Physiology Flashcards
Pt has motor aphasia (pt speech is slow and has many deleted prepositions). What area is damaged?
Broca’s area (44 and 45)
Pt speaks but makes mistakes unknowingly owing to his inability to understand his own words. What area of the brain is damaged?
Wernicke’s area (22)
Describe the common components of a reflex.
1) Stimulus
2) Receptor
3) Afferent limb
4) Central synapse
5) Efferent limb
6) Effector organ
Describe the components of a deep tendon reflex.
1) Stimulus = tendon stretch
2) Receptor = Muscle spindle fibers
3) Afferent limb
4) Spinal cord segment
5) Efferent limb
6) Effector organ = muscle contraction
What are the cells of the CNS?
1) Astrocytes - creates blood-brain barrier
2) Microglia - CNS phagocyte
3) Oligodendrocyte (myelinates multiple axons)
What is the marker for astrocytes?
GFAP
What cells myelinate the PNS neurons?
1) Schwann cells
What does the alpha motor neuron unit innervate?
Extrafusal muscle fibers
What does the gamma motor neuron unit innervate?
Intrafusal muscle fibers
Describe the passage of the upper motor neuron/first order neuron.
1) Motor neuron originates from the precentral gyrus
2) Initiation of movement arises from the premotor cortex
3) UMN runs through the posterior limb of the internal capusle
4) UMN crosses over in the medulla at the pyramids
5) Once it reaches its spinal level it synapses with the lower motor neuron in the anterior grey horn
What cranial nerves are myelinated by oligodendrocytes?
Cranial nerves I and II (olfactory and optic)
Where do CN I-II originate? III-IV? V-VIII? IX-XII?
1) From the CNS (brain)
2) Midbrain
3) Pons
4) Medulla oblongata
What muscles does CN III innervate?
All of the extraocular muscles except for the lateral rectus (innervated by VI) and the superior oblique (innervated by IV)
What are the pure motor CN?
1) CN IV, VI, and XII
What is the reflex arch for the pupillary light reflex?
1) Stimulus = light
2) Afferent = CN II
3) Synapse = Nucleus of Edinger-Westphal in midbrain
4) Effrent = CN III
5) Effector organ = pupillary constrictor muscle of iris
What is the cerebellum made up of?
1) Vermis
2) Hemispheres
3) Flocculonodular lobe
What spinal tract is involved with conscious proprioception for the lower extremities? for the upper extremities?
1) fasciculus gracilis
2) fasciculus cuneatus (need the cuneatus in order to feel the C made for Go Cru!)
Where does the spinothalmic tract cross in the spinal cord?
1) It cross immediately at the spinal level and ascend contralterally
How is a vibration (conscious proprioception) sensation in the toe projected to the cerebrum?
1) Stimulus triggers peripheral afferent nerve which travels up the ipsilateral side and synapses at the nucleus gracilis or cuneatus
2) 2nd order neuron crosses over at the medial lemniscus and synapses at the contralateral thalamus
4) 3rd order neruon from thalamus sends signal to the sensory cortex
How is pain sensation projected to the cerebrum?
1) Stimulus triggers peripheral afferent nerve which synapses in the Lamina II of the grey horn
2) 2nd order neuron crosses over at the same spinal level and travels in the spinothalamic tract
3) Neuron ascends on the contralateral side
4) Neuron synapses in the contralateral thalamus
5) 3rd order neuron from the thalamus sends signals to the sensory cortex
Where are the organ of corti hair cells located and what is the hair cells associated with the organ of corti function? What CN receives their signal?
1) Located within the cochlea
2) Function in receiving sound
3) CN VIII
Where are cristae located? What is the gelatinous material they are found in? What is the function of the hair cells associated with cristae?
1) Located within the semicircular ducts
2) Found in cupula
3) Recognize angular acceleration
Where are maculae located? What is the gelatinous material they are found in? What is the function of the hair cells associated with maculae?
1) Located within the saccule and utricle
2) Found in otolithic membrane
3) Recognize linear acceleration
What structure of the membranous labyrinth holds endolymph?
Semicircular canals
What is the function of the saccule? the Utricle?
1) saccule measures linear movement in a vertical plane
2) Utricle measures linear movement in a horizontal plane
What produces CSF?
Choroid plexus located in the lateral and 3rd ventricles
What makes up the basal ganglia?
1) Caudate nucleus
2) Putamen
3) Globus Pallidus
What is the lenticular nucleus?
1) Putamen
2) Globus Pallidus
Free ribosomes found in the neuron soma?
Nissl bodies
What is found on dendrites which allows for greater synaptic surface area? What is the result of absence of these structures in the cerebral cortex?
1) Dendritic spines
2) Cause mental retardation
What carries the synaptic vessicles to and from the soma body to the axon terminal?
