Regulation and Control Homeostasis Objectives: outline the need for communication systems within mammals to respond to changes in the internal and external environment Learning Activity Prepare a presentation using text book or internet on any one of the following in 10 mins: organisation of multicellular organisms, internal changes, changes in external environment, endocrine, nervous system, reflexes. Negative feedback Present your ideas in five minutes

BRAIN PITUITARY GLAND RIBS INTERCOSTAL MUSCLE RIGHT LUNG HEART DIAPHRAGM STOMACH PANCREAS KIDNEY BLADDER SKIN

Control of a possible football situation RISU are trailing 1-0 to ISU in the final of the Rainbow Cup. All of a sudden (student A) pulls up with a suspected torn hamstring. (Student B) spots this and immediately sends a message to Mr Colley what happens. Mr Colley makes a decision. He decides to replace (student A) with (Student C). Student C went on to score a hatrick. Final Score RISU 3 ISU 4 What was the problem (stimulus)? Who detected it? Who was the decision maker is the system? What was the response?

Body Temperature Control Homeostasis: Body Temperature HIGH LOW Increased body temperature eg when exercising Decreased body temperature eg due to cold surroundings

Regulation of Body Temperature Put the statements below in the correct boxes on the other side of the page: Brain detects DECREASE in blood temperature. Capillaries widen (VASODILATION). Heat radiates from skin. Capillaries narrow (VASOCONSTRICTION). Reduces heat loss from skin. Body temperature decreases. Cooling mechanisms shut down. Shivering generates heat. Brain detects RISE in blood temperature. Evaporation of sweat cools body. Body temperature increases. Warming mechanisms shut down

Effects of Hot and Cold on the Skin Heat lost by Radiation Evaporation of the sweat cools the skin Sweat Gland Hot Weather Cold Weather Very little heat lost by radiation Sweating Stops Blood Vessels Widen Blood Vessels Narrow VASODILATION VASOCONSTRICTION

Objectives: describe the cellular structure of an islet of Langerhans from the pancreas and outline the role of the pancreas as an endocrine gland; explain how the blood glucose concentration is regulated by negative feedback control mechanisms, with reference to insulin and glucagon Control of Blood Glucose

Regulation of Body Temperature Put the statements below in the correct boxes on the other side of the page: Brain detects DECREASE in blood temperature. Capillaries widen (VASODILATION). Heat radiates from skin. Capillaries narrow (VASOCONSTRICTION). Reduces heat loss from skin. Body temperature decreases. Cooling mechanisms shut down. Shivering generates heat. Brain detects RISE in blood temperature. Evaporation of sweat cools body. Body temperature increases. Warming mechanisms shut down.

What happens after we eat?

Insulin Control

Islet of langerhans

Beta cells have channels in the plasma membrane that serve as glucose detector. They secrete a small protein hormone insulin (polypeptide of 21 amino acids They stimulate skeletal muscles, liver cells, fat cells to convert glucose to glycogen (glycogenesis) They stimulate the hypothalamus to reduce appetite. Taken together, all of these actions result in: the storage of the soluble nutrients absorbed from the intestine into an insoluble product (glycogen) a drop in the level of blood sugar

Alpha cells of the islets situated on the outer rim of the islet secrete GLUCAGON, also a protein hormone of 29 amino acids Glucagon acts principally on the liver Glucagon secretion is stimulated by low levels of glucose in the blood and inhibited by high levels. In the liver it stimulates the conversion of glycogen into glucose which is deposited in the blood. (glycogenolysis) The physiological significance of this is that glucagon functions to maintain a steady level of blood sugar level between meals.

(a) Describe how the level of blood glucose in a human is maintained at a constant level by hormones with reference to the source of the hormones involved

What happens when insulin is not produced? Diabetes is a disease where the concentration of glucose in the blood is not controlled properly by the body. In type 1 diabetes, the pancreas does not produce enough insulin. This can lead to high levels of glucose in the blood, which can be fatal.

Too much insulin can also be harmful.

Cells of Islets of Langerhans 1.Name the cells of Islet of Langerhans 2.State their roles in homeostasis and their structural differences

Diabetes mellitus Homework: Research and make notes on different diabetes and how they are controlled