Water and WasteWater and Waste

Animal Survival Animal Survival

Pages 130 – 137 Pages 130 – 137

TorranceTorrance

Water BalanceWater Balance We We gain watergain water from from

foodfood, , drinkdrink and and chemical reactionschemical reactions

We We lose waterlose water from from sweatingsweating, , breathingbreathing, , passing passing urineurine and and passing passing faecesfaeces..

Water gainWater gain must must equalequal water losswater loss

See fig 14.6 p131See fig 14.6 p131

Kidney Structure and FunctionKidney Structure and Function Our two kidneys are Our two kidneys are

attached to our blood attached to our blood supply by the supply by the renal arteryrenal artery and and renal veinrenal vein..

The The renal arteryrenal artery carries carries “dirty” blood “dirty” blood toto the the kidneyskidneys

The The renal veinrenal vein carries carries “clean” blood “clean” blood awayaway from from the the kidneyskidneys

A A ureterureter carries carries urineurine from the from the kidneyskidneys to the to the bladderbladder

The kidneysThe kidneys The The kidneyskidneys are the are the main organsmain organs for for

regulatingregulating the the water contentwater content in a in a mammalmammal The kidneys work by The kidneys work by filtration of bloodfiltration of blood and and

re absorptionre absorption of of useful materialsuseful materials such as such as glucoseglucose

UreaUrea is a is a wastewaste product product removedremoved in the in the urineurine

CREDITCREDIT UreaUrea is formed in the is formed in the liverliver from the from the

breakdown of surplus amino acidsbreakdown of surplus amino acids.. It It passespasses into the into the bloodblood and is carried round and is carried round

the body until it reaches the the body until it reaches the kidneyskidneys where it where it is is removedremoved

Urinary System DiagramUrinary System Diagram

11

22

33

44

55

66

Renal artery – transports blood to the kidney

Kidney – filters blood

Renal vein – transports blood from the kidney

Urethra – transports urine to outside of body

Ureter – transports urine to bladder

Bladder – stores urine

The Structure of a Kidney The Structure of a Kidney CREDITCREDIT

• Each kidney is made up of tiny filtration units called nephrons

•A nephron is made up of a Bowman`s capsule, a glomerulus and a tubule.

•Two main processes occur here :

• Filtration and Reabsorption

Nephron Diagram Nephron Diagram CREDITCREDIT

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22

33

44

Glomerulus - filters blood

Bowman’s Capsule – collects filtrate

Blood capillaries – reabsorbs useful substances

Collecting duct – collects urine

Nephron function Nephron function CREDITCREDIT

StructureStructure FunctionFunction DecriptionDecription

GlomerulusGlomerulus

Bowman`s Bowman`s capsulecapsule

Blood capillariesBlood capillaries

Collecting ductCollecting duct

Filtration of blood

Proteins and cells stay in blood. Water, glucose and urea forced out

Collects glomerular filtrate

Contains water, glucose and urea

Useful materials (water and glucose) leave tubule and enter blood

Carries urine to the ureter

Urine contains water and urea only

Reabsorb and transport useful materials

Water BalanceWater Balance The kidneys The kidneys controlcontrol the the

water balancewater balance of the body of the body in a in a mammalmammal

70% of the body is water70% of the body is water

We produce We produce differentdifferent volumesvolumes of urine to of urine to regulate our water needs.regulate our water needs.

The kidneys are controlled The kidneys are controlled by a hormone called by a hormone called ADHADH (anti diuretic hormone)(anti diuretic hormone)

ADH is released by the ADH is released by the pituitary glandpituitary gland in the in the brainbrain . .

Pituitary and ADHPituitary and ADH

How How ADHADH regulates the kidneys regulates the kidneys CREDITCREDIT

ADHADH is produced by the pituitary gland is produced by the pituitary gland in the brainin the brain

If the If the waterwater content of our blood is content of our blood is too hightoo high - - Less ADHLess ADH is produced and is produced and the kidneys make the kidneys make lotslots of of watery watery urineurine..

If the If the waterwater content of the blood is content of the blood is too lowtoo low we produce we produce more ADHmore ADH and and the kidneys make the kidneys make small volumessmall volumes of of concentratedconcentrated urine urine

See p132 fig 14.7 for detailsSee p132 fig 14.7 for details

Role of ADH Role of ADH CREDIT CREDIT

3

1

2

4

5

6

sweating

High ADH

Small volume of

Concentrated urine

High water in blood

little water reabsorbed

low water back into blood

1

2

3

6

5

4

Low water in blood

Lot of water reabsorbed

Lot of water back into blood

Drinking lots of water

Low ADH

Large volume of dilute urine

•Too much water drunk

• High water level in blood

•Pituitary releases less ADH

•Kidney reabsorbs less water

•High volume of dilute urine produced

ADHADH and and too muchtoo much water water CREDITCREDIT

1

2

3

ADHADH and and too littletoo little water water CREDITCREDIT

Too little water drunk

Low water level in blood

Pituitary releases more ADH

Kidney reabsorbs more water

Low volume of concentrated urine

2

4

3

1

Kidney failure treatmentsKidney failure treatments Since the kidney is responsible for the Since the kidney is responsible for the removalremoval of of

wasteswastes from the blood, any from the blood, any damagedamage, either from , either from accidentsaccidents or or diseasedisease, can lead to a , can lead to a build up of build up of poisonous wastespoisonous wastes in the body. in the body.

Kidney MachineKidney Machine Kidney Kidney transplanttransplant

BenefitsBenefits

LimitationsLimitations

Purifies the blood

No rejection

Can live a more normal life if it is successful

Expensive

dialysis takes 12 hours twice a week

Rejection of kidney

Anti rejection drugs reduce bodies ability to fight disease

Kidney DIALYSISKidney DIALYSIS

Involves being Involves being connected to connected to a machinea machine for for long periods long periods of timeof time