homeostasis by abhishek jaguessar

8/4/2019 Homeostasis by Abhishek Jaguessar

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Homeostasis

By

Abhishek Jaguessar


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Glossary

Maintain keep up.

Constant the same.

Internal inside the body. Environment surroundings of the body.


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What is Homeostasis?

Body cells work best if they have the

correct

Temperature

Water levels

Glucose concentration

Your body has mechanisms to keep the

cells in a constant environment.


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What is Homeostasis?

The maintenance of a

constantenvironment in the

body is calledHomeostasis


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Controlling body temperature

All mammals maintain a constant body

temperature.

Human beings have a body temperature

of about 37C.

E.g. If your body is in a hot environment your

body temperature is 37C

If your body is in a cold environment your

body temperature is still 37C


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Animals with a large surface area

compared to their volume will lose heat

faster than animals with a small surface

area.

Volume = _______

Surface area =______

Volume : Surfacearea ratio =___________

Volume = _______

Surface area =______

Volume : Surfacearea ratio =___________


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Volume :Surface arearatio = 1:6


For every 1

unit of heatmade, heatis lost out of6 sides

For every 1

unit of heatmade, heatis lost out of5 sides


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The bigger theVolume : Surface Arearatio

is, the faster heat will


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Penguins huddling to keep

warm


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What mechanisms are there to cool

the body down?

1. Sweating When your body is hot, sweat glands are

stimulated to release sweat. The liquid sweat turns into a gas (it

evaporates)

To do this, it needs heat. It gets that heat from your skin.

As your skin loses heat, it cools down.


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Sweating

Theskin


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What mechanisms are there to

cool the body down?2. Vasodilation Your blood carries most of the heat

energy around your body. There are capillaries underneath

your skin that can be filled with

blood if you get too hot. This brings the blood closer to the

surface of the skin so more heat

can be lost.


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If thetemperaturerises, the bloodvessel dilates

(gets bigger).

This means more heat is lost from the surfaceof the skin


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What mechanisms are there toWhat mechanisms are there to

warmwarm the body up?the body up?

1. Vasoconstriction This is the opposite of vasodilation

The capillaries underneath your skinget constricted (shut off).

This takes the blood away from the

surface of the skin so less heat canbe lost.


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If thetemperaturefalls, the bloodvessel

constricts (getsshut off).

This means less heat is lost from the surface ofthe skin


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What mechanisms are there toWhat mechanisms are there to

warm the body up?warm the body up?

2. Piloerection This is when the hairs on your skin

stand up . It is sometimes called goose

bumps or chicken skin!

The hairs trap a layer of air next tothe skin which is then warmed bythe body heat

The air becomes an insulating layer.


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Controlling GlucoseControlling Glucose

levelslevelsYour cells also need an exact level ofYour cells also need an exact level of

glucose in the blood.glucose in the blood. Excess glucose gets turned intoExcess glucose gets turned into

glycogen in the liverglycogen in the liverThis is regulated by 2 hormonesThis is regulated by 2 hormones

(chemicals) from the(chemicals) from the pancreaspancreas

called:called:InsulinInsulin

GlucagonGlucagon


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If there is toomuchglucose inthe blood,

Insulinconvertssome of it toglycogen

Glycogen

Insulin

Glucose in the blood


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If there is notenoughglucose inthe blood,

Glucagonconvertssomeglycogeninto glucose.

Glycogen

Glucagon



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DiabetesDiabetes

Some people do not produce enoughSome people do not produce enough

insulin.insulin.

When they eat food, the glucoseWhen they eat food, the glucose

levels in their blood cannot belevels in their blood cannot be

reduced.reduced.

This condition is known as DIABETES.This condition is known as DIABETES.

Diabetics sometimes have to injectDiabetics sometimes have to injectinsulin into their blood. They have toinsulin into their blood. They have to

be careful of their diet.be careful of their diet.


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Time

lucoseoncentration

Meal eaten

Insulin is

produced andglucose levelsfall to normalagain.

Glucose levelsrise after a

meal.

Normal


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Time

Glucose

Concentration

Meal eaten

Insulin is not

produced soglucose levelsstay high

Glucose levelsrise after a

meal. Diabetic


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The glucose inthe bloodincreases.

Glycogen

Insulin


But there is noinsulin toconvert it intoglycogen.

Glucoseconcentrationrises to

dangerouslevels.


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Controlling water levels

The control of water levels is carried out

by the KIDNEYS.

It is closely linked to the excretion of urea.

Urea is a waste product that is made when

the LIVER breaks down proteins that are

not needed by the body.

Urea contains the element Nitrogen.


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The kidneys

The kidneys clean the blood of wasteproducts and control how much wateris kept in the body. The wasteproducts and water make up urine

which is excreted via the ureter.

Dirty blood enters the kidneythrough the renal artery. Then,several things happen to clean theblood...


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Blood enters the tubule area ina capillary.

The capillary forms a smallknot near the kidney tubule.

The blood is filtered so all thesmall particles go into thetubule.

The capillary then carries on torun next to the tubule.

1. Filtration


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The kidney tubule now containslots of blood componentsincluding:

Glucose:Ions:Water:Urea:


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2. Reabsorb sugar

The body needs to have sugarin the blood for cells to use inrespiration. So all the sugar isreabsorbed back into the

capillary.


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2. Reabsorb sugar

The body needs to have sugarin the blood for cells to use inrespiration. So all the sugar isreabsorbed back into the

capillary.


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3. Reabsorb water

Water and ions are the next tobe absorbed. It depends onhow much is needed by thebody.


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3. Reabsorb water

Water and ions are the next tobe absorbed. It depends onhow much is needed by thebody.


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Reabsorbing water

If you have toolittle water in your

blood, you willproduce veryconcentrated urine.

(very little water init)

If you have toomuch water in your

blood, you willproduce very diluteurine.

(lots of water in it)


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5. Excrete the waste

Everything that is left in thekidney tubule is waste:

All the ureaExcess water

This waste is called urine. It isexcreted via the ureter and isstored in the bladder.

The clean blood leaves thekidney in the renal vein.

Renal vein

Ureter


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Summary of urine production

Urea is a waste product made in the LIVER

Water content of the body is controlled in

the KIDNEYS

Urea, water and other waste makes up

URINE.

Urine travels down the URETER and is

stored in the BLADDER

Urine is excreted through the URETHRA.

homeostasis by abhishek jaguessar

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