What do the following have in common?

• The Titanic• The London underground• A tri-athlete • A London Marathon Runner• Four asylum-seekers• Pensioners Raymond and Doreen Elsom

Look at the following slides and

discuss why the people died?

Titanic – 1,502 died – WHY?• It was 2:20 am on Monday 15th

April 1912. The Titanic had collided with an iceberg at 11:40 pm on 14th April and had floundered 3.5 hours later. About 650 passengers were lowered in lifeboats capable of holding 1178; the remaining passengers entered the sea as the Titanic sank. Hundreds of people thrashed about in water that was less than -2 degrees, well below freezing point. It was 4:10am before another ship arrived to collect the survivors. Only 705 of the 2207 survived - 1502 died.

• Many of the passengers had life jackets and there was a lot of debris to hang onto. It was a calm and still night. Why did they die?

People die on underground trains all over the world during the hot summer

months – WHY?

An elderly couple died in bed after forgetting to switch their electric hob off in the kitchen. No fire broke out, there was no evidence of fire damage. Just two dead

bodies ........ WHY?

After the London Flora Marathon. Why did this man collapse?

Why is this tri-athlete more likely to get hyperthermia when wet?

Four asylum-seekers die in a tragedy. Police have discovered the bodies of four suspected asylum-seekers in a container. The four,

all young men are believed to be have been Romanian. The bodies were found in a container load of tiles bound for the UK.

The grim discovery was made when police noticed seals had been broken on the container and investigated.

WHY did they die?

Homeostasis

Objectives:

*Define homeostasis

** Explain the concept of negative feedback

*** Explain the control of blood glucose concentration in terms of negative feedback

• Homeostasis is maintaining a nearly constant conditions in the body.

• Why nearly constant?

• Why this is necessary?

Clue: metabolism, enzymes

Who has the overall control of body processes?

What things need controlling?

• Homeostasis makes sure our body has the correct levels of;

Temperature

Carbon dioxide

OxygenWater

Blood sugar(glucos

e)

pH and ions

What happens if you are in your living room and experience either of these two situations?

Brain stimulates the body to sweat more to release more heat.

Brain stimulates the production of more heat in the muscles by shivering and by increasing respiration rate in the liver. It also stimulates the body to conserve more heat by decreasing sweat production by the sweat glands. Most body heat is generated in the deep organs like liver and brain

How does your heating work?

Nice comfortable temperature

Too hot

Too cold

Temp. drops at night

Heating is switched on by thermostat

Temp. increases during the day

Heating is switched off by thermostat.

This is NEGATIVE FEEDBACKWhat should we be controlled using negative feedback?

Negative Feedback

Draw a negative feedback diagram of controlling temperature in an oven

Reqd oven temperature

Oven gets hot

Thermostat switches heater off

Temp falls

Reqd oven temperature

Temp rises

Thermostat switches heater on

Oven gets cold

The Pancreas Insulin controls........

Glucose is a sugar needed by cells for piraRestion.

It is important that the concentration of glucose in the blood is kept at a constant level.

blood sugar levels in our

bodies.

Copy this down into your books

Changing glucose levels

• After a meal the level of glucose in our bodies [increases/decreases]?

• After exercise the levels of glucose in our bodies [increases/decreases]?

• Why do you think this happens?I think this happens

because......................

The pancreas detects the change in blood glucose concentration and releases the appropriate hormone(glucagon)

Insulin and glucagon(the hormones)Stimulate liver cells to change glucose to glycogen or vice versa. Both made in pancreas. They are not enzymes so they stimulate changes to blood glucose level but do not convert one to another. The enzymes in the liver and muscle help do the conversion.