B6.1 Flashcards
living organisms can detect and respond to what?
a stimulus
what is a stimulus?
a change in the environment of an organism such as light, temperature etc
what are receptors stimulated by?
the stimulus
what is a simple reflex
a rapid automatic response
what do the simplest animals rely on for the majority of their behaviour?
reflex actions
what do the reflex actions ensure for the animals?
that the animal will respond in a way that is most likely to result in its survive (finding food, sheltering from predators)
newborn babies:
stepping reflex-
when held under its arms in an upright position with its feet on a firm surface, a baby makes walking movements with its legs
newborn babies:
grasping reflex
a baby tightly grasps a finger that is out in its hand
newborn babies:
startle reflex
a baby shorts out its arms and legs when startled (sudden loud noise)
adult:
pupil reflex
bright light causes muscles in the eye to contract so that the retina is not damaged
adult:
knee-jerk reflex
when the knee is strict just below the knee cap, the leg will kick out
adult:
dropping hot object reflex
when picking up a very hot object, the response is to throw it away to prevent damage to the hand
what does nervous co-ordination in an animal require?
step 1 of 3
the presence of one or more different receptors to detect stimuli (e.g light detected by eyes)
nervous co ordination in an animal
2
processing centres to receive information and co ordinate responses
nervous coordination in an animal
3
effectors to produce the response
what are the two ways of sending signals in the body?
- via electrical impulses through long, wire-like cells called neurons (nerve cells)
- via chemicals called hormones that are produced in the glands and travel in the blood
way of sending signals in the body:
electrical impulses
- sensory= receptors–> CNS
* Motor=CNS–> effectors
what do electrical impulses target?
effectors
chemical signals are ______ than electrical impulses
slower
where do chemical signals move to?
how long do their effects last?
target organs
a long time
example of chemical signal
insulin which controls blood sugar levels
what did the development of nervous and hormonal communication systems depended on?
the evolution of multicellular organisms
what do receptors produce?
a rapid, involuntary response called a simple reflex
