A&P Lecture 4

Soma

Cell body

What surrounds the nucleus of a nerve cell

Endoplasmic reticulum, mitochondria, and golgi apparatus

What makes up the cytoskeleton in the neuron

Microtubules and actin/neurofibrils

What causes Alzheimers

Neural tangles

What makes up the plasma membrane of the neuron

Polyunsaturated fatty acids and cholesterol

What changes plasma membrane width in a neuron

FA chain length

What is the separation of charge in a neuron

At resting, negative on the inside of membrane, and positive outside

Dendrite vs axon

Dendrites accept signals, axons send them out

What are the parts of an axon

Terminal arborization (branches), synaptic knob (bulbs)

What is lipofuscin

A pigment on neurons that indicates aging and wear and tear, accumulate in cell lysosomes

What are the universal neuron properties

Excitability/irritability, action potential conduction, neurotransmitter secretion

What are the functional neuron classes

Sensory (afferent), interneurons (association), and motor (efferent)

Afferent

Inform CNS about the world around us, cell bodies outside of spinal cord

Efferent

Allow CNS to act on the world around us, cell bodies in spinal cord

What are somatic neurons

Control more voluntary movements with skeletal muscles

What are the three primary types of neurons

Multipolar, bipolar, and unipolar

What are multipolar neurons

Most common in the body, contain many dendrites

What are bipolar neurons

Associated with smell, one main dendrite and one axon

What are unipolar neurons

Dendrite and axon, soma is off to the side

What are the common characteristics of neurons

Established membrane potential (sodium outside, potassium inside), hyperpolarized (90 mVolts on average), excitability, self-promoting depolarization

Unipolar neuron

Bipolar neuron

Multipolar neuron

Action potential

A change in membrane potential that moves between locations on a plasma membrane to provide information to a cell

What are the four required qualities of action potentials

All-or-none, non-decremental (keeps size), self-propagate, irreversible

What carries action potential toward the cell body

Dendrites

What carries action potential away from the cell body

Axon

What happens if a stimulus occurs artificially in the middle of an axon

The action potential travels both ways

What is the ratio of neuroglial cells to neurons

50:1

What are astrocytes

Glial cells found in the central nervous system

What is the role of astrocytes in the brain tissue

Make up 90% of brain tissue, support and protect neurons, blood brain barrier

What are ependymal cells

Make CSF

What are microglial cells

Macrophages of the CNS

What are oligodendrites

Form myelin sheath around axons in CNS

What are satellite cells

Near soma of neurons of PNS

What are schwann cells

Form myelin sheath around axons in PNS

What makes up the myelin sheath

PUFAs, sensitive to toxic lipids

What are the gaps of exposed axolemma called

Nodes of ranvier

How is the myelin sheath different from the neuron

it does not permit electrical conduction

What does the myelin sheath do

Greatly increases action potential velocity

How does myelin sheath help damaged axons

Creates pathway for them to follow and grow into following an injury