homeostasis Flashcards
(26 cards)
what is homeostasis
maintenance of stable internal state (e.g. body temperature, blood sugar levels)
requires constant physiological adjustments
essential for survival of organism
who created the term homeostasis?
walter cannon
homeo “similar”
stasis “state”
negative feedback
physiological response in OPPOSITE direction to the detected change
this occurs due to a change from a set-point (narrow range of a variable)
negative feedback systems have the following what?
sensor- detects change in external environment
integrator- compares detected change with set point of system
effector- induces response to restore system back to set point
antagonistic control
control changes in a variable in BOTH directions
e.g. body temp
too hot > sweat
disadvantages of negative feedback
may not function properly in extreme environments
delay in stopping response (overshoot beyond set-point)
delay between when change is detected and response is initiated
adaptations in negative feedback
ANTICIPATION
predicts external change before it occurs
turns off compensatory response before it ‘overshoots’ set-point
ACCLIMATISATION
an adaptation that alters negative feedback gradually in a new environment
positive feedback
mechanism to create a rapid, temporary change from set-point
change detected causes further change in the SAME direction
example of positive feedback
oxytocin during labour
enantiostasis
this is maintaining homeostasis by changing on physiological variable to compensate for a change in another separate variable
what can ongoing disruption of homeostasis or changing oof set points cause
illness
death
how can animals be classified based on how they maintain homeostasis
conformers- internal state matches external state
regulators- maintain constant internal state
avoiders- maintain internal state by avoiding environmental change (migration)
cell
smallest unit of organisation capable of processes associated with life
whats an organ
body structure that integrates different tissues and carries out a specific function
basic cell functions
-produce energy (ATP), eliminate waste (CO2) byproducts
-obtain nutrients (sugar,fats) and energy source
-synthesise proteins needed for cellular function
specialised cell functions
different cell types in animals show specialised functions that evolved from certain basic cell functions e.g. gland cells secrete molecules
what is a tissue
group of cells with similar specialised functions
-epithelial
-connective tissue
-muscular
-nervous
muscular tissue
consists of cells specialised for contraction and force generation
vertebrates have 3 types of muscle
-skeletal which is the voluntary movement of skeleton and body
-cardiac which is the involuntary pumping of blood by heart
-smooth which is the involuntary movement of hollow tissues and organs
whats a system
2 + organs working together towards a common function e.g. digestive system
how is homeostasis controlled
homeostasis is controlled at different levels beyond individual cells
-intrinsic and extrinsic
intrinsic
regulated by one type of organ (e.g. muscle) or tissue type.
control is fast because it occurs locally
extrinsic
regulated by interactions between different organ systems
control is slower because is occurs throughout the body.
control systems
control systems regulate homeostasis indirectly via other systems
name the 2 control systems
-nervous system
rapid coordination of body systems in response to external change
simple reflexes (via spinal cord, muscle)
complex behaviour (via brain, spinal cord, muscle)
-endocrine system
slower, longer lasting regulation of body systems
digestion (via digestive tract)
