homeostasis

Question 1

What are both definitions of ‘Homeostasis’

Answer 1

A) The process of maintaining a constant internal environment despite fluctuations
in the external environment.

B) The process of maintaining a dynamic (steady state) equilibrium where input and output of materials and energy is balanced.

Question 2

What are the three functions of ‘Interstitial fluid’?

Answer 2

1. Bathes ALL cells
2. Represents the cell’s immediate environment
3. Provides optimum conditions for cell function

Question 3

What properties of interstitial fluid are maintained through homeostasis?

Answer 3

• Body temperature
• Blood pressure
• Fluid concentrations (osmotic pressure, diffusion, electrochemical gradients)
• Acidity (pH)
• Concentrations of nutrients (e.g. glucose), metabolic wastes and gases

Question 4

Explain an example of ‘Steady State’

Answer 4

If our body temperature gets too high, we sweat, and this returns our temperature to a safe level. If we get too cold, we shiver, and this produces extra body heat.

Question 5

Define ‘Tolerance limits’

Answer 5

The range of conditions in which the body can function.

Question 6

What happens if the conditions change beyond the tolerance limits?

Answer 6

The body is out of homeostasis for a prolonged period, and our body systems cannot function properly.

Question 7

Name all body processes responsible for maintaining homeostatic balance (steady state control mechanisms)

Answer 7

• Sweating/shivering
• Vasodilation
• Vasoconstriction
• Breathing rate
• Cardiac output
• Kidney function

Question 8

What does ‘Sweating/shivering’ maintain homeostatic balance of?

Answer 8

Body temperature

Question 9

What does ‘Vasodilation’ maintain homeostatic balance of?

Answer 9

Body temperature

Question 10

What does ‘Vasoconstriction’ maintain homeostatic balance of?

Answer 10

Body temperature

Question 11

What does ‘Breathing rate’ maintain homeostatic balance of?

Answer 11

• Oxygen and carbon dioxide levels
• pH

Question 12

What does ‘Cardiac output’ maintain homeostatic balance of?

Answer 12

Most homeostatic functions

Question 13

What does ‘Kidney function’ maintain homeostatic balance of?

Answer 13

• Getting rid of wastes
• Fluid balance
• pH

Question 14

What is the role of positive feedback?

Answer 14

The response to a stimulus is intensified

Question 15

What is an example of positive feedback intensifying stimuli?

Answer 15

The release of Oxytocin from the posterior pituitary gland during childbirth

Question 16

What is the role of the liver in controlling blood sugar concentration?

Answer 16

• Can convert glucose into glycogen for storage
• Can convert glycogen to glucose for release into the blood

Question 17

Where does most of the liver’s blood supply come from?

Answer 17

The hepatic portal vein

Question 18

Where does the hepatic portal vein bring blood directly from?

Answer 18

• Stomach
• Spleen
• Pancreas
• Small and large intestines

Question 19

When hepatic portal vein carries glucose to the liver, explain what may happen to the glucose.

Answer 19

• May be removed from blood by liver to provide energy for liver functioning
• May be removed by the liver and/or muscles and converted into glycogen for storage
• Continue to circulate in blood, available for body cells to absorb and use as a source of energy
• Converts to fat for long term storage if in excess of that required to maintain both normal blood sugar and tissue glycogen levels

Question 20

Explain ‘Glycogenesis’

Answer 20

Glucose molecules are chemically joined in long chains to form glycogen molecules

Question 21

What is glycogenesis stimulated by?

Answer 21

Pancreatic hormone: insulin

Question 22

What is glycogen available to do when it is stored in the liver? And what does it do?

Answer 22

Convert into glucose to maintain blood sugar levels and supply energy for liver activity

Question 23

What does glycogen provide when stored in muscle cells?

Answer 23

Provides the glucose required for muscle activity

Question 24

What process occurs when the level of glucose drops below normal? And what happens?

Answer 24

Glycogenolysis: Glycogen in the liver/muscle cells break down into glucose