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75 Cards in this Set
- Front
- Back
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multipolar neuron
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many processes off cell body, all dendrites except 1 axon
-most abundant, major type in CNS |
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bipolar neuron
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cell body in middle, 2 extensions off it (one axon, one dendrite)
-rare, found in specializ sensory organs |
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unipolar neuron
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one process extends and forms central and peripheral processes, comprising one axon
-found mainly in the PNS (common in dorsal root ganglia of spinal cord and sensory ganglia of cranial nerves) |
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peripheral nerve regeneration
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macrophages invade schwann and clean up debri (in CNS oligodendrites won't allow invasion), proximal axon sprouts filaments and work their way thru schwann cell to reconnect with distal segment
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MS
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demyelination of CNS axons, autoimmune disease
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NA K pump
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3 sodium for 2 potassium
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graded potential
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chemical stimulus, repolarization occus when stimulus is absent, can be summed
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action potential
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voltage stimulus, repolarization dependent on voltage, all or none
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gap junctions
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channel between cells, a lot in the brain, cardiac tissue and smooth muscle
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at a chemical synapse (6 steps)
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1) AP arrives at ternimal
2) voltage-gated Ca channels open and enters 3) Ca entry causes vesicles to release neurotransmitter contents by exocytosis 4) neurotransmitter diffuses across synaptic celft and binds to receptors on postsyn membrane 5) binding of neurotransmitter opens ion channels, resulting in graded potentials 6) effects are terminated by reuptake thru transport proteins, enzyme degradation or diffusion away from the synapse |
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EPSP
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local depolariz, brings axon hill closer to AP threshold, opens ion channels that allow simultaneous passage of Na and K
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IPSP
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hyperpolariz, drives away from threshold and opens K or Cl channels
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nicotinic receptors
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on skeletal muscle, autonomic ganglia and in the CNS
-excitatory, direct action |
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muscarinic receptors
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on visceral effectors and in CNS, excitatory or inhibitory, indirect action via 2nd messengers
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ACh is used at ALL
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-neuromuscular junctions with skeletal muscle
-all preganglionic autonomic fibers -parasympathetic postganglionic fibers |
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Norepinephrine
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CNS-brain stem, midbrain, limbic system, cerebral cortex
PNS-main neurotransmitter of ganglionic neurons in sympathetic NS Indirect-neurotransmitter binds with receptor, activates 2nd messenger to change membrane perm to open channels |
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parasympathetic
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craniosacral outflow
-no rami communicantes, minimal branching,all pre/postganglionic fibers release Ach Digestion, defecation, diuresis |
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sympathetic
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thoracolumbar outflow
-grey and white rami (white is myelin pregang, grey is unmyelinated postg), extensive branching, all pregang release Ach postganglionic norepinephrine -exercise, excitement, emergency, embarrassment |
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sympathetic chain
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23 pairs, individual paravertebral ganglia linked together as "sympathetic chain"
-preganglionic neurons get out thru grey (info out) and white (info in) rami communicantes |
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every preganglionic neuron originates in lateral horn, once reaches a trunk ganglion, one of three things can happen to the axon (3 pathways)
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1) synapse at same level- travels out thru ventral root, goes into sym chain in white ramus, postgangl exits thru grey ramus and goes to organ
2) synapse at higher or lower level-goes in and goes up or down sym chain before synapsing (allows effects ot be extended to a larger region) 3) synapse in a distant collateral ganglion anterior to the vertebral column (in symp chain, passes into splanchnic nerve, goes into prevertebral ganglion before going on) |
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prevertebral ganglia
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located out near target organ (some for digestive, reproductive)
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location of ganglia
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para- within the visceral organ or close to organ served
sym- within a few cm of CNS; alongside vertebral column and anterior to vertebral column |
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pre/post ganglionic length
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para-long pre, short post
sym-short pre, long post |
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urinary effects
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para-contraction of smooth muscle, voiding
sym-relaxation, inhibits voiding |
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nicotinic locations, etc
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all ganglionic neurons, adrenal medullary, neuromuscular junctions of skeletal muscle (excitation!!)
