Lab Nervous System Flashcards
CNS
- Brain- in skull
* spine- in vertebral canal
Peripheral nervous system (PNS)
- Cranial nerves-attached to brain
* spinal nerves- attached to spinal chord
Functions of the nervous system:
- forms communication network throughout the body
- system acts to control body muscle movements
- coordinated and integrates actions between body organs
CNS functions
- receivers sensory information from the PNS
* initiates body movements
PNS functions
- picks up sensations inside and outside the body
- controls skeletal muscles
- controls actions of internal organs
Two cells that make up the nervous system:
- Neurons
* neuroglia (nonneural cells)
Neurons
- nerve cells
* carry info from one part of the body to another
Neuroglia
Support cells that aid in the activities of the neurons
3 Types of neurons
- sensory
- motor
- interneurons
Sensory neurons
- afferent
* pick up stimuli and carry info to the CNS
Motor neurons
- efferent
* carry info from the CNS to organs and muscles
Interneurons
- association neurons
- located in the CNS only
- conduct action potentials from one neuron to another
Cell body (neuron structure)
- soma=body
* contains nucleus and most organelles
Dendrites
- (dendros=tree)
- branching receptive projection off neuron cell body(soma)
- receives stimuli
- conducts potential towards cell body
Axon (neuron structure)
- nerve fibers
- central process if a neuron
- conducts action potentials away from cell body
Axon (special features)
- could be Short or Long
- can form branches called collaterals to better reach multiple other cells
- ends called presynaptic terminals
Myelin sheath (special features)
•covering over axon made by neuroglial wrapping
•PNS- called Schwann cells
- white matter made of lipoprotein material(myelin)
•made to insulate axons and Speed up action potential
•space between Schwann cells is called “nodes if Ranvier”
Sensory neuron dendrites
- endings on sensory neurons are designated to pick up special types of information
- types that react to things like: touch sound odor vision…
Neuroglia (glial cells)(nerve glue)
Located where?
PNS neuroglia
CNS neuroglia
PNS neuroglia
•Schwann cells: glial cells wrap around portions of the axon, leaving small gaps aka node of Ranvier
CNS neuroglia 4 types
- oligodendrocytes
- astrocytes
- microglia
- ependymal cells
Oligodendrocytes
- cells that produce myelin in the CNS
- white(lipoprotein)
- matter of spinal chord and brain
Astrocytes
- branched glial cells
- cover the surfaces if blood vessels, neurons and the pia mater
- Nourish neurons
- provide barrier between blood and nervous tissue
Microglia
- small glial cells that are mobile
- phagocytic
- digest foreign substances that invade the nervous tissue
Ependymal cells
Line the ventricles of the brain
•line central canal of the spinal chord
•helps form cerebrospinal fluid which fill cavities
Spinal cord
- longitudinal structure
* located in spinal vertebrae for protection
Spinal chord structure enlargements (2)
•Cervical enlargement: wider area in the neck
-inferior cervical region
•lumbosacral enlargement:wider area in lower back (inferior thoracic, lumbar, and superior sacral regions)
Spinal terminal areas:
- upper end
- lower end
- filum terminale
- cauda equine (horses tail)
Upper end of spinal terminal
- superior
- connects superiorly with medulla oblongata of brain
- passes through foramen magnum of skull
Lower end of spinal terminal
- distal end
- forms a cone shaped structure called conus madularis (tip of)
- the tip is the inferior end of the spinal cord
- extends to the second level of the lumbar vertebrae
Filum terminale terminal of spine
- extension of pia matter that anchors the spinal column in place
- thin thread of connective tissue
- connects spinal cord to first coccygeal vertebra
- limiting superior movement
Spinal nerves
- Spinal nerves leave vertebral column through openings between vertebrae (vertebral foramen)
- 31 pairs of spinal nerves
- divided into 5 areas
31 spinal nerves, divided into 5 sections:
- Cervical nerves- 8pairs- (1-8)
- Thoracic nerves-12pairs-(1-12)
- Lumbar nerves- 5pairs-(1-5)
- Sacral nerves- 5pairs-(1-5)
- Coccygeal nerves-1 pair(c0)
Cross section of spine reveals:
- central position is gray matter
- outer area is white matter
- several openings and fissures along spinal nerve connections
Openings and fissures around spinal canal:
- Central canal
- Anterior (ventral) median fissure
- Posterior (dorsal) median salcus
Central canal
- runs length of spinal cord
- middle of gray commissure filled with cerebral spinal fluid
Anterior median fissure
•Anterior (ventral) median fissure:
•deep depression along anterior surface of spinal cord
- in white matter
Posterior median salcus
•Posterior (dorsal) median salcus:
- depression on posterior surface of spinal cord
- in white matter
Gray matter(butterfly)
- central area of chord appears gray
- contains:gray commissure, across bar connecting both sides of gray matter
- central canal: hole in the middle or cord or gray commissure
- neuron cell bodies of motor and interneurons, dendrites and axons
Gray matter structural features:
Posterior horn: “narrow” receives info from somatic nerves
Anterior horn: “rounded, wide” sends motor signals to spinal nerves
Lateral horn: “some places” associated with ANS sends motor signals to spinal nerves
White matter spinal chord
Contents:
•bundles of nerve cell axons with myelin sheathes
•bundles form tracks:
- dorsal column, ventral column, lateral column, anterior median fissure, posterior median sulcus
White matter spinal structure:
Divided into tracks
•ascending tracks- take sensory info to brain
•descending tracks- motor info from the brain
Spinal nerve roots
•spinal nerves connect with the chord in small sections called roots
•each root carries info from different body areas
-anterior nerve roots
- posterior nerve roots
-dorsal root ganglion
-spinal nerve
Anterior nerve roots
Attach to front of cord
•contains axons of motor neurons
•Carrys info away from spine
Posterior nerve roots
- attach to back of cord
- contains axons if sensory neurons
- carries info to distal horn or spinal cord
Dorsal root ganglion
- swelling or knot
- back of nerve root
- contains nerve cell bodies or sensory nerves
Spinal nerve
- goes two ways
- composed of axons of both ventral and dorsal nerve root
- carries info into(sensory) and out of(motor) the spinal cord
Special functions of the spinal cord:
Spinal cord is apart of the cNS and acts to coordinate body functions
•relay system: between lower body and the brain
•ascending nerve tracks: (sensory) white matter takes into to brain
-white matter specially mapped to deliver info to specific place
•descending nerve tracks: white matter takes info from brain to relay impulses to skeletal muscles and internal organs
Reflexes and the spinal cord:
Reflexes protect body from injury
•maintain upright posture
•control actions of internal organs
