Exam I Flashcards
Describe the mechanism of muscle contraction
- nerve impulse triggers release of ACH into synaptic cleft - initiates muscular impulse
- as muscle impulse spreads to T-tubulues, Calcium ions are released
- Calcium ions bind to troponin - troponin changes shape, moving tropomyosin and exposing actin binding sites
- Myosin binds to exposed actin sites
- Myosin heads pivot, moving thin filaments toward the sarcomere center. ATP binds myosin and is broken down into ADP. Myosin detach from thin filaments and return to original position.
- Repeat of step 5 results in sliding of thick and thin filaments past one another (contraction)
- When impulse stops, calcium ions are transported into sarcoplasmic reticulum, tropomyosin reverts back, and filaments relax
Understand compartmentalization of body fluids
Total Body Water: 60%
ICF: 40%
ECF: 20%
ECF split:
- -ISF: 15%
- -Plasma: 5 %
transcellular fluid: CSF, digestive secretions, synovial fluid, etc.
Know types and examples of membrane transport especially passive vs. active transport
- Active transport: against gradient & requires ATP
A. Primary: Na/K+ ATPase
B. Secondary: carrier mediated; uphill (SGLT glucose) - Passive transport: with gradient; no energy
A. Facilitated diffusion: GLUTS
Discuss difference between electrical and chemical gradients
Electrical gradient: electrical force
Concentration gradient: chemical force
- at equilibrium: no net movement of ions
- determined by ion conc. gradients
- ***K+ (leak)
- ***Na/K+ pump (low intracell. Na; High intracell. K+)
What is the normal resting membrane potential across the membrane?
-70 to -80 mV
- established by diffusion potentials
- K+
Know everything about each stage of an action potential
- Upstroke: Depolarization (less neg.)
- -open voltage gated Na channels
- -Na influx - Overshoot
- -influx of sodium
- -potential very + - Falling: Repolarization
- Voltage gated K+ channels open
- Na channels close - Undershoot (Hyperpolarization)
- slow closure of K+ channels
Fiber types
A-fast (somatic sensory)
B-Fast (pre-ganglionic ANS)
C-slow (pain, temp; post-ganglionic)
Describe Skeletal Muscle activation
- action potential
- Depol along T-tubules
- Ca2+ release
- Ca2+ binds troponin C
- expose myosin binding site
- cross-links
Describe SM activation
- stimulus for Ca2+ entry into cell
- Inc. intracellular calcium
- Binding of Ca2+ to calmodulin
- myosin light chain kinase
- phosphorylation of light chain kinase
- Inc. myosine ATPase
- myosin-actin binding
Autonomic regulation is coordinated by
hypothalamus and brain stem
The nervous system is split into somatic and visceral. Describe visceral
Afferent: Viscerosensory
Pain (e.g., ischemia,
distension, cramping)
& REFLEX
Efferent: SM & CM and glands
Describe origins of sympathetic vs. parasympathetic
Sympathetic:
– “Thoracolumbar”
Intermediolateral cell column T1-L2 (IML) of SC
Intermediate gray: sympathetic pre-ganglionic neurons
Parasympathetic
- “Craniosacral”
- CN’s 3,7,9,10 *
- S2-S4
The adrenal medulla is a specialized ganglion in the sympathetic division of the autonomic nervous system. The cell bodies of its pre-ganglionic neurons are located in the thoracic spinal cord. They travel to the greater splanchnic nerve where they synapse and release
Ach on nicotinic receptors
- secretes mainly epinephrine
- -PMNT
Sympathetic have ___ pre- and ___ post ganglionic cells. Parasympathetic have ___ pre and ___ post.
Sympathetic:
- Pre = short; Ach to nicotinic
- Long post = Norepinephrine; adrenergic receptors
Parasympathetic:
- Pre = long (Ach, nicotinic)
- Post = short (Ach, muscarinic)
Sympathetic pre-ganglionic and post-ganglionic info
Pre:
T1-L2 lateral horn
Post:
- paravertebrl ganglia (sympathetic chain)
- pre-vertebral ganglia (celiac)
- adrenal (chromaffin)
Parasympathetic pre-ganglionic vs. post-ganglionic
Pre: CN 3, 5, 7, 9
Post: wall/effector organs; associated with CN
Adrenoreceptors (Sympathetic)
- Inc. heart
- Constricts SM vessels
- Dilates SK (SM) vessels
- Dec. GI motlity
- Bronchodilator
- Ejaculation
- Relax bladder wall; constrict sphincter
- Inc. sweating (M sympathetic)
- Dilates pupil (eye)
- Inc. renin
- Inc. lipolysis
a1:
- vascular SM
- GI, sphincters
- bladder
- iris (radial muscle)
a2:
- GI
- adrenergic neurons
B1:
- heart
- salivary
- adipose
- kidney
B2:
- cronchioles
- skeletal muscle SM (vascular)
- GI
- bladder
G-proteins and their receptors
GI: inhibition of cAMP
–A2, D2, M2
Gs: Inc. cAMP, adenylyl cyclase
–B1, 2, 3 & D1
Gq: Phospholipase C, IP2, DAG; Ca2+
-M1, M3, A1
Spinal cord arrangement
Inner: gray (neuronal cell bodies)
Outer: white matter (tracts; myelin)
Dorsal: sensory
Ventral: Motor
DRG: all sensory info from periphery and CNS (pseudounipolar)
Somatotropic organization: the lateral cortex controls
Face and arms
Somatotropic organization: the central gyrus is split into pre and post. What neurons are in these sections?
