- collection of axons - axons arranged in parallel and wrapped in CT - nerve can contain myelinated and/or unmyelinated, sensory and/or motor axons

- neural tissues, blood vessels, and CT - responsible for integrating, processing, and coordinating sensory data and motor commands - where higher functions occur (intelligence, memory, learning, and emotion)

ALL NERVES OUTSIDE OF THE SPINAL CORD AND BRAIN - link all regions of the body to CNS - carries motor commands to peripheral tissues (innervates) and systems - includes ganglia: clusters of cell bodies of neurons - sensory nerves innervate areas of skin

- Afferent info - travels towards (at) the CNS - free nerve endings in almost all body tissues - Includes receptors for: touch, pain, pressure, vibration, temp, proprioception (sense of body in space) in skin, body wall, and limbs - "special" somatic: vision, hearing, balance

- Efferent info - travels from CNS to body. Exits brain or spinal cord - voluntary nervous system - signals the contraction of skeletal muscle tissue

- Sensory Afferent - Motor Efferent - Dorsal Afferent - Ventral Efferent

- Satellite cells: surround cell bodies in ganglia, modulate neurotransmitter levels - Schwann cell: wraps around axons, myelin

- many individual axons with interspersed nuclei of glial cells - long parallel myelinated axons visible when viewed oblique or longitudinally

Lab 8 Flashcards by Riley Cissell

Nervous System Functions

Receive, process, and respond to info. Transmit electrical signals throughout the body

sensory input: monitor external and internal changes
integration: process sensory input and determines response
motor output: dictates response by activating effector organs

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Nervous sensory and motor response action order

receptor (stimuli)
afferent (sensory) neuron
integration center (brain)
efferent (motor) neuron

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Structure of a neuron

Neuron = nerve cell

soma = cell body (contains nucleus, cytoplasm, and organelles)
dendrites = receive signal, transmit to cell body, receptor sites for incoming signals
axon = transmit signal to end, conduct signal away from cell body
myelin = insulates neuron, helps propagate signal (made from glial cells - Schwann or oligodendrocytes)

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Nerves

collection of axons
axons arranged in parallel and wrapped in CT
nerve can contain myelinated and/or unmyelinated, sensory and/or motor axons

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Divisions of NS

Central NS
- spinal cord and brain

Peripheral NS
- all neural tissues outside of spinal cord and brain

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CNS

neural tissues, blood vessels, and CT
responsible for integrating, processing, and coordinating sensory data and motor commands
where higher functions occur (intelligence, memory, learning, and emotion)

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PNS

ALL NERVES OUTSIDE OF THE SPINAL CORD AND BRAIN

link all regions of the body to CNS
carries motor commands to peripheral tissues (innervates) and systems
includes ganglia: clusters of cell bodies of neurons
sensory nerves innervate areas of skin

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CNS structure

Grey Matter
- composed of dense aggregations of neuron cell bodies, dendrites, and ganglia
- synapses here

White Matter
- myelinated regions of CNS
- include axons and glia
- bundles of axons are nerve tract

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Somatic Sensory

Afferent info - travels towards (at) the CNS
free nerve endings in almost all body tissues
Includes receptors for: touch, pain, pressure, vibration, temp, proprioception (sense of body in space) in skin, body wall, and limbs
“special” somatic: vision, hearing, balance

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Somatic Motor

Efferent info - travels from CNS to body. Exits brain or spinal cord
voluntary nervous system
signals the contraction of skeletal muscle tissue

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SAME DAVE

Sensory Afferent
Motor Efferent
Dorsal Afferent
Ventral Efferent

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Glial cells of the CNS

Provide supportive functions to neurons in the CNS and PNS

Microglia: immune cells
Oligodendrocytes: processes wrap around neurons, myelin
astrocytes: maintain blood-brain barrier
Ependymal cells: line ventricles, produces cerebrospinal fluid

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Glial Cells of PNS

Satellite cells: surround cell bodies in ganglia, modulate neurotransmitter levels
Schwann cell: wraps around axons, myelin

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PNS Histology

many individual axons with interspersed nuclei of glial cells
long parallel myelinated axons visible when viewed oblique or longitudinally

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The Meninges

three layers of CT that surround the brain and spinal cord

Dura Mater (tough mother)
- outer most layer, thick and durable
- close to or attached to bone

Arachnoid Mater (spider-like mother)
- middle layer
- attached to dura mater
- has fluid layer deep to it

