Nerves and Sensitivity Flashcards
What are the two organ systems an animal has?
Nervous system, and the endocrine (hormone) system
What is the name for plants responding to the environment?
Tropism
Define ‘stimulus’
The change in the surroundings
Define ‘receptor’
The organ that detects the change in the environment
Define ‘effector’
The muscles that respond to the change in the environment
What makes the link between the stimulus and the response?
The nervous system
What does the eye receptor change into nerve impulses?
Light
What does the ear receptor change into nerve impulses?
Sound
What does the tongue receptor change into nerve impulses?
Chemical
What does the nose receptor change into nerve impulses?
Chemical
What does the skin (touch receptors) change into nerve impulses?
Pressure
What does the skin (temperature receptors) change into nerve impulses?
Heat
What does the central nervous system consist of, and what does it do?
Brain and the spinal cord
Coordinates nervous responses
What does the peripheral nervous system consist of?
All the nerves that send impulses to the effectors
What are the three types of neurones?
Sensory neurone, relay neurone & motor neurone
Which neurone passes impulses from the receptors to the brain and spinal cord (CNS)?
Sensory neurone
Which neurone receives impulses from the sensory neurones in the CNS?
Relay neurone
Which neurone passes impulses to the effectors from the CNS?
Motor neurone
What type of impulses are carried along the neurones, from receptors, to CNS, to effectors?
Electrical signals/impulses
Define ‘nucleus’
Contains all the genetic information of a cell
Define ‘dendrite’
Tree like projections connecting many different neurones
Define ‘cell body’
The main section of the cell, containing the nucleus
Define ‘axon’
Carries the electrical impulses
Define ‘myelin sheath’
Insulates the axon, and speeds up transmission of impulses
Define ‘reflexes’
Automated actions not involving the brain, but still involving the three neurones - sensory, relay & motor
What is the movement of an impulse between the receptor and the effector?
Reflex arc
Describe the reflex arc with this example: you touch a hot surface
1) Receptor (skin - temperature) detects the stimulus change (hot surface), and sends an electrical impulse along the sensory neurone
2) Sensory neurone passes electrical impulse along the spinal cord to a relay neurone, through a synapse, which then passes the electrical impulse to a motor neurone, through a synapse
3) Motor neurone causes the effector (arm muscles) to contract, moving your arm away from the stimulus (hot surface)
Describe the reflex arc with this example: a ball is thrown at you
1) Receptor (eye) detects the stimulus change (ball approaching), and sends an electrical impulse along the sensory neurone
2) Sensory neurone passes electrical impulse along the spinal cord to a relay neurone, through a synapse, which then passes the electrical impulse to a motor neurone, through a synapse
3) Motor neurone causes the effector (arm muscles) to contract, moving your arm to catch the stimulus (ball)
Define ‘synapse’
The gap between the neurones
Describe the iris reflex for dim light
1) Receptor (eye) detects the stimulus change (light dimming), and sends an electrical impulse along the sensory neurone
2) Sensory neurone passes electrical impulse along the spinal cord to a relay neurone, through a synapse, which then passes the electrical impulse to a motor neurone, through a synapse
3) Motor neurone causes the effectors (radial muscles and circular muscles in the iris) to contract and relax, respectively, shrinking your iris to allow more light into your eye
Describe the iris reflex for bright light
1) Receptor (eye) detects the stimulus change (light brightening), and sends an electrical impulse along the sensory neurone
2) Sensory neurone passes electrical impulse along the spinal cord to a relay neurone, through a synapse, which then passes the electrical impulse to a motor neurone, through a synapse
3) Motor neurone causes the effectors (radial muscles and circular muscles in the iris) to relax and contract, respectively, enlarging your iris to allow less light into your eye
Define ‘cornea’
The curved disk in front of your eye, which does most of the focusing
Define ‘pupil’
A circular opening, whose size is controlled by the iris
Define ‘iris’
A ring of muscles circling the pupil, controlling the amount of light entering the eye
Define ‘lens’
A soft, flexible & transparent layer that fine tunes the focusing of light onto the retina
Define ‘ciliary muscles’
A ring of muscles circling the iris, which control the thickness of the lens - when it contracts, the lens gets fatter, when it relaxes, the lens gets thinner
Define ‘suspensory ligaments’
Strong fibres attaching the lens to the ciliary muscles
Define ‘retina’
Contains light sensitive cells called rods and cones, and is where images are displayed (upside down)
Define ‘optic nerve’
Consists of many neurones, which carry impulses from the retina to the brain
Define ‘fovea’
The region of the retina with the greatest number of cones
Define ‘conjunctive’
A mucous membrane covering the eye, to prevent infection
