HomeostasisHomeostasis

1.1. Maintain – Maintain – keep upkeep up..

2.2. Constant – Constant – the samethe same..

3.3. Internal – Internal – inside the bodyinside the body..

4.4. Environment – Environment – surroundings of the bodysurroundings of the body..

What is Homeostasis?What is Homeostasis?

The maintenance of a The maintenance of a constant environment constant environment in the body is called in the body is called

HomeostasisHomeostasis

What is Homeostasis?What is Homeostasis?

1.1. Body cells work best if they have the correctBody cells work best if they have the correct

a)a) TemperatureTemperature

b)b) Glucose concentrationGlucose concentration

c)c) Water levelsWater levels

2.2. Your body has mechanisms to keep the cells in a Your body has mechanisms to keep the cells in a constantconstant environment. environment.

Dueling MechanismsDueling MechanismsWhat goes up, must come down!What goes up, must come down!

ThermoregulationThermoregulationSweating (cooling) vs. shivering (warming)Sweating (cooling) vs. shivering (warming)

Blood PressureBlood PressureVasconstriction vs. vasodilationVasconstriction vs. vasodilation

OsmoregulationOsmoregulationHypotonic vs. hypertonicHypotonic vs. hypertonic

Controlling body Controlling body temperaturetemperature

1.1. All mammals maintain a constant body All mammals maintain a constant body temperature.temperature.

2.2. Human beings have a body temperature of about Human beings have a body temperature of about 3737ººC.C.

a)a) E.g. If your body is in a hot environment your E.g. If your body is in a hot environment your body temperature is 37body temperature is 37ººCC

b)b) If your body is in a cold environment your If your body is in a cold environment your body temperature is still 37body temperature is still 37ººCC

What mechanisms are there What mechanisms are there to cool the body down?to cool the body down?

1.1. SweatingSweating

2.2. When your body is hot, sweat glands are When your body is hot, sweat glands are stimulated to release sweat.stimulated to release sweat.

3.3. The liquid sweat turns into a gas (it The liquid sweat turns into a gas (it evaporates)evaporates)

4.4. To do this, it needs heat.To do this, it needs heat.

5.5. It gets that heat from your skin.It gets that heat from your skin.

6.6. As your skin loses heat, it cools down.As your skin loses heat, it cools down.

Sweating

The skin

What mechanisms are there What mechanisms are there to to coolcool the body down? the body down?

1. Vasodilation

a)a) Your blood carries most of the heat energy Your blood carries most of the heat energy around your body.around your body.

b)b) There are capillaries underneath your skin that There are capillaries underneath your skin that can be filled with blood if you get too hot.can be filled with blood if you get too hot.

c)c) This brings the blood closer to the surface of This brings the blood closer to the surface of the skin so more heat can be lost.the skin so more heat can be lost.

d)d) This is why you look red when you are hot!This is why you look red when you are hot!

If the temperature rises, the blood vessel dilates (gets bigger).

This means more heat is lost from the surface of the skin

What mechanisms are there to What mechanisms are there to warmwarm the body up? the body up?

1.1. VasoconstrictionVasoconstriction

a)a) This is the opposite of vasodilationThis is the opposite of vasodilation

b)b) The capillaries underneath your skin get The capillaries underneath your skin get constricted (shut off).constricted (shut off).

c)c) This takes the blood away from the This takes the blood away from the surface of the skin so less heat can be lost.surface of the skin so less heat can be lost.

If the temperature falls, the blood vessel constricts (gets shut off).

This means less heat is lost from the surface of the skin

What mechanisms are there to What mechanisms are there to warm the body up?warm the body up?

2.2. PiloerectionPiloerectiona)a) This is when the hairs on your skin This is when the hairs on your skin

“stand up”“stand up”

b)b) It is sometimes called “It is sometimes called “goose goose bumpsbumps””

c)c) The hairs trap a layer of air next to The hairs trap a layer of air next to the skin which is then warmed by the skin which is then warmed by the body heatthe body heat

d)d) The air becomes an insulating layer.The air becomes an insulating layer.

Controlling Glucose Controlling Glucose levelslevels

1.1. Your cells also need an exact level of Your cells also need an exact level of glucoseglucose in the blood. in the blood.

2.2. Excess glucose gets turned into Excess glucose gets turned into glycogenglycogen in the liver in the liver

3.3. This is regulated by 2 hormones This is regulated by 2 hormones (chemicals) from the pancreas called:(chemicals) from the pancreas called:

InsulinInsulinGlucagonGlucagon

If there is too much glucose in the blood, Insulin converts some of it to glycogen

Glycogen

Insulin

Glucose in the blood

If there is not enough glucose in the blood, Glucagon converts some glycogen into glucose.

Glycogen

Glucagon

Glucose in the blood

DiabetesDiabetes

1. The blood glucose level is the amount of glucose in the blood.

2. Glucose is a sugar that comes from the foods we eat, and it's also formed and stored inside the body.

3. It's the main source of energy for the cells of our body, and it's carried to each cell through the bloodstream.

DiabetesDiabetes

4.4. Some people do not produce enough Some people do not produce enough insulin.insulin.

5.5. When they eat food, the glucose levels When they eat food, the glucose levels in their blood cannot be reduced.in their blood cannot be reduced.

6.6. This condition is known as This condition is known as DIABETESDIABETES..

7.7. Diabetics sometimes have to inject Diabetics sometimes have to inject insulin into their blood. They have to insulin into their blood. They have to be careful of their diet.be careful of their diet.

Time

Glucose Concentration

Meal eaten

Insulin is produced and glucose levels fall to normal again.

Glucose levels rise after a meal.

Normal

Time

Glucose Concentration

Meal eaten

Insulin is not produced so glucose levels stay high

Glucose levels rise after a meal.

Diabetic

The glucose in the blood increases.

Glycogen

Insulin

Glucose in the blood

But there is no insulin to convert it into glycogen.Glucose concentration rises to dangerous levels.

Diabetes - HyperglycemiaDiabetes - Hyperglycemia

1. Hyperglycemia is the medical word for high blood sugar levels. High blood sugar levels happen when the body either can't make insulin

Diabetes - HypoglycemiaDiabetes - Hypoglycemia

1. Low blood glucose, also called hypoglycemia, happens if your blood glucose drops too low.

2. Low blood glucose can be caused by missing a meal, delaying a meal, exercising more than usual, or drinking alcoholic beverages.

Controlling water levelsControlling water levels

1.1. The control of water levels is carried out by the The control of water levels is carried out by the KIDNEYS.KIDNEYS.

2.2. It is closely linked to the excretion of urea.It is closely linked to the excretion of urea.

3.3. Urea is a waste product that is made when the Urea is a waste product that is made when the LIVER breaks down proteins that are not needed LIVER breaks down proteins that are not needed by the body.by the body.

4.4. Urea contains the element Nitrogen.Urea contains the element Nitrogen.

OsmoregulationOsmoregulation

Hypotonic vs. hypertonicHypotonic vs. hypertonic