Nervous System: spinal Cord Flashcards Preview

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Flashcards in Nervous System: spinal Cord Deck (81):
1

Sections of the spinal Cord and how many in each section

Cervical (8) Thoracic (12) Lumbar (5) Sacral (5) Coccygeal (1)

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Conus medullaris

tapering inferior end

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Tapering inferior end

Conus medullaris

4

Cauda Equina

Nerve root (like horse tail)

5

Nerve root (like horse tail)

Cauda equina

6

Filum terminale

Thin strand of pia mater

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Thin strand of pia mater

filum terminale

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Composition of Spinal nerve

Epineurium (surround nerve, dense irreg CT), perineurium (Around fasicles, dense irreg CT), endonurium (surround neuron)

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Epidural layer

Areolar CT and adipose CT

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Dura mater

one layer, provides stability

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Subdural space

potential space

12

Arachnoid mater

collagen and elastic fibers,

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Subarachnoid space

contains CSF

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Pia mater,

Areolar CT, hugs spinal cord

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Denticulate ligaments

stabilize spinal cord in transverse plane. Pia mater extensions

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Posterior horns

somas of interneurons and sensory axons

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Lateral horns

T1-L2. Somas for autonomic motor neurons

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Anterior horns

somas for somatic motor neurons (Somatic more anterior than autonomic)

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Posterior funiculus

Posterior white matter

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Lateral funiculus

Lateral white matter

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Anterior funiculus

Anterior white matter

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Spinal cord conduction pathways Characteristics

Decussate, (contralateral)
paired tracts,
2 or 3 neurons

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Primary neuron

dendrites at receptors, axon goes to spinal cord

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secondary neuron

Interneuron, soma in posterior horn, goes to thalamus or cerebellum

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tertiary neuron

soma in thalamus, axon to postcentral gyrus

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Posterior funiculus-Medial leminiscal pathway

Discrimitive touch, proprioception, precise pressure, vibration. Cross over in medulla

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Anterolateral Pathaway

Crude touch, pain, temperature, pressure. Cross over in spinal cord

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Motor pathways neurons

Upper motor neurons: precentral gyrus.
Lower motor neurons: Stimulate effector

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Corticobulbar tract

Through spinal nerves

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Corticospinal tracts

thorugh spinal cord. Upper motor from precentral gyrus * on interneuron and *on lower motor neuron in spinal cord, * on skeletal muscle

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Nerve plexues

network of interweaving anterior rami of spinal nerves formed by anterior rami of most spinal nerves that innervate a specific body part.

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Intercostal nerves

anterior rami of spinal nerves T1-T11 between ribs, intercostal muscles, axilla skin, medial surfaces of arm, lateral chest, abdominal muscles

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Cervical plexuses

C1-C4. innervate anterior neck muscles, skin of neck and portions of head and shoulders

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Brachial plexuses:

C5-T1, innervate pectoral girdle and limb

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Lumbar plexuses

L1-L4, innervate some legs, thigh,

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Sacral plexuses

L4-S4 gluteal region, pelvis, perineum, posterior thigh and most of leg and foot

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Characteristics of reflexes

pre-programmed, stimulus required, rapid response, involuntary

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Reflex arc steps

1. stimulus activates receptor,
2. nerve signal travels though sensory neuron to CNS
3. info from nerve is processed in "integration enter" by interneurons,
4. Motor neuron transmits a nerve signal to effector
5. Effector responds

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Stretch reflex

Muscle spindle detects stretch, sensory nerve singal to CNS, synapes on motor neuron, motor neuron contracts effected muscle. interneurons synapse on motor neurons which inhibit opposite muscle (recipricol inhibition)

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Golgi tendon reflex

golgi tendon organ senses too much tension. Recipricol activation

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Withdrawl reflex

detect pain. Activates flexor,

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Cross tensor reflex

other interneurons cross over to extensor on other side of body to support weight

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Structural differences: axon length

Parasympathetic: Preganglionic=long, post ganglionic=short
Sympathetic: Preganglionic=short, postganlionic=long

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Structural differences: Axon branches

Parasympathetic: Few

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Structural differences: ganglia location

Parasympathetic: close to or in effector
Sympathetic: in sympathetic trunk or prevertebral ganglia

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Functional differences:

Parasympathetic: rest and digest: constrict pupil, saliva and mucus secretion, decrease diameter of airways, lower heart rate and force of contraction. Pelvic organs, lower GI tract, erection of penis or clitoris
Sympathetic: fight or flight. Pupil dilation, increase heart rate, adrenal gland, decrease mobility of digestive system, sweat glands, dilates vessels to skeletal muscles.

