Ch 12: Anatomy of the Nervous System - The Brain and Spinal Cord

Biol 2301 - Margartia Bracamonte - HCCS

What are the organs of the nervous system?

BrainSpinal cordSpecial senses: eyes, ears, etc.

What are the two groups that the nervous system is divided into?

Central nervous systemPeripheral nervous system

What are the oragans of the central nervous system?

BrainSpinal cord

What is the function of the central nervous system?

What are the organs of the peripheral nervous system?

Nervous tissue outside of CNSNervesGangliaSense organs

What are the functions of the peripheral nervous system?

SensoryIntegrativeMotor

What is the peripheral nervous system’s sensory function like?

Detects internal and external stimuli – pain, raindrops, etc.

What is the peripheral nervous system’s integrative function like?

Sensory information processed and decisions for appropriate responses are made.

What is the peripheral nervous system’s motor function like?

Activation of effectors like muscles or glands through cranial or spinal nerves.

What is the tissue that makes up most of the nervous system?

Nervous tissue.

What are the subtypes of nervous tissue?

None.

What are the two types of cells in nervous tissue?

NeuronsNeuroglial

What do neurons look like?

Spiders.

What do glial cells look like?

Dots all over the tissue.

What is the main cell of nervous tissue?

Neurons.

What is the function of neurons?

To send nerve pulses (action potentials) to effectors like muscles, glands, or other neurons.

Are all neurons the same?

No, they vary in shape and size.

What are the three main parts of neurons?

BodyAxonDentrites

What is another name for the body of a neuron?

The soma.

What is the cell body of a neuron?

The main and biggest physical part of the cell where all its branches meet and the nucleus lives.

What does the neuron body contain?

The nucleus, perikaryon, and the Nissl bodies.

What is the perikaryon?

The cytoplasm of the neurons.

What are the Nissl bodies?

The dense area of the rough endoplasmic reticulum and ribosomes that make neural tissue appear grey.

What are the two colors of the brain?

WhiteGrey

Where in the colored sections of the brain can neurons be found?

In the grey matter.

What color are the Nissl bodies in the neurons colored on diagrams?

Green.

What is the broad section of the body of a neuron connecting it to an axon?

The axon hillock.

What occurs at the axon hillock?

Nerve impulses are created and get sent into the axon.

What do the dendrites look like?

Small little branching fingers off of axons.

What is the function of dendrites?

Sensory part of neuron sends stimuli and transmits information to the cell body.

How many dentires are there per cell body?

A lot lol.

What do axons look like?

Longer and thicker branches that come out of cell bodies.

What is an axon?

Long processes that extend from

How many axons per neuron?

One.

Why does it appear that a neuron has more than one axon?

Since they connect cells to each other, it branches out continually in order to increase surface area.

What is the function of an axon?

What do axons connecting together create?

Nerves.

What is a common name for axons?

Nerves.

What direction are nerve impulses transmitted in? Away from the cell body.

What connects the axon to the cell body?

The axon hillock.

What is the part of the axon closest to the axon hillock called?

The initial section.

What is the name of the branches of the axons called?

The collaterals.

What is the name of the branches that come out of the collateral?

The telodendria.

Why does an axon have so many branches?

To maximize attachment to other cells and increase surface area.

What are the ends of the telodendria called?

The axon terminals.

What occurs at the axon terminals?

Store neurotransmitters that appropriate stimuli responses come out of.

What is another name for axon terminals?

Synaptic terminals/knobs.

What is the main trunk of the axon? The part before between the initial segment and the collateral of the axon.

What is contained in the axon starting from the initial segment to the axon terminals?

Many voltage-gated sodium channels.

What two types of axons are there?

MyelinatedNon-myelinated

What are myelinated axons?

Axons wrapped with a sheet of myelin many times, look like insulation layered tubes on axon branches.

What is myelin made out of?

Cell membrane material – phospholipids.

Is myelin permeable?

No, sodium cannot pass through it.

