Multicellular Organisms Controlling Body Temperature Learning Intentions: What is homeostasis? How is homeostasis of body temperature achieved?

Homeostasis Note: Living things must be able to keep their internal environment constant despite changes in the environment. We call this homeostasis.

Controlling Body Temperature Mammals and Birds can maintain a constant body temperature. This is why they can inhabit cold regions. Because reptiles and amphibians cannot regulate their body temperature, most species are restricted to the tropics.

Controlling Body Temperature The human body temperature needs to be maintained at 37ºC. If it rises by more than 4ºC above this, can cause permanent damage. This is because enzymes that help our body work become denatured (permanently damaged).

Controlling Body Temperature If we get too cold then Hypothermia will set in and kill us. Heat for our bodies is generated by chemical reactions going on inside us – such as the one for respiration. Much of the heat is generated by chemical reactions in the liver.

Controlling Body Temperature Our body temperature is controlled by the thermoregulatory centre in the brain. This makes sure that the body is warmed or cooled according to outside temperatures.

Controlling Body Temperature If we get too cold, then we start to shiver. This means our muscles start to contract very quickly. This needs respiration to happen. When respiration happens, heat is generated and it warms our body up.

Controlling Body Temperature If we get too hot, we may start to sweat. The pores in our skin secrete water (and some ions) onto our skin surface. When the water evaporates it takes away heat.

Controlling Body Temperature Another way in which the body can control temperature is by widening the blood vessels at the skin’s surface (vasodilation) and narrowing the blood vessels at the skins surface (vasoconstriction).

Vasodilation The blood vessels near the skin’s surface enlarge so heat is lost from the blood to the air. This cools us down.

Vasoconstriction The blood vessels near the skin’s surface narrow so less heat is lost to the air. This keeps us warm.

Controlling Body Temperature Copy and Complete: Mammals and Birds can maintain a ________ body temperature. This is why they can inhabit cold regions. The human body temperature needs to be maintained at ____. If it rises by more than ______ above this, permanent damage can be done. This is because _________ that help our body work become denatured (permanently damaged). Our body temperature is controlled by the thermoregulatory centre in the _______. If we get too cold: _____________ generates heat from respiration. Vasoconstriction reduces amount of heat lost to the air from our _______. If we get too hot: Vasodilation allows more blood to flow near the surface of the skin so it loses _______ to the air. Sweating allows water to evaporate from the surface of the skin, this takes heat away and cools our body. We also lose ______ when we sweat. constant heat brain 37ºC blood 4ºC enzymes shivering ions

Controlling Body Temperature Tasks: Read pages 80-84 of Intermediate 1 text book Answer questions 1-4 on page 84 of Intermediate 1 textbook

Body Temperature Practical Designing a practical as a class to determine if gender has an effect on control of body temperature. How are you going to make your test reliable? What are your variables? How are you going to make your test fair?

Multicellular Organisms Control of Blood Sugar Levels Learning Intentions: I know the role of hormones in the body. I understand how blood glucose is regulated. I know how problems with blood sugar regulation lead to Diabetes.

What are Hormones? Note: Hormones are chemical messengers. Hormones are released by Endocrine glands into the bloodstream. They are carried in the blood to specific organs on which they exert their effect.

Endocrine Glands

Hormones Hormones are like enzymes… Note: Hormones have a specific target tissue and will only work on that tissue type.

Control of Blood Glucose Note: Animals get energy from respiring glucose, so the body needs a constant supply glucose which is transported in the blood. Blood glucose cant get too high or cells will lose water by osmosis.

Control of Blood Glucose Note: Glucose receptors in the pancreas monitor the glucose concentration in the blood.

Control of Blood Glucose Note: The liver acts as a carbohydrate store and turns extra glucose as the insoluble carbohydrate glycogen.

Control of Blood Glucose The liver and the pancreas are separate organs hormones are required to allow them to communicate with each other. The hormones required are: Insulin Glucagon

Control of Blood Glucose Note: Insulin is produced when blood glucose levels rise (after eating). Insulin is released from the pancreas and travels to the liver where it binds to receptors, this causes the liver to convert glucose in the storage carbohydrate glycogen.

Control of Blood Glucose Note: Glucagon is produced by the pancreas when glucose levels are low (during exercise). It travels to the liver where it binds receptors and converts glycogen to glucose which is released into the blood.

Controlling Blood Glucose Levels Insulin produced by the _________ causes the _______to covert excess glucose into ________ pancreas Glucose rises (________) liver Eat food glycogen Normal blood glucose level. Normal blood glucose level. ________ released by the pancreas which causes the liver to convert Glycogen back into _________ Glucagon Glucose falls (_______) exercise glucose

Diabetes Note: Diabetes is a disease caused when there is a problem with the body’s control of blood glucose. There are two types of Diabetes; Type 1 and Type 2.

Type 1 Diabetes Note: Type 1 diabetes is caused when a person does not produce enough insulin, or sometimes no insulin at all. Insulin signals the cells to absorb glucose so glucose will remain in the blood stream. Type one diabetes is treated with regular injections of insulin.

Type 2 Diabetes Note: Type 2 diabetes is caused when the cell in the body no longer respond to insulin so glucose levels in the blood stay high. Type 2 diabetes is treated by lifestyle changes i.e. weight loss and eating healthily.

Tasks Complete with the correct word: Chemical messengers secreted directly into the bloodstream are called enzymes/hormones Cells on a target tissue bear specific receptors/effectors to a particular hormone. Insulin and Glucagon are made in the liver/pancreas. The conversion of glucose to glycogen in the liver is promoted by glucagon/insulin. The conversion of glycogen to glucose in the liver is promoted by glucagon/insulin. Summarise blood glucose control on a revision poster.