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26 Cards in this Set

  • Front
  • Back
three cells at NMJ
motor neuron
schwann
muscle fiber
Presynaptic features of NMJ
AcH vesicles surround active zone(has Ca channels)

active zones above junctional folds(secondary synaptic cleft)

mito under the schwann cell(upper half)
Presynaptic(perisynaptic) features of schwann cells
attenuate synaptic transmission and help reinnervate muscle fibers
Postsynaptic features
primary junctional folds
secondary - crests have AcH R

nuclei and mito are underneath nn terminal
Synaptic cleft features
synaptic basal lamina passes through primary synaptic cleft and into secondary synaptic cleft, enriched in agrin neuregulin and acetylcholinesterase
motor nn at smooth muscle
less elaborate, NT released from boutons(varicosities)

beads on a string en passant

one varicosity can innervate MULTIPLE smooth muscle cells(skeletal = only one per terminus)

synaptic cleft is wider, NO JUNCTIONAL FOLDS
active zones not prominent
CLINICAL CORRELATES
kjsgf
lambert eaton syndrome

cause
symptoms
Ab against presynaptic Ca channels in active zone

muscle weakness and fatigability
Myasthenia gravis

cause
symptoms
Ab against postsynaptic ACh R

muscle weakness and fatigability
Muscular dystrophies
most by mutation in dystrophin, link b/w ECM and subsarcolemma cytoskeleton
Where it comes from, cellular cause, symptoms

Botulinum

Bungarotoxin

Tick paralysis
botulism - bacteria, blocks NT release, muscle paralysis

bungarotoxin - snake, irrev binds ACh R, muscle paralysis

Tick - tick, inhibits ACh release, flaccid paralysis
Where it comes from, cellular cause, symptoms

latrotoxin

tetanus
latrotoxin - black widow, stim synaptic vesicle fusion, muscle fatigue and PARALYSIS

Tetanus - bacterium, CNS inhibits NT release from INHIBITORY spinal motor neurons
sense position of the entire body or body part
proprioreceptor

a physiological classification
sense pressure vibration touch sound
mechanoreceptor
a physiological classification
what type of nn ending?

loose all covering, end w/o specialization, majority of sensory receptors of skin
base of hair roots, sense pain, mechanical, warm, cold
free nerve endings(peritricial)
Type of anatomical nerve ending

slow adapting mechanoreceptors
basal layer of epidermis
unmyelinated cutaneous nn terminal form flattened discs that sits close to a modified epithelial cell attached to neighboring cells by desmosomes
expanded tip endings

MERKLE's CORPUSCLE
anatomical type of nn ending

CT sheath surrounding nerve terminal,
encapsulated endings

Pascinian corpuscle
Ruffini endings
Meissners corpuscle
Muscle spindles
Golgi tendon endings
Pacinian corpuscle

Location
Stimulus(function)
Structure
location: glabrous and hairy subcutaneous layer

Stimuli - rapid adapting mechanoreceptors, high frequency touch/vibration

Structure: outercore of flattened fibroblasts, inner core of flattened schwann continuous with endoneurial sheath, nerve in middle ending in knoblike spray
Ruffini ending

Location
Stimulus(function)
Structure
Location - deep dermis of hairy and glabrous skin, joint capsules

Stimulus(function) - slow adapting mechanoreceptors, low freq vibration/pressure from stretching of collagen in skin

Structure - elongated fusiform, parallel to skin, callagen fibers running through
Meissner's Corpuscle (not merkle cell)
Location
Stimulus(function)
Structure
Location - dermis papilla

Stimulus(function)- rapid adapting , fires transient at onset to low freq irreg vib/pressure

Structure - small cylindrical perpendicular to skin, schwann cell horizontal flat inside fibrous CT, axonal ending spiral throughout
Muscle spindle
Location
Stimulus(function)
Structure
Location - skeletal muscle

Stimulus(function)- changes in muscle length causing contraction of extrafusal fibers (knee jerk reflex)

Structure - capsule of fibroblasts connected by desmosomes, surrounds CAPSULAR SPACE containing tissue fluid
which two encapsulated endings have desmisomes
merkle's corpuscle - between merkel cell and nighboring cell

muscle spindle - between fibroblasts of capsule
Intrafusal fibers
inside capsular space, non contractile middle, striated ends, smaller

nuclear bag fibers - cluster of nuclei

nuclear chain fiber - chain of nuclei
innervation of spindles
EFFERENT: gamma motor neurons on striated portion of intrafusal, contractions makes the fusal fibers more sensitive to muscle stretch

AFFERENT - each spindle recieves a primary sensory ending(myelinated afferent), also many smaller secondary sensory endings
Golgi tendon

Location
Stimulus(function)
Structure
Location - in tendons of muscle

Stimulus(function)- muscle contraction, monitors load, protective reflex

Structure - thin fibroblastic capsule filled with collagenous fibers(continuous with muscle tendon) and extrafusal muscle fibers
how is golgi tendon innervated
ONLY AFFERENT

large myelinated sensory looses myelin after encapsulation and ends in small sprays of free nerve endings

signal to spine through dorsal root ganglia, along inhibitory interneuron, and to alpha motor neuron which innervates the MUSCLE(not tendon)