Exam 4: Questions from previous exams Flashcards
Where is the occipital lobe?
Posterior cerebral cortex
The two hemispheres of the brain are separated by what?
Interhemispheric fissure
In the peripheral nervous system, groups of neuronal somata are called ________, and bundles of axons are called _________.
ganglia, nerves
What is the primary function of myelin?
increases the conduction velocity of action potentials
Motor neurons that send their axons out of the central nervous system and connect to muscles develop from cells in what region of the embryonic neural tube?
basal plate
The dorsal root (spinal) ganglia, part of the peripheral nervous system, develop from what embryonic cell group?
neural crest
Failure of the caudal (tail) end of the neural tube to close completely in the embryo will result in a condition in the infant called…
spina bifida
Which of the primary germ layers gives rise to the nervous system in development?
ectoderm
The lateral ventricles derive from which secondary neural vesicle?
telencephalon
Cerebral spinal fluid (CSF) in the subarachnoid space normally drains into the ….
dural venous sinuses
Which layer of the meninges is tightly adherent to the surface of the brain?
pia mater
What structure produces most of the cerebrospinal fluid?
Choroid plexus
Blood from the brain leaves the skull mainly via what pair of veins?
internal juglar veins
What effect will increased CO2 have on blood circulation to the brain?
Vasodilation
In a normal healthy person, approximately what percentage of the blood flow is to the brain?
20%
Blood to the brain enters the skull mainly via what arteries?
Internal carotid arteries and vertebral arteries
Synthesis of mRNA from DNA in the nucleus is a process called…
Transcription
Which of the following is true regarding Schwann cells?
They myelinate axons in peripheral nerves.
How many chromosomes do humans normally have?
22 pairs plus two sex chromosomes
What happens during translation regarding protein synthesis?
Proteins are synthesized by linking together amino acids in a specific sequence.
An axon with which of the following characteristics would be expected to have the fastest conduction velocity?
5μm diameter, myelinated
why do neurons have the refractory period?
Ensures that the action potential is only propagated in one direction
Action potentials are due mainly to what?
Sodium channels opening when a cell becomes sufficiently depolarized.
Activation of excitatory synapses is likely to have what effect on a neuron?
The neuron will initially depolarize
SNARE proteins on synaptic vesicles are activated by…
Ca++
After the neurotransmitter glutamate is released, it typically …
is recycled through astrocytes back to the presynaptic terminal.
In humans, which of the following neurotransmitters is released by motor neurons to initiate contraction of muscles?
acetylcholine
Metabotropic receptors, when activated by an appropriate neurotransmitter, will…
activate an enzyme cascade inside the neuron that leads to opening or closing of nearby ion channels.
Which tract in the spinal cord carries pain information to the brain?
spinothalamic
Where in the vertebral column does the spinal cord end in the adult?
Upper lumbar
What level of the spinal cord has the most white matter?
cervical
Where do axons of the spinocerebellar tract synapse?
cerebellum
list brain structures in the correct rostral-to-caudal order?
- spinal cord, medulla, cerebellar vermis, thalamus, frontal lobe
- spinal cord, cerebellar vermis, medulla, thalamus, frontal lobe
- frontal lobe, thalamus, cerebellar vermis, medulla, spinal cord
- frontal lobe, medulla, thalamus, cerebellar vermis, spinal cord
frontal lobe, thalamus, cerebellar vermis, medulla, spinal cord
what diencephalon structure cannot be seen in a ventral view of the human brain?
thalamus
What artery supplies much of the lateral surface of the cerebral cortex?
middle cerebral artery
The olive and inferior olivary nucleus are major landmarks for what part of the central nervous system?
Upper medulla
The fourth ventricle is on the dorsal surface of what part of the brain?
pons and medulla
The superior colliculus is on the ____ surface of the ____
dorsal surface of the midbrain
To which layer(s) of neocortex does the thalamus project?
Layer IV
What is the function of the thalamic reticular nucleus?
It inhibits the output of other thalamic nuclei to the cerebral cortex.
What layer of myelinated axons divides the thalamus into medial, lateral, and anterior regions?
