homeostasis Flashcards
what is homeostasis
is the state of steady internal, physical, and chemical conditions maintained by living systems
The process by which the body reacts to changes in order to keep conditions inside the body, for example temperature, the same
what is the
homeostatic range
the condition of optimal
functioning for the organism
and includes many variables,
such as body temperature and
fluid balance, being kept within
certain pre-set limits- the
homeostatic range
factors homeostatically regulated
conc of nutrient molecules, CO2 O2, waste products, water, salt, other electrolytes
Volumes and pressure
Temperature
pH
Homeostatic control System definition
is a functionally interconnected network of body components that operate to maintain a given physical/ chemical factor in the internal environment relatively constant around an optimal level
how can homeostatic control systems be classified
intrinsic + Extrinsic
- inherent compensatory responses of an organ to a change
- responses of an organ that are triggered by factors external to the organ by the nervous/endocrine systems
what principles do the types of homeostatic controls generally operate on
Negative/ Positive/Feed forward mechanism
what is positive feedback
the output is continually enhanced/amplified so that the controlled variable continues to be moved in the direction of the initial change or a pathway in which the response reinforces the stimulus
Negative feedback
homeostatic control factor triggers a response that seeks to restore the factor to normal by moving the factor in the opposite direction of its initial change or it is a pathway where the response opposes or removes the the signal.
what does the Negative feedback loop require
sensor, set point and effector
if sensor does not equal set point = error signal = restore variable to desired level
limitations of negative feedback
initiated after variable has been disturbed
Amount of correction to be applied assessed by magnitude of
error signal –> incomplete correction
Overcorrection –> oscillations in controlled variable
how the negative feedback disadvantages overcome
Disadvantages overcome by multiple regulatory mechanisms
What is the multiple regulatory mechanisms:
involuntary (paracrine, endocrine, ANS and CNS)
voluntary (CNS)
positive feedback for labour
onset of labour, oxytocin released from hypothalamus, increased uterine contractions, Baby’s head pushed through cervix, stretch of cervix, more oxytocin released, interested uterine contractions
rising phase of action potential process and is it an example of positive or negative feedback
positive feedback example
depolarisation, opens Na channels, Na entry, Further depolarisation, UNTIL STOP when Na channels inactive
Feedforward Mechanism
It brings about compensatory response in anticipation of a change in regulated variable
example of feedforward mechanism
increased production of saliva and gastric secretions at smell and sight of food
example of feed forward and anticipatory change - renal
Changes in renal function in preparation for changes brought on
by food intake resulting in changes in concentration of ions in the
plasma that will need to be controlled within physiological range
what does the ER do
Synthesis and transport of
membrane proteins and lipids
what does golgi apparatus do
Synthesis and packaging of secretory
molecules; membrane protein
targeting
what does the plasma membrane contain
contains membrane proteins which transport
water, ions and hydrophilic
molecules
