Communication and homeostasis 5.1 Flashcards
why do multicellular organisms need a communication system
to coordinate their organs and respond to internal and external changes to survive
what is and examples of external stimuli/changes
when organisms need to respond to their environment
- temp, predators,light
what is and examples of internal changes/stimuli
conditions inside the body must remain stable
- blood glucose levels, pH, temp
how does coordination between organs work
- different organs work together to maintain homeostasis
- nervous and hormonal system work together in response to danger
what is a stimulus?
response to a change in the environment
how are stimulus detected?
by receptors
what is an effector?
brings out a response
what are examples of effectors?
muscle/glands
define paracrine signalling
signalling between cells that are close together (adjacent)
define endocrine signalling
signalling between cells that are far apart (distant)
what is negative feedback?
to keep the body conditions at an optimum
explain the negative feedback loop
. A receptor – to detect a stimulus
. A coordination system (nervous system and endocrine system) – to transfer information between different parts of the body
. An effector (muscles and glands) – to carry out a response
why is homeostasis important- 1st reason
- maintains enzyme activity - optimal temp and pH
- regulate blood glucose levels
- balances water potential
- helps organisms survive changing environment
what is positive feedback?
enhance the effect of the original stimulus
give an example for when positive feedback is used
oxytocin increases contractions during childbirth
define thermoregulation
regulation of body temperature at an optimum
why is thermoregulation important
maintain body at optimum temperatures for enzymes to work
describe ectotherms and give examples
unable to maintain internal body conditions so rely on external sources such as sunlight
e.g reptiles and amphibians
describe endotherms and give examples
they’re able to generate their heat metabolically by maintaining a constant internal body temperature.
e.g mammals and birds
what are the advantages of ectothermy?
- less food used in respiration
- need to find less food - can survive long periods without food
what are the disadvantages of ectothermy?
- less active in cooler temperatures
- at risk from predators
- cant take advantage of food availability when cold
physiological responses of endotherms
- Vasodilation/Vasoconstriction – Controls blood flow to the skin.
- Sweating/Panting – Cools the body through evaporation.
- Shivering – Generates heat via muscle contractions.
behavioural responses in endotherms
- Seeking shade or shelter.
- curling up to conserve heat
physiological responses of ectotherms
- change skin colour - absorb more heat
behavioural responses of ectotherms
- Basking in the sun to warm up.
- Hiding in burrows/shade to cool down.
what are peripheral temperature receptors
detect external temperature changes
what type of response do ectoherms and endotherms rely on more
- ectoherms - behavioural responses because cant regulate internal conditions
- endotherms - physiological because vice versa