Internal medullary lamina
Axons from thalamus project to the cerebral cortex via what major bundle of axons?
internal capsule
Which cranial nerve carries somatosensory information from most of the face?
Trigeminal
Which of the following cranial nerves is most important for pointing your eyes at the text when you are reading?
- Facial
- Trochlear
- Vagus
- Accessory
- Hypoglossal
Trochlear
What is the only cranial nerve that exits from the dorsal surface of the brainstem?
Trochlear (CN IV)
What happens when photoreceptors are exposed to light?
They hyperpolarize
The ciliary muscle in the eye is important for what function?
adjusting the diameter of the pupil
The axons from retinal ganglion cells on the nasal (nose) side of the left retina …
synapse in the right lateral geniculate nucleus
What part of the retina is specialized for high acuity vision?
fovea
Cutting the right optic tract would be expected to result in
Loss of the left half of one’s visual field
The main nucleus in the thalamus for relaying visual information to primary visual cortex receives axons of retinal ganglion cells. Which of the following best describes this input?
The input to the thalamus on one side of the brain comes from both eyes, but the axons from the two eyes are segregated into separate layers in the nucleus
Which of the following nuclei is particularly important for the pupillary light reflex?
pretectal nucleus
Vision is processed in the cortex in two main streams. Which of the following statement best describes the ventral stream from primary visual cortex?
It projects to temporal lobe for recognition of objects and faces
Which of the following accurately describes Piezo2?
It can form a channel through which ions pass, causing the cell to depolarize.
Axons in the right dorsal column of the spinal cord carry primarily what information?
proprioception and touch information from the right side of the body
Sensory neurons associated with muscle spindles are activated by what?
Stretch of the muscle
Where is the cell body (soma) of a primary afferent neuron sensing pain in the skin of the leg?
Dorsal root (spinal) ganglion
Which of the following describes pain that outlasts healing?
Chronic pain
what is true regarding the dorsal column pathway and spinothalamic pathway?
Information relayed by these two pathways is carried to the same cortical region.
Stimulation of the periaqueductal gray results in…
analgesia
Sound is conducted through the middle ear by vibration of several structures. What is the correct sequence of these structures from the external ear to the inner ear?
tympanic membrane – three bones – oval window
The sensory apparatus in the semicircular canals are most sensitive to what?
Rotation
The primary auditory cortex, which is important for the conscious perception of sound, is in what lobe of the brain?
Temporal lobe
Suppose a tone with a frequency of 220 hz. resonates 2 mm from the apex of the cochlea. A tone with a frequency of 440 hz resonates 5 mm from the apex of the cochlea. Roughly where will a tone with a frequency of 880 hz resonate?
8 mm from the apex of the cochlea
How many odorant receptors are expressed by one olfactory primary afferent neuron?
1
Where do axons of olfactory receptor neurons synapse?
olfactory bulb
T2-type taste receptors are involved with sensing which of the following tastes?
Bitter
Which taste(s) are innately aversive to humans?
- bitter
- sour
what histological staining methods is most helpful for visualizing dendritic spines?
Golgi
Which of the following statements is TRUE about action potentials?
- The repolarization phase is eliminated if voltage-gated potassium channels are blocked.
- The depolarization phase requires voltage-gated potassium channels.
- Potassium ions enter the cell when the voltage-gated potassium channels open.
- Sodium ions enter the cell when the voltage-gated sodium channels open.
- The membrane potential becomes negative at the peak of the action potential.
Sodium ions enter the cell when the voltage-gated sodium channels open.
Tetrodotoxin (TTX) is a compound that blocks the action of voltage-gated sodium channels. What would be the effect of applying TTX to neurons?
It would be more difficult to generate an action potential.
The resting membrane potential of a cell is closest to the equilibrium potential of which ion?
potassium
Unilateral damage to motor cortex leads to paralysis mainly on the ____ side of the body. Unilateral damage to the spinal cord leads to paralysis mainly on the ____ side of the body.
contralateral, ipsilateral
Where can lower motor neurons be found?
ventral horn of the spinal cord
What neurotransmitter is released at neuromuscular junctions to initiate muscle contraction?
acetylcholine
Each muscle fiber is targeted by how many neuromuscular junctions?
