Basics of the Neuron/glia Overview of the NS Outline
Dec 14, 2015
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
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
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)
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
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
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!!!!
- 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
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?
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.
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–role of ventricles
• ADV:
• DISADV:»hydrocephaly
CNS
3 main divisions of brain
◦ hindbrain; midbrain; forebrain
brain
Metencephalonmyelencephalon
Mesencephalon
Telencephalondiencephalon
medulla
◦ basic reflexes heart rate, blood pressure, respiration, vomiting many cranial nerves enter through the medulla
hindbrain
Frontal◦ Motor function
Prefrontal – higher “executive function”
Parietal◦ Somatosensory function
4 lobes of cerebral cortex
Frontal◦ Motor function
Prefrontal – higher “executive function”
Parietal◦ Somatosensory function
Temporal◦ Audition◦ Emotion
4 lobes of cerebral cortex
Frontal◦ Motor function
Prefrontal – higher “executive function”
Parietal◦ Somatosensory function
Temporal◦ Audition◦ emotion
Occipital◦ vision
4 lobes of cerebral cortex
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◦ Sends commands to muscles
Association cortex◦ Sends coordinated commands to primary motor
cortex
Role of primary motor and associative cortices
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)
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
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 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!