Topic 6C: Homeostasis

Question 1

What is Homeostasis?

Answer 1

Maintaining a constant/stable internal environment.

-Changes in your external environment can affect your internal environment.

Question 2

What 3 main things should be maintained in the body?

Answer 2

• Temperature
• Blood pH
• Blood Glucose Conc

Question 3

If body temp is too high…

Answer 3

-enzymes denature because
-they vibrate too much
-breaks hydrogen bond
-alters tertiary structure
-changes shape of active site
-No longer works as a catalyst
-METABOLIC REACTION less efficient
-

Question 4

If body temp too low…

Answer 4

-Low enzyme activity

slow metabolic reactions

Question 5

What is the optimum body temperature?

Answer 5

37 degrees C

Question 6

If the blood pH is too low/too high…

Answer 6

• enzymes denature because
• breaks hydrogen bond
• alters tertiary structure
• changes shape of active site
• No longer works as a catalyst
• METABOLIC REACTION less efficient

Question 7

What is the optimum pH?

Answer 7

pH7

Question 8

If blood glucose conc is too high…

Answer 8

• lowers water potential
• water molecules diffuse out of cell and into blood
• by osmosis
• cells shrivel up and die

Question 9

If blood glucose conc is too low…

Answer 9

cells are unable to carry out normal activity because not enough glucose is the cells for respiration to provide energy.

Question 10

What is Negative Feedback Mechanism?

Answer 10

A response when the homeostatic system detects change.

Question 11

Receptors, a Communication system and effector are in…

Answer 11

the homeostatic system

Question 12

What do receptors do in the homeostatic system?

Answer 12

• detects if levels are too high/too low

- sends a signal to the nervous system or the hormonal system

Question 13

Name two types of communication system?

Answer 13

Nervous and Hormonal

Question 14

What do effectors do in the homeostatic system?

Answer 14

respond to counteract change to bring levels back to normal.

Question 15

If the change in the internal environment is too big…

Answer 15

• effectors can not counteract the change

- no negative feeback

Question 16

Multiple negative feebacks gives…

Answer 16

a faster response and more control

Question 17

What is Positive Feedback Mechanism?

Answer 17

amplify a change from the normal level.

Question 18

What do effectors do in a positive feedback mechanism?

Answer 18

Further increases the level away from normal

Question 19

Examples of positive feedback?

Answer 19

• blood clots after injury

- hypothermia (low body temperature)

Question 20

What is the concentration of glucose in the blood normally?

Answer 20

90mg per 100cm3

Question 21

When does blood glucose concentration increase?

Answer 21

When we eat food containing carbohydrates.

Question 22

When does blood glucose concentration decrease?

Answer 22

-after exercise because more glucose is used for respiration to release energy.

Question 23

Name three hormones that control the blood glucose concentration.

Answer 23

• Insulin
• Glucagon
• Adrenaline

Question 24

Which hormones do the hormonal system control

Answer 24

Insulin and Glucagon

Question 25

What is a hormone?

Answer 25

A chemical messenger that travels in the blood to their target cells (effectors)

Question 26

Where are insulin and glucagon secreted?

Answer 26

cluster of cells in the pancreas called the islet of Langerhans

Question 27

What types of cells are in the islet of Langerhans?

Answer 27

Beta cells which secrete insulin | Alpha cells which secret glucagon

Question 28

What does insulin do?

Answer 28

-lowers the blood glucose concentration in blood when it is too high.

Question 29

How does insulin lower blood glucose concentration?

Answer 29

-insulin bind to specific receptors on liver and muscle cells. This... 1) increases the permeability of cell membranes to glucose. This involves increases channel proteins too. 2) activates enzymes in liver and muscle cells to convert glucose into glycogen (glycogenesis) 3 increases the rate of respiration

Question 30

What does glucagon do?

Answer 30

-raises the blood glucose concentration in blood when it is too low.

Question 31

How does glucagon lower blood glucose concentration?

Answer 31

- Glucagon bind to specific receptors on liver cells. This... 1) activates enzymes in liver to break down glycogen to glucose (glycogenolysis) 2) activates enzymes that make glucose from glycerol and amino acids. (glyconeogenesis) 3) decreases rates of respiration)

Question 32

What is Glycogenesis?

Answer 32

Making glycogen from glucose as a energy storage.

Question 33

What is Glycogenolysis?

Answer 33

Break down of glycogen to glucose

Question 34

What is Glyconeogenisis?

Answer 34

Forming glucose from amino acids and glycerol.(non-carbohydrates)

Question 35

Name a channel protein/glucose transporter?

Answer 35

GLUT4

Question 36

Which cells contain GLUT4?

Answer 36

Cardiac and Skeletal muscle cells

Question 37

Where are GLUT4 stored in cells?

Answer 37

Vesicles in the cytoplasm

Question 38

What triggers the movement of GLUT4 from the cytoplasm to the cell membrane?

Answer 38

The binding of insulin and receptors on the cell-surface membrane.

Question 39

How is the glucose transported through GLUT4?

Answer 39

Faciliated Diffusion

Question 40

Where is adrenaline secreted from?

Answer 40

Adrenal glands

Question 41

When is adrenaline secreted from?

Answer 41

- When there is a low concentration of glucose in the blood. - stress - after excercise

Question 42

What does adrenaline do?

Answer 42

- activates glygenolysis - inhibits gylcogenesis - activates glucagon secretion - inhibits insulin secretion

Question 43

How does adrenaline and glucagon activate glycogenolysis inside a cell?

Answer 43

- Adrenaline and Glucagon bind to receptors that have a complementary shape to them. (on cell membrane) - activates an enzyme called adenylate cyclase - Adenylate cyclase converts ATP into a chemical signal called cyclic AMP - This is a secondary messenger - cAMP activates protein kinase A - this activates a cascade of glycogenolysis

Question 44

Adrenaline and Glucagon can only work via...

Answer 44

a secondary messenger