hsc 476 exam 1

\*Which anatomical structures are visible only with the aid of a microscope?

Neurons

\*How many neurons are in the entire nervous system?

100 billion

\*EPSPs are created by a bombardment by neurotransmitter quanta on which structure?

Dendrites

\*IPSPs are created by a bombardment by neurotransmitter quanta on which structure?

Cell bodies

\*What is the initial segment and what does it do?

\-processes/computes EPSPs and IPSPs (to generate an action potential with enough epsps)

\-trigger zone

\*Which classes of neurons are myelinated?

A and B classes

\*which class of neuron is unmyelinated?

C class

\*What kind of neurons innervate skeletal (extrafusal) muscles?

A-alpha neurons

\*Where is the cerebral longitudinal fissure and what does it do?

major fissure that runs on the sagittal plane, Extends from front to back, separates two hemispheres, not a complete cut

\*in the pns, myelin is made from

schwann cells

\*in the cns, myelin is made from

Oligodendrocytes

Function and location of schwann cells

\-Assist in repair

\-promote regrowth

\-located in PNS

\-makes myelin in pns

Function and location of Oligodendrocytes

\-Inhibit repair

\-inhibit regeneration

\-located in CNS

\-makes myelin in cns

Glial cells

\-Makes up myelin

\-encapsulates axons

\*What is the purpose of myelin/what does it do?

\-insulation, create faster conduction velocity

\-blocks ion movements (action potential must jump from node to node)

\*neurons that are unmyelinated will have

a very slow conduction velocity, no insulation, and no nodes of ranvier

Where are the Nodes of Ranvier and what do they do?

\-Interruptions in the myelin sheath where the axon is exposed to surrounding fluids

\-facilitates the rapid conduction of nerve impulses

\*from which structure is neurotransmitter released form the neurons?

released from vesicles located in the axon terminal

\*neurotransmitters are stored in

vesicles in the axon terminals

\*Which area of the muscle spindle contains sensory endings?

Central area

\*Which area of the muscle spindle contracts and stretches?

Polar area

\*when the polar area stretches and contracts, this causes

the central/sensory area to react

\*Are the gamma motor neurons a part of the pyramidal or extrapyramidal system?

extrapyramidal

\*we can also control the muscle spindles voluntarily with the pyramidal motor system as evidenced by the fact that

we can inhibit a reflex consciously, we can modify this extra pyramidal system if we need to (it can be controlled voluntarily if needed)

\*Where are multipolar neurons commonly found?

in vertebrates

\*what are striated muscles called?

extrafusal

\*striated/extrafusal muscle fibers are primarily involved in

supplying force of contraction

\*what are muscle spindles called?

intrafusal muscle fibers

\*How many cervical vertebrae are there?

7

\*How many thoracic vertebrae are there?

12

\*How many lumbar vertebrae are there?

5

\*vertebral column protects the

spinal cord

\*What's the biological advantage of having convolutions?

convolutions create a bigger surface area, enabling us to have a greater brain mass in a small skull (they are present in intelligent animals)

\*This plane separates tissue into a front and back and divides the body into anterior and posterior portions

coronal dissection

\*This plane divides the body into left and right portions

sagittal dissection

\*This plane creates an upper and lower division and divides the body into superior and inferior portions

transverse dissection

\*Where is the foramen magnum located?

base of the cranium (the inferior side of the skull)

what happens when the brain stem passes through the foramen magnum?

it becomes the spinal cord

\*What constitutes white matter?

fiber tracts (Myelinated axons, oligodendrocytes, fibrous astrocytes, kinds of microglