Body Temperature and Blood Glucose

Sun Hwa Dong

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

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

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∴

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

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

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

Diabetes

When blood glucose controlling does not work well thus the concentration rises or falls beyond normal limits

Type 1 Type 2

Onset During childhood After childhood

Cells Beta cells produce insulin

Target cells become insensitive to insulin

Insulin injection Used to control glucose levels

Not usually needed

Diet Can’t control condition

Low carbohydrate diet controls condition

Vocabulary

Hypothalamus Negative feedback Blood glucose Alpha cells: Alpha cells are endocrine cells in the islets of Langerhans

of the pancreas. Beta cells: Beta cells (beta-cells, β-cells) are a type of cell in the

pancreas in areas called the islets of Langerhans. Insuline Glycogen glucagon Diabetes

Bibliography

Study guide pg 55 Course Companion pg