1. Body Temperature and Blood Glucose Sun Hwa Dong

2. Control of Body temperature Hypothalamus monitors temp. and compares it with a set point (around 37°C ) Lower/ higher – send messages (carried out by neurons) to body parts for response – temp. back Negative Feedback Responses affect: heat production and loss rate, rate of heat transfer between body parts in blood

3. Responses to Overheating Wider skin arterioles blood flows through skin Blood transfers heat from body core to skin Skin temp. heat loss Skeletal muscles rest no heat generation Sweat glands secret sweat skin surface becomes damp + water evaporates = cooling effect

4. Responses to Chilling Narrower skin arterioles blood flow Blood capillaries in skin do not move but blood flow Skin temp heat loss Many small, rapid contractions of skeletal muscles that generates heat - Shivering Sweat glands do not secret sweat dry skin

5. Control of Blood Glucose Blood Glucose concentration kept between 4-8 millimoles per dm3 of blood Low/ high - cells in pancreas monitor concentration – send hormone messages to target organs Responses by organs affect rate at which glucose is loaded into blood or unloaded from it Negative Feedback

6. Responses to High Blood Glucose Levels Beta cells produce insulin – it stimulates liver and muscle cells to absorb glucose and convert it to glycogen Granules of glycogen stored in cytoplasm Other cells are stimulated to absorb glucose and use it for cell respiration - BGL

7. Responses to Low Blood Glucose Levels Alpha cells produce glucagons – it stimulates liver cells to break glycogen down into glucose – release it into blood BGL

8. Diabetes When blood glucose controlling does not work well thus the concentration rises or falls beyond normal limits Type 1Type 2 OnsetDuring childhoodAfter childhood CellsBeta cells produce insulin Target cells become insensitive to insulin Insulin injectionUsed to control glucose levels Not usually needed DietCant control condition Low carbohydrate diet controls condition

9. Vocabulary Hypothalamus Negative feedback Blood glucose Alpha cells: Alpha cells are endocrine cells in the islets of Langerhans of the pancreas.endocrinecellsislets of Langerhanspancreas Beta cells: Beta cells (beta-cells, β-cells) are a type of cell in the pancreas in areas called the islets of Langerhans.cell pancreasislets of Langerhans Insuline Glycogen glucagon Diabetes

10. Bibliography Study guide pg 55 Course Companion pg