Chapter 44

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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).