Homeostasis

Question 1

Define

Homeostasis

Answer 1

The maintenance of the internal environment in a constant state within an organism despite external changes

Question 2

Why is it important to maintain internal body temperature?

Answer 2

• If too low, enzyme activity is reduced
• If too high, enzymes will denature

Question 3

Why is it important to maintain internal body pH?

Answer 3

• Too high or low and enzymes will denature

Question 4

Why is it important to maintain internal blood glucose concentrations?

Answer 4

• Too high and cells will lose water due to it moving into the blood
• Too low and cells will gain water due to it moving out of the blood

Question 5

Define

Negative feedback

Answer 5

• Brings about a reversal of any change in conditions
• Ensures an optimum steady state cna be maintained

Question 6

Define

Positive feedback

Answer 6

• Increasess any change in conditions
• Rapidly activates processes in the body
• Can occur when there has been a breakdown in homeostatic mechanisms

Question 7

Define

Glycogenesis

Answer 7

Converting glucose to glycogen

Question 8

Define

Glycogenolysis

Answer 8

Converting glycogen to glucose

Question 9

Define

Gluconeogenesis

Answer 9

Converting non-carbohydrates into glucose

Question 10

Describe what happens when

Hyperglycemia occurs

Answer 10

• Rise in glucose levels is detected by beta cells in the pancreas
• The beta cells release insulin
• Insulin binds to receptors on liver, fat & muscle cells
• There is an increase in glucose channel proteins
• There is an increase in glycogenesis
• There is an increase of glucose used in respiration
• The glucose blood level falls

Question 11

Describe what happens when

Hypoglycemia occurs

Answer 11

• Fall in glucose levels is detected by alpha cells in the pancreas
• The alpha cells release glucagon
• Glucagon binds to receptors on liver cells
• There is a decrease in glucose channel proteins
• There is an increase of glycogeneolysis
• There is an increase in gluconeogenesis
• There is a decrease of glucose used in respiration
• The glucose blood level rises

Question 12

How are glucose channel proteins stored?

Answer 12

In vesicles in the cell that fuse to the cell membrane when needed

Question 13

What are

Second messengers?

Answer 13

A molecule activated by the first messanger binding to a receptor

Question 13

What is type II diabetes caused by?

Answer 13

Beta cells don’t produce enough insulin or target cells become less responsive

Question 13

What is type I diabetes caused by?

Answer 13

Autoimmune disease - the beta cells of the pancreas are attacked by the immune system & therefore cannot produce insulin

Question 13

What are the risk factors for type II diabetes?

Answer 13

• Lack of excersise
• Obesity
• Poor diet
• Family history
• Ethnic origin

Question 13

Describe

The process inside the cell when adrenaline or glucagon bind

Answer 13

• Adenylaye cyclase activated
• ATP coverted to cAMP
• cAMP activates protein kinase A
• Cascade of enzyme actions
• Glucogenolysis (Glycogen converted to glucose)

Question 13

When is adrenaline secreted?

Answer 13

• There’s a low blood glucose concentration
• You’re stressed
• You’re exercising

Question 13

What does adrenaline do for blood glucose concentration?

Answer 13

• Activates glycogenolysis (glycogen to glucose)
• Inhibits glycogenesis (glucose to glycogen)