmoconformers Body actually hyperosmotic water enters body Sharks don’t drink water Excess water removed in kidneys
Opposite problems of marine animals Bodies must be hyperosmotic Problem of gaining water by osmosis
and losing salts by diffusion Balance by drinking no water and
excreting large amounts of dilute urine Salt replenished by eating and uptake
across gills Chloride cells in gills move salts in
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Why do all land animals have to conserve water?
• always need water for life• always lose water (breathing & waste)• may lose life while searching for water
Water balance freshwater = hypotonic
▪ manage water moving into cells▪ salt loss
saltwater = hypertonic▪ manage water loss from cells▪ salt accumulation
land▪ manage water loss▪ need to conserve water
Threat of dehydrationHumans die if lose 12% of body
waterBody coveringNocturnalLose water in urine, feces, across
skin, gas exchange etc.Balance by eating and drinking Produce water by metabolism
Energy CostCost depends on how large
difference is between internal and external environments
Diffusion will try to equalize and so osmoregulators must expend energy to keep osmotic balance
Active Transport- to manipulate solute concentration
1 or more layers of specialized epithelial cells that regulate solute movement
Specific solutes in specific directions
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Salt secreting glands of marine birds remove salt from blood allowing them to drink sea water during months at sea secrete a fluid much
more salty than ocean water
How does structure of epithelial cells govern water regulation? different proteins in
membranes sea birds pump salt out of
blood freshwater fish pump salts
into blood from water
|
What waste products? what do we breakdown?
▪ carbohydrates = CHO CO2 + H2O
▪ lipids = CHO CO2 + H2O
▪ proteins = CHON CO2 + H2O + N
▪ nucleic acids = CHOPN CO2 + H2O + P + N▪ relatively small amount in cell
H
HN–C–
R
|HC–OH||OH
CO2 + H2O
NH2 =
ammonia
Animals can’t storeproteins
Ammonia (NH3) very toxic
▪ carcinogenic very soluble
▪ easily crosses membranes must dilute it & get rid of it… fast!
How you get rid of N-wastes depends on who you are (evolutionary relationship) where you live (habitat)
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Ammonia most toxic freshwater
organisms
Urea less toxic terrestrial
Uric acid least toxic egg layers most water
conservative
N waste
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Nitrogen waste disposal in water if you have a lot of water you can
dilute ammonia then excrete ▪ freshwater fish pass ammonia
continuously through gills▪ need to excrete a lot of water anyway
so excrete very dilute urine
▪ freshwater invertebrates pass ammonia through their whole body surface
Nitrogen waste disposal on land evolved less toxic waste product
▪ need to conserve water▪ urea = less soluble = less toxic
kidney▪ filter wastes out of blood
▪ reabsorb H2O
▪ excrete waste▪ urine = urea, salts, excess sugar & H2O
urine is very concentrated concentrated NH3 would be too toxic
2NH2 + CO2 = urea combined in liver
Requires energy to produce worth the investment
of energyCarried to kidneys by
circulatory system
H
HN
H
HN
C O
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Nitrogen waste disposal in egg no place to get rid of waste in egg need even less soluble molecule
▪ uric acid = less soluble = less toxic birds, reptiles, insects
Polymerized urea large molecule precipitates out of
solution▪ doesn’t harm embryo in egg
▪ white dust in egg
▪ adults excrete white paste▪ no liquid waste▪ white bird poop!
And that folks…is why a male bird doesn’t have… a you know what!
Protonephridia- flatworms Network of dead end
tubes external opening Tubes branch through
body Cell units called “flame
bulbs” cap branches of each protonephridium
Covered with cilia draws water and solutes from interstitial fluid through bulb releasing to outside
Urine has low solute concentration
Annelids- earthworms
Excretory organ that open internally to coelom
Each segment of worm has a pair of metanephridia
Pass dilute urine
Insects and terrestrial arthropods
Remove wastes and osmoregulate
Come out from dead end tubes in hemolymph to digestive tract
Key functions filtration
▪ body fluids (blood) collected ▪ water & soluble material removed
reabsorption▪ reabsorb needed substances back
to blood
secretion▪ pump out unwanted substances to
urine
excretion▪ remove excess substances &
toxins from body
Urinary system filters blood & helps maintain water balance (osmoregulation) pair of
bean-shaped kidneys
supplied with blood▪ renal artery▪ renal vein
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nephron
that’s called a “counter current exchange system”
Functional units of kidney
1 million nephrons per kidney
Function remove urea & other
solutes (salt, sugar…)
Process liquid of blood (plasma)
filtered into nephron selective recovery of
valuable solutes
Interaction of circulatory & excretory systems
Circulatory system glomerulus =
ball of capillaries Excretory system
nephron Bowman’s capsule loop of Henle
▪ descending limb▪ ascending limb
collecting duct
Filtered out H2O glucose salts / ions urea
Not filtered out cells proteins
Descendinglimb
Ascendinglimb
Proximal tubule reabsorbed
▪ NaCl ▪ active transport Na+
▪ Cl- follows by diffusion
▪ H2O▪ glucose▪ HCO3
-
▪ bicarbonate▪ buffer for
blood pH
Descendinglimb
Ascendinglimb
Loop of Henle descending
limb many aquaporins in
cell membranes high permeability to
H2O low permeability to
salt
reabsorbed H2O
structure fitsfunction!
