1-3. Homeostasis Flashcards
Homeostasis
to maintain a fairly constant internal body environment (constant within a very narrow range of physiological limits)
What is the internal environment composed of?
the extracellular fluid (ECF) - all of the fluid found outside the cell
What are the two major places ECF is found?
interstitial fluid (between tissue cells) and plasma (inside blood vessels)
ECF
extracellular fluid; all of the fluid found outside the cell
interstitial fluid
ECF found in microscopic spaces between tissue cells
plasma
ECF found inside blood vessels (liquid portion of blood)
Which of the two organ systems are primarily responsible for maintaining homeostasis?
nervous system and endocrine system
What is the nervous system’s role in maintaining homeostasis?
detects changes in the environment and sends signals to the proper organs to counteract the stress
What is the endocrine system’s role in maintaining homeostasis?
glands that secrete hormones into blood to counteract stress
Feedback System
loop where information about the status of the temp, etc, is feed back to a control center
What are the four parts of the feedback system?
stimulus > receptor > control center > effector
receptor
first part of feedback loop
monitors environment, detects and responds to stimuli by sending signal to the control center
control center
second part of feedback loop
determines set point, analyzes input, and sends output to effector
effector
third part of feedback loop
organ that responds to control center output, feeding back to stimulus
negative feedback
stimulus initiates action to reverse the stimulus (going in opposite direction)
What are some examples of negative feedback?
tempature goes up > sweat brings it down
blood glucose
pH balance
positive feedback
stimulus exaggerates original stimulus (going in same direction)
What are some examples of positive feedback?
blood clotting
labor contractions
disease
homeostasis imbalance or change
signs
characteristic change in body due to disease that can be observed or measured
symptom
subjective change in body due to disease that is felt by the patient, but not observable
What is the difference between a sign and a symptom?
a sign can be observed or measured; a symptom is subjective and not observable
