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Summer Course > Neuro > Flashcards

Neuro Flashcards

Neuro Objectives

1
Q

How are dendrites different from axons?

A

Dendrites are many projections that carry messages to cell body.
Axon is one large projection that carries messages away from cell body.

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2
Q

What are 3 types of neurons?

A
  1. Sensory/Afferent (deliver information to CNS).
  2. Motor/Efferent (deliver commands to peripheral effectors from CNS)
  3. Interneuron (integrate and interpret sensory signals)
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3
Q

What are myelinated neurons?

A

Neurons that have axons covered with neuroglial cells with protein myelin.
Schwann cells in PNS, help regenerate injured PNS axons.
Oligodendrocytes in CNS.

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4
Q

What are nodes of Ranvier?

A

Spaces on axon between glial cells.
Allow for ion to diffuse in and out of neuron, propagating electrical signal down the axon. Allow signal to jump from node to node.

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5
Q

What is a gated channel?

A

Ion channel in cell membrane that opens or closes in response to stimulus. Changes the transmembrane potential.

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6
Q

What are 3 kinds of gated channels?

A
  1. Chemically regulated channels (most abundant on dendrites and cell body of neuron, sites of synaptic communication)
  2. Voltage regulated channel (open and close in response to change in transmembrane potential)
  3. Mechanically regulated (important in sensory receptors responding to touch, pressure, vibration)
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7
Q

What is a graded potential?

A

Changes in transmembrane potential that do not reach threshold to generate action potential. Can be inhibitory or excitatory

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8
Q

What is depolarization?

A

Potential becomes more positive

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9
Q

What is repolarization?

A

Membrane returns to more negative potential (Na+ pumped out of cell)

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10
Q

What is sodium/potassium pump?

A

3 sodium out, 2 potassium in

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11
Q

What is threshold?

A

Typically at -60 to -55 mV, the point at which an action potential is generated

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12
Q

What is resting cell membrane potential?

A

-70 mV. Maintained by keeping + and - ions apart by cell membrane. Leak channels and Na+/K+ pumps maintain resting potential.

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13
Q

What is the sequence of an action potential?

A
  1. Resting potential of -70 mV (Voltage gated K+ and Na+ are closed)
  2. Depolarization to -60 mV threshold (Voltage gated Na+ channels open)
  3. Rapid depolarization to +10 mV (Na+ rushes in)
  4. Inactivation of Na+ channels and activation of K+ channels at +30 mV (K+ pours out of cell, repolarization begins)
  5. Closing of K+ channels at -90 mV (brief hyperpolarization occurs)
  6. Leak channels and Na+/K+ pump return membrane to resting -70 mV potential.
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14
Q

What are 2 types of synapses?

A
  1. Electrical synapse (cardiac cells), gap junctions spread membrane potential to neighboring cardiac muscle cells
  2. Chemical synapse. Synaptic cleft, neurotransmitters.
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15
Q

What is a neurotransmitter?

A

Chemicals release from axon terminals at end of neural impulse, diffuses through synaptic cleft to receptor sites on receiving neuron.

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16
Q

What is sequence of events at a cholinergic synapse?

A
  1. Action potential arrives at axon terminal.
  2. Depolarization opens voltage gated calcium channels, calcium rushes into cytosol, releasing ACh through exocytosis.
  3. ACh diffuse through synaptic cleft and bind to receptors on postsynaptic membrane. Chemically gated channels open to allow Na+ enter postsynaptic membrane.
  4. ACh broken down by ACh-esterase in synaptic cleft and presynaptic cleft reabsorption and resynthesis
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17
Q

Compare and contrast spatial summation with temporal summation

A
  1. Spatial: Simultaneous stimuli arrive at the same time but from different locations.
  2. Temporal: membrane receives different stimuli from same source in rapid succession, 2nd stimulus added to 1st
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18
Q

What are the cranial nerves?

