Neurons Term 2 Flashcards
Describe the structure and function of neurons/nerve cells
Highly specialised NS cells designed to
-rapidly generate electrochemical nerve impulses
-carry info from one part of body to other
Define glial cells/tissue
Support, protect and provide nutrition’s to neurons and insulate them from each other
Define cell body structure and function
part of neuron containing nucleus
-granular cytoplasm (ribosome clusters)
-abundant organelles
-responsible for controlling the functioning of the cell
Define dendrites structure and function
short extensions of the cytoplasm of the cell body
-highly branched
-carry messages/nerve impulses into cell body
-synapse/joins with other neurons or receptors
Define axon structure and function
Single, long nerve fibres/extension of the cytoplasm
-connect with muscles (neuromuscular junction), glands (neuroglandular), and other neurons (complex neurons
-carry nerve impulses away from cell body
-axon divides into many small branches that terminate at axon terminals
Recall that a nerve consists/Define what a nerve is
bundle of nerve fibres held by connective tissue outside brain and spinal cord
Define nerve fibre
long projection/extension of cytoplasm of a nerve cell body (also known as axon)
Define neurilemma
sheath surrounding nerve fibre
-protective function for peripheral nerve fibers
Describe and give the function of the myelin sheath
fatty sheath made by Schwann cells that wrap around the axon of most neurons
-speeds up nerve transmission along axon
-acts as insulator
-protects nerve fibres/axon from damage
Define node of Ranvier and function
microscopic gaps found in myelin sheath-speed up nerve impulses
Define synapses structure and function
junction between axon terminal of one neuron with dendrite of another neurons cell body
-neurons do not physically touch at synapse=small gap
How are messages carried across synapse gap?
Messages are carried across gap by the movement of chemicals called neurotransmitters
Define neurotransmitter
molecule that carries a nerve impulse across the small gap between branches of adjacent nerve cells/neurons
Define neuromuscular junction
Synapse where an axon meets a skeletal muscle cell
-jucntion between branches of a motor nerve cell and the muscle fibre=motor end plate
Name the three functional types of neurons
Sensory/afferent, Motor/efferent, Interneuron
identify and give the function of the sensory neurons
afferent, carry messages form receptors in the sense organs, or skin, to the CNS (brain and spinal cord)
identify and give the function of the motor neuron
efferent, carry messages form CNS to the effectors, muscles and glands
identify and give the function of interneurons
association neurons, located in CNS and are the link between sensory and motor neurons
Name the four structural types of neurons
multipolar, bipolar, unipolar, pseudounipolar
Define multipolar neurons and examples
one axon and several dendrites extending from cell body
includes: most of the interneurons in brain/spinal cord, and the somatic motor neurons
Define bipolar neurons and examples
one axon and one dendrite extending from cell body
-occur in the eye, ear and nose where they take impulses from the receptor cells to other neurons
Define unipolar neurons and examples
one axon extending from cell body
-not found in humans but insects
Define pseudounipolar neurons and examples
properties of uni/bipolar
-one axon separating into two extensions
-one connects to dendrites other to axon terminals
-includes most sensory neurons carrying messages to spinal cord
Distinguish between a neuron, a nerve, and a nerve fibre
neuron=nerve cell
nerve=bundle of nerve fibres held together by connective tissue
nerve fibre=projection from a nerve cell body (usually axon)
