**L2 - Neurons Flashcards
what is a NEURON?
NEURONS are SPECIALISED NERVE CELLS that MOVE ELECTRICAL IMPULSES to and from the CENTRAL NERVOUS SYSTEM (CNS)
What parts are there to a NEURON? (NMC SAND)
1) (N) Nucleus
2) (M) Myelin Sheath
3) (C) Cell Body
4) (S) Schwann Cells
5) (A) Axon
6) (N) Nodes of Ranvier
7) (D) Dendrites
what is the ‘N’ in NMC SAND?
NUCLEUS - contains GENETIC MATERIAL
what is the ‘M’ in NMC SAND?
MYELIN SHEATH - INSULATING LAYER that PROTECTS the AXON and SPEEDS UP the TRANSMISSION of the ELECTRICAL IMPULSE
what is the ‘C’ in NMC SAND?
CELL BODY - CONTROL CENTRE of the NEURON
what is the ‘S’ in NMC SAND?
SCHWANN CELLS - make up the MYELIN SHEATH
what is the ‘A’ in NMC SAND?
A LONG FIBRE that carries the ELECTRICAL IMPULSE from the CELL BODY to the AXON TERMINAL
what is the second ‘N’ in NMC SAND?
NODES OF RANVIER - GAPS IN THE MYELIN SHEATH.
THEY SPEED UP THE ELECTRICAL IMPULSES ALONG THE AXON
what is the ‘D’ in NMC SAND?
DENDRITES - RECEIVE an ELECTRICAL IMPULSE (ACTION POTENTIAL) from OTHER NEURONS or SENSORY RECEPTORS (e.g eyes, ears, tongue and skin)
what are the THREE TYPES of NEURON and how do they DIFFER?
SENSORY, MOTOR and RELAY NEURONS.
All three types of neuron consist of SIMILAR PARTS, however, their STRUCTURE, LOCATION and FUNCTION are DIFFERENT.
draw SENSORY NEURON
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what are SENSORY NEURONS?
SENSORY NEURONS are found in SENSORY RECEPTORS. They carry ELECTRICAL IMPULSES from the SENSORY RECEPTORS to the CNS (spinal cord and brain) via the PERIPHERAL NERVOUS SYSTEM
SENSORY NEURONS CONVERT INFORMATION from SENSORY RECEPTORS into ELECTRICAL IMPULSES, when these impulses reach the BRAIN they are CONVERTED INTO SENSATIONS, such as HEAT, PAIN ETC so that the BODY CAN REACT APPROPRIATELY
Some sensory impulses TERMINATE at the SPINAL CORD, this allows REFLEXES TO OCCUR QUICKLY without the DELAY OF WAITING for the BRAIN TO RESPOND
what are MOTOR NEURONS?
MOTOR NEURONS are LOCATED in the CNS but project their axons OUTSIDE OF THE CNS.
They send electrical impulses via LONG AXONS to the GLANDS and MUSCLES so they can AFFECT FUNCTIONS
GLANDS and MUSCLES are called EFFECTORS. When motor neurons are STIMULATED they RELEASE NEUROTRANSMITTERS that BIND TO THE RECEPTORS on MUSCLES TO TRIGGER A RESPONSE, which LEADS TO MOVEMENT
what are RELAY NEURONS?
RELAY NEURONS are found in the CNS. They CONNECT SENSORY NEURONS to MOTOR NEURONS so that they can COMMUNICATE with one another.
During a REFLEX ARC (e.g you put your hand on a hot kettle) the RELAY NEURONS in the SPINAL CORD are involved in an ANALYSIS OF THE SENSATION and DECIDE HOW TO RESPOND (e.g to lift your hand) WITHOUT WAITING FOR THE BRAIN TO PROCESS THE PAIN.
draw MOTOR NEURON
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