1
The major input to the striatum is from …
cerebral cortex
Which axon tract divides the striatum?
internal capsule
Which of the following nuclei is NOT part of the striatum?
- caudate nucleus
- nucleus accumbens
- globus pallidus
- putamen
globus pallidus
Degeneration of neurons in what results in Parkinson’s disease?
substantia nigra
What is a major direct input to Purkinje cells? Axons from …
cerebellar granule cells
In most regions of the cerebellum, Purkinje cells send axons to the …
a deep cerebellar nucleus.
Parallel fibers originate from what?
Granule cells
what is a major source of axons that leave the cerebellum (i.e. output of the cerebellum)?
Deep cerebellar nuclei
What is TRUE about the effects of the brain on locomotion?
Descending glutamatergic pathways are required to initiate walking.
Golgi tendon organs relay information via ____ fibers about ____.
Ib, weight bearing
what is TRUE regarding the central pattern generator (CPG) for walking?
The CPG includes inhibitory interneurons whose axons cross the midline of the spinal cord.
Typically, while walking, activation of the motor neurons for extensor muscles in one leg will roughly coincide with…
inhibition of the motor neurons for flexor muscles in the same leg.
Which eye movements do you make when you are reading?
fixation followed by a saccade
Which type of movement is most essential for reading a street sign when you are walking down the street?
Vestibulo-ocular reflex
Which cranial nerve directly innervates the medial rectus muscle?
oculomotor (CN III)
If you want to look to the left, which extraocular muscles must contract?
lateral rectus muscle of the left eye and medial rectus muscle of the right eye
Urbach-Wiethe disease, which results in the bilateral loss of the amygdala, leads to…
decreased feelings of fear.
Septal lesions can cause which of the following?
Enhanced aggression
what is a symptom of Korsakoff’s syndrome?
confabulation
In the Papez circuit, neurons in the mammillary bodies receive input directly from the ____ and then project their axons to the ____
hippocampus via the fornix, anterior nucleus of the thalamus
Which of the following are characteristics of hypothalamic control of anterior pituitary function?
Hypothalamic releasing hormones are transported to the anterior pituitary via a portal vein.
The hypothalamus appears to regulate feeding. Which of the following statements regarding feeding is TRUE?
- Ghrelin is a hormone produced by white fat cells that creates the sensation of fullness.
- Ghrelin, leptin and orexin are synthesized by the arcuate nucleus of the hypothalamus.
- Leptin is a hormone synthesized by the stomach that creates a sensation of hunger.
- Orexin is a hormone synthesized by white fat cells that creates the sensation of hunger.
- Stomach filling inhibits release of ghrelin.
Stomach filling inhibits release of ghrelin
A blow to the head that completely severs the pituitary stalk most likely would result in …
loss of the milk-ejection reflex
What part of the hypothalamus contains neurons that are directly activated by INCREASED body temperature?
Preoptic nucleus
Neurons that are part of the enteric nervous system are in the …
intestine
If a person’s blood pressure was too high, you might consider giving them a drug to block signaling by what neurotransmitter?
norepinephrine
Which of the following is a characteristic of the sympathetic nervous system?
Preganglionic neurons are in the thoracic spinal cord.
Preganglionic parasympathetic axons for control of the heart, lungs and a portion of the gut run in the …
vagus nerve (CN X).
During the two-point discrimination test, the mean distance at which students could reliably discern whether they were probed by one or two pins was 2mm on the index finger and 20mm on the forehead. The p value comparing these two regions was 0.03, with significance defined as 0.05. Which of the following statements is true?
- Density of sensory receptors in the skin of the index finger is higher than that of the sensory receptors in the skin of the forehead.
- The sensory receptors in the skin of the forehead are significantly less sensitive to pain compared to those on the skin of the index finger.
- The sensory receptors in the forehead have a lower resting membrane potential and therefore they are less sensitive.
- There was no statistically significant difference between the discrimination of the index finger and the forehead.
Density of sensory receptors in the skin of the index finger is higher than that of the sensory receptors in the skin of the forehead.
What structure is responsible for the blind spot?
Optic nerve head
Where is the first synapse for touch and proprioceptive information from the leg?
Nucleus gracilus
