OMSI- FAAM V

muscle fibers

a muscle cell. Same as a myofiber

myoblast

immature muscle cell

myofibril

contractile unit of a muscle cell

myoepithelial cell

• modified epithial cells found at the base of glandular elements to push product through duct

• contracts to narrow the acinar and the early duct

• flattened cells curving around acinar, may have elongated processes. Very eosinophilic staining, bright magenta in H and E

myofibroblast

contractile cells from a fibrocyte/fibroblast population in the area

• used in wound healing, pulls it shut during healing

• will de-differentiate or apoptose after wound is healed

smooth muscle cells

• not very large, enlongated spindle shape

• 1 centrally located nucleous. will be elongated when relaxed, coiled when contracted

• stains pale and lightly eosinophilic

• surrounded by external lamina (similar to basal lamina)

external lamina

what smooth muscle cells attach to. composed of:

• lamina rara- clear layer on electron micrograph

• lamina densa- darker on electron micrograph

• 3 layers of rara-densa-rara

smooth muscle cells structures

• communicate through gap junction because 1 nerve will control several muscle cells. shares contractile signals

• sarcoplasmic riticulum is composed of finger-like tubules

• myosin and actin contractile units. Ca concentration is regulated through calmodulin

• dense bodies- membranous anchor points for contracile filliments. cell will contract from the plasma membrane

skeletal muscle cell

• large, can be up to 4 cm in length

• multiple nuclei, located on the periphery of the cell

• will have fibroblasts and sateline precurser cells in the periphery

sarcomere parts

• H band: only myosin, will be slightly darker on electron microscope

• A band: myosin and actin, will be paler than H band and Z line

• I band: only actin, includes Z line.

• Z line: where actin attaches. will be very dark on electron microscope

cardiac muscle

• smaller than skeletal muscle, similar to smooth muscle size

• 1, centrally located nucleus (may have 2)

• striated.

• dark bands are called interculated discs, connect cells together end to end with gap junctions. made of modified macula adherens

mesenchymal cells and muscle cells

• in embryos, mesenchymal connetcive tissue will differentiate into myoblasts

• will fuse to form a myotube, which will start synthesizing proteins for myofiliments

• will start to form striations

• some precursor cells will hang around in the periphery in case of damage. will look like a small, slightly rounder cell

sarcomere acessory structures

• T-tubules, transduct signals from neuromuscular junction. WIll run over A-band I band junction

• 2 terminal cristernal surround T tubules, connected to sarcoplasmic reticulum surrounding sarcomere

transverse tubule system in cardiac muscle

similar to skeletal, but there’s only 1 T-tubule and 1 terminal cisternae.

Cross bridge cycle

• Myosin is bound to an ADP

• Calcium exposes actin binding sites, myosin associates

• myosin dissasociate from ADP, causes a shape change where the myosin will pull actin

• ATP will associate, myosin will release

• ATP hydralized, now myosin can restart

how do smooth muscle contract

contracts around the cell instead of within, twisting it

1. calcium channels open and calcium binds to calmodulin

2. calmondulin activates myosin light chain kinase enzyme

3. MLC kinase will transfer phosphates to myosin, activating in

4. cross bridge initiates

sarcomere accessory proteins

maintain alignment and stabilizes sarcomere

• alpha actin: attaches thin filiments and titin to Z line

• titin: anchors thick filament to Z line. Can act as a tension gage

• M line proteins and protein C: stabilize thick filaments and anchors titan

• desmin: attaches Z lines to Z lines

costamere

striated muscle only. protein complex that connects cell cytoskeleton to sarcolemma and sarcolemma to extracellular matrix through dystophin.

how to scan for deep vein thrombosis

superior to inferior to prevent possibly dislodging the blood clot

• common femoral artery and vein at inguinal ligament

• at saphenous opening, where Great Saphenous drains into common femoral

• where the lateral perforating vein drains into common femoral

• where deep femoral vein drains into femoral vein

• popliteal fossa

*and in between

deep vein thrombosis scan techniques

• compression chain- compress and release at 1-2 cm intervals. just hold till the walls kiss

• pt knee should be slightly flexed and externally rotated. probe marker is up

how to scan the patellar tendon

• have pt flex knee about 20-30 degrees

• transducer on interior aspect of the patella, marker towards pt head

• can rotate probe marker to pt right for short axis

how to scan medial knee

• flex about 20-30 degrees and externally rotate the leg

• align probe with tibia on the medial aspect of knee joint

• view with long axis, probe marker towards head

how to scan lateral knee

• pt slightly flex and internally rotate knee

• palpate head of fibula, put transducer on fibula head. probe marker superior and anterior

how to scan medial ankle

• to view tarsal tunnel, place probe on medial malleolus. do not angle probe

• can tilt probe to brighten image

What does the autonomic nervous system supply

both CNS and PNS elements. involuntary movement in:

