1 communication and homeostasis Flashcards
what is cell signalling
the way in which cells communicate with each other
why do cells need to communicate with each other
maintain internal conditions (temperature, pH, aqueous environment, free from toxins etc.)
what is a stimulus and response
change in environment
way in which the organism changes its behaviour/ physiology
what will a good communication system do
cover the whole body
enable cell communication
enable rapid communication
enable specific communication
short and long term responses
ensure that different parts of the body work together
compare nervous and hormonal system
nervous - uses neurones, electrical impulses, short lasting, quick response
hormonal - uses blood, hormones/ chemicals, long lasting, slow response
what is the CNS and PNS
central nervous system (CNS) – the brain and the spinal cord
peripheral nervous system (PNS) – all of the nerves in the body
why is a multicellular organism more efficient then a single celled organism
cells are differentiated = so are specialised to perform specific functions
homeostasis
maintaining a constant internal environment around an optimum despite changes in external and internal factors
examples of what homeostasis controls
temperarure
blood glucose concentration
blood salt concentration
blood water potential
blood pressure
CO2 concentration
response pathway to a stimulus
stimulus - receptor - (cell signalling) - effector - response
sensory receptors
cells that respond to a stimulus in the internal/external environment of an organism and can create action potentials
effectors
cell/tissue/organ that brings about a response
negative feedback
mechanism that brings conditions back towards equilibrium
positive feedback
mechanism that increases a change, takes system further away from optimum
hormones
chemicals/ cell signalling molecules that are produced by glands and released into the blood
ectotherm
a type of organism that depends on its environment to maintain its body temperature
endotherm
a type of organism which can regulate its own body temperature without relying on external heat sources
temperature control in ectotherms
do not use internal energy sources
relies on behavioral responses
not warm enough = try to absorb more heat from the environment (move into sun, lie on warm surface, expose larger SA)
too hot = avoid gaining more heat, try to increase heat loss
(move out of sun, underground, reduce body SA exposed )
advantages of ectothermy
do not use up energy to keep warm
less food used in respiration
more energy/nutrients converted to growth
find less food
survive for long periods without food
disadvantages of ectothermy
less active in cooler temperatures
risk from predators whilst cold and unable to escape
cannot take advantage of food available when cold
temperature control in endotherms
relies on effectors in the skin and muscles
chemical reactions release energy as heat
can increase respiration to release heat
physiological mechanisms - blood redirection
advantages of endothermy
maintain fairly constant body temperature
remain active when cold environment - take advantage of prey
inhabit colder parts of the planet
disadvantages of endothermy
use significant amounts of energy intake to maintain body temperature
need more food
may overheat
role of hypothalamus
detects change in core body temperature
in the brain
sends quick impulses to prevent further change
role of peripheral temperature receptors
monitor the temperature in the extremities
info is fed to the thermoregulatory centre in the hypothalamus
behavioural mechanisms can be initiated to maintain temp of the body
