Homeostasis

Question 1

Define homeostasis

Answer 1

The maintenance of nearly constant conditions in the internal environment referred to as a STEADY STATE

Question 2

Define steady state. Is it the same as equilibrium? If it is not the same how is it different?

Answer 2

it is the maintenance of nearly constant conditions over time. It is not the same as equilibrium because it requires the input of energy while at equilibrium no energy is required.

Question 3

Define equilibrium

Answer 3

when a system’s solute concentrations and other parameters are constant in time without requiring the input of energy from metabolism or other sources

Question 4

What is the concept of mass balance?

Answer 4

For a system at steady state for metabolism means that an substance taken in by the body is nearly equal to the amount leaving the body plus that removed by metabolism.

Question 5

What is Basal metabolic rate (BMR)?

Answer 5

the energy expenditure at rest (kcal/hr/sq meter body surface area). It is the largest proportion of our daily energy usage.

Question 6

What can decrease BMR?

Answer 6

Sleeping only

Question 7

What can increase BMR?

Answer 7

Arousal, fever, ingesting food, normal activity, and most profoundly by strenuous exercise.

Question 8

A healthy young man requires ~30kcal/kg body weight to sustain daily resting metabolism. What is this called?

Answer 8

Resting Metabolic Rate (RMR)

Question 9

What can raise the RMR?

Answer 9

Increasing muscle mass, body size, hormones (thyroid hormone, growth hormone, testosterone, epi/norepi). (Poor nutrition lowers RMR)

Question 10

What happens to the RMR as we age?

Answer 10

It declines, mostly due to reduced muscle mass.

Question 11

Is RMR higher in people living in the tropics or the arctic?

Answer 11

Arctic. TH adaptive effect.

Question 12

What is the primary extracellular electrolyte? What is the primary intracellular electrolyte?

Answer 12

Extracellular = Na. Intracellular = K. The sodium potassium ATPases keep this by pumping three Na out for every 2 K in.

Question 13

What three components do negative feedback systems include?

Answer 13

Receptor, integrator and effector

Question 14

What is the major process used to maintain a stable internal environment (Homeostasis)?

Answer 14

Negative feedback

Question 15

This system of control regulates the body systems, particularly when a change with time is desirable.

Answer 15

Feedforward control

Question 16

This form of feedback accelerates a process and can thus be unstable.

Answer 16

Positive feedback

Question 17

The degree of effectiveness with which a control system maintains constant conditions is determined by what?

Answer 17

The Gain of the negative feedback. The capacity of the system to restore a controlled variable to its set point after a perturbation is called the gain.

Question 18

What does a high gain imply?

Answer 18

It implies that the system is better able to restore a controlled variable to its set point in response to perturbation.

Question 19

How do you calculate gain?

Answer 19

Gain = Correction / remaining error