Chapter 5: Reflexes and Reaction Times

cell body/soma

large part of the neuron containing the nucleus and organelles

dendrites

short projections continuous with the soma and function to receive information

axon

single long projection responsible for transmitting information fro the cell body to the next cell

axon hillock

portion of the axon connecting the cell body

axon hillock

site of action potential generation

axon terminal

the end of an axon that branches slightly

axon terminal

responsible for converting the electrical impulse to a chemical signal and passing information to the next cell in line

synapse

a junction between two nerve cells

pre-synaptic neuron

the neuron sending the signal though its axon terminals

post-synaptic neuron

the neuron receiving the signal through its dendrites or cell body

action potential

an electrical impulse that travels down the axon of a neuron

neurotransmitter

a chemical that is used to communicate between neurons released when action potential reaches the axon terminal and triggers a release

local potential

triggered when neurotransmitter binds to proteins in the post-synaptic cell membrane

local potential

a small electrical impulse that fades over distance

excitatory

type of local potential in dendrites and cell body of post-synaptic neuron that causes a neuron to initiate an action potential in its axon

inhibitory

type of local potential in dendrites and cell body of post-synaptic neuron that causes a neuron to be less likely to initiate an action potential

afferent (sensory) neuron

convey impulses toward CNS from sensory receptors found throughout the body

efferent (motor) neuron

convey impulses away from CNS to a target which can be a muscle or a gland

interneuron

found within the CNS, connect afferent and efferent neurons and integrate sensory input and motor output

relfex

very fast, involuntary response to a stimulus

components of a reflex arc

receptor detects change in internal or external environment, sensory neurons transmit signal toward CNS, within CNS interneurons integrate sensory information and communicate with motor neurons, motor neurons transmit a signal to a target/effector, effector is a muscle or gland that responds to the stimulus

muscle stretch reflex

follows the five steps of a typical reflex arc and is triggered when a muscle is rapidly stretched

latency

the amount of time that passes between the initial stimulus and the response

muscle spindles

muscle fibers with sensory neuron axon terminals wrapped around them

patellar reflex

other name for a knee-jerk response like a doctor does to strike below the knee at the patellar tendon

dorsal root ganglion

where is the cell body of the afferent neuron located

ventral horn

where is the cell body of the efferent neuron located

dorsal root

where is the axon of the afferent neuron located

ventral root

where is the axon of the efferent neuron located

dorsal root ganglion

where is the synapse between the sensory and motor neurons located

white matter

contains axons of neurons that are wrapped in an insulated sheath known as myelin. myelin consists of proteins and fats and therefor appears white

grey matter

contains primarily cell bodies of the neurons of the spinal cord, they are not covered in myelin and appear darker

lateral horn

location of cell bodies of neurons in the autonomic nervous system

spinal nerve

dorsal root and ventral root off spinal cord combine to form the _______

same

was the time difference between the normal latency and jendrassik latency the: same, shorter, or longer