Homeostasis by Abhishek Jaguessar
Transcript of 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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Controlling body temperature
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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Controlling body temperature
Volume :Surface arearatio = 1:6
Volume :Surface arearatio = 1:5
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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Controlling body temperature
Volume :Surface arearatio = 1:6
Volume :Surface arearatio = 1:5
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
Glucose in the blood
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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
Glucose in the blood
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.