Homeostasis

Question 1

How is the body organized in terms of # of cells?

Answer 1

We start life as a single cell which eventually multiplies into us having roughly about 10^14 cells

Question 2

What is homeostasis defined as by Vander?

Answer 2

“Relatively stable condition of ECF that results from regulatory actions”

Question 3

What is extracellular fluid (ECF)?

Answer 3

Fluid outside the cell/surrounding the cell or environment outside the cells resulting from regulatory actions

Question 4

What are two key things that must be maintained in homeostasis?

Answer 4

Function and internal environment

Question 5

Homeostasis is defined as the ability of a cell to do what?

Answer 5

The ability of a cell or organism to regulate its environment

Question 6

When homeostasis is occuring, is it always one system that works to regulate it?

Answer 6

No; most of the times you expect to see multiple systems involved in regulating homeostasis

I.e. Running up the stairs may require more oxygen to be used so the pulmonary system needs to be used, but this may also require the cardiovascular system to constrict blood flow only to the legs

Question 7

What is this image trying to show?

Answer 7

Cells make up our tissues, organs, etc of the body system. The body systems maintain homeostasis which in turn allows cells to function

Question 8

What are some examples of things we tend to see homeostatically regulated?

Answer 8

1. Concentration of nutrient molecules
2. Concentration of O2 and Co2
3. Concentration of waste products
4. pH (power of Hydrogen)
5. Concentration of water, salt, electrolytes
6. Blood Plasma Volume & Pressure
7. Temperature

• All of these are regulated by the body to maintain an optimal environment

Question 9

How are we able to coordinate a response to set everything into homeostasis?

Answer 9

Feedback response

Question 10

What does a feedback response consist of? Give an example of how it would look like?

Answer 10

Consists of: Sensory System, Relay Station, Response System

• When you are working out your brain gets an affective signal to let it know that the heart should be pumping a lot of blood. It then sends a response to the heart to pump more effectively and increase cardiac output

Question 11

What are the main types of feedback? Which is more common?

Answer 11

1. Negative feedback - more common; does a contradicting action in response to initial stimulus
2. Positive feedback - Response adds to initial stimulus

Question 12

What is constant feedback?

Answer 12

Constant feedback is a type of feedback that is always running.

I.e, when you breathe in, your body knows it must breathe out to expel the air or else you’ll be in trouble. It is a constant flow

Question 13

What is feedforward regulation?

Answer 13

It primes the system for challenges to come; it uses anticipatory situation to increase the response to stimulus

Question 14

What is meant by anticipatory situations and feedforward regulation

Answer 14

Feedforward regulation is aided by anticipatory situations. Anticipatory situations are cases that help increase the response to the stimulus even if you haven’t physically done something

In a sense it is a primal response

Example: You’re going to give a lecture and your heart rate gets faster thinking about it, not because you exercised.

Question 15

What are some general things that should be noted when looking at homeostatic control?

Answer 15

1. Stability is achieved by balancing the inputs and outputs
2. Need some form of sensory mechanism to detect deviations from set points
3. Set points can be reset (up or down)
4. Set points are maintained over a small range
5. Hierarchy of control: some things are more important than others