Intro, Body Fluids, And Cell Physio

Question 1

How does the body maintain homeostasis?

Answer 1

Feedback control - positive and negative

Question 2

What happens when errors exceed the ability of the control system to adjust?

Answer 2

Disease and pathology

Question 3

Define and give an example of negative feedback?

Answer 3

Output reduces initial error (common)

Example:

Question 4

Define and give an example of positive feedback

Answer 4

Output is the same as the initial change (rare and leads to an event)

Example:

Question 5

Define homeostasis - steady state.

How does steady state differ from equilibrium?

Answer 5

Definition: Inputs change and produce error, but outputs remain normal. This requires energy input.

Equilibrium means the same (equal concentrations throughout)
Steady state means healthy concentrations, but not necessarily equal inside and outside of cells

Question 6

What happens when there is a deviation from setpoint?

When is this process complete?

Answer 6

The body will attempt to compensate.

As long as error signals remain, compensation is never complete.

Question 7

What happens to compensatory mechanisms as time progresses?

Answer 7

They breakdown or initiate changes that lead to pathology and disease.

Question 8

What general things must occur in order to return to full health?

Answer 8

The underlying error must be identified, treated, and stopped.

Question 9

Describe Full Compensation?

Answer 9

The bodies best response. Normal function may not be restored.

Question 10

Describe intracellular fluid, its location, and what encloses it.

Answer 10

ICF allows all solute a to be dissolve in the same medium - allowing metabolic reactions to occur.
It is the fluid inside ALL cells of the body.
Maintained by the cell membrane.

Question 11

Describe extracellular fluid and its location.

Answer 11

ECF is split into two compartments by the capillary wall…interstitial fluid (fluid around cells) and plasma (fluid portion of blood).

Question 12

What is ICF mostly composed of?

Answer 12

Potassium and proteins

Question 13

What is ECF mostly composed of?

Answer 13

Sodium and chloride

Question 14

What portion of total body water do ICF and ECF make up?

Answer 14

ICF: 2/3
ECF: 1/3

Question 15

What does it mean to say that ICF and ECF are electroneutral and isotonic?

Answer 15

Balanced in charge and amount of dissolved stuff

Question 16

Describe the location and selectivity of a capillary membrane.

Answer 16

Located in ECF between interstitial fluid and plasma.
Not selective - filters based on size. There are no proteins in interstitial fluid (too large to pass from plasma through the capillary membrane)

Question 17

Describe the location of and selectivity of the cell membrane.

Answer 17

Located between the intracellular fluid and extracellular fluid.
Very selective - few things can cross without help.
Small, non-polar solutes can diffuse across (O2, CO2, Ethanol, Steroid hormones, water…even though it’s polar)