Pre: primary motor
post-primary sensory
PCMl detects
discriminative touch, pressure, vibration, two point discrimination, proprioception
ALS detects
pain, temp, light touch
PCML lower extremity signals travel through what fasciculus? Upper?
Lower: Midline: grascilis fasciculus
Upper: cuneatus fasciculus
How are images viewed?
Inverted vertically
Reversed horizontally
Describe vision pathway
Nerve Chasm Tract Last. Geniculate body Cenuculo Cerebral cortex
Describe what occurs when you cut parts of the eye
- Optic nerve: ypsilateral blndness (same eye)
- Optic chiasm: bitemporal hemianopia
—both eyes; bitemporal loss - Tract: contralateral hemianopia
- loss of temporal in one eye, loss of nasal in the other
Cones of the eye are responsible for
Color
3types: iodopsin
R,B,G
20/20 vision
Rods of the eye are responsible for
Black/white vision
Rhodopsin: purple/blue
Phototransduction:
- Light closes Na gated channels
- Dec. influx; dec. dark current
- Hyperpolarize
- Dec. glutamate
- Inhibit retinal nerves
- Excitation
Flow of CSF
- Lateral ventricle
- Interventricular foramen
- 3rd ventricle
- Cerebral aqueduct
- 4th ventricle
- —branch either to foramen lunches OR to Median aperture
- subarachnoid space
- Arachnoid villi
- Superior Sagittal sinus
Hydrocephalus
Block cerebral aqueduct
Choroid plexus
Lines ventricles
- where CSF is made
- infections (meningitis)
Ependymoma
Cancer of 4th ventricle (CSF flow)
CST: cortisol spinal tract steps
- motor
- 2 neuron pathway
(Primary/upper motor neuron)
- Primary motor cortex
- Midbrain
- Cerebral peduncles
- Pons
- Medulla
Desiccates (secondary/lower motor neuron)
- Cervicomedullary junction (lateral cortico spinal tract; LCST)
- Synapse at anterior horn cells
- Skeletal muscle
Basal ganglia is part of The limbic system. Describe
Areas:
Substantia Nigra
Nucleus accumbens: addiction
Functions: -motor movement -blocks unwanted movements Habit -cognition -emotion
Dysfunction: huntington’s; Parkinson’s,s
Describe cortico-basal-ganglia-loop
Dopamine-dependent
D1: direct
- wanted movements (excitatory)
- dysfunction leads to hypokinesia (ex: parkinson’s)
D2: indirect
- inhibits unwanted movements
- dysfunction: hyperkinesis (ex: huntington’s Choreoform or turrets)
Cerebellum
Fine tunes motor movements
- Purkinje: GABA-ergic to deep cerebellum nuclei
- Disinhibition for motor learning
- interconnected with vestibular system
Damage: clumsy motor movements (tremors)
Broca’s area
Speech formation
Broca’s aphasia: comprehend but can’t make correct sounds/words
Slurring
Wernicke’s area
Language comprehension
Wernicke’s aphasia: difficulty understanding language and their speech doesn’t make sense
Disinhibition
Inhibit the inhibitor thus causing excitation
Glial cells
Support cells
- Microglia: macrophages
- Ependymal: choroid plexus; CSF
- Astrocytes: BBB tight junctions & reactive gliosis
- oligodendrocytes- myelin
Post-mitotic
**tumors
Taste innervation
CN: 7 (anterior; chordates tympani)
CN 9, 10 (posterior 1/3 of tongue)
-gag; epiglottis
Synapses: nucleus solitaris, medial meniscus
Thalamus
Taste is controlled by what parts of the brain
Frontal cortex: perception
Hypothalamus/Amygdala: motivation/emotion
Hippocampus: memory
Smell is controlled by what parts of the brain
Frontal cortex: perception of smell
Hypothalamus/Amygdala: motivation/emotion
Hippocampus: memory
Smell is innervated by
CN I (olfactory nerve)
- olfactory receptor neurons
- to olfactory bulb
Alpha motor neurons
From anterior horn to muscle
Brown Sequard syndroms
1) Lesion below medulla
1) PCML: ypisilateral symptos
2) ALS: contralateral
3) LCST (motor): loss of motor function (ypsilateraL
B12 deficiency
1) Subacute combined degeneration of the spinal cord