Descendinglimb
Ascendinglimb
structure fitsfunction! Loop of Henle
ascending limb low permeability to
H2O Cl- pump Na+ follows by
diffusion
reabsorbed salts
maintains osmotic gradient
Distal tubule reabsorbed
salts H2O
HCO3-
bicarbonate
Nephron: Reabsorption & Excretion Collecting duct
reabsorbed H2O
excretion urea passed through
to bladder
How is all this re-absorption achieved? tight osmotic
control to reduce the energy cost of excretion
as much as possible, use diffusion instead of active transport
Not filtered out (remain in blood) cells u proteins
Reabsorbed: active transport Na+ u amino acids Cl- u glucose
Reabsorbed: diffusion Na+ u Cl-
Reabsorbed: osmosis H2O
Excreted urea u H2O any excess solutes
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Monitor blood osmolarity amount of dissolved material in blood
in brain
ADH = anti-diuretic hormone
High solutes
High blood osmolarity level too many solutes in blood
▪ dehydration, salty foods release ADH (anti-diuretic hormone) made in
hypothalamus and stored in posterior pituitary (in brain)- also called vasopressin
increases permeability of collecting duct & reabsorption of water in kidneys▪ increase water absorption back into blood▪ decrease urination
also stimulates thirst = drink more
Get more water into blood fast
Alcohol inhibits ADH… makes you urinate a lot!
Low blood osmolarity level or low blood pressure
Low solutes
renin activatesangiotensinogen
angiotensin triggers aldosterone
aldosteroneincreases absorptionof NaCl & H2O in kidney
Low blood osmolarity level or low blood pressure JGA releases renin in kidney renin converts angiotensinogen to angiotensin angiotensin causes arterioles to constrict
▪ increase blood pressure angiotensin triggers release of aldosterone
from adrenal gland increases reabsorption of NaCl & H2O in
kidneys▪ puts more water & salts back in blood
Get more water & salt into blood fast
Why such a rapid response system?
Kidney disease is one of the costliest illnesses in the U.S. today.
Each year, more than 50,000 Americans die because of KidneyDisease.
More than 260,000 Americans suffer from chronic renal failureand need dialysis or kidney transplantation to stay alive.
More than 35,000 patients are waiting for kidney transplants, but only about 11,000 will receive transplants because of a shortage of suitable organ donors.
The Facts About Kidney Disease
Review: how do your kidneys function?
Your kidneys do some important jobs to keep your body healthy:
Balance your body fluids. Excess fluid is filtered out as urine. Remove waste products from your blood. Remove drugs and toxins from your body. Release hormones into your blood to : - Control blood pressure - Make red blood cells - Keep your bones healthy.
Kidney diseases are diseases of the kidney substance that alter the structure and
function of the kidney.
There are many diseases of the kidneys such as glomerulonephritis, pyelonephritis &
polycystic kidney.The treatment and potential for recovery depends on the type of
disease. Kidney diseases can lead to kidney failure.
Normal Kidneys Polycystic kidneys
Healthy kidneys eliminate waste from the blood &maintain the body’s normal chemical balance.
Fluid filled sacs, called cysts, characterize autosomalDominant polycystic kidney disease.
What are kidney diseases?
Kidney failure is a condition where the kidneys are incapable of performing its normal function. Certain toxic substances which should have been excreted such as urea and creatinine are accumulated in the body. The two main causes of kidney failure are Diabetes & High Blood Pressure. Many other conditions can harm the kidneys. These include :
Glomerulonephritis, a disease that causes inflammation in the kidneys.
Inherited diseases like polycystic kidney disease, which causes many cysts to form in the kidneys. IgA nephropathy or other nephropathy. Essentially an autoimmune problem. Exact trigger not well known.
Very large, long standing kidney stone.
NSAID or pain killer like ponstan, voltaren can cause kidney failure.
What is kidney failure ?
Who is at Risk ?
Risk factors for chronic kidney disease include :
Diabetes
High blood pressure
A family history of chronic kidney disease
Older age
Drug overdose, excessive use of alcohol
Long term use of pain medications such as aspirin, panadol, ibuprofen
and treatment with antibiotic.
1. Blood in urine. Most often not visible. But sometimes may appear tea color urine.
2. Protein in urine, low urine output.
3. Swelling of face and legs
4. Tiredness, fatigue
5. Pale and sallow complexion
6. Have dry and itchy skin
7. Poor appetite, sometimes accompanied with nausea and vomiting
8. High blood pressure. Especially when it is hard to bring it to good control.
How to early detect kidney ailments?
Dialysis is a type of treatment that removes wastes and excess fluid from your blood. 3 forms of dialysis can be done – hemodialysis, peritoneal dialysis and continuous ambulatory peritoneal dialysis ( CAPD ).
A kidney transplant is an operation to place a new kidney in your body to take over the work of your failed kidneys. The kidney may come from someone who has died or from a living donor who may be a close relatives, friend or possibly a stranger who wished to donate a kidney to anyone in need of a transplant.
You need dialysis when you developEnd stage renal disease – usually by the time you lose about 85 – 90% of your Kidney function.
Dialysis and Kidney Transplant – what are they ?
Kidney transplantation is the most effective therapy for end-stage renal disease.
The transplanted organ can come from either a live donor or deceased donor.
Most deceased donor organs come from brain dead donors.
Non-standard criteria donors: Expanded criteria donors (ECD). Donation after cardiac death (DCD).