Basics of the Neuron/glia Overview of the NS

Outline

1. neurons – 10 to 100 billion neurons◦ Role:

- can vary tremendously in size and shape but all have 3 components

cell body or soma contains genetic material, provides

nutrients,

2 primary cell types in nervous system

1. neurons – 10 to 100 billion neuronscan vary tremendously in size and shape but all have 3 components

cell body or soma contains genetic material, provides nutrients,

Dendrites Primarily responsible for receiving info from adjacent

neurons

2 primary cell types in nervous system

neurons – 10 to 100 billion neurons◦ cell body or soma

dendrites axons –

Primarily important for conveying info from one neuron to the next

2 primary cell types in nervous system

Info

rmati

on

flow

motor neurons◦ efferent – carry info from CNS

sensory neurons◦ afferent – carry info toward CNS

interneurons◦ carry info within regions

3 primary types of neurons

Glial cells provide imp supportive role: ◦ providing nutrients to neurons

neurotrophic factors

◦ provide support for neurons myelin sheaths

◦ play a role in response to neuronal injury astrocytes

◦ play a role in brain development radial glia

Glial cells – 10 to 100X the number of neurons

So where do we find these neurons and glia ?

CNS – Central Nervous System◦ brain, spinal cord

PNS – Peripheral Nervous System

2 divisions of the nervous system

PNS - peripheral nervous system2 components

1. autonomic nervous system - “involuntary”- role in emotion and stress

controls smooth muscles, cardiac muscles and glands

two anatomically separate components

“fight or flight”

◦ activated during emergencies, stress and/or arousal

ex.

Sympathetic Nervous System(part of autonomic NS)

Maintain homeostasis, energy restoration◦ physiological changes:

Parasympathetic nervous system

Somatic nervous system

◦ conveys sensory info to the CNS and motor commands from the CNS to the muscles

31 pairs of spinal nerves ◦ ** NERVE – BUNDLE OF AXONS OUTSIDE THE

CNS

2nd part of the peripheral nervous system

Copyright © 2006 by Allyn and Bacon

Terminology NoteCNS PNS

Clusters of cell bodies

Nuclei (singular nucleus)

Ganglia(singular ganglion)

Bundles of axons

Tracts Nerves

voluntary nervous system 31 pairs of spinal nerves

◦ ** NERVE – BUNDLE OF AXONS OUTSIDE THE CNS

◦ sensory nerves

2nd part of the peripheral nervous system Somatic nervous system

voluntary nervous system 31 pairs of spinal nerves

◦ ** NERVE – BUNDLE OF AXONS OUTSIDE THE CNS

◦ sensory nerves

afferent; dorsal roots dorsal root ganglion

2nd part of the peripheral nervous system Somatic nervous system

Section of Spinal Cord AND Spinal Nerves

◦ motor nerves ventral

cell bodies in ventral horn

efferents

Section of Spinal Cord AND Spinal Nerves

Importance of the location of injury in spinal cord in understanding the type and extent of damage thata person with spinal cord injury will have

Importance of the location of injury in spinal cord in understanding the type and extent of damage thata person with spinal cord injury will have

dermatome map

Cervical – green Thoracic- blue

Lumbar- purple

Sacral- red

Importance of the location of injury in spinal cord in understanding the type and extent of damage thata person with spinal cord injury will have

A high cervical injury vs a low thoracic injury will result in very different outcome!!!!

Christopher Reeve’s damage was between C1 and C2

- brought to the attention of many the need forresearch in spinal cord injury

- strong advocates of stem cell research

- changed our beliefs about spinal cord injury

What about sensory/motor communication for head and face?

Cranial nerves primarily serve head and face

Cranial nerves

Differences between cranial nerves and motor/sensory nerves◦ Cranial go directly into brain (rather than spinal

cord)◦ Cranial can be sensory, motor or both

What about sensory/motor communication for head and face?

What issphenopalatine ganglioneuralgia?

sphenopalatine ganglioneuralgia

Cranial nerves primarily serve head and face

How to get rid of “brain freeze”? Touch tongue to your soft palate.

◦ Underside of tongue may be warmer than the top (which probably cooled by the Slurpee you just chugged.

Drink something warm Make a mask with your hands to cover your

mouth and nose. Breathe quickly, raising the temperature inside your mouth.

Press a warm thumb against your palate. Wait it out.

