Nervous System Flashcards
coordinated response requires ……………..
a stimulus, a receptor and an effector
central nervous system consists of …………..
brain and spinal cord
central nervous system is linked to sense organs by ……….
nerves
Peripheral nervous system is composed of:………..
peripheral nerves
Peripheral nervous system contains:
sensory neurons
motor neurons
Function of PNS
sends information to CNS from receptors
carries instructions from CNS to effectors
Function of CNS
receives information from PNS, processes this and sends instructions to PNS
cells specialised for transmitting impulses
neurons
motor neuron
cell body in spinal cord (CNS)
transmits impulses from relay or sensory neurons to effectors
sensory neuron
cell body just outside spinal cord (CNS)
transmits impulses from receptors to relay or motor neurons
relay neuron
found in CNS
relays impulses from sensory to motor neurons
a synapse between a motor neuron and muscle
neuromuscular junction
State two features that distinguish motor neuron
from other types of nerve cell
cell body in spinal cord (CNS)
transmits impulses from relay or sensory neurons to effectors
…………is a change in an animal’s surrounding, ……….. is the reaction to that change
Stimulus, response
A tiny electrical signal that passes down a nerve cell caused by movements of ions in and out of the axon
nerve impulse
The biological name of a nerve cell…………
neurone
Synapse of a nerve cell on a muscle
neuromuscular junction
covering made of a lipid material that surrounds an axon .
myelin sheath
What is myelin sheath and what is its function?
covering made of a lipid material that surrounds an axon . Nerve cells that have myelin sheath are described as myelinated.
its function is to insulate the axon preventing short circuits with other axons
Extension of the cytoplasm of a neurone that carries impulses towards the cell body
dendron
Fine extensions of the dendron of the neurone
dendrites
junction between two neurones
synapse
long extension of a neurone that carries nerve impulses in a direction away from the cell body.
axon
a middle layer of the skin containing many sensory receptors
dermis
The diagram shows a horizontal section through the human eye. Which is the retina?
A,B,C or D ?
C
White tough outer coat of the eye
Sclera
colour-sensitive receptors are concentrated here
fovea
Controls how much light enters the eye by changing size of pupil
iris
contains light receptors, some sesitive to light of different colours
retina
a trasparent layer that refracts light
cornea
hole that allows light into the eye
pupil
carries nerve impulses to the brain
optic nerve
refracts light to focus it onto retina
lens
What are the two types of receptor cells in the retina ?
Rods which are sensitive to dim light
Cones which distinguish between different colours in bright light
The role of the iris is to control the amount of light entering the eye. Explain how.
The iris contains two types of muscles. circular muscles form a ring shape in the iris and radial muscles lie like the spokes at a wheel. In bright light the pupil is constricted(made smaller) . This happens because the circular muscles contract and the radial muscles relax. in dim light the opposite happens.