2) Demyelination of PCML
3) LCST: muscle weakness, spastic paralysis
4) + Romberg test
5) + Babinsky
Lesion above the dessucation
1) PCML: contralateral symptoms
2) ALS: contralateral symptoms
UMN vs LMN lesions
UMN:
Weakness, Inc. atrophy & reflexes, tone, **Babinsky
LMN:
Weakness, Dec. atrophy and reflexes, tone, **Fasciculations
Know what constitutes an UMN vs. LMN and know characteristics signs if they’re damaged
1) Upper motor neuron lesion: spastic paralysis; everything goes up
2) Lower motor neuron lesion: flaccid paralysis (everything goes down)
3) Babinsky:
1) present in upper motor neuron: toes point up
2) Absent in lower motor neuron: toes don’t point up
Anterolateral system
2) Anterolateral system (Spinothalamic tract):
1) Pain
2) termperature
3) light touch
4) Information travels:
1) A-delta and C-fibers: slow, small diameter, unmyelinated
5) Direction:
1) First order neurons decussate immediately at anterior commissure of spinal cord (primary afferent)
2) 2nd order neurons in thalamus
3) Third order neuron in somatosensory
4) 4th order neuron in
- *first order neurons have cell bodies in DRG (substantia gelatinosa)
- *synapse at level of pain or travel via Lissauer’s tract
- lose info on contralateral side
- Lesion in DCS: results in loss of ypsilateral fine touch and proprioception
- Lesion in ALS: contralateral loss of pain and temp
PCML system
1) Dorsal column system (PCML):
1) fine touch (mechanoreceptors)
2) pressure,
3) two point discrimination,
4) vibration (Tuning fork test)
5) proprioception (Romberg test)
Information travels:
6) Lower extremity: gracilis fasciculis;
7) Upper extremity: cuneatus fasciculus
8) A-Beta fibers
Direction:
9) Ascend ypsilaterally – decussate contra-laterally at lower medulla
1) Crosses midline in the brainstem
2) 1st order neurons: ypsilateral to brainstem (past spinal cord)
3) 2nd order neurons: thalamus
4) 3rd order neurons: sensory cortex
Types of sensory receptors
1) Mechanoreceptors – pressure/changes in pressure (Pacinian corpuscles; baroreceptors)
2) Photoreceptors (light/vision)
3) Chemoreceptors (chemicals – olfaction, taste, detect O2 and CO2) (carotid body)
4) Thermoreceptors – temperature (TRPV1)
5) Nociceptors –pain; extremes of pressure, termperature, noxious chemicals
Sensory transduction vs. receptor potential
3) *Sensory transduction: environmental stimulus (light, pressure) activates a receptor and converts it into electrical energy (ex: TRPV1 – responds to heat/capsaicin)
4) Receptor potential: inc. or dec. likelihiodd that action potential happens
Hearing is controlled by what cranial nerve?
CN 8 (vestibulocochlear)
- external ear: Pinna (sound waves)
- Tympanic membrane (eardrum) between external and internal
- Middle ear: Malleus, stapes, incus (sound amplification)
- Oval windown
- Inner Ear: cochlea (hearing and equilibrium)
Sound amplification
- mechanoreceptors
- Eardrum vibrates – causes malleus to vibrate increasing vibration in incus and stapes
- Hair cells: vibrations/sound waves
Hair cells in the organ of corti transduce sound signals. How?
Organ of corti: sensory organ for sound
-K+ enters – depolarizes – transduction
Hearing muscles
stapedius: CN 7 (stapedial branch)
Tensory tympani: CN 5 (V3)
Vestibular system is involved with balance. What are structures?
Semicircular canals: rotary movements
Endolymph: motion sensors
Saccules: tilt vertical; gravity
Utricles: tilt horizontal
Describe pupillary light reflex
- Light enters
- Into optic nerve (CN 2)
- to Occipital lobe
- -pre-tectal area
- -lateral geniculate nucleus
- -**Eddinger westfall nucleus (both eyes)
Out:
- CN 3 oculomotor
- pre-ganglionic to cilia to post-ganglionic
* sphincter papillary muscle
- -constriction/dilation
