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