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Location and funtion of the 4 lobes of the cerebral hemisphere.
Primary Sensory is TOP, Frontal is motor
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What are the 3 components of the brainstem? What are some of the important functions?
Important function: cranial nerve 3-8; resp and cardio function; both visceral and somatic sensory and motor
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What kind of sensory information does the cerebellum integrate?
- planning movements
- accurate movements (simple/skilled)
- learning new skilled movements
- postural adjustment
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Which spinal nerves have somatic (motor and sensory) and which ones have visceral (motor and sensory) innervation?
- T1-L2 and S2-S4: visceral
- All segments: somatic
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What are the three meninges from outer to inner?
- Dura mater (two layers - outer (periosteal) layer and inner (meningeal) layer)
- Arachnoid mater
- pia mater
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Describe the major input pathways to the CNS
- Skeletal muscle and other sensation: both cranial and spinal nerves.
- Special senses:
- 1) Olfaction and vision to cerebral hemisphere via CN's
- 2) Taste and hearing and balance to brainstem via CN's
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Describe the major output pathways from the CNS
- somatic motor: Brainstem (via CN's) and all spinal nerves
- visceral motor: Cranial nerves III, VII, IX, X; spinal nerves T1-L2 and S2-S4
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What are the cranial nerves involved in the parasympathetic nervous system?
- Oculomotor Nerve (III): pupil and lens
- Facial Nerve (VII): salivation and lacrimation (crying)
- Glossopharyngeal Nerve (IX): salivation
- Vagus Nerve (X): Thoracic and abdominal viscera; heart and lungs
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Where does visceral sensory information travel?
- Visceral pain: sympathetic fibres ONLY
- Cardio and resp sensory info: CN's IX and X
- Other types of sensory info (distension, emptiness, etc) via both symp and parasymp
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Where does the visceral sensation from CN's IX and X ender the brainstem?
The NTS, the nucleus tractus solitarius.
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What are the three divisions of the motor-specific cerebrum
- Supplementary motor area: Program complex series of movements
- Primary motor cortex: execution, force, and direction of movement
- Premotor cortex: integration of visual and sensory cues
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What are the brain areas comprising the medial and lateral motor systems?
- Lateral: cerebral cortex - lateral corticospinal (appendicular musculature controlled)
- Medial: brainstem and cerebral cortex (appendicular musculature controlled)
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What are the three subdivisions of the cerebellum and what motor system are they in?
- Vestibulocerebellum (medial MS): balance, vestibulo-ocular reflex
- Spinocerebellum (lateral MS): coordination of muscles, ongoing movement
- Pontocerebellum (lateral MS): motor planning
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Compare and contrast enteroceptors, proprioceptors, and exteroceptors
- Enteroceptors: Sense the internal environment (e.g. nociceptors)
- Proprioceptors: sense length or tension in space, give positional information, (e.g. GTO)
- Exteroceptors: Sense the external environment (e.g. thermo receptors)
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Describe the structures muscle spindle and GTO
- Muscle spindle: intrafusal muscle with nerve ending wrapped around it all wrapped up in a CT sheath.
- GTO: Specialized nerve endings which become intertwined with the collagen bundles of the tendon.
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How does the myotatic reflex work? How is the monosynaptic reflex related to this?
- 1) muscle is stretched by hammer (strong spindle signal)
- 2) singals directly to motor neurons (big Ia afferent synapses directly with alpha motor neurons)
- 3) inhibitory interneurons are also stimulated for the opposing muscle groups
- 4) muscle contracts in the stretched muscles and opposing muscle groups remain relaxed.
monosynaptic reflex is the same bit without the inhibitory interneurons to the opposing muscle group
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How does the withdrawl reflex work? Use the example of stepping on a nail with right foot.
- 1) nociceptors (A delta or C afferent fibres) travel into the spinal cord
- 2) On right thigh: flexors are activated and extensors are inhibited.
- On left thigh: extensors are activated and flexors are inhibited
- 3) move away from painful stimulus.
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What do neural crest cells differentiate into (list 5)?
- Cranial nerve ganglia
- Dorsal root ganglia (MOST IMPORTANT)
- Sympathetic trunk and pre-aortic ganglia
- Parasymp. ganglia of the GI tract
- Adrenal Medulla
- Schwann Cells
- Glial cells
- Meninges
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What are the three layers of the developing spinal cord and what do the last two form?
- Ventricular
- Mantle (grey matter)
- marginal (white matter)
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What is the cause and potential symptoms of Anencephaly?
- - cause is the failure of the Cranial neural tube to close
- - skull cap fails to form
- - abnormal forebrain development
- - failure of fusion in other areas
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What is the cause and potential symptoms of Spina Bifida?
- - Failure of the caudal neuropore to close
- -2 types:
- 1) SB Occulta
- failure of vertebral arches to fuse, common, tuft of hair
- 2) SB cystica
- a) meningocele: meninges protrude into sac
- b) meningomyelocele: spinal cord and meninges protrude into sac
- c) Myeloschisis: undeveloped neural tissue is full exposed (most severe)
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How does carrier mediated transport work?
The solute acts as a ligand, causing a conformational change in the channel and allowing the solute to pass through
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What are the intracellular and extracellular concentration of K+, Na+, Cl-, Ca++
- K+: extracellular (5 mM), intracellular (150 mM)
- Na+: extracellular (150 mM); intracellular (15mM)
- Ca++: extracellular (2 mM); intracellular (0.0002 mM)
- Cl-: extracellular (150 mM); intracellular (13 mM)
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How does the Na+ and K+ ATPase pump work
- 3 sodium out
- 2 potassium in
- at the expense of 1 ATP
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How does secondary transport work?
Uses energy in a concentration gradient to move a second solute.
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What are 4 types of gated channels?
ligand gated; voltage gated, phosporylaation-gated, stretch (or pressure) gated
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Name three methods through which voltage gated channels become inactivated (refrectory state)
- a certain level of depolarization
- A solute binds to them (e.g. calcium) after a certain amount of it is allowed to enter the cell
- The channel dephosphorylizes sometime after depolarization
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What are the three states of the sodium channels?
- resting (ready to be activated)
- activated (when the membrane depolarizes)
- inactivated (if membrane depolarization persists), will only stop if repolarization "resets" the gates. stops the positive feedback loop that causes the steep rise in the action potential
- critical in setting the max firing frequency of neurons
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What is saltatory conduction propagation?
The AP "skips" from node of ranvier to node of ranvier
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What is the gate theory of pain?
- Nociceptive information in spinal cord is modulated by concomitant activation of large myelinated fibers associated
- with low-threshold mechanoreceptors.
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How does the baroreflex work?
- 1) Stretch-sensitive channels in baroreceptors are opened (respond to increased BP)
- 2) baroreceptors fire faster if these channels are opened
- 3) carotid bodies take glossopharyngeal nerve to medulla and aortic bodies take vagus nerve to medulla
- 4) enter medulla at the nucleus tractus solitarii
- 5) decrease in sypmathetic activity in blood vessels (vasodilation) and vagus nerve releases ACh to slow SA firing rate
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How does the pulmonary stretch (Hering-Bruer) reflex works?
- 1) slowly adapting stretch receptor from the thorax travels in the vagus nerve to the dorsal resp. group in the NTS
- 2) NTS exerts an inhibitory effect on the on the nerves responsible for stimulation of the diaphragm
- 3) NTS also inhibits the nucleus ambiguosus (NA) which will travel back down the vagus and decrease parasympathetic activity to the smooth muscles in lung.
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