Exam I Flashcards
1
Q
What day during development does the superior/cranial neuropore close? What day does the inferior/caudal neuropore close?
A
Anterior = day 27
Posterior = day 30
2
Q
What is anencephaly and holoprosencephaly?
A
Anencephaly - failure of cranial end of neural tube to close
Holoprosencephaly - failure of prosencephalon to divide into two cerebral hemispheres; facial deformations = cleft lip and palate, single orbit w/ 2 eyes, 1 eye, 0 eye
3
Q
Differentiate between occulta and cystica in spinal bifida defects
A
Occulta - failure of closure of inferior neuropore; failure of developed vertebral arches
Cystica - sac-like cyst at caudal end of spinal cord (3 types)
Meningocele
Meningomyelocele (meninges & spinal cord, abnormal spine growth, bowel and bladder dysfunction)
Myeloschisis (total paralysis)
4
Q
Functions of basal nuclei of the telencephalon
A
Basal nuclei - subconscious motor contol and muscle tone
5
Q
Function of epithalamus, thalamus, & hypothalamus in the diencephalon
A
Epithalamus:
Habenular nuclei = emotional & visceral responses to odors, pineal body
Thalamus:
Major relay center for afferent & efferent info. to & from cerebrum & other brain parts
Hypothalamus:
ANS control
Mamillary bodies involved in Olfactory reflexes & emotional responses to odors
Intermediary b/w nervous and endocrine system
body temp
Maintain ECM volume
Biorhythm oscillator
6
Q
Functions of the superior/inferior colliculus and tegmentum of the mesenchephalon
A
Superior - visual reflexes
Inferior - auditory & olfactory reflexes
Tegmentum - red nucles, substantia nigra, tracts
7
Q
Functions of the pons (what centers it contains?) and cerebellum of the metencephalon
A
Sleep and Respiratory Centers
Cerebellum:
Coordinated skeletal muscle movements
Maintains equilibrium & posture
Synergic control of muscle activity
8
Q
What vital reflex centers does the medulla of the myelencephalon contain? Olives, pyramids, nuclei
A
Cardiac, Vasomotor, & Respiration centers
pyramids - lateral corticospinal tracts
olives - nuclei related to cerebellum
9
Q
What are the 3 major subdivisions of the nervous system? What are their main components?
A
CNS - brain (sensory, motor, cognitive) & spinal cord
ANS - sympathetic, parasympathetic
PNS - cranial & spinal nerves (entirely motor)
10
Q
Define nucleus and tract
A
You’re on tract if you’re using your brain
dendrites and nerve cell bodies in CNS
Tract - bundle of axons in CNS
11
Q
Define ganglion & nerve
A
Dendrites and nerve cell bodies in PNS
(gangs go out in the periphery/streets and they get on my nerves with all that noise)
Nerve - bundle of axons in PNS
12
Q
White vs. Gray Matter
A
White = myelinated axons
Gray = unmyelinated axons, cell bodies, dendrites
13
Q
White ramus communicans vs. Gray ramus communicans
A
White - carries myelinated pre-ganglionic fibers
Gray - carries unmyelinated post-ganglionic fibers back to spinal nerve
14
Q
Define dendrites and their characteristics vs. axon
A
Receptive unit
- carry info to the cell body
- contain NT receptors
- Conduct local potentials
AXON:
Conductive unit
- Conducts action potential
- Releases NT
15
Q
Paravertebral ganglia vs. Prevertebral ganglia
A
Para - cell bodies contain postganglionic sympathetic nerves
Site of synapses b/w preganglionic myelinated symp. neurons & postganglionic non-myelinated symp. neurons
Pre - anterior to abdominal aorta
Site of synapse b/w preganglionic myelinated symp. neurons & postganglionic non-myelinated neurons
16
Q
What are the components of the reflex arc? (3)
A
Afferent - sensory to CNS
SomatoSensory from nonvisceral (skin, skeletal muscle)
Somatomotor from viscera
Efferent - motor
Somatomotor to skeletal muscle
Somatovisceral to smooth/cardiac muscles
Interneuron (association)
In CNS, modulator
17
Q
List the components of a synapse
A
Presynaptic membrane
Synaptic cleft
Postsynaptic membrane
18
Q
Describe the 3 physiologic states of a neuron
A
Resting = -65mV
Excited = -45mV
Inhibited = -70mV
19
Q
List in order the components of the somatosensory axis
A
PASRCTS
Peripheral receptors
Afferent neurons (primary, secondary, tertiary)
Spinal cord/brainstem
Reticular substance; pons, medulla, mesencephalon
Cerebellum
Thalamus
Somesthetic areas of cerebral cortex
20
Q
ACh; site of secretion and effect?
