GCSE Core ScienceHuman Biology. GCSE Core ScienceHuman Biology Learning objectives: by the end of the lesson you will be able to Explain the processes

GCSE Core Science Human Biology


Learning objectives:

by the end of the lesson you will be able to

• Explain the processes that take place in the body to maintain a constant temperature.

• Explain the importance of keeping temperature at 37oC to allow the enzymes in the body to achieve there optimum rate of reaction.

• Describe how water and ions are lost through the skin when sweating.


Name______________ Class___________ Date __________ _______________ are chemical messengers. They are secreted by _______________ found around the body. They travel through the _______________ to organs where they control important processes. The system of glands and hormones is called the endocrine system. It is controlled by the _______________ which sends hormones to the _______________ gland to control other organs. Organs controlled by hormones include the testes and ovaries. bloodstream brain glands hormones pituitary

Starter


Feeling the heat

When you feel too hot, how does your body react?

You sweat, which helps to cool you down.

Another cooling effect is that blood vessels in the skin expand.

This means that more blood gets near the surface of the skin, which is why some people go red when they are too hot!

The expansion of blood vessels uses some of the energy released by respiration. How do blood vessels use this energy?


The conditions outside your body are constantly changing.

One minute they can be hot, the next cold.

Thermoregulation

37oCThe body needs to remain at 37oC is because this is the temperature at which our enzymes work most effectively.

Despite these changes, your body must be kept at a constant temperature of…


Body temperature is controlled by a region of the brain.

As blood flows around the body,

it passes through the thermoregulatory centre in the brain. rest of

the body

The brain senses body temperature

by sensing the temperature of the

blood.

Once the brain knows what the body temperature is, it can act to keep it steady.

Sensing body temperature

How does the body react to hot and cold temperatures?


Enzymes are temperature-sensitive chemicals that control many of the chemical reactions in the body.

How are enzymes are affected when body temperature changes?

37oC37oC

Enzymes work most effectively and body is fine.

Enzymes work slowly and the

body is suffering.

Enzymes are heat-damaged and body can

become ill.

Temperature and enzymes

hotterhottercoldercolder


When blood flows to the surface of the skin, it passes near the air surrounding the body.

This air is much cooler than the temperature of the blood.

The heat within the blood escapes to the cool air. You also lose water and sodium chloride when you sweat. This causes body temperature to drop and you feel cooler.

bloodskin

airheat heat heat

Increasing heat loss from the skin


Name______________ Class___________ Date __________ Your body tries to keep a steady internal _______________ of 37 °C. This is the temperature at which _______________ work best. _______________ is a source of energy for cells. The pancreas monitors the level of glucose in the blood. Your _______________ control the amount of water in your blood. They are controlled by ADH (anti-diuretic hormone). Salt contains sodium and chloride ions. They are needed to help your body work properly. Levels of sodium and _______________ ions are controlled by the kidneys. chloride enzymes glucose kidneys temperature

Plenary



by the end of the lesson you will be able to

• Explain the processes that take place in the body to maintain a constant temperature.

• Explain the importance of keeping temperature at 37oC to allow the enzymes in the body to achieve there optimum rate of reaction.

• Describe how water and ions are lost through the skin when sweating.




by the end of the lesson you will be able to:

• explain that blood sugar levels provides cells with energy.

• explain how the body regulates blood sugar levels through negative feedback.

• understand that negative feedback is part of homeostasis and helps the body maintain its internal environment.

• explain what happens if the body fails to maintain blood sugar levels.


Which body system?

Starter


Some hormones affect only one target organ, but most affect more than one.

When the hormone has had the desired effect, further production of the hormone needs to be controlled.

Hormone production is controlled by a process called negative feedback.

The regulation of blood glucose level is an example of negative feedback.

Negative feedback


The brain, the pancreas and the liver are all involved in regulating blood sugar.

Negative feedback – blood glucose

Which of these parts of the body are involved in the negative feedback process that regulates blood glucose?


Negative feedback – high blood glucose

The brain detects the level of glucose in the blood.

When the level of blood glucose increases above normal, what hormone does the pancreas release?

increased blood glucose



The pancreas is stimulated to release insulin. What effect does this have?

The insulin stimulates the liver to take glucose from the blood and convert into glycogen, which is stored in the liver.

insulinincreased blood glucose


The level of glucose in the blood decreases, causing the pancreas to stop producing insulin.

What would happen if the pancreas kept on producing insulin?

blood glucose returns to normal


increased blood glucose insulin


Negative feedback also occurs when the blood glucose level decreases below normal.

This time the brain detects decreased blood glucose and so the pancreas is stimulated to release which hormone?

Negative feedback – low blood glucose

decreased blood glucose


The pancreas produces the hormone glucagon.

Glucagon stimulates the liver to convert glycogen back to glucose and release this glucose into the bloodstream.


decreased blood glucose glucagon


The level of glucose in the blood increases, causing the pancreas to stop producing glucagon.

What would happen if the pancreas kept on producing glucagon?


decreased blood glucose

blood glucose returns to normal

glucagon


Blood glucose activity


When hormones go wrong – diabetesWhat happens if the pancreas is unable to produce the hormone insulin?

After a person with diabetes has eaten, their blood glucose level increases. What happens to this glucose?

The absence of insulin means that glucose is not converted to glycogen and stored in the liver, so the blood of a

Lack of insulin production means that the blood glucose level is unregulated and causes

the condition known as “sugar diabetes”.

diabetic contains extra glucose.


When hormones go wrong – diabetes

Glucose is essential for the body, so why is excess glucose a danger for people with diabetes?

When the glucose is used up, coma and convulsions may occur. So how is diabetes controlled?

Regular insulin injections and a careful diet can control the condition.

The ability of the kidneys to absorb glucose is also exceeded, so the excess is excreted in urine.


Multiple-choice quiz

Multiple-choice quiz



by the end of the lesson you will be able to:

• explain that blood sugar levels provides cells with energy.

• explain how the body regulates blood sugar levels through negative feedback.

• understand that negative feedback is part of homeostasis and helps the body maintain its internal environment.

• explain what happens if the body fails to maintain blood sugar levels.

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GCSE Core ScienceHuman Biology. GCSE Core ScienceHuman Biology Learning objectives: by the end of the lesson you will be able to Explain the processes