wk1 / c3 (homeostasis) Flashcards
homeostasis:
Homeostasis-
1st aspect of homeostasis-
controlled condition/ set point:
-
Normal physiological range for the monitored variables within the body
ie. blood glucose, blood pressure, ph of blood, body temp (these kinds of physiological processes)
Homeostasis-
controlled conditions work at which levels?
(4)
- cellular
- tissue
- organ
- systems
leves
(homeostasis occurs in all these systems, and btw these systems as they interact)
Homeostasis- stimulus
we have the controlled conditions occuring w/in our body all the time, however we are _
dynamic organisms
homeostasis- stimulus
there are many biological conditions _
interacting within our bodies
homeostasis- stimulus
we are also _ and _ with the external environment
responding and interacting with the external environment
homeostasis- stimulus
stimulus:
any external or internal factor which changes the controlled conditions
homeostasis- stimulus
when we change the controlled condition we are?
disrupting homeostasis
(by either increasing or decreasing that variable beyond the normal physiological range)
homeostasis- stimulus
examples of stimuli to the body?
(5)
homeostasis-
1st key component of homeostasis
what detects change to homeostasis?
a receptor
homeostasis-
1st key component of homeostasis
receptor:
homeostasis- receptor
1st key component of homeostasis
example
nerve cell detecting changes in?
temperature
homeostasis- receptor
1st key component of homeostasis
example
nerve cell detecting changes in?
pressure
homeostasis- receptor
1st key component of homeostasis
example
nerve cell detecting changes in?
chemicals
ie. in our mouths, diff tastes
homeostasis- receptor
1st key component of homeostasis
how is info picked up by receptors, in 2 diff ways?
specialise nerve cells pick up change, via a nerve impulse (fast acting) ie. pics on left
or
a specialised receptor protein which sits in the surface of the cell, that can detect the change and send a chemical signals (slow acting)
ie. pic on right
homeostasis -
2nd key component
control centre:
homeostasis- control centre
2nd key component of homeostasis
in most cases the control center is?
the brain
(although there are exceptions to this rule)
homeostasis- control centre
2nd key component of homeostasis
process of the control centre?
pic
homeostasis- control centre
2nd key component of homeostasis
input flowing to the control center is also called?
afferent pathway
homeostasis- control centre
2nd key component of homeostasis
output flowing away from the control centre is called?
efferent pathway
(once the brain processes the info and sends out instructions to the effector, or because its travelling away from the brain)
homeostasis- control centre
2nd key component of homeostasis
how is info sent to the control centre?
again by
nerve impulses (fast acting)
or
chemical signals (slower acting)
ie. hormones or other small chemical molecules
what is the purpose of sending info to the control centre?
to try and elicit a response
homeostasis - 3rd key
component
effector:
homeostasis - 3rd key
component
effector-
what is this example?
molecules that are sensing, sitting on the surface of an organ,
that are receiving a chemical signal (hormone or diff chem mole)
or
it could this could happen by a specialised nerve cell that receives that nerve impulse
example of a nerve impulse
nerve impulse contracts one of the muscles,
which is attached to one of the hair bulbs,
so that the hair stands up on the surface of the skin
example of recieving a signal in the lungs
to change the size of the airways within our lungs,
to either dialate or constrict
some of the air passage ways
example of signal to heart
changes to the muscles of the heart,
which can cause the heart to beat faster or slower
explain all example of effectors here
- skin, muscles att constrict to stand up hairs
- lungs, open or close airways
- heart, muscles contract to beat faster or slower
- blood vessels, dialate or contract to speed up or slow blood flow
- eye, pupil dialate
- liver, changes so other chem may be secreted
- kidney, changes to retain or release more water
- adrenal gland, release chem hormones that effect other tissues and organs of the body
effector is dependant on what the _ is
and which biological pathway has been _
stimulus
disrupted from homeostasis
summary of homeostasis
(occurs as a loop)
- stimulus - disrupts homeostasis, by increasing or decreasing..
- controlled conditions - that are constantly monitored by..
- receptors - that send (thu afferent pathway/input) nerve signals or chemical impulses to a..
- control centre- that recieves the input and sends (thu efferent pathway/output) nerve impulses or chemical signals (such as hormones) to …
- effectors- detect msg sent, that bring about a change so that we get a ..
- response- that alters the controlled condition
we return to homeostasis only when that response brings the controlled condition back to normal
summary of homeostasis
diagram
homeostasis-
homeostasis occurs as a loop, called a?
feed back loop
2 types
- positive
- negative
feedback loops
feedback loop-
positive feedback loop:
when the response
enhances or intensifies
the stimulus
(the only way to stop that loop is for the stimulus to be removed)
feedback loop-
negative feedback loop:
when the response reverses the stimulus
(and brings the controlled condition back into its normal range)
feedback loop-
negative feedback loop:
(these types of fb loops are extremely common, and govern a number of biological processes that occur throughout the body
example blood pressure
- stimulus- (may be stress) disrupts homeostasis by increasing..
- controlled condition - of blood pressure
- receptors- baroreceptors (specialised receptors that are in the lining of the blood vessels) in certain blood vessels, the detection of the blood pressure is then sent via afferent pathways/input as a nerve impulse to the ..
- control center- in this case the brain, the brain processes that information, then sends an output/efferent pathway via nerve impulses again to the ..
- effectors- in this ex. blood vessels and the heart
- response- the blood vessels dialate, let more blood thu, that will decrease the blood pressure as well as the heart rate
we return to homeostasis when the responses bring the blood pressure back to normal
(may not happen immediately, may need to go though the loop a few times, depend on the the particular change we are taking about and the intensity of the stimulus)
feedback loop-
negative feedback loop:
diagram
feedback loop-
positive feedback loop:
example birth contractions
(less common as opposed to neg)
- stimulus- the contractiof the wall of the uterus, that force the babies head and body into the cervix, means increase in controlled condition
- controlled condition- stretching of the cervix
- receptors- that detect this increase stretching of the cervix are the stretch sensive nerve cells in the cervix, they pick this change up, they send the info to the control centre via nerve impulses (afferent pathway/input)
- control centre- the brain, interprets info, processes that info and sends via output/efferent pathway and releases oxytocin, travels in the blood stream to the ..
- effectors- and it effects the muscles in the wall of the uterus, and causes them to start contracting more forcefully
- response- babies body starts to stretch the cervix more
continue to go round this loop, the increase stretching of the cervix causes the release of more oxytocin (so can see why its positive loop/more of the hormone, more stretching) the only way it ends is the interuption of the cycle (by baby being born, decreases the stretch of the cervix and breaks cycle)