A
Excitatory
Pyramidal cells (cerebral cortex)
Basal nuclei neurons
Alpha motor neurons
ANS preganglionic neurons
Parasymp. postganglionic neurons
21
Q
NEpi; site of secretion and effect?
A
Either Excitatory or Inhibitory
Brain stem & hypothalamus neurons
Neurons in pons
Most postganglionic neurons of symp. system
22
Q
Dopamine; site of secretion and effect?
A
Inhibitory
Most neurons originating in substantia nigra
23
Q
Glycine; site of secretion and effect?
A
Inhibitory
Synapses in spinal cord
24
Q
GABA; site of secretion and effect?
A
Inhibitory
Spinal cord and cerebral cortex
25
Glutamate; site of secretion and effect?
**Excitatory**
Sensory pathways entering CNS
Areas of cerebral cortex
26
Define electrotonic conduction
The direct spread of electrical current by ion conduction in the **dendritic fluids without generating an Action potental**
Does not generate an ap; becomes weak and dies out
27
Define decremental conduction
Dendrites are long and **thin**
Dendrites are partially permeable to K+ and Cl- ions, causing leakage, causing the potential to be lost
28
What are the factors that determine firing rate?
The normal excitatory rate
Changes in the excitatory rate due to superimposition of additional excitatory or inhibitory signals
(neuron will fire repetitively if signal remains above threshold)
29
Define fatigue of synaptic transmission, explain the mechanism of fatigue
When excitatory synapses are repetitively stimulated at a rapid rate; firing rate becomes progressively less
A protective mechanism against excess neuronal activity
Mechanism; exhaustion or partial exhaustion of the NT in the presynaptic terminals
30
Describe the effects of alkalosis, acidosis, and hypoxia on synaptic transmission
Alkalosis - **enhances excitability**
Acidosis - **depresses excitability**
Hypoxis - **_complete inexcitability_**
31
Describe the effects of caffeine, theophyllin, theobromine, strychnine, and anesthetic on synaptic transmission
Caffeine - **enhances excitability; reduces threshold**
Theophyllin - **enhances excitability; reduces threshold**
Theobromine - **enhances excitability; reduces threshold**
Strychnine - **enhances excitability; lowers inhibitory transmitters**
Anesthetics - **decreases synaptic transmission; increases excitation threshold**
32
Define synaptic delay
The time it takes to transmit a signal from a **presynaptic neuron to a postsynaptic neuron**
33
What are the factors that contribute to synaptic delay? (5)
Time it takes to releases the **Nt from the presyn. neuron**
Time it takes for the **NT to diffuse across the synaptic cleft**
Time it takes for **the receptor to increase membrane permeability**
Time is takes for the **inward diffusion of Na+ ions**
How the **NT acts on the postsynaptic membrane**
**Minimal time = 0.5msec**
34
Distinguish among the fusiform, granular, and pyramidal neurons in the cerebral cortex
**Fusiform -** smaller output neurons (sends info from cortex to other brain parts)
**Granular -** interneurons; short axons (both excitatory; glutamate and inhibitory; GABA)
**Pyramidal -** large output neurons (sends info down to spinal cord)
35
Most output neurons from the cerebral cortex originate from which of the following layers?
I,II,III
IV
V,VI
**V, VI**
I.II.III - intracortical association functions (integrate info within cortex among layers)
IV. - terminal sensory fibers
V.VI - origin of most output signals
36
Primary motor vs. Primary sensory area
Primary motor - **direct connection w/ specific muscles**
Primary sensory - **detect specific sensations**
37
Secondary motor vs. Secondary sensory
Secondary motor - **_patterns_ of motor activity**
Secondary sensory - **_analyze meaning_ of specific sensory signals**
38
List the functions of the association areas and name and describe the 3 important association areas. What major centers do these contain?
Receive and analyze signals simultaneously from multiple motor and sensory cortices
**Limbic association area -** behavior, emotions, motivation, facial recognition (**temporal region)**
**Parieto-occipitotemporal -** _Wernicke's area_ (language comprehension; intelligence; **left side of brain**), angular gyrus area
**Prefrontal -** _Broca's area_ (word formation) almost always **dominant of left side of brain**, planning effective movement
39
Describe the functions fo the angular gyrus, where is it located?
