Communication and homeostasis Flashcards
Explain why it is important for multicellular organisms, such as humans, to have communication systems?
. humans need to respond to changes in their environment
. information will be passed on from a receptor to an effector in order to bring a response about
. an example of this is homeostasis where internal and external conditions in the body are kept constant to promote optimum conditions for enzyme and cell function
what does a receptor do?
detects a change in the stimuli (environment)
what does an effector do?
responds to the change detected by receptors
two examples of effectors?
muscles and glands
what are two communication systems?
- nervous system
- endocrine system
define homeostasis?
a process which keeps the internal and external body conditions constant within restricted limits so conditions are at their optimum for enzyme action and cell function
examples of homeostasis that keeps body conditions constant and regulated?
blood glucose concentration
water levels in the body
blood ph
body temperature
what is cell signalling?
when cells in a multicellular organism communicate with each other by secreting chemicals
name the two chemicals found in the nervous and endocrine system which are secreted during cell signalling?
nervous : neurotransmitters
endocrine : hormones
what is autocrine cell signalling?
cell signalling to itself and receives its own signal
what is endocrine signalling?
signalling between distant cells via the bloodstream
what is paracrine signalling?
signalling between adjacent cells
what molecule is always secreted by the endocrine signalling system and where are they transported between?
molecule always a hormone
transported between circulatory systems
explain each step of the negative feedback loop?
6 stages
- optimum conditions
- changes away from optimum conditions
- receptor detects change
- communication system informs effector
- effector responds and reacts to reverse the change
- return to optimum conditions
explain the steps of the positive feedback loop?
5 stages
- optimum condition
- changes away from optimum condition
- receptor detects change
- communication system informs effector
- Effexor reacts increasing change
then goes BACK to stage 2!
what is a feedback loop? definition?
informs receptor of changes the system brought about by effectors
how to endotherms control their body temperature?
within restricted limits
control body temp independently from external temperatures
how to exotherms control their body temperature?
rely on external sources of heat, like a heat lamp
may use behavioural mechanisms to control body temp
name the 4 ways an endotherm may use to warm up?
- exergonic actions like respiration that releases energy
- vasocronstriction
- shivering
- piloerection = goosebumps
what is vasoconstriction and how does it warm an endotherm up?
. when arterioles constrict
. blood shunted away from the skin so less heat is lost
how does shivering warm an endotherm up?
- multiple rapid contractions of skeletal muscle
- more respiration in muscle cells
- more heat energy released
how does piloerection warm an endotherm up?
hairs stand on the end which creates a warm layer of air trapped around skin for insulation
name the two ways in which an endotherm will cool down?
. vasodilation
. sweating
how does vasodilation cool down an endotherm?
- arterioles dilate
- blood shunted towards the skin
- more heat lost
how does sweating cool down an endotherm?
- the sweat water molecules absorb the heat energy from the skin
- causes sweat / water from skin to evaporate
- causes skin to lose heat energy
describe two ways ectotherms warm up?
. absorb heat energy from solar radiation
. condition to absorb heat energy from rocks and other surfaces
what are two ways ectotherms cool down?
seeking shade
drinking water
strengths of endotherms?
name three?
- stable internal temperature allows to remain active with wide range of environments
- can be active at any time and season
- sustain high levels of activity because enzymes constantly at optimum temperatures
weaknesses of endotherms?
name 3
- high energy demand , need to eat more food for thermoregulation
- more energy from food goes into maintaining body temperature rather than growth or reproduction
- may struggle to survive with scarce food environments
name 3 strengths of ectotherms?
- use less energy for thermoregulation , can survive with less food
- more energy from food goes into growth and reproduction
- survive in environments of limited food
name 3 weaknesses of ectotherms?
- Activity levels are temperature-dependent
- Limited to warmer environments
- Less control over internal temperature so may be more vulnerable