1) Dynein- carries synaptic vesicles to the soma
2) Kinesin- carries synaptic vessicles to the axon terminal
Axonal transport motor protein that carries synaptic vesicles to the axonal terminal? to the soma?
1) Kinesin
2) Dynein
What determines muscle fiber type?
The motor neuron that innervates the muscle fiber
What are the characteristics of a type 1 muscle fiber?
“One Slow, Fat, Red Ox”
1) Involved in sustaining force, such as weight bearing
2) Slow twitch
3) Increased lipids
4) Red color
5) Abundant myoglobin and oxidative enzymes
What are the characteristics of a type 2 muscle fiber?
1) Involved in sudden, purposeful movements
2) Abundant glycogen
3) Fast twitch
4) White in color
What is normal cerebral blood flow? Ischemia? Infarction?
1) 50cc/100gm/min
2) <1cc/100gm/min
Describe the D1 and D2 receptors function involved in the basal ganglia?
1) D1 receptors are involved with the direct pathway (stimulate the putamen output)
2) D2 receptors are involved with the indirect pathway (inhibit the putamen output)
What is the role of the putamen output?
1) Putamen has an inhibitory affect on the globulus pallidus
What is the role of the globulus pallidus?
1) Globulus pallidus has an inhibtory affect on the thalamus and the subthalamic nucleus
What is the effect of D1 recepors on the thalamus? D2?
1) D1 results in activation of the inhibitory affect of the putamen on the globulus pallidus; results in the thalamus being uninhibted
2) D2 receptors have an inhibitory affect on the putamen resulting in the globulus pallidus being uninhibited, this causes the subthalamic nucleus to be inhibited by the globulus pallidus; inhibited subthalmic nucleus results in there being no activation of the globulus pallidus resluting in uninhibited thalamus
What is the function of the subthalamus nucleus?
1) Causes a stimulatory affect on the globululs pallidus resulting in inhibition of the thalamus
What do both direct and indirect pathways of the basal ganglia result in?
1) Both result in the inhibition of the Globulus palidus
Where does dopamine act in the brain?
1) Nigrastriatal
2) Mesolimbic
3) Mesocortical
Where does the basal ganglia input in the thalamus?
The ventral lateral nucleus
Where do the spinothalamic and dorsal columns input into the thalamus?
The ventral posterolateral nucleus
Where does the trigeminal pathway input into the thalamus?
Think= Make up goes on the face (VPM)
Ventral posteromedial nucleus
Where does the optic nerve input in the thalamus?
Think Lateral = Light
Lateral genticulate nucleus of the thalamus
Where does the superior olvie and inferior colliculus input in the thalamus?
Think Medial = music
Medial genticulate nucleus
Function of Trochlear nerve?
1) Motor- innervates the superior rectus oblique muscle
2) Involved with down and out motion of the eye
Function of the Abducens nerve?
1) Motor- innervates the lateral rectus muscle
2) Involved with abducting the eye
What is the only difference between cranial motor nerves and lower motor neurons?
1) CN motor nerve receive bilateral upper motor neuron control
Describe the Anatomy to maintain horizontal eye movement.
1) Begins in the frontal eye field in the motor cortex
2) Para-pontine Reticular Fasciulus (receives from contralateral FEF)
3) CN VI (receives from the ipsilateral PPRF)
4) MLF
5) CN III (receives from the MLF coming from contralateral side)
What horizontal eye movement does not have MLF involvement?
Accomodation
Where do the cell bodies of the preganglionic parasympathetic fibers lie?
1) CN III, VII, IX, X
2) S2-4
Where do the cell bodies of the preganglionic sympathetic fibers lie?
1) T1-L2
What exits out of the foramen rotundum?
2nd branch of the trigeminal nerve
What exits out of the foramen ovale?
3rd branch of the trigeminal nerve
What passes through the superior orbital fissure?
CN III, IV, and VI
What junctions between cells make up the blood-brain barrier?
Tight junctions
What does the notochord become?
1) Nucleus pulposus
What does the telencephalon become? Diencephalon? Mesencephalon? Metencephalon? Myelencephalon?
1) Cerebral hemispheres
2) Thalamus
3) Midbrain
4) Pons and Cerebellum
5) Medulla
What is the embryologic origin of the thalamus?
Diencephalon
What are the innervations for taste on the tongue?
1) First 2/3 (CN VII)
2) Last 1/3 (CN IX and X)
3) All go to the solitary nucleus in the medulla
What supplies sensation to the tongue? What embryological orgin is this nerve from?
1) CN V3
2) Pharyngeal Arch 1 (Chew!)
What is the motor innervation of the tongue?
1) CN XII
What is the purpose of myelin?