Initial processing of visual language, inferior parital lobe
Located within the **parieto-occipitotemporal association area**
40
Describe the results of cutting the corpus callosum
Corpus callosum - **major commissure b/w the two hemispheres**
Blocks the transfer of info from Wernicke's area to nondominant motor cortex
Prevents the transfer of somatic and visual info from right hemisph. into wernickes area
Results in two entirely separate conscious portions of the brain
(can't comprehend what you're holding, unless you see it in your face)
41
Distinguish between declarative memory and skill/reflexive memory
Declarative memory - **memory of various details of an integrated thought** (surrounding, time relationships, cause of experience)
Skill/reflexive memory - **associated with motor activities**
42
List the 5 basic types of sensory receptors; what do they do
1. **Mechanoreceptors -** tactile, deep tissues, hearing, equilibrium, arterial pressure
2. **Thermoreceptors**
3. **Nociceptors -** free nerve endings to pain
4. **Electromagnetic receptors -** vision
5. **Chemoreceptors -** taste, smell, osmolarity, arterial oxygen, bood CO2, blood glucose, aa, FAs
43
Explain what is meant by differential sensitivities
Each type of receptor is highly sensitive to one type of stimulus and almost nonresponsive to other types
44
Define modality
Each of the principal types of **sensation**
think of a disease, always expresses the same way
45
Describe the labeled line principle
Nerve fibers that transmit only one modality of sensation
Refers to the specificity of nerve fibers for transmitting only one modality of sensation
46
What are the four mechanisms of receptor potentials? MEAT
Mechanical Deformation
Electromagnetic radiation
Application of a chemical
Temp change
47
Describe the receptor potential of the Pacinian corpuscle, what's the relation between the stimulus intensity & receptor potential? Can it stimulate an AP? If so, how?
Deformity Changes membrane permeability which allows more Na+ to enter
Modality gated Na+ channels are open **in response to membrane deformation caused by touch or pressure**
A local, decremental potential is usually created
AP is created if local potential mechanically induces enough channels to open, if strong enough on the first node of ranvier, the local potential will drive a current to generate an AP
48
Define adaptation of receptors
When all receptors are partially or completely adapted to any **constant stimulus** after a period of time
49
Compare tonic vs. phasic receptors
**Tonic**
* slow-adapting
* continuous strength
* transmits impulses as long as stimuli is present
**Phasic**
* Rapidly adapting
* Non-continuous signal
* Only stimulated when stimulus strength changes
50
Differentiate b/w type A and type C fibers
**A**
* Large & medium sized fibers of spinal nerves
* Myelinated
* Fight signal conduction
* Subdivisions - alpha, beta, gamma, delta
**B**
* Small fibers
* Nonmyelinated
* Low velocity conduction
* Group VI - pain, itch, temp, crude touch
51
Spatial vs. Temporal Summation
**_Spatial_**
Increasing signal strength via **progressively increasing the number of fibers**
**_Temporal_**
Increase in signal strength by **increasing the nerve impulse frequency fiber**
52
Describe the discharge, facilitated/inhibition zones of a neuronal pool
**Discharge Zone**
all output fibers stimulated by the incoming fiber
**Facilitated/Inhibition Zones**
Facilitated but not excited
Lay on the outside of the discharge zone
53
Define reverberatory circuit/Oscillatory circuits, what is it caused by?
Caused by (+) feedback within neuronal circuit
Goes on **repetitively**
Continues to fire until another source turns it off
54
Define commissure
Tract in the CNS that decussates
55
What is the function of the cortical layer I.II.III?
