5.1 Communication and Homeostasis

What is an effector

Cell, tissue or organ that brings about a response

Homeostasis

Maintaining a constant internal environment

Negative feedback

Mechanism that reverses a change, bringing a system back to optimum

Positive feedback

Mechanism that increases a change, taking system further away from optimum

Sensory receptors

Nerve endings that respond to a stimulus in the internal and external environment

what does the body maintain with homeostasis

temperature, pH, aqueous environment, toxins, inhibitors

what types of responses can occur due to changing environments

behavioural, physiological

what effect can a build up of toxins have on the internal environment

reduces activity of cells so less waste is produced

which systems can cell signalling work through

neuronal, hormonal

how do messages travel between neurones

a neurotransmitter will diffuse across a synapse

where are hormones released from

glands

how do hormones travel in the body

in the blood

what is the benefit of using hormones

longer-term responses

where are sensory receptors located

surface of the body

how does negative feedback work

receptors detect a stimulus and send an input to the coordination centre where an output is sent to effectors

why can positive feedback be dangerous

destabilises the system

what is an example of positive feedback

dilation of a cervix when giving birth

what chemical is involved in uterine contractions

Oxytocin

ectotherm

organism that relies on external sources of heat to maintain body temperature

endotherm

organism that uses heat from metabolic reactions to maintain body temperature

Hypothalamus

area of brain that conducts homeostatic responses

why do chemical reactions speed up in warmer temperatures

molecules have more kinetic energy

what happens when an enzyme denatures

tertiary structure changes shape and molecule is no longer able to function

what might ectotherms do to warm up (2 answers)

move to a sunny area, lie on a warm surface

what might ectotherms do to cool down (2 answers)

move into shade, move underground

what is an advantage of being an ectotherm

survive long amounts of time without food

what is a disadvantage of being an ectotherm

less active when cold, so at risk

what does exergonic mean

releasing energy as heat

what do endotherms do

control their own body temperature

what will endotherms use to warm up (6 answers)

trap air, vasoconstriction, shivering, lie in sun , remain dry, move around

what will endotherms do to cool down (6 answers)

sweat, hair lies flat, vasodilation, fewer muscle contractions, hide from sun, wet skin

what are two advantages of being endotherms

maintain constant body temperature, inhabit colder areas

what are three disadvantages of being an ectotherm

lots of energy required, need more food, overheat in hot weather

what does the hypothalamus monitor to check core body temperature

blood temperature

where are peripheral temperature receptors

skin

what is an advantage of peripheral temperature receptors

can give early warning that body temperature may change