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Organization of ANS

White rami carry preganlionic axons to sympathetic trunk,
gray rami: postganlionic axons from trunk through spinal nerve.

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Sympathetic nerve pathways

Spinal nerve pathway
Postganglionic sympathetic nerve pathway
Splanchnic nerve pathway
Adrenal medulla pathway

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Acetecholine

Released by Cholinergic neurons
binds to cholinergic receptors.

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Types of cholinergic receptors

(ACh)
Nicotinic receptors: allows more Na+ in than K+ out. EPSP
Muscarinic receptors, either excitatory (like GI tract) or inhibitory (cardiac muscle)

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Nicotinic receptors

cholinergic

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Muscarinic receptors

cholinergic

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Norepinephrine

Released by adrenergic neurons,
binds to adrenergic receptors

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Types of adrenergic neurons

alpha 1, alpha 2, beta 1, beta 2

released by postganglionic neurons in the sympathetic nervous system.

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Alpha 1

(norepinephrine)
In all blood vessels except those to heart, liver, skeletal muscles. Stimulate contractions of those blood vessels. stimulate erector pili muscles (hackles on doggies), internal urethral sphincter (so you don't pee in stressful situations)
Exicte

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Alpha 2

in pancreas. Stimulating release of insulin, contract GI sphincters. (increases glucose uptake)
Excite

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Beta 1

Found in heart, increase rate and force of heart contractions, increases production of renin to increase blood pressure
Excite

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Beta 2

relaxes blood vessels to heart, liver, and skeletal muscles

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Where are A1,A2, B1, B2 receptors

in the effectors

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Stimuli

Change in internal or external environment that is detected by receptors

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sensation

conscious awareness due to processing in cerebral cortex

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Properties of sensory receptors

receptors as tranducers, receptive field, tonic and phasic receptors (adaptation)

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Receptor classification

Distribution (general vs special)
Origin (exteroceptors vs interoceptors)
Modality of stimulus

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Modality of stimulus

chemoreceptors
thermoreceptors
photoreceptors
mechanoreceptors
baroreceptors
nociceptors

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Free nerve ending

uncapsulated tactile receptor
pain, light touch, pressure.

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Root hair plexus

Uncapsulated tactile receptor.
With hair, sensitive to light movement

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Tactile discs

Merkel
Uncapsulated tactle receptor.
fine touch, texture differences.

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End bulbs

Encapsulated tactile
vibration

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Lamellated corpuscles,

pacinian
encapsulated tactile
Deep pressure

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Bulbous corpuscles

Ruffini.
Encapsulated tactile
Deep pressure, skin distortion

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Tactile corpuscles

Meissner.
Encapsulated tactile receptor.
Discriminative touch, fine touch

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Olfaction receptors and path

olfactor receptor cells = primary neuron
Odorants in mucus hit receptors, the bipolar olfactory receptor cells which
* on olfactory bulb.
Secondary neuron axon through olfactory tracts, synapse on olfactory cortex, amygdala, hypothalamus

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Audition pathway

Auricle funnels sound waves into external acoustic meatus where it conducts the waves to the tympanic membrane. This vibrates moving auditory ossicles which hit the oval window. This creates pressure waves in the fluid in the inner ear (cochlea) the waves in the cochlea follow the spiral organ and stimulate hair cells in the basilar membrane which result in an EPSP in the cochlear branch of the CN VIII . This * on an interneuron in the medulla and brainstem and thalamus. Tertiary neuron goes to auditory cortex in the temporal lobe.

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Gustation

Gustatory cell is chemoreptor for taste.
Chemicals in saliva(with mucus) stimulate gustaty cells in the taste buds which stimulate CN IX or CN VII. These * on the medulla oblongata. The secondary neuron * on the thalamus. Tertiary neuron * on the insula.

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3 layers of the eye

Fibrous tunic, vascular tunic, retina

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Fibrous tunic

sclera: dense irreg CT
Cornea

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Vascular tunic

Chorid: lots of blood vessels
Ciliary body: muscles that change the shaw of lens
Iris: controls light into eye

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Retina

Pigmented layer: absorbs light
Neural layer: layer with rods and cones

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Posterior compartment:

Contains vitrious humer

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Anterior compartment:

Contains aqueous humer

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Vision pathways

Light goes through cornea, into pupil, hits lens (flat and relaxed to see far, thickened to see close) LIght is focused on retina by lens. It hits pigmented layer first, then hyperpolorize the cones and rides. these stimulate the bipolar primary neurons which synapse at the optic nerve. Half of the neurons cross over at the optic chasm. This neuron synapses at the brainstem, then synapses on the thalamus, and then synapse on the occipital lobe where the image is perceived.