A
  1. Ofactory/Sense/Smell
  2. Optic/Sense/Vision
  3. Oculomotor/Motor/S., M., I. rectus, inferior oblique, eyelid elevation, pupil constriction/dilation.
  4. Trochlear/Motor/Superior oblique (eye downward and lateral)
  5. Trigeminal/Both/ Motor (mastication) Sense (facial and mouth sensation and corneal reflex)
  6. Abducens/Motor/ Lateral rectus (eye laterally)
  7. Facial/Both/ Motor (facial expression, eyelid and lip closure, lacrimal and submandibular and sublingual glands, motor part of corneal reflex) Sense (facial proprioception, taste anterior 2/3 of tongue)
  8. Vestibulocochlear/Sense/ Hearing and equilibrium
  9. Glossopharyngeal/Both/ Motor (gagging and swallowing, parotid gland) Sense (taste on posterior 1/3 of tongue and pharynx and soft palate, info on blood pressure and gas concentrations from carotid chemo/baroreceptors)
  10. Vagus/Both/ Motor (swallowing, parasympathetic fibers to heart and GI) Sense (Relay sensory info from GI, respiratory tract)
  11. Accessory/Motor/ Shoulder movement, head rotation, vocal cords, voluntary swallowing
  12. Hypoglossal/Motor/Tongue movement
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19
Q

What is the dura mater?

A
  1. Consists of fibrous layers (periosteal/outer and meningeal/inner), fused to periosteum of cranium in skull.
  2. Epidural space only in spinal cord.
  3. Between periosteal and meningeal layer are blood vessels (including dural sinuses) which can cause epidural hemorrhage (shows up as “football shape” on CT)
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20
Q

What is arachnoid mater?

A
  1. Simple squamous epithelium arachnoid membrane in contact with dura mater
  2. Subarachnoid space w/ trabeculae and CSF, shock absorber and diffuses gas, nutrients, etc.
  3. Veins crossing between dura mater and arachnoid mater can cause subdural hemorrhage (Shows up as crescent shape on CT) Veins low pressure = slow, gradual bleed
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21
Q

What is pia mater?

A
  1. Consists of collagen and elastic fibers.
  2. Bound tightly to surface of brain by astrocytes (extends into folds and fissures)
  3. Blood vessels superior to pia mater (in subarachnoid space) can bleed causing a subarachnoid hemorrhage (shows up in CT as swelling in spaces “inside” brain that follows folds and fissures). Mixes blood and CSF
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22
Q

What is gray matter?

A
  1. Nuclei = masses of gray matter in CNS
  2. Contains cell bodies of neurons, neuroglia, unmyelinated axons
  3. Integrates information and initiates commands
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23
Q

What is white matter?

A
  1. Mostly myelinated axons

2. Relays motor and sensory information

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24
Q

Describe path of sympathetic chain ganglia

A
  1. Sympathetic chain ganglia: (T1-L2. body wall, thoracic cavity, head, neck, limbs). Preganglionic neuron cell body in lateral gray horns. Travels through ventral root to spinal nerve (where ventral and dorsal root converge) to white ramus comunicans to ganglion and synapses, postganglionic exits through gray ramus comunicans, to either the dorsal ramus (back) or ventral ramus (front). Nerves going to heart and lungs form “sympathetic nerve” bundles
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25
Q

What’s the difference between white and gray ramus comunicans?

A

White ramus carries myelinated pre-ganglionic visceral motor fibers to sympathetic ganglion. “In-door” to ganglion.
Gray ramus carries unmyelinated post-ganglionic fibers from ganglion to target tissue. “out-door” to ganglion.

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26
Q

Describe path of collateral ganglia

A
  1. Collateral ganglia: (abdominopelvic viscera) Preganlionic begins in lateral gray horn, travels through ventral root, through white ramus, straight through ganglia to splanchic nerve, synapses in collateral ganglia, post-ganglionic to target tissue.
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27
Q

Describe sympathetic path to adrenal medullae

A

Preganglionic cell body in lateral gray horn, travels through ventral root, to spinal nerve, to white ramus, straight past ganglia to adrenal medulla, synapse with neuroendocrine cells which release epinephrine and norepinephrine

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28
Q

What level is the conus medullaris?

A

L1/L2

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29
Q

What level is the cauda equina?

A

L2 through L5

30
Q

Compare convergence and Divergence

A
  1. Convergence: multiple inputs from a variety of cells terminate at a single neuron (raise hand above head and catch piece of paper)
  2. Divergence: Single neuron axon may have branches that terminate at different cell (one output going to multiple areas)
31
Q

What are the steps of a neural reflex?

