Homeostasis Video Notes

four types of cell tissues

1. muscle

   1. cardiac, skeletal, smooth

2. nervous

3. connective tissue: dense/loose…irr/regular

4. epithelial: transportation, secretion and absorption - stratified

define extracellular fluid and intracellular fluid

extracellular fluid is fluid that is not contained within a cell. There are two types:

1. plasma (within blood vessels)

2. interstitial fluid (between the actual cells)

intracellular fluid is fluid that is within the cell - makes up 2/3 of the fluid within the body

give a basic definition of homeostasis. what type of process is this? how specifically is it regulated?

homeostasis is the regulation of a stable internal environment

• dynamic process; constantly changing

• regulated via feedback/forward systems

define a negative feedback loop vs positive feedback loop

• a negative feedback loop shuts a system off once the original set point has been reached

  • blood oxygen levels

• a positive feedback loop gets something done

  • childbirth or blood clotting

  • unregulated

what is a feedforward system?

a feedforward system is a response that happens in anticipation of a change

• insulin entering blood when you see food, before you have consumed food and before blood glucose levels have risen

three things a control system must be able to do in order to function properly

1. detect a deviation from the set point

2. integrate information, signal to the brain something is wrong

3. make adjustments in activity og bodily functions to restore normal level

describe the basic points of a control system, from deviation to restored variable

1. deviation

2. deviation detected by sensor

3. signal travels down afferent pathway to integrator (brain)

4. effector travels down efferent pathway to target

5. compensatory response

6. variable restored

what are the two ways to control homeostatic systems?

1. intrinsic response: local control

2. extrinsic response: nervous system orchestrates a change

ex) when blood-oxygen supply to a specific muscle is low, the skeletal muscle will dilate its vessels to receive more blood locally (INTRINSTIC)

this will be related to the integrator, the brain, and the nervous system will respond by increasing heart rate and dilating vessels in surrounding skeletal muscles (EXTRINSIC)

four ways cells can communicate

1. hormones

   1. secreted from endocrine glands OR cells scattered throughout an organ

   2. travels via blood supply

2. nerves

   1. neurotransmitters (electrical signal)

3. paracrine substances

   1. cell releases substance to communicate with neighbors; close proximity

4. autocrine substances

   1. substance release acts on cell which secreted it