NEURON STRUCTURE AND TYPES

FAIZAN, OMER, ABDULLAH

NEURONS

BASIC UNITS OF THE NERVOUS SYSTEM RECEIVE, INTEGRATE, AND TRANSMIT

INFORMATION OPERATE THROUGH ELECTRICAL IMPULSES COMMUNICATE WITH OTHER NEURONS THROUGH CHEMICAL SIGNALS MORE ABOUT NEURONS AND NEURONAL ANATOMY LATER

BASIC STRUCTURE

Central Nervous System (CNS)Central Nervous System (CNS)

BrainBrain Spinal CordSpinal Cord

Peripheral Nervous System (PNS)Peripheral Nervous System (PNS)

Sensory NeuronsSensory NeuronsMotor NeuronsMotor Neurons

Somatic Nervous System• voluntary movements via

skeletal muscles

Somatic Nervous System• voluntary movements via

skeletal muscles

Autonomic Nervous System• organs, smooth muscles

Autonomic Nervous System• organs, smooth muscles

Sympathetic- “Fight-or-Flight” responses

Sympathetic- “Fight-or-Flight” responses

Parasympathetic - maintenance

Parasympathetic - maintenance

THE NERVOUS SYSTEMThe Nervous SystemThe Nervous System

TYPES

SENSORY NEURONSENSORY NEURONS ARE TYPICALLY CLASSIFIED AS THE NEURONS RESPONSIBLE FOR CONVERTING VARIOUS EXTERNAL STIMULI THAT COMES FROM THE ENVIRONMENT INTO CORRESPONDING INTERNAL STIMULI. THEY ARE ACTIVATED BY SENSORY INPUT (VISION, TOUCH, HEARING, ETC.), AND SEND PROJECTIONS INTO THE CENTRAL NERVOUS SYSTEM THAT CONVEY SENSORY INFORMATION TO THE BRAIN OR SPINAL CORD. UNLIKE NEURONS OF THE CENTRAL NERVOUS SYSTEM, WHOSE INPUTS COME FROM OTHER NEURONS, SENSORY NEURONS ARE ACTIVATED BY PHYSICAL MODALITIES SUCH AS LIGHT, SOUND, AND TEMPERATURE.

RELAY NEURON

AN RELAY NEURON IS A NEURON THAT FORMS A CONNECTION BETWEEN SENSORY NEURON AND MOTOR NEURON IN THE CENTRAL NERVOUS SYSTEM.

MOTOR NEURON

IN NEUROLOGY, THE TERM MOTOR NEURON APPLIES TO NEURONS LOCATED IN THE CENTRAL NERVOUS SYSTEM THAT PROJECT THEIR AXONS OUTSIDE THE CNS AND DIRECTLY OR INDIRECTLY CONTROL MUSCLES. MOTOR NEURONES ARE NEURONES THAT CARRY SIGNALS FROM THE SPINAL CORD TO THE MUSCLES TO PRODUCE MOVEMENT.

STRUCTURE

CELL BODY

THE PART OF A NEURON CONTAINING THE NUCLEUS BUT NOT INCORPORATING THE AXON AND DENDRITES.

AXON

AN AXON ALSO KNOWN AS A NERVE FIBER; IS A LONG, SLENDER PROJECTION OF A NERVE CELL, OR NEURON, THAT TYPICALLY CONDUCTS ELECTRICAL IMPULSES AWAY FROM THE NEURON'S CELL BODY. THE FUNCTION OF THE AXON IS TO TRANSMIT INFORMATION TO DIFFERENT NEURONS, MUSCLES AND GLANDS.

DENDRITE

DENDRITES ARE THE BRANCHED PROJECTIONS OF A NEURON THAT ACT TO CONDUCT THE ELECTROCHEMICAL STIMULATION RECEIVED FROM OTHER NEURAL CELLS TO THE CELL BODY OF THE NEURON FROM WHICH THE DENDRITES PROJECT.

NEURILEMMA

NEURILEMMA IS THE OUTERMOST NUCLEATED CYTOPLASMIC LAYER THAT SURROUNDS THE AXON OF THE NEURON. IT FORMS THE OUTERMOST LAYER OF THE NERVE FIBER IN THE PERIPHERAL NERVOUS SYSTEM.

MYELIN SHEATH

• FATTY MATERIAL MADE BY GLIAL CELLS• INSULATES THE AXON• ALLOWS FOR RAPID MOVEMENT OF

ELECTRICAL IMPULSES ALONG AXON• NODES OF RANVIER: GAPS IN MYELIN

SHEATH WHERE ACTION POTENTIALS ARE TRANSMITTED• MULTIPLE SCLEROSIS IS A BREAKDOWN OF

MYELIN SHEATH• SPEED OF NEURAL IMPULSE RANGES FROM

2 – 200+ MPH

SYNAPSE

A junction where the axon or some other portion of one cell (= presynaptic cell) terminates on the dendrites, soma, or axon of another neuron (post synaptic cell). The term was introduced in nineteenth century by the British neurophysiologist Charles Sherrington

THE WITHDRAWAL REFLEX

THE END