A
  1. Arrival of a stimulus and activation of receptor.
  2. Activation of a sensory neuron.
  3. Information processing in CNS (Simple: sensory synapses with motor. Complex: involves interneurons)
  4. Activation of motor neuron.
  5. Response of peripheral effector
32
Q

Compare monosynaptic with polysynaptic reflexes

A
  1. Monosynaptic: Single synapse, deep tendon reflexes. e.g. “stretch reflex” hit patella with hammer
  2. Polysynaptic: Multiple synapses, can be excitatory or inhibitory. e.g. withdrawal reflex (hot frying pan) or crossed extensor reflex (step on tack)
33
Q

What is positive Babinski sign?

A

After age of two, stroking lateral sole of foot causes toes to fan up, due to damage to CNS or descending tracts

34
Q

What is a hypo/absent reflex?

A

Disruption along sensory nerve, spinal cord, or lower motor neuron

35
Q

What is hyper reflex?

A

Disruption of signal to brain (spinal cord above reflex arc), disruption to brain itself, disruption in inhibitory pathways descending to the applicable muscle

36
Q

What is the corneal reflex?

A

Contact with corneal surface causes blinking of the eyelids (afferent 5 trigeminal, efferent 7 facial)

37
Q

What is tympanic reflex?

A

Loud nose causes reduced movement of auditory ossicles (afferent 8 vestibulocochlear, efferent 7 facial)

38
Q

What is pupillary reflex?

A

Pupil constricts to light (afferent 2 optic, efferent 3 oculomotor)

39
Q

What is pharyngeal (gag) reflex?

A

Contraction of pharyngeal muscles when an object touches back of tongue or throat (afferent 9 glossopharyngeal, efferent 10 vagus)

40
Q

What is a dermatome?

A

Skin sensation supplied by a single nerve.

A dermatome map is useful for diagnosing shingles or localizing pathology.

41
Q

What is the blood-brain barrier?

A

Extensively interconnected capillary endothelial cells (tight junctions), prevents diffusion.
Only lipid-soluble compounds cross. All other materials through regulated channels.
Astrocytes control permeability of endothelium.

42
Q

Where is BBB not present?

A

Portions of hypothalamus, capillaries in pineal gland, pituitary, and choroid plexus (specialized ependymal cells maintain blood CSF barrier instead)

43
Q

Where is the choroid plexus and what does it do?

A

3rd and 4th ventricles. Produces and maintains CSF.

44
Q

What is the flow of CSF?

A

Lateral ventricles through interventricular foramina to third ventricle through cerebral aqueduct to fourth ventricle through lateral and median aperture (roof of 4th ventricle) to subarachnoid space through arachnoid villi to superior sagittal sinus (enter venous circulation)

45
Q

What is location and function of medulla oblongata?

A
  1. Above spinal cord, anterior to cerebellum, posterior to pons, inferior to midbrain.
  2. Reflex centers (Breathing rhythm, BP, thermoregulation, body posture, sleep/alertness)
  3. Cranial nerves 8-12
  4. Sensory and motor relay
46
Q

What is function of Pons?

A
  1. Cranial nerves 5-8
  2. Pneumotaxic and Apneustic centers (processes info from chemoreceptors)
  3. Links cerebellum to medulla, cerebrum, spinal cord.
  4. Sensory and motor pathways
47
Q

What is function of cerebellum?

A
  1. Controls postural muscles to maintain balance.
  2. Fine motor movements.
    (conscious- touching your nose. Subconscious- riding bike)
48
Q

What is cerebellar ataxia?

A

Intention tremor, improves when NOT paying attention.

49
Q

What is function of mesencephalon (midbrain)?

A
  1. Red nucleus (upper limb subconscious movement)
  2. Substantia nigra (inhibits subconscious control of muscle tone and learned movements–Parkinson’s)
  3. Cerebral peduncles (Descending fibers to cerebellum and spinal cord/voluntary. Ascending fibers to thalamus)
50
Q

What is function of hypothalamus?

