homeostasis Flashcards
what is homeostasis?
maintaining relative constant environment in the body.
maintaining internal equilibrium by adjusting its physiological processes.
explain how sweating maintains homeostasis and what excessive sweating can do.
its is released to cool the body from the outside.
but too much sweat causes blood volume to decrease = drop in BP and disrupts homeostasis
how does increased heart rate maintain homeostasis?
heart rate increases because there is a need for increased blood flow in the body. once the heart rate increases so does BP
how is thirst a signal of homeostasis?
increase in water intake is signaled because they need to replenish water that is lost in sweat
what is the set point?
the ideal normal value of a variable.
what is the normal range?
the range of fluctuation from the set point that is normal
what is the set point and normal range for body temp?
set point = 37 degrees
normal range = 36.5 to 37.5
how do the organ systems help maintain homeostasis?
- controls the internal environment
- allows communication between cells, tissues and organ systems
- NS and endocrine system gather sensory info form internal and external environment to send signals throughout the body = maintain homeostasis
what are the 3 components of the feedback system?
receptor = monitors the value of a variable
control center = establishes set point
effector = can change the value of the variable
what is the stimulus
causes the “change” like deviation from set point that’s detected from the receptor
what is the response produced by
effector
what are the two types of feedback systems?
negative and positive
describe negative feedback system.
negative feedback only happens when the deviation from the set point is made smaller (resisted) aka bringing body back to normal level
- stimulus - disrupts homeostasis by increasing or decreasing a controlled condition
- the controlled condition is monitored by receptors
- the receptors send nerve impulses to the control center (brain)
- control center receives the input and provides nerve impulses or chemical signals to effectors
- effectors bring a change or response that alters controlled condition
- controlled condition is returned to normal = HOMEOSTASIS RETURNED!
what are some examples of negative feedback?
body temperature
regulation of BP
blood sugar levels
what is a positive feedback system?
when a deviation occurs and the response is to make the deviation greater
- the stimulus disrupts homeostasis by increasing the controlled condition
- the controlled condition is monitored by receptors
- the receptors send nerve impulses to the control center (brain)
- control center receives the input and provides nerve impulses or chemical signals to effectors
- effectors bring a change or response that alters controlled condition
!!DISTRUPTION!! - controlled condition is returned to normal after disruption = back to increased controlled condition
what is an example of positive feedback? explain it.
childbirth
- contractions of the wall of the uterus force baby head into cervix
- increases stretching of the cervix (controlled condition)
- receptors = stretch-sensitive nerve cells in the cervix send nerve impulses to the brain
- the brain interprets the input and releases oxytocin
- this causes the effectors (muscles of the uterine wall) to contract more forcefully
- the response - baby’s body stretched the cervix more
DISTRUCPTION = baby birth = decreases stretching = breaking positive feedback cycle - increased stretching of cervix causes the increased release of oxytocin = more cervix stretching = BACK TO INCREASED STRETCHING OF CERVIX CONDITION
how can positive feedback lead to death?
in healthy humans leading away from homeostasis is unusual.
harmful positive feedback:
hemorrhage (dramatic loss of blood) leads to a decrease in BP and the heart cant pump blood b/c there isnt enough getting to it
is BP during exercise non-homeostatic?
no, but the normal range can change temporarily depending on body situation
- increase in exercise = increase in BP
- blood flow and BP have direct corelation
- when exercising increase blood flow may be needed b/c of increase 02 and nutrient intake
THEREFORE: exercise = larger normal range b/c the body’s demands change so much
what happens when you loose homeostasis?
disease
death - if disease isnt controlled in normal range = death
describes what happens with the Acromegaly condition.
rare condition where the body produces too much growth hormone b/c of the loss of homeostasis, causing body tissues and bones to grow more quickly.
can be caused by a tumor in pituitary gland - pituitary gland controls homeostasis