Intracortical association functions
56
Describe the primary, secondary, and tertiary neurons in the ascending pathways
**Primary**
via **external receptors**, travel thru dorsal roots of spinal cords and synapse with secondary neurons
**Secondary**
Tracts located in spinal cord and brainstem, terminate in the thalamus and synapse with tertiary neurons
**Tertiary**
From the thalamus to sensory cortex and travel through the internal capsule
57
What are the two spinothalamic pathways and what modalities do they carry? Describe their pathways
_Lateral spinothalamic tract_
**Pain and Temp**
**Secondary axons decussate; joined in brainstem**
**Travel up lateral column**
_Anterior Spinothalamic tract_
**Crude touch, pressure, tickle, itch**
Secondary neurons decussate in anterior gray/white commissure
Synapse w/ tertiary in VPL nucleus of thalamus
Tertiary travel thru internal capsul to primary sensory cortex
58
What modalities does the dorsal column-medial lemniscal system carry? What are the two pathways? Describe them
**Two-point sensation (discriminatory/fine touch), presure, vibration**
**Primary synapse w/ secondary (decussate) in _medulla_, tertiary ascend thru internal capsule to primary sensory cortex**
**Fasciculus gracilis/**slender
Medial; _sensations below_
**Fasciculus cuneatus**/wedge-shaped
Lateral; _sensations above_
59
Desribe primary neurons in sensory pathways; originate where, cell bodies, decussation, synapse
* Originate in periphery
* Cell bodies in dorsal root ganglia
* Synapse in spinal cord with secondary neurons
60
Desribe secondary neurons in sensory pathways; originate where, cell bodies, decussation, synapse
* Originate in spinal cord
* Travel through myelinated columns
* Can decussate through the white/gray commissures
* Synapse with tertiary neurons at VPL in thalamus
61
Desribe tertiary neurons in sensory pathways; originate where, cell bodies, decussation, synapse
* Travel thru internal capsule (myelinated pathway) to the cerebral cortex (primary sensory cortex)
* Synapse at the somatosensory cortex
62
Fast pain vs. Slow pain
Time, Myelination, Fiber type, Termination, which tract do they make up
**Fast**
0.1 sec; **small diameter**, **myelinated** **Type A fibers** = glutamate; Terminate in **lamina I** of dorsal horn; mechanical & thermal stimuli, **Neospinothalamic tracts**
**Slow**
1 sec; **Type C** fibers terminate in spinal cord layer **II & III of dorsal horns (substantia gelatinosa)** of spinal cord = glutamate, **nonmyelinated**; Terminate thruout brainstem layers,
Aching, slow burning, throbbing, nausea, chronic
Elicited by mechanical, thermal, chemical stimuli
63
What type of pain travels through neospinothalamic and paleospinothalamic pathways? (fast/slow)
**Neospinothalamic = fast** (contain tertiary that ascend to somatosensory cortex)
**Paleospinothalamic = slow -** secondary terminate throughout brainstem
64
Define the Brown-Sequard syndrome and its characteristics, what's it caused by?
**Hemisection of the spinal cord**
**All motor functions blocked on the _side of the transection and below_**
Loss of:
pain, heat, and cold (spinothalamic pathway) on the **opposite side below the level of transection**
Kinesthetic and position sensation, vibration sensation, two-point discrimination (medial lemiscus) on **same side below the level of transection**
65
List the 3 components of the analgesia system; what is it?
* Absence of pain sensibility, pain relief without loss of consciousness
* **Periaquaductal gray and periventricular**
* **Raphe magnus nucleus and reticular nuceli**
* **Pain inhibitory complex in dorsal horns of spinal cord**
66
What is the mode of action of thermal receptors and how are temperature sensations projected?
**Warmth nerve endings**
C-Type fibers
**Cold receptors**
A-Type fibers
67
What conditions result in severe pain?
**A diffuse stimulation of pain nerve endings thruout viscera**
**Type C fibers**
68
Define refraction
The bending of light waves at an angulated surface of a transparent material
69
Define refractive index
The ratio of the velocity of light in air to the velocity of light traveling in the substance
RI air = 1
70
Define refractive power
A measure of how much a lens bends light waves
Measured in dipoters
71
Define focal point
The point through which all parallel rays of light will pass after passing through each part of the lens
72
Define focal length
The distance from the center of the lens to the focal point
73
# Define diopter
1 diopter = 1 meter/focal length of a lens
74
Define emmetropia
Normal vision
Parallel light rays from distant objects are in sharp focus on the retina when **ciliary muscle is completely relaxed**
75
Define hyperopia
**Farsightedness**
**Eyeball is short**
**Can see far but not near**
76
Define Myopia
**Nearsightedness**
**When ciliary muscles are relaxed, light rays coming from distant objects are focused in _front of the retina_**
**Can see near but not far**
77
Define visual acuity and resolving power. what is the max visual acuity of the human eye for two-point light sources?
**Resolving power**
The ability to distinguish small/closely adjacent images
**Visual Acuity**
The measurement of resolving power
Light from a distant point source will normally create a spot with a diamter of ~11um and a center that is brighter than the periphery
**Max visual acuity = 1.5-2um**
78
Describe/Trace the Rhodopsin-Retinal visual cycle. What does rhodopsin + light create? What is rhodopsin made up of?
Rhodopsin = Scotopsin + 11-cis-retinal
## Footnote
**Scotopsin + all-*trans*-retinAl**
79
Describe ion flow in rods and compare ion flow in the dark and ion flow in the light
Rod excitation causes hyperpolarization of the intrarod membranous potential
**Outer Segment in the Dark:** (rod activated in dark)
Membrane is leaky to Na+ via cGMP-gated channels which neutralizes the (-) inside the cell, therefore there's reduced electronegativity inside the membrane (-40mV rather than -70 to -80mV)
**Outer Segment in the Light:**
When exposed to light, rhodopsin is cleaved
Retinal stimulates transducin (G-protein) ---\> cGMP phosphodiesterase ---\> catalyzes cGMP ---\> 5'GMP
cGMP reduction **closes Na+ channels and cell becomes hyperpolarized**
80
List the cellular layers of the retina; which ones interneurons, which one forms the optic nerve?