1) Increase conduction velocity (reduces time)
2) Reduce disipation of potential (increases space constant)
Sensory corpuscle that senses dynamic, fine/light touch; position sense; found on hairless skin
Think: quick touching me, I’m not Meissner’s around!
Meissner’s corpuscle
Sensory corpuscle that senses Vibration and pressure
think: Pacinian = Pressure and Proprioception (vibratory)
1) Pacinian corpsucle
Sensory corpuscle that senses pressure, deep static touch, and position sense; located with hair follicles
1) Merkel’s discs
What makes up the blood brain barrier?
1) Tight junctions of endothelial cells
2) Basement membrane
3) Astrocyte foot processes
What are the areas of the brain that do not have a blood brain barrier?
1) Area postrema
2) Neurohypophysis
What is the function of the hypothalamus
Think: the hypothalamus wears TAN HATS
1) Thirst and water balance
2) Adenohypophysis control
3) Neurohypophysis releases hormones produced in hypothalamus
4) Hunger
5) Autonomic regulation
6) Temperature regulation
7) Sexual urges
What makes ADH?
Supraoptic nucleus of the hypothalamus
What makes oxytocin?
Paraventricular nucleus of the hypothalamus
Function of the lateral area of the hypothalamus?
Think: If you zap your lateral area you shrink laterally
1) Controls hunger
2) Destruction leads to anorexia
3) Inhibited by leptin
Function of the ventromedial area of the hypothalamus?
Think: If you zap your ventromedial nucleus you grow ventrally and medially
1) Controls satiety
2) Destruction leads to hyperphagia
3) Stimulated by leptin
Function of the anterior hypothalamus
Think: Anterior = A/C
1) Controls cooling
2) PNS innervation
Function of the posterior hypothalamus
1) Controls heating
2) SNS innervation
Function of the supraoptic nucleus of the hypothalamus
1) Controls circadian rhythm
2) Produces ADH
What does the neurohypophysis release?
1) ADH
2) Oxytocin
What sense does the thalamus not receive?
Olfaction
What structures make up the limbic system?
1) Amygdala
2) Hippocampus
3) Cingulate gyrus
4) Mammillary bodies
What is the function of the limbic system?
Think: the Five F's Involved with in the emotion, memory, and behavior modulation of the following: 1) Feeding 2) Fleeing 3) Fighting 4) Feeling 5) Sex
What are the deep nuclei of the cerebellum (from lateral to medial)
think: Don’t Eat Greasy Foods
1) Dentate
2) Emboliform
3) Globose
4) Fastigial
What is the function of the lateral portions of the cerebellum? Medial?
1) Lateral = voluntary movement of extremities
2) Medial = balance and trunk coordination
What is the primary driver for cerebral perfusion?
1) pCO2 (directly proportional)
2) pO2 is only influential in severe hypoxia (<50 mmHg)
What is common in a pt with increased intracranial pressure?
1) hyperventilation
2) Low pCO2 –> Decreased perfusion –> decreased pressure
What exits out of the optic foramen
CN II
What exits out of the superior orbital fissure?
1) CN III
2) CN V1
3) CN IV
4) CN VI
What exits out of the stylomastoid foramen?
CN VII
What exits out of the jugular foramen?
1) CN IX
2) CN X
3) CN XI
How does CSF exit the 4th ventricle?
1) Lateral via Foramina of Luschka
2) Medial via Foramina of Magendie
Dermatome location for T4? T10? L1? S2,3,4?
1) nipple (T4 = Teat pore)
2) umbilicus (belly butTEN)
3) Inguinal Ligament
4) Penis (S2,3,4 keeps the penis off the floor)
Movement of head toward one side if cheek or mouth is stroked
Rooting reflex
Curling of fingers if palm is stroked
Palmar reflex
Abduct/Extend limbs when startled and then draw together
Moro reflex
Conjugate vertical gaze center
Superior colliculi
Function of inferior colliculi
auditory
What passes through the cavernous sinus?
1) CN III, IV, V1-2, and VI
2) Internal carotid artery
CN V motor lesion
Jaw deviates toward
CN X lesion
Uvula deviates away
CN XI lesion
Ipsilatral drooping of shoulder
CN XII
Tongue deviates toward
UMN lesion of CN VII
Paralysis of Lower face on contralateral side
LMN lesion of CN VII
Paralysis of entire face on ipsilateral side
Muscles of mastification
Think: Ms Munch, Lateral Lowers
1) Masseter
2) Temporalis
3) Medial pterygoid
4) Lateral pterygoid (only one that opens jaw)
What nerve is in close proximity with the superior thyroid artery? What does it innervate? Why is this important?
1) Superior laryngeal nerve
2) Cricothyroid muscle (involved with speech)
3) Commonly clipped during thyroid surgery
Cell body rounding, peripheral displacement of the nuclei, dispersion of Nissl substance in the periphery of the cell
Axonal reaction