• smooth muscle

• glands

• cardiac muscle

*while not sensory, visceral sensory nerves will accompany ANS fibers

Autonomic pathway

2 neurons

• preganglionic neuron (with cell body in spinal cord) will synapse postganglionic neuron (whose cell body is within a PNS ganglia)

• postganglionic neurons will synapse with target organ

somatic motor pathway

1 neuron pathway

• CNS to skeletal muscle

autonomic preganglionic cell bodies

found in intermediolateral section of the ventral horn gray matter. will exit ventrally

somatic motor cell bodies

found in the ventral horn of spinal cord

what structures are primarily sympathetic nervous

• vessels

• adrenal glands

• skin

• possibly adipose

where do parasympathetic nerves outflow

• cranial

• sacral

sympathetic nervous system anatomical characteristics

largest division of nervous system. Aka the thoracolumbar outflow (since that’s where the fibers exit spinal cord)

• preganglionic cell bodies are in 12 throacic and 2 or 3 first lumbar

• postganglionic cell bodies are close to the spinal cord. paravertebral ganglia or prevertebral ganglia

• sympathetic chain: structure that runs from base of the skull to coccyx. One on right and left side. composed of connected paravertebral ganglia

sympathetic nervous system pregalglionic nerves

• begin in gray matter of IML at T1-L2/3

• preganglionic fibers exit through ventral root with the somatic motor

• will go into ventral ramus to innervate viscera

• preganglionic nerves will break off of ventral ramus as white ramus communicans. will run into sympathetic chain

• they can:

  • Synapse at the paravertebral ganglion

  • fibers can ascend, snapse at with a prevertebral ganglion at another level

  • descend and synapse

  • can pass through chain and not synapse

ramus communicans

a nerve that connects to other nerves. Connects branch of spinal nerve and sympathetic trunk.

• white- more myelin. only at T1-L2/3, made of preganglionic fibers

• gray- less myelin. at all levels, postganglionic fibers

sympathetic nervous system postganglionic nerves

many possibilities

• originate at paravertebral ganglia of the sympathetic chain. goes through gray ramus, joins with spinal nerve, and goes to target organ.

• preganglionic will synapse at a higher paravertebral ganglion. postganglion will join with closest spinal nerve to target

• preganglionic will decend to lower paravertebral. postganglion will join closest spinal nerve.

• preganglionic cell will leave sympathetic chain and form splanchnic nerves. will synapse at prevertebral ganglion around major arteries. Supplies visceral pelvic.

cervical sympathetic chain

innervates thoracic viscera. 3 parts

• superior: largest ganglia

• middle

• inferior

thoracic sympathetic chain

supplies thoracic viscera. receive white rami and give off gray rami. Can also give off thoracic splanchnic nerves that will synapse at prevertebral ganglion including:

• greater splanchnic (T5-T9)

• lesser splanchnic (T10-T11)

• least splanchnic (T12)

lumbar sympathetic chain

includes 4 paravertebral ganglia

• upper 2 or 3 receive white Rami

• all give off gray rami

sacral sympathetic chain

no white Rami, only gray

ganglion impar

on the anterior aspect of coccyx. left and right sides of chain will fuse and terminate here.

parasympathetic anatomical characteristics

aka craniosacral outflow

• preganglionic cell bodies are either in nuclei of 4 cranial nerves (II, VII, IX, X) or in ventral roots and rami of sacral spinal nerves (S2,3,4)

• synapse at terminal ganglia close to target organ

• postganglionic cell bodies at or near target organ. much shorter than preganglionic

types of visceral sensory fibers

sensation in the organs, accompaning ANS

• pain afferent: sends pain inpulses to CNS. dull and difficult to localize. follows sympathetic nervous system.

• monitoring afferent: a constant scanning pulse to organs, will accompany parasympathetic fibers. through vagus nerve. stretch, spasms, ischemia (not enough blood supply)

nissil substance

found in neuron cell bodies, the abundant rough ER and free ribosomes stains dark basophilic and splotchy

efferent neurons

motor. interpolar neurons (cell body at 1 end and synapse at other)

afferent neurons

sensory neurons. bipolar or unipolar

• somatic: sensory info from skeletal muscle

• visceral: sensory info from viscera, glands, and blood vessels

neuron cell bodies on light micrograph

• large, euchromatic nucleus. large nucleolus

• lots of nissil substance

• Axon hillox (red arrow)- transition between axon and soma. where nissl substance stops.

what triggers the release of neurotransmitters

voltage gated calcium channels. Calcium ions facilitate mediated exocytosis.

