Nervous System stack Flashcards Preview

ima kkongbu > Nervous System stack > Flashcards

Flashcards in Nervous System stack Deck (31)
Loading flashcards...

PNS, sensory division

carries sensory signals by way of afferent receptors to the CNS

receptors: cells and organs that detect stimuli


PNS, motor division

carries motor signals by way of efferent nerve fibers from the CNS to effectors

effectors: cells and organs that carry out the body's resonses; mainly gland and muscle cells


sensory, visceral

carries signals mainly from the viscera of the thoracic and the abdominal cavities (i.e., heart, lungs, stomach, urinary bladder)


sensory, somatic

carries signals from receptors in the skin, muscles, bones and joints


motor, visceral

* ANS (autonomic nervous system): para/sympathetic
* carries signals to glands, cardiac muscle & smooth
* no voluntary control and system operates at an unconscious level
* responses of this system and its effectors are visceral reflexes


motor, somatic

* carries signals to the skeletal muscles
* produces muscular contraction that are under voluntary control
* also involuntary muscle contractions (somatic reflexes)



* tends to prepare the body for action by (...see below)
* accelerates heartbeat & increases respiratory airflow but inhibits digestion
* fight or flight (or freeze) response



* tends to adopt the body to state of rest by reducing heart rate & respiratory airflow and stimulates digestion
* rest & digest


neuroglia, definition

* AKA "glial cells"
* protect the neuron & aid functions
* bind neurons together
* in fetus, guides migrating neurons to their destinations
* wherever a mature neuron is not in synaptic contact with another cell, covered with glial (neurological) cells; prevents contact with each other except at {PTS?} specialized for signal transmission; precision to conduction pathways


neuroglia, oligodendrocytes

* CNS: bulbous body with many armlike processes
* each process reaches out to a nerve fiber and spirals around it like an electrical tape around wire
* spiral wrapping = myeline sheath
* myelin sheath: insulates the nerve fiber from the extracellular fluid & speeds up signal conduction in nerve fiber


neuroglia, astrocytes

* most abundant & functionally diverse glia
* "star shaped"
* cover entire brain surface & most nonsynaptic regions of neurons in gray matter
* supportive framework
* perivascular feet: BBB (blood brain barrier)
* convert blood glucose to lactate (neuron nourishment)
* secrete growth factors that promote neuron growth and synapse formation
* regulate chemical composition of the tissue fluid; absorb K+ ions and neurotransmitters (prevent from accumulation)
* form hardened masses of scar tissue & fill space of damaged neurons; astrocytosis / sclerosis


neuroglia, ependymal cells

* CNS: resembles cuboidal epithelium
* produce CSF fills internal cavities
* has cilia to aid in CSF circulation


neuroglia, microglia

* CNS: small macrophages that develop from white blood cells
* wander {in?} CNS and phagocytize dead nervous tissues, microorganisms & other foreign matter
* become concentrated in areas damaged by infection, trauma or stroke


neuroglia, Schwann cells

* envelop nerve fibers of PNS
* form a sleeve (neurilemma)
* myelin sheath between nerve fiber & neurilemma
* assist in regeneration of damaged fibers


neuroglia, satellite cells

* surrounds the neuron cell bodies in ganglia


myelin sheath

* rapid nerve signal
* consists of plasma membrane (20% protein; 80% lipid (cholesterol, phospholipds & glycolipids))
* unmyelinated: one Schwann cell (not myelin) to axons / nerves


MS (multiple sclerosis)

* definition: deterioration of myelin sheath
* nerve disruption depend on where damaged; numbness, double vision, blindness, tremors, neurosis or speech defects
* eventually bedridden & dies
* T-cells attacks myelin (autoimmune)
* MRI shows plaques





CNS, nerve tissue

Where most information processing by the nervous system occur.
Consists of brain & spinal cord, which are enclosed and protected by the cranium and vertebral column.


PNS, nervous tissue

* remainder of nervous system
* serves for input to and output from CNS
* composed of nerves and ganglion



knotlike swelling in a nerve where the cell bodies of neurons are concentrated



* Bundle of nerve fibers wrapped in fibrous connective tissue
* Emerges from CNS through foramina of the skull and vertebral column and carry signals to & from other organs of the body


meninges, definition

* Three connective tissue membranes that encloses spinal cord and brain
* separate the soft tissue of CNS from bones of the skull & vertebrate
* superficial to deep
- dura mater
- arachnoid mater
- pia mater
* forms loose-fitting sleeve (dura sheath) around spinal cord; tough, collagenous membrane with thickness & texture similar to a kitchen glove
* epidural space: space between sheath & vertebral bone; occupied by blood vessels, adipose tissues & loose connective; anesthetics @ this site selective & numbing


meninges, arachnoid mater

* simple squamous epithelium inside of the dura
* subarachnoid space: between arachnoid membrane and pia mater
* anesthetics: spinal tap; numbness from the point & downward


meninges, pia mater

* delicate, follows contours of spinal cord
* coccygeal ligament: anchors cord to vertebra
* dentriculate ligament: (extension of pia mater) extend through arachnoid to the dura, anchoring the cord and preventing side to side movements


gray matter

* contains little myelin; has somas, dendrites & proximal parts of axons of neurons
* site of synaptic contact between neurons to all of synaptic integration in CNS
* dorsal (posterior) horns:
- rope with bulb
- synapse with interneuron
* ventral (anterior) horns: contain large somas of somatic motor neurons
* gray commissure: links left to right; has central canal (open-lined with ependymal cells, CSF)
* dorsal root: carries sensory nerve fibers
* ventral root: axons from neurons (of ventral horn) exit by this lead to the skeletal muscles
* spinal nerve: where dorsal / ventral roots meet & on
* lateral horn: thoracic & lumbar regions; side of gray matter; neurons of sympathetic via ventral root & somatic efferent


white matter

* myelinated fibers / axon
* columns / funiculi: dorsal posterior, lateral and ventral / anterior in pairs
* each column consists of subdivisions called tracts (fasculi)
* decussation: cross over from left to right, vice versa ("other controls")
* contralateral: when origin and destination of tract are on opposite sides of the body
* ipsilateral: when a tract does not decussate; origin & destination of fiber on same side of body


ascending tracts, definition

* carries sensory information up the cord, typically across three neurons:
1st order neurons, detects a stimulus and transmits signal to the spinal cord or brainstem
2nd order neurons, continues to "gateway" (thalamus) upper end of brainstem
3rd order neurons, carries to sensory region of cerebral cortex


ascending tract, granule fasciculus

* in medulla oblongata
* limb & trunk position & movement (mid-thoracic & lower)
* deep & discrimniative touch (precise identification)
* visceral pain, vibration
* proprioception of lower limbs & trunk
* proprioception: nonvisual sense of the position & movements of the body
* below T6
* first order neurons


ascending tracts, cuneate fasciculus

* same as gracite fasciculus but above T6
* fibers ends in cuneate nucleus on ipsilateral side of medulla oblongata
* medulla lemniscus: where 2nd order neuron of gracite & cuneate decussate
* 3rd order: thalamus to cerebral cortex