What is osmoregulation?

WALT: Describe the control of the water content of blood Know the role of the pituitary gland and ADH.

Why is water important?The human body is about 60-70% water.

Water is produced by the body during respiration, and absorbed from food and drink.

Water is lost from the body in exhaled air, sweat, urine and faeces.

How is water gained and lost?

Water molecules and ions constantly move in and out of cells, and are essential for all life processes.

Dehydration (loss of too much water from the body) damages cells.

How is Water Lost? Choose all that apply

A) Exhaled air

B) Food intake

C) Sweat

D) Urine

E) Faeces

Dehydration and its causesJust a 1% decrease in body weight due to water loss is

enough to cause mild dehydration.

Mild dehydration can cause dizziness, a dry mouth and concentrated urine. Severe dehydration can cause death.

What causes dehydration? heavy sweating

low water intake

eating salty food

breathing dry air

caffeine and alcohol

diarrhoea.

True or False

Severe dehydration can cause death...

Detecting a change

• If blood water concentration changes from the ‘norm’ specialised cells (osmoreceptors) in the hypothalamus gland in the brain detect this change

Blood water levels

The volume of water in our blood also needs to be adjusted to ensure blood does not become too ‘thick’ or too dilute

Our blood water levels are checked & corrected by negative feedback to ensure we have the correct level of water in the blood

• Osmoregulation means the way the body controls water concentration(and consequently salts and ions)

• The hypothalamus in the brain contains the osmoreceptors

• ADH (produced by the pituitary gland) increases the volume of water reabsorbed from glomerular filtrate in the kidney

Control of blood water levels & the kidney

• Water concentration in the blood may decrease if a person ______, does not _____ or consumes _____ foods

• Revision: the kidneys are responsible for controlling water concentration though the action of __ __ __

• More __ __ __ means _____ water is reabsorbed by the cells around the tubule

• Less __ __ __ means _____ water is reabsorbed by the cells around the tubule

NORMAL (SETPOINT)

NORMAL (SETPOINT)

RECEPTORS EFFECTORS

EFFECTORSRECEPTORS

DECREASE IN WATER CONC OF BLOOD

INCREASE IN WATER CONC OF BLOOD

MESSAGE

MESSAGE

Corrective response brings about NEGATIVE FEEDBACK CONTROL

Corrective response brings about NEGATIVE FEEDBACK CONTROL

Osmoregulation

OSMORECEPTORS IN HYPOTHALAMUS

PITUITARY

Kidney tubules and ducts become

LESS permeable

Little ADH produced

Less water reabsorbed into blood,

large volume of dilute urine produced

OSMORECEPTORS IN HYPOTHALAMUS

PITUITARY

Much ADH produced

Kidney tubules and ducts become

MORE permeable

MORE water reabsorbed

into blood, smallvolume of

concentratedurine produced

NORMAL (SETPOINT)

NORMAL (SETPOINT)

RECEPTORS EFFECTORS

EFFECTORSRECEPTORS

DECREASE IN WATER CONC OF BLOOD

INCREASE IN WATER CONC OF BLOOD

MESSAGE

MESSAGE

Corrective response brings about NEGATIVE FEEDBACK CONTROL

Corrective response brings about NEGATIVE FEEDBACK CONTROL

Osmoregulation

OSMORECEPTORS IN HYPOTHALAMUS

PITUITARY

Kidney tubules and ducts become

LESS permeable

Little ADH produced

Less water reabsorbed into blood,

large volume of dilute urine produced

OSMORECEPTORS IN HYPOTHALAMUS

PITUITARYMuch ADH produced

Kidney tubules and ducts become

MORE permeable

MORE water reabsorbed

into blood, smallvolume of

concentratedurine produced

NORMAL (SETPOINT)

NORMAL (SETPOINT)

RECEPTORS EFFECTORS

EFFECTORSRECEPTORS

DECREASE IN WATER CONC OF BLOOD

INCREASE IN WATER CONC OF BLOOD

MESSAGE

MESSAGE

Corrective response brings about NEGATIVE FEEDBACK CONTROL

Corrective response brings about NEGATIVE FEEDBACK CONTROL

Osmoregulation

OSMORECEPTORS IN HYPOTHALAMUS

PITUITARY

Kidney tubules and ducts become

LESS permeable

Little ADH produced

Less water reabsorbed into blood,

large volume of dilute urine produced

OSMORECEPTORS IN HYPOTHALAMUS

PITUITARY

Much ADH produced

Kidney tubules and ducts become

MORE permeable

MORE water reabsorbed into blood,

small volume of concentratedurine produced

Affect of ADH

Water concentration

of blood

Action of pituitary gland

Affect of ADH on kidney tubules

Level of water

reabsorbed into blood

Volume of urine

produced

High Release

less

ADH

Less

permeable

Less High

volume

Low Release

more

ADH

More

permeable

More Low

volume

True or False

1. ADH is produced by the thyroid gland

True or False

ADH is produced when we are thirsty

True or False

ADH causes kidney tubules to reabsorb more water

True or False

1. ADH has the effect of decreasing the volume of urine produced

The Leah Betts Story

• Leah Betts died after taking an ecstacy tablet

• The ecstacy caused lots of ADH to be released

• How would this affect urine production?

• Lots of ADH prevents production of lots of dilute urine

• This then caused a build up of water inside body cells especially the brain

• Brain cells soak up fluid causing them to swell

• This caused the brain to be crushed against the inside of the skull

Brain damage Coma Death

Leah Betts Story

Osmoregulation

• What is the general name for a cell or organ that detects changes in the internal environment?

Osmoregulation

• Where are these cells located in animals?

Osmoregulation

• What is the general name for a cell or organ that carries out a corrective mechanism to return a change in the internal environment back to normal?

Osmoregulation

• What is the name of this organ in animals?

Osmoregulation

1. Hormones are chemical messengers that travel in the bloodstream. What is the name of the hormone that targets the kidney tubules?

2. What effect does ADH have on the kidney tubules if:a. The water concentration of the blood is high. b. The water concentration of the blood is low.

Answers

1. Hormones are chemical messengers that travel in the bloodstream. What is the name of the hormone that targets the kidney tubules?

ANTI DIURETIC HORMONE (ADH)

2. What effect does ADH have on the kidney tubules if:a. The water concentration of the blood is high. LESS ADH = LESS

PERMEABLEb. The water concentration of the blood is low. MORE ADH = MORE

PERMEABLE

Your tasks…Must complete…

Copy fig33.4: homeostatic control of blood water conc. (page 308)

Should complete…Answer in full sentences:(1) Where are osmoreceptors found?(2) Outline how negative feedback controls water

conc. of the blood(3) Compare the volume and the concentration of

urine produced if (a) a lot of ADH is present in the blood (b) a little ADH is present in the blood

Could complete…Practice past paper questions