Pia Mater (tender mother)
- thin delicate layer
- directly attached to brain and spinal cord

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Spinal Cord functions

transmit sensory and motor innervation to/from body
two-way conduction pathway for signals between body and brain
major centers for reflexes

Spinal cord location

extends from foramen magnum to level of 1st/2nd lumbar vertebra
31 pairs of spinal nerves (PNS)
Cervical and lumbar enlargements for nerves of upper and lower limbs

Inferior spinal cord

inferior end of spinal cord is called conus medullaris
nerve roots at inferior end of vertebral canal is called cauda equina
filum terminale is a long filament of pia mater that attaches to the coccyx

Spinal cord structure

grey matter forms an “H” in the center
posterior (dorsal) arms of H are dorsal horns
Anterior arms are ventral horns, which contain the motor neurons of spinal nerves

Spinal Meninges

the spinal cord is protected by bone, meninges, and CSF
Dura Mater: spinal dural sheath
Epidural space: filled with fat and veins
Subdural space, arachnoid mater, subarachnoid space, and pia mater similar of the brain
Denticulate ligaments: anchor the spinal cord laterally to the dura mater

Brain parts

cerebrum
diencephalon
cerebellum
Brain stem: midbrain, pons, and medulla oblongata

Structure of the Cerebrum

Gyri are ridges of brain tissue
Sulci are grooves
lobes of the brain are named after overlying bones

Cerebrum function

intelligence, complex thinking, sensory and motor processing

3 functional areas
- sensory: conscious awareness of sensation
- association areas: integrate info
- motor: voluntary motor functions

Sensory areas of Cerebral cortex

primary somatosensory cortex: postcentral gyrus of parietal lobe
primary auditory cortex: in temporal lobe
Primary visual cortex: in occipital lobe

Motor areas of the cerebral cortex

- Primary motor cortex: in the precentral gyrus of the frontal lobe - Broca's area: in the left frontal lobe, involved with the physical production of language (damage to area will have trouble speaking)

Wernicke's Area

- in the left hemisphere (parietal and temporal) - recognizing and understanding speech - fluent aphasia, speaking with no meaning

White matter of the cerebrum

- corpus callosum: large bank of axons that connect the right and the left hemispheres of the cerebrum

Diencephalon

- surrounded by the cerebral hemispheres - contains 3rd ventricle: lateral walls = thalamus, floor = hypothalamus

Thalamus

- lateral walls of the 3rd ventricle - gateway to the cerebral cortex - process all sensory info (except smell) coming into the cerebrum

Hypothalamus

- main visceral control center of the body, regulates many activities - controls autonomic NS, endocrine system, emotional responses, and motivational behavior - regulates body temp, hunger/thirst, and sleep-wake cycles - formation of memory

brain stem: pons and midbrain

- midbrain is located between diencephalon and pons - internal cavity is cerebral aqueduct - pons is located between the midbrain and the medulla, separated from the cerebellum by the fourth ventricle

brain stem: medulla oblongata

- the most caudal part of the brain stem, continuous with the spinal cord - pyramids carry voluntary motor - most fibers will cross over to the opposite side of the brain in the medulla - left brain communicated with the right side of the body, vice versa

Cerebellum

- 11% of brain mass - 50% of the neurons - functions: coordinated body movements, helps maintain posture and equilibrium, and language

Cerebellum Structures

- 2 hemispheres connected by the vermis - folia ae leaf-life folds that increase surface area - outer cortex is made up of grey matter, arbor vitae is made of white matter

Ventricles and Dural Sinsuses

- CSF is made by ependymal cells of the choroid plexus in the ventricles - eventually CSF drains into dural venous sinuses made of two layers of dura mater Ventricles - lateral (L and R) - third - fourth

Arteries of the head

- R/L common carotid arteries both ascend into the neck and head and divide into internal and external carotid arteries - internal and external carotid a. feed the head, brain, and orbital region

Arteries of the brain

- internal carotid a. divides into anterior and middle cerebral a. - anterior cerebral a. joins anterior communicating a. - middle cerebral a. supplies parts of temporal and paietal lobes (about 80% of the cerebrum)

Posterior arteries of the brain

- R/L vertebral a. fuse to become basilar a. which divides into poster cerebral arteries - these are connected by posterior communicating a.

Cerebral Arterial Circle (circle of willis)

- anastomosis to protect brain's blood supply - formed by: posterior cerebral a, posterior communicating a, internal carotid a, anterior cerebral a, and anterior communicating a