The Neuron

Soma meaning

body

Axon

Long projections come off the cell body, have mitochondria, and use ATP

Axon hillock

the triangular structure that comes off the bottom of the cell body, starts an action potential that will go down the axon

Axon terminal

bulbous structures attaching to dendrites of the main neuron create a space called the synaptic cleft between axon terminals and other neurons

cell body (soma)

central portion of neuron, has most of the neuron’s vital organelles, including the nucleus

dendrite

projections coming off the cell body to receive information from other neurons, interact with axon terminals of other neurons

Endoneurium

Connective tissue structure that wraps around the myelin sheath, providing protection to the axon. covers the entire length of the neuron

Myelin Sheath

fatty structure provided by Schwann cells. Naturally white, and provides physical protection and electrical insulation

Node of Ranvier

gaps in between adjacent myelin sheaths, sections that are unmyelinated, allow action potentials to occur at these nodes

Nissl bodies

light blue blobs scattered throughout the cell body and dendrites. They are clumps of rough endoplasmic reticulum and create secreted proteins, including neurotransmitters

Nucleolus

resides inside the nucleus and helps to make ribisomes

nucleus

located in the center of the cell body, stores DNA

Schwann Cell Nucleus

flat appearance, embedded in the myelin sheath, responsible for making the myelin sheath

Neuroglia (glial cell)

support cells to neurons

Nervous system responses

Fast, usually short lived

Endocrine system, response

Slower to respond, longer lasting

What is the CNS

Brain and spinal cord, integrates and processes info

What are the special senses

sight, smell, taste, balance, hearing

Somatic senses

Touch, pain, temp, joint position

Visceral senses

Organ senses

Afferent meaning

Sensory nerves arrive with info to the CNS

What are efferent nerves

Motor nerves that commands in response to stimulus

Somatic control

Skeletal muscle response (reflex or voluntary)

Autonomic control

SNS and PSNS, involuntary control

Sympathetic NS

Fight or flight, respiratory rate and higher senses, shuts down non essential functions and prioritizes being able to get away

Schwann cells

Create myelin sheath

Parasympathetic NS

Rest and digest, opposite effect as the SNS

What are neurons

Nerves cells responsible for the transfer and processing of information in the nervous system

Neuroglia

Supporting cells

Glial cells of the PNS

Schwann cells, Satellite cells

Satellite cells

Orbit around the neuron and regulates exchange of nutrients and waste with environment

Glial cells of the CNS

Oligodendrocytes, Astrocytes, microglia, ependymal cells

Oligodendrocytes

Create myelin sheath on several neurons

Astrocytes

Orbit around the neuron and regulates exchange of nutrients and waste with environment, guide neuron growth and synaptic development

Microglia

Phagocytes of debris and pathogens

Ependymal cells

CSF liners and monitors

What does impulse conduction velocity depend on

Presence of a myelin sheath, diameter of the axon make it faster

Saltatory conduction

Outage gated channels are concentrated at nodes; electrical impulses jump from node to node instead of traveling down the entire axon

multipolar neuron

Motor and Interneurons, multiple dendrites and one axon

Bipolar neuron

Sensory, found in retina, two axons

Unipolar

Most of the Sensory neurons, one connection coming off

Motor (efferent division)

Sends info from the CNS to the periphery, maybe somatic or autonomic nerves

Interneurons

Entirely in the CNS, between motor and sensory neurons, analyzes sensory input and coordinates the motor outputs, may be excitatory or inhibitory

Sensory (afferent nerves)

Almost all are unipolar, sends info from PNS to CNS, may be special, somatic, or visceral sensory

Types of synapses

Neuron-neuron, neuron-muscle, neuron-gland

Vesicular synapse

Involves a neurotransmitter

Non-vesicular synapse

Cells tightly bonded, ions flow right across

CNS Gray matter

Cell bodies in the cerebral cortex, spinal cord, and isolated clusters in the brain

CNS White matter

Bundles of axons running from one part of the brain to another (tracts), bundles of axons running up and down the spinal cord (columns)

PNS gray matter

Cell bodies isolated in clusters within body (ganglia)

PNS White matter

Bundles of axons within the body (nerves)