A
  1. Produces ADH and oxytocin.
  2. Controls HR, BP, thermoregulations via medulla
  3. Controls circadian rhythm (pineal gland)
  4. Coordinates nervous and endocrine system
  5. Subconscious emotional response of skeletal muscles
  6. Stimulates feeding/thirst/satiety center
  7. Limbic system (emotions, memory storage retrieval, link conscious w/subconscious)
51
Q

What is function of thalamus?

A
  1. Affects emotional states (limbic)
  2. Sends info on emotional state to frontal lobes
  3. Integrates/relays sense/motor/special sense info
52
Q

What is function of prefrontal cortex?

A

Abstract intellectual functions such as prediction, inhibition, temporal awareness

53
Q

What are functions of temporal lobe?

A
  1. Auditory cortex
  2. Auditory association area
  3. Olfactory cortex
54
Q

What is Wernicke’s area?

A

Near auditory cortex, language comprehension, “wordbank”

55
Q

What is Broca’s area?

A

Near motor cortex, coordinates breathing and phonation to produce normal speech

56
Q

What are alpha 1 receptors?

A
  1. Excitatory
  2. Peripheral vasoconstriction (reduce flow to unnecessary organs)
  3. GI and urinary sphincters close
57
Q

What are alpha 2 receptors?

A
  1. Inhibitory
  2. Preganglionic neurons
  3. Allow sympathetic to inhibit parasympathetic
58
Q

What are beta 1 receptors?

A
  1. Increases metabolic activity
  2. Increases skeletal muscle metabolic activity
  3. Increases heart rate and contractility
59
Q

What are beta 2 receptors?

A
  1. Inhibitory

2. Bronchodilation (asthma inhaler)

60
Q

What is difference between cholinergic and adrenergic?

A

Cholinergic is stimulated by acetycholine. All parasympathetic use ACh. Most sympathetic use adrenergic receptors (some use ACh).
Adrenergic= epi or norepi.

61
Q

What are functions of parasympathetic?

A
  1. Decrease metabolic rate
  2. Decrease HR and BP.
  3. Increase salivary and digestive secretions.
  4. Increase GI motility and blood flow
  5. Stimulation of urination and defecation
62
Q

What is parasympathetic effect on eyes?

A

Pupil constriction

63
Q

What is P.S. effect on Lungs?

A

Bronchoconstriction and increased airflow resistance

64
Q

What is P.S effect on genitourinary system?

A

Controls detrusor muscle which contracts and relaxes bladder. Also initiates and maintains penile erection

65
Q

What are nicotinic and muscarinic receptors?

A

Both are cholinergic receptors.

  1. Nicotinic: Autonomic nervous system ganglia (PNS and ANS). Muscular contraction. Always EXCITATORY.
  2. Muscarinic: Muscles and glands. At few cholinergic junctions of SNS (sweat glands). Excitatory or inhibitory
66
Q

What is Posterior Column tract?

A
  1. Ascending
  2. Proprioception, fine touch, pressure, vibration
  3. Rises on side it enters, decussates at medulla, goes to primary sensory cortex
67
Q

What is Spinothalamic tract?

A
  1. Ascending
  2. Crude touch, pain and temperature
  3. Decussation at level of entry, continues to thalamus and cerebrum
  4. Tract located on anterior and lateral white matter of spinal cord
68
Q

What is spinocerebellar tract?

A
  1. Ascending
  2. Proprioception
  3. Destination: cerebellum
  4. Anterior tract crosses over at level of entry; posterior tract does not cross over
69
Q

What is corticospinal pathway?

A
  1. Descending
  2. From primary motor cortex, decussates at medulla, to skeletal muscles
  3. Corticobulbar: eye, jaw, face muscles
  4. Anterior and lateral tracts to spinal cord and skeletal muscles
  5. Conscious muscle
70
Q

What is Medial pathway?

A
  1. Descending
  2. Reticulospinal: No decussation, eye and respiratory reflexes
  3. Vestibulospinal: No decussation, balance, posture, muscle tone
  4. Tectospinal: Decussation at midbrain, responses to visual and auditory stimuli
  5. All subconscious
71
Q

What is lateral pathway?

A
  1. Descending
  2. Subconscious
  3. From Red nuclei of midbrain, decussates at midbrain, to upper limbs

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