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muscarinic locations, etc
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ALL PARASYM TARGET ORGANS (excitatory mostly, inhib of heart)
-limited sym targets (eccrine sweat gland activation, vasodilation of blood vessels in skeletal muscle) |
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B1
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heart predominantly, also kidneys and adipose tissue (incr HR, stim renin release)
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B2
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lungs and most other sym target organs, blood vessels serving heart liver and skeletal muscle (mostly inhib, dilates blood vessels and bronchioles and relaxes smooth muscle of organs)
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B3
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ADIPOSE TISSUE (stim lipolysis by fat cells)
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alpha 1
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VIRTUALLY ALL SYM TARGET ORGANS EXCEPT HEART, blood vessels serving skin mucosae abdominal viscera kidneys and saliv glands (shunts blood to heart by constricting blood and visceral organ sphincters, dilates pupils)
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alpha 2
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membrane of adrenergic axon terminals, pancreas, blood platelets (inhibits NE release from adrenergic terminals, inhibits insulin secreation and promotes blood clotting)
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hypertrophy
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muscle fibers get bigger by incresaing number of myofibrils
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hyperplasia
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increase in muscle fibers, we dont have potential for
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binding, bending, breaking 1
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cross bridge formation: energized myosin head attaches to actin myofilament, forming a cross bridge
(need Ca and ATP) |
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binding, bending, breaking 2
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2) the power stroke: ADP and Pi are released and myosin head pivots and bends, changing to its bent low-energy shape. as a result, it pulls on the actin filament sliding it toward the M line
(MYOSIN HEAD FALLS FORWARD, PUSHES FILAMENT) |
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binding, bending, breaking 3
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cross bridge detachment: after ATP attaches to myosin, the link between myosin and actin weakens and the myosin head detaches
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binding, bending, breaking 4
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cocking of myosin head: as ATP is hydrolyzed to ADP and Pi, the myosin head returns to its prestroke high-energy or "cocked" position
(ATP IS HYDROLYZED, CAUSING IT TO COCK BACK UP AGAIN) |
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direct phosphorylation
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coupled rxn of CP and ADP, makes creatine and 1 ATP per CP, 15 sec
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anaerobic: glycolysis (and lactic acid formation)
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use glucose from glycogen breakdown or delivered from blood, glycolysis in cytosol yields 2 ATP/glucose molecule and lactic acid, 60 seconds or more
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aerobic cell respiration
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use glucose, which makes pyruvic acid and combines with FA's from adipose tissue and AA's from protein catabolism to do aerobic respiration in mitochondria, yielding 32 ATP per glucose, CO2 and H20, duration is hours
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greater the load
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less muscle shortens, less duration of contraction and slower contraction, increased latent period (increased EC coupling)
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slow oxidative
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fibers smaller, red, many mito and capillaries
-slow twitch=slow myosin ATPase activity, aerobic, recruitment 1 |
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fast oxidative
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red to pink, intermediate size, many mito and cap
-fast twitch, aerobic with some anaerobic |
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fast glycolytic
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white, large fibers, few mito and cap
-fast twitch, anaerobic |
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training has influence on which fiber type
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IIa intermediate fibers
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Smooth muscle
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involuntary by ANS, shorter/thinner than skeletal, covered only by endomysium
multiunit-less common, in large airways and arteries, fibers are independent single-unit- cells contract as unit (gap junctions allow them to propagate to adjacent cells) |
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caveolae
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little pockets where Ca (extracellular) gets in and waits to be allowed in cell
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varicosities release into
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wide synaptic cleft (diffuse junction)
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smooth similarities to skeletal
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thick and thin filaments, sliding filament mechanisms fueled by ATP, trigger for contraction is rise in IC Ca levels
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differences to skeletal (smooth)
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no troponin, thick to thin is 1:13 vs 1:6, SR less developed and no t-tubules, no sarcomeres (has intermediate filament bundles), caveoli, gap junctions, pacemaker cell, varicosities, HOW THEY CONTRACT
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smooth muscle contraction
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-Ach binds to muscarinic receptor
-influx of IC/EC calcium -Ca binds to calmodulin -calmodulin-ca complex phosphorylates myosin light chain kinase -transfer ATP to myosin to allow binding with thin filiament (actin) -cycle terminated by MLC-phosphorylase |
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other differences in smooth/skeletal contraction
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-smooth slower to reach peak force (30x) but is fatigue resistant and more efficient (can sustain force over longer period of time with less ATP)
-stress-relaxation response -smooth under stress retains integrity and shape |
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smooth muscle hyperplasia
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can increase number of muscle cells, good uterus bad artery wall (can contribute to blockage)
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cardiac muscle differences
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connected by gap junctions, intercalated discs (serve to spread impulse with gap junctions)
-more mitochondria (25% by volume), more capillaries, both autorhythmic and myocytes |
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I band
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thin filaments only, z line is in middle of
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A band
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thick and thin filaments
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H zone
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thick filaments only
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M line
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thick filaments linked by acc proteins, prevents thick filaments from moving "anchors them in"
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thick filaments
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myosin molecules whose heads protrude at opposite ends
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thin filaments
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consists of 2 actin subunit strands twisted into a helix plus 2 types of reg proteins (troponin and tropomyosin)
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sarcomere extends from..
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one z line to the next
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relax--> contracted
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A bands no change in length, but get closer together
I bands get shorter no change in M line no more H zone |
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steps in EC coupling in muscle contraction
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1) AP is propagated along the sarcolemma and down the T tubules
2) calcium ions are released 3) Ca binds to troponin and removes the blocking action of tropomyosin 4) contraction begins |
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CNS
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brain and spinal cord
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PNS
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cranial nerves and spinal nerves
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astrocytes
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most abundant CNS neuroglia, hold things together and provide structure, ensure capillaries in close proximity to neurons
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microglia
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defensive cells, protect against entry of foreign bodies, function like macrophages
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ependymal cells
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line CSF-filled cavities, produce CSF, contain cavities
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oligodendrites
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have processes that form myelin sheaths around CNS nerve fibers
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schwann function identical to...
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OLIGODENDRITES!
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satellite cells
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protective, defensive, insulator of cell body
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cranial nerves
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12 pairs, know...
III-occulomotor VII-facial IX-glassopharyngeal X-vagus nerve (THESE ARE MOTOR SIGNALS OF PARASYMPATHETIC) trigeminal nerve (V)- sensory only, main innervation to upper and lower jaw, use anesthetics injected into this nerve to block this sensory info (ophthalmic, maxillary and mandibular divisions) |
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"mixed" spinal nerves
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31 pairs, cervical (8), thoracic (12), lumbar (5), sacral (5), coccygeal (1)
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funiculus
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represent large tracts of axons either ascending or descending the cord (myelinated)
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3 layers of tissue (meninges) covering the brain and SC
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pia mater-innermost, thin, delicate
arachnoid mater-middle, spider-web like dura mater-outermost, tough mother |