Swelling or compression of the 7th cranial nerve◦ causes:

◦ treatment:

◦ recovery:

Bell’s Palsy

How is it protected?◦ Skull

obvious - advantages of skull

less obvious - disadvantage- closed head injury

coup - site of injury contre coup

CNS

How is it protected?◦ Skull

◦ CSF - cerebrospinal fluid CSF production

CNS

• How is it protected?– Skull

– CSF - cerebrospinal fluid

• CSF production–role of ventricles

• ADV:

• DISADV:»hydrocephaly

CNS

How is it protected?◦ Skull

◦ CSF - cerebrospinal fluid

◦ meninges

CNS -

meninges-

infections within the meninges –bacteria – bacterial meningitisviral – viral meningitis

How is it protected?◦ Skull

◦ CSF - cerebrospinal fluid

◦ meninges

◦ blood brain barrier

CNS

Gray matter-◦ Butterfly shaped ◦ Contains cell bodies

Spinal Cord

Gray matter

Gray matter-

white matter- axons

Spinal Cord

Section of Spinal Cord AND Spinal Nerves

Gray matter-

white matter

spinal tracts – bundle of axons inside the CNS

Spinal Cord

3 main divisions of brain

◦ hindbrain; midbrain; forebrain

brain

Metencephalonmyelencephalon

Mesencephalon

Telencephalondiencephalon

medulla

hindbrain

medulla

pons

hindbrain

medulla

◦ basic reflexes heart rate, blood pressure, respiration, vomiting many cranial nerves enter through the medulla

hindbrain

Copyright © 2006 by Allyn and Bacon

medulla

pons

hindbrain

medulla

pons

hindbrain

medulla

pons

cerebellum-

hindbrain

medulla

pons

hindbrain

medulla

pons

cerebellum-◦ balance and coordination◦ motor memory

hindbrain

Sensory information

movement

◦ substantia nigra -

midbrain

forebrain

What might you look at to determine intelligence of species?

Cerebral cortex

◦ role of convolutions

forebrain

Frontal◦ Motor function

4 lobes of cerebral cortex

frontal

Frontal◦ Motor function◦ Prefrontal – higher “executive function”

4 lobes of cerebral cortex

Prefrontal cortex

Frontal◦ Motor function

Prefrontal – higher “executive function”

Parietal◦ Somatosensory function

4 lobes of cerebral cortex

frontal

parietal

Frontal◦ Motor function

Prefrontal – higher “executive function”

Parietal◦ Somatosensory function

Temporal◦ Audition◦ Emotion

4 lobes of cerebral cortex

frontal

parietal

temporal

Frontal◦ Motor function

Prefrontal – higher “executive function”

Parietal◦ Somatosensory function

Temporal◦ Audition◦ emotion

Occipital◦ vision

4 lobes of cerebral cortex

frontal

parietal

temporaloccipital

Different roles for primary and association

◦ Start with primary motor since it is different than the others!

Primary and Association Cortex

Primary motor◦ Sends commands to muscles (via motor neurons)

Role of primary motor and associative cortices

primary motor strip

Primary motor◦ Sends commands to muscles

Association cortex◦ Sends coordinated commands to primary motor

cortex

Role of primary motor and associative cortices

Motor association cortex

Primary sensory cortex –◦ Receives sensory input from that sensory system

Association cortex-◦ Interprets the input (info) that comes in from the

sensory neurons

Sensory lobes (parietal, temporal and occipital)

Association cortex

Visual association cortex

Auditory association cortex

Some subcortical structures thalamus – important relay for sensory

and motor information

has tremendous projections of neurons across many regions of the cerebral cortex

The thalamus communicates with much of the cerebral cortex - serving as a sensory and motor information relay.

Some subcortical structures hypothalamus

◦ 4 F’s – feeding, fleeing, fighting and copulating

◦ hypothalamus contains many nuclei (collections of cell bodies in CNS) also…. controls maternal behaviors (at least in rodents) thirst and drinking

Two brothers – same exact age.

One with a lesion (damage) to a nucleus in the hypothalamus

Some subcortical structures limbic system – number of structures

important in emotion

◦ limbic system also includes the hippocampus – important for learning and memory!

Some subcortical structures basal ganglia

◦ important in Parkinsons Disease

Some subcortical structures corpus callosum – sole purpose of the

corpus callosum is to serve as a “bridge” between left and right hemispheres◦ contains millions and millions of axons ◦ allows left and right side of brain to know what

each other is doing!

Corpus callosum