types of synapses

• axosomatic: between cell axon and cell body

• axodentritic: between axon and dendrites

• axoaxonix: between two axons. usually inhibitory

cells in CNS gray matter

• neurons

• glial cells- smaller nuclei than neurons

• neuropil- a network of neuronal and glial processes. the space between cell bodies

types of CNS glial cless

• astrocyte- maintains envirnment. star shaped with protrusion wrapping around vessels and axons

• oligodendrocyte- CNS mylination/protection. 1 cell can mylinate/encircle many. in light micrograms will have a halo due to myelin’s high fat content

• microglia- a type of macrophage. small, flat appearance while inactivated (most of the time)

• ependymal cells- epithelia that lines ventricles and central canal, produces CSF.

astrocyte

very abundant in CNS, maintains the envirnment, provides structure, blood-brain barrier, and will respond to CNS injury

• protoplasmic astrocytes- gray matter

• fibrous astrocytes- white matter

peripheral nerve linings

• endoneurium- around individual neurons

• perineurium- around fasciles. forms blood brain barrier, adhered by tight junctions. contains blood vesseles

• epineurium- around nerve. dense irregular, contains larger vessels

ganglia vs gray matter

ganglia: grouped cells bodies, neuroglia is around somas orderly

gray matter: diapered cells bodies, ganglia is also more scattered

satelite cells

glia cells in the PNS, does the same thing as atrocytes in the CNS. surrounds neuronal cell bodies.

schwann cells

similar to oligocytes, surrounds the axon.

• mylinating: produces myelin sheath. only 1 axon at a time

• non-myelinating. simply encases the axon, can wrap around many axons this way

nerve conduction

aka action potential propogration. will be anterograde (towards terminal)

• localized voltage gated channels will open

• cell membrane potential will become more positive due to sodium entering cell

• sodium ions will diffuse, depolarizing adjacent membrane

saltartory conduction (active)

in mylinated cells with nodes of ranvier. At each node there are a lot of voltage gated channels that will allow a large sodium ion influx. positive ion charge will have more force and spread down to the next node and and activate those channles

electronic conduction (passive)

describes how the sodium behaves once inside cell, not action potential itself. In unmyelinated cells. depolarization spread fueled by sodium ion passive diffusion though voltage gated sodium channel. creates “wave” of depolarization.

action potential steps

1. voltage gated sodium channels open.

2. ions rush in, membrane is depolarized through passive conduction. this opens adjacent channels

3. afterwards, Na channels inactivate (a state where they can’t be stimulated to reopen- ensures action potential only travels in one direction. creates the refractory period)

4. membrane is repolarized through potassium ion efflux. this will overshoot and hyperpolarize

5. resting membrane potential is restored, sodium channels will reactivate but remain closed

membrane resistance

prevents flow of ions across membrane

axonal resistance

makes flowing ions in axon more difficult. will conduct faster if axon has larger diameter.

how does myelin affect action potentials electronically

• increases membrane resistance

• decreases membrane permiability

• decreases capacitance

* opposite properties to the nodes of ranvier

how will a nerve conduct an action potential

compound action potential of all the nerve fibers. Will create a bell curve of stimuli between the slowest, average, and fastest neurons.

electrical synapse gap junctions

• neurons are joined by pairs of connexons (channels of 6 connexin proteins)

• no delay in communication, cytoplasm is continuous. For cells that need to fire at the same time.

• reciprocal synapse- flows in both directions

• rectifying synapse- flows in one direction

chemical synapse

• neurotransmitters are released by the presynaptic terminal. typically triggered by a voltage gated calcium channel at the terminal.

• will diffuse across synaptic cleft

• activate receptors on the receiving cell

  • ionotropic receptors- triggers an ion influx

  • metabotropic receptors- triggers cell signaling cascade

inhibitory vs exitatory neurtransmitters

• inhibitory: induces an inhibitory post-synaptic potential. lowers membrane.

• exitatory: induces a exitatory post-synaptin potential. raises membrane potential.

aceytlcholinesterase

clears acetylcholine from neuromuscular junction

how does stimulation of a muscle cells end

• ACh is destroyed by enzyme

• presynaptic re-uptake of acetylcholine

• ACh simply diffuses away

what does Ach do at neuromuscular junction of MSK

• will bind to nicotinic receptors on motor end plate

• sodium influx into muscle cells, has it’s own action potential and threshold

• action potential travels down membrane and enter through T-tubules. will trigger SR to release calcium through dihydropyradine receptor

why does cardiac action potential have a plateu

cell repolarization is delayed by an influx of calcium ion

types of reflexes

• monosynaptic: sensory => motor

• polysynaptic: sensory => interneuron => motor

both pass through spinal cord

where are proprioceptive receptors

in muscles, tendons, joint

proprioceptor types

• Muscle spindles: embedded in skeletal muscle fiber at the belly

• golgi tendon organs: interface of muscles and tendons

• joint receptors: in joint capsules, low threshold

muscle spindle

reacts to lengthening by contracting, made of specialized intrafusal muscle fibers

• spindle activation

• 1a sensory nerve fiber gives into to spinal cord

• synapse directly with gamma motor neuron, causes contraction. innervate spindle, not extrafusal fibers.