In the peripheral nervous system, what glial cell’s membrane forms the myelin sheet?

The Schwann cell.

What appearance do myelinated axons give the brain?

The white matter.

What is the Node of Ranvier in an axon?

The small gap between the myelin sheets.

In the central nervous system, what glial cell’s membrane forms the myelin sheet?

The oligodendrocyte cell.

What is the main difference between the physical appearance of the Schwann cell and the oligodendrocyte?

The oligodendrocyte can extend from myelin sheets to myelin sheets rather than needing a ‘naked’ section.

What is the function of the myelin in axons?

Increases the speed of an action potentialServes as electrical insualtionMakes axons appear white

What are the two things neurons can be classified by?

How are neuron structural classifications determined?

By the amount of processes on the cell.

What are the four main types of neuron structural classifications?

AnaxonicBipolarUnipolarMultipolar

How many axon processes does an anaxonic neuron have?

No axon processes.

How many dendrite processes does an anaxonic neuron have?

Many dendrite processes.

Where are anaxonic neurons found?

They are rare in the brain and sense organs.

What kind of neuron is this (structural classification)?

An anaxonic neuron.

How many axon processes does a bipolar neuron have?

One axon processes.

How many dendrite processes does a bipolar neuron have?

One dendrite processes.

Where are bipolar neurons found?

In the peripheral nervous system.

What kind of neuron is this (structural classification)?

A bipolar neuron.

How many axon processes does a unipolar neuron have?

One elongated axon processes.

How many dendrite processes does an anaxonic neuron have?

No dendrite processes.

Where are dendrite processes found in unipolar neurons?

At one of the ends of its elongated axon.

Where are unipolar neurons found?

In the peripheral nervous system.

What kind of neuron is this (structural classification)?

A unipolar neuron.

How many axon processes does a multipolar neuron have?

One axon processes.

How many dendrite processes does a multipolar neuron have?

Several dendrite processes.

Where are multipolar neurons found?

Mainly in the central nervous system, but some in the peripheral nervous system.

What kind of neuron is this (structural classification)?

A multipolar neuron.

How many axon processes do most (excluding only one structural classification) have?

One axon process.

What are the three kinds of neurons based on function?

Sensory/AfferentInterneruronsMotorEfferent

What is the function of afferent neurons?

To collect information outside the brain and spinal cord and relay it to the central nervous system.

Where are afferent neurons found?

In the peripheral nervous system, inside the eyes, ears, skin, etc.

What is the shape of afferent neurons?

Unipolar.

What is the function of interneurons?

To transmit information from the sensory to the motor neurons.

Where are interneurons found?

Most are in the central nervous system but a few in the peripheral nervous system.

What is the shape of interneurons?

Multipolar.

What is the function of efferent neurons?

To relay information from the brain to the spinal cord.

Where are efferent neurons found?

In the central nervous system.

What is the shape of efferent neurons?

Multipolar.

What is the function of glial cells?

To protect and support neurons.

What are the 6 different kinds of glial cells?

EpendymalAstrocytesOligocytesMicrogliaSatelite cellsSchwann cells

What are the glial cells found in the central nervous system?

EpendymalAstrocytesOligocytesMicroglia

What are the glial cells found in the peripheral nervous system?

Satelite cellsSchwann cells

What are the types of neuroglial cells in neurons?

EpendymalAstrocytesOligodendrocytesMicrogliaSatellite cellsSchwann cells

Which are the glial cells in the central nervous system?

EpendymalAstocytesOligodedrocytesMicroglia

Where can you find ependymal cells?

They line the ventricles in the brain and the central canal of the spinal cord.

What is the function of ependymal glial cells?

Assist in production, circulation, and monitoring of cerebrospinal fluid.

What are functions of astrocytes?

Maintain blood-brain barrierProvide structural supportRegulate ion, nutriernt, and dissolved gas concentrationsAbsorb and recycle neurotransmittersForm scar tissues after injury

What are the functions of oligodendrocytes?

Myelinate CNS axonsProvide structural framework