PHBAG; **P**ublic **H**ousing **B****AG**s
**Photoreceptors**
**Horizontal cells**
**Bipolar cells**
**Amacrine cells = _interneurons_**
**Ganglion cells = _optic nerve_**
81
3 neuron indirect pathway for cone vision vs. 4 neuron pure rod vision pathway
BiG BAG
3 neuron cones: BG
**Cones, Bipolar Cells, Ganglion**
4 neuron rods; BAG
**Bipolar, Amacrine, Ganglion**
82
What are the 3 ganglion cells (vision)? Describe them; diameter, what are their functions?
**XYZ**
X - small; transmit 8 m/sec
* Receive excitation from rods and use **bipolar and amacrine cells**
Y - medium; transmit 14 m/sec
* signals represent discrete retinal locations
* Responsible for **color visions**, signal represents discrete retinal locations
Z - large; transmit 50 m/sec
* Respond to rapid changes in visual image; CNS;
83
How much decussation occurs in the optic chiasm?
50%
Both sides of brain receives info from both retinas
84
Trace the visual pathway; what's the function of the lateral geniculate nucleus in transmission gating?
**Optic radiation**
**Lateral geniculate body**
**Optic tract**
**Optic chiasm**
**Optic nerve**
Lateral geniculate nucleus
II.III.V. - receive signals from lateral half of ipsilateral retina; **transmit black and white**
I.IV.VI - receive signals from medial half of opposite retina; **transmits color**
85
# Define primary visual cortex
What are the layers of the primary visual cortex? (6) Define color blobs, where are they located?
Receives the visual data from the lateral geniculate where signals from the two eyes enter alternating stripes of columns in layer IV
**III.IV.V. - transmit signals that depict accurate spatial detail and color**
**IV. -** various subdivisions
**Color blobs** - found in secondary visual areas **(I.II.III.V.VI);** receive lateral signals from adjacent visual columns and are activated specifically by color signals
86
How does accomodation change from children to older individuals?
Children: refractive power = 20-30 diopters
Older Individuals: refractive power = \<2 diopters
Age 70 = 0 diopters
Lens become larger and thicker and more elastic, prebyopia
87
Define impedance matching, what structures are involved?
* Provided by the **tympanic membrane and ossicular system** between the sound waves in air and the sound vibrations in fluid of the cochlea
* When the ossicular system reduces the distance of the stapes and increases the force of movement
* Increased force exterted on the cochlea fluid than the tympanic membrane
* **effectively transmit air-born sound into the fluid of the inner ear**
88
How would hearing sensitivity be affected in the absence of the ossicular system and the tympanic membrane?
Sound waves will be able to travel directly to the cochlea at the oval window **decreasing the sensitivity** of the ear
15-20 decibels less
While normally, tympanic membrane and stapedius muscle dampens the system, creating rigidity of the ossicular system
89
What is the function of Reissner's membrane?
* Maintains a special fluid within the scala media
* Creates a compartment filled with endolymph, important for the function of the organ of corti, functions as a diffusion barrier
* Plays no role in sound conduction and is required for normal function of the sound-receptive hair cells
90
Describe the arrangement of basilar fibers within the cochlea
* Length increases form the oval window to the apex of the cochlea
* Diameter decrease from oval window to the cochlea apex
* **Oval window = short, stiff fibers, high frequency**
* **Cochlea apex = long, limber fibers, low frequency**
91
What is the relation between endolymph and perilymph; where are they found. What's the origin of endolymph? How do these fluids relate to the endonuclear potential?
* Endolymph = **fills scala media (high K+, low Na+)**
* Perilymph = **fills scala vestibuli & scala tympani (high Na+, low K+)**
* Scala media more (+) creating a difference in potential = **endochochlear potential** which is generated by continual secretion of K+ ions into the scala media by the **stria vascularis**
* Hair cells project thru reticular lamina & bathed by endolymph (w/ -150mV potential), & lower hair cells surrounded by perilymph (w/ -70 mV) = high electrical potential = **Cell sensitized increasing ability to respond to slightest sound**
92
In the slow chronic pain, most fibers terminate where?
**Reticular foramen**
93
All visceral pain passes through A delta fibers
T/F
False
