communication and homeostasis and hormonal com. Flashcards
what is the need for communication systems in multicelluar organisms
animals and plants must respond to changes in their environment both internal and external as enzyme controlled reactions can only take place if conditions are right eg) pH, ion conc, temp, water balance
> Organisms use chemical and electrical systems to monitor and respond to any changes and maintain DYNAMIC EQUILLIBRIUM
describe how communication between cells by cell signalling occurs
using receptors and effectors
>sensory receptors detect changes in the internal and external environments of an organism
>information from these sensory receptors is transmitted back to the brain and impulses sent along motor neurones to the effectors to restore equiliibrium
effectors can be muscles or glands that react to motor stimulus
what is the difference between receptors and effectors
A receptor detects the stimuli and converts it into an impulse and an effector converts the impulse into an action. An example of a receptor is a light receptor in the eye which detects changes in light in the environment. An example of an effector is a muscle.
what is a positive feedback
fewer positive feedback systems in body
examples like contractions during childbirth or the blood clotting cascade
receptor detects and effectors are stimulated to reinforce that change and increase the response
what is a negative feedback
majority of feedback in body is negative feedback
> small change detected by SENSORY receptors and effectors work to change and restore conditions
involved in temperature control and water balance
eg) increase detected»> responds lower levels»_space;>ideal conditions
ectotherms
what is their core body temp dependent on
their surroundings
fish, invertebrates, amphibians and reptiles (most animals)
why do ectotherms that live in water not need to regulate body temp?
-Due to higher heat capacity of water, the temperature of the environment doesn’t change much
why is it important ectotherms on land regulate temp?
- drastic seasonal and daily changes in temp (these can increase or reduce radiation they absorb from sun)
- need to warm up to carry out metabolic reactions that happen fast enough to be active.
eg) lizard in sun warm up to catch prey fast
How do ectotherms increase body temp by conduction
press body against warm ground
give an example of how ectotherms use exothermic metabolic reactions to warm up
Galapagos lizards contract muscles and vibrate which increases cell metabolism to raise body temps
-butterflies and moths also do this
how do ectotherms cool down and why
opposite to warming up processes
- must cool down to prevent core body temp being too high resulting in denaturation of enzymes
- shelter from sun in cracks in rocks, digging
- press body against cool earth, stones or nearby water and mud
- orientate to minimise surface area in sun
What physiological adaptations do ectotherms have
- dark colours absorb more radiation (lizards in cold are darker vice versa)
- alter heart rate to increase/decrease metabolism and effect of warming and cooling on their surface
are ectotherms or endotherms more vulnerable to changes in environment
ectotherms- adapted for conditions
why do ectotherms need less food
they use less energy regulating body temps, therefore can survive in places food is in short supply eg deserts
What factors are effecting the external environment of an organism
temperature, pH, light intensity
water availability, oxygen availability
threats, sounds, pain
What factors are effecting the internal environment of an organism
blood glucose, internal temp, waste products like urea, hormone levels, osmoregulation, pH
what are the two communication systems in the body
nervous system- cells and neurones
endocrine system- hormones