*know structure

golgi tendon organ

reacts to force production by causing relaxation

• 1b sensory fiber carries info to spinal cord

• synapse with interneuon- is inhibitory to alpha motor because it can only induce contactions

• synapse with alpha motor neuron, neuron is deactivated to relax

types of intrafusal fibers

• nuclear bag- the many nuclei of a muscle fiber is all clustered together

• nuclear chain- the nuclei are in a row

1a sensory fiber wraps around nucleus area, called annulospial ending. Group II fibers will branch and form many synapses with the muscle cells but not wrap around, called flower spray ending

spindle stimulus response- 1a

• when length increases, more action potentials become more clustered.

• frequency will level out once length has plateu.

• Will stop during shortening, and continue sporadically once held at shorter length

spindle stimulus response- II

always firing, tells only if the muscle is moving or not. 1a is more detailed

example- patellar tendon reflex

monosyaptic reflex, an example of a muscle stretch reflex

• tendon is tapped, the deformation makes quad muscle quickly increase in length

• sensed by primary spindle (1a)

• synapse directly with alpha motor neuron

• induces contraction

why does the muscle spindle work like it does?

• regulates muscle stiffness and proprioception, muscle must stay taught for spindle to be effective

• protects against over stretching and tearing

golgi tendon reflex

will sense force changes, too much force causes golgi tendon to start relaxation by inhibiting the alpha motor neuron. protects against tearing muscle

withdrawl (flexor) reflex

• involves whole limb, needs many neruons to fire simultaneously

• a sensory neuron synapses with interneuron in the spinal cord

• interneuron activates several interneurons to activate motor neurons or inhibit antagonist muscles

• triggers other arm/leg to do the opposite action to counterbalance harsh movements

Glutamate

excitatory neurotransmitter

GABA

inhibitory neurotransmitter, opens chloride channel

how does myelin decrease capacitance

capacitance is the interaction of two charges across a space. So, with the thick myelin, the membrane charge is not able to interact with the extracellular space, getting rid of the capacitance factor.

• extracellular positive concentrations will not effect the sodium depolarizing the membrane. makes sodium diffuse faster

length constant

quantified the distance a signal will travel until 37% of the max value.

• axon with more channels => smaller length constant

• will be equal for retrograde and anterograde, but retrograde would not do anything since the sodium channels are inactivated

time constant

time it takes for the response to a stimuli to reach 63% of it’s maximum response

• in a neuron, it’s the depolarization in membrane potential after a stimulus

• larger tc => slower neuronal responses

how does summation work

considered by time and length constants. A change in voltage at the soma has to be strong enough to propogate towards the axon hillox. with multiple stimuli, they can compete or amplify the voltage.

• longer time constant means stimuli will build on eachother. short means the first will dissipate before the next comes.

• longer length constant also means they can build on eachother

what do joint receptors sense

angle

what can visualize unstained cells

• bright field microscopy- hard to see detail

• phase contrast microscopy- enhances contrast, dense regions are dark

• differential interface contrast- enhances contrast somewhat, gives 3D appearance. best for imaging surface

acid/base stains

• eosinophilic (basic structures), most cytoplasmic proteins and extracellular fibers

• basophilic (acidic structures), neuclaic acids such as DNA, RNA, and ribosomes

trichrome stains

• mix of 3 dyes in series, ment to increase contrast

• helps distinguish cells, especially the nuclei, from ECM

types of trichrome stains

• masson’s trichrome stain- nuclei are black, muscle is pink, collagen/cartilage is blue/greem

• Mallory trichrome stain: red nuclei and muscle, RBC and keratin is orange. Collagen, cartilage, and bone are blue

periodic acid schiff

over an H and E stain, makes pollysaccharides bright pink. good for highliting GAGs in basement membrane

write (giemsa) stains

good for blood or bone marrow smears

• stains leukocyte granules

• nuclei are purple

• erythrocytes are pink

silver/gold preparations

good for very thin fibers like neurofilaments, reticular fibers, basement membranes

elastinc stains

highlights elastic fibers brown or purple.

osmium tetroxide

stains lipids and myelin black, need to use a special type of prep that doesn’t remove lipids.

luxol fast blue

myelin stain, gray matter is purple while white matter is dark blue/violet

cresyl violet

nissil stain, basic stain for RER in neuron somas