4.5.2 the human nervous system Flashcards
What is the human nervous system
- made up of the brain + spinal cord
- enables bodily reactions when surroundings alter
-stimuli picked up by sense organs.
Name the 4 sense organs + their features
Eyes — sensitive to light and movement
Ears — sensitive to sound / balance
Nose / tongue — sensitive to chemicals for taste + smell
Skin — sensitive to touch, pressure, temperature and pain.
What is an effector
An organ that does something in response to a stimulus.
Name the two effectors and their features/ purposes
Muscles — these contract or get shorter, for example muscles in an arm contract and pull away from a hot radiator
Glands — produce / release hormones into the blood stream, for example, salivary glands respond to stimulus by secreting saliva.
What do both neurones and animals share in common?
Cell membranes, cytoplasm, nuclei.
What are myelin sheaths?
They surround the main body of the neuronal cells (in neurones) which are a fatty layer acting as an insulator.
What is the order of events within the human nervous system?
Stimulus
Receptor
Sensory neurone
Central nervous system (brain / spinal cord)
Motor neurone
Effector
What is the stimulus
Changes in environment
What is a receptor
Cells in sense organ
What is the sensory neurone
Carries impulses from receptors to CNS
What is the central nervous system
It’s the brain / spinal cord
What is the motor neurone
Carries impulses from CNS to effector
What is an effector
Muscle / gland carrying out the change
Which are quicker, reflex actions or actions in the central nervous system? And why?
Reflex actions are faster as they enable our bodies to respond to a change in stimuli without much thought / hesitation — avoids danger and prioritises safety.
What is the order of events in reflex actions?
Stimulus — Receptor — Sensory Neurone — Relay neurone — motor neurone — efftecorn
