b10 - human nervous system Flashcards
define homeostasis
maintaning optimum body conditions by regulating internal changes in response to external/internal changes
define endocrine system
the network of hormone-producing glands in the body
define hormones
hormones are chemical messengers that travel in the
bloodstream to their target tissues.
define blood glucose
glucose is transported into blood because cells need it for respiration. the concentration of blood glucose needs to be controlled.
define stimulus
change in environment which is detected by receptor cells e.g: light, sound, chemicals
define a nerve
a collection on neurons (nerve cells). these transmit information as electrical impulses.
name four factors that need to be controlled by homeostasis
1) blood glucose concentration
2) blood temperature
3) water levels
4) nitrogen levels
define the role of receptors
the receptor detects the stimulus and passes electrical impulses along the sensory
neurone to the CNS.
define the role of coordination centres
- recieve information from receptor cells and process it. e.g: brain, spinal cord, panreas
define the role of effectors
- muscle or glands
- these carry out respones directed by the coordination centre
- muscles: contract
- glands release chemicals e.g hormones
define the human nervous system
- network of neurones bundled into nerves
- includes central nervous system (brain, spinal cord)
- allow us to react to surroundings and control behavious
- can act involuntary or voluntary
what happens when receptors detect a stimuli
1) stimulus deteced by receptor and electrical impulses are passed via the sensory neurone to the CNS
2) the gap between the sensory and relay neurones is a synapse. a chemical is released here and diffuses across the gap to cause an electrical impulse to pass along relay neurone.
3) there is another synapse between the relay neurone and the motor neurone so this repeats
4) the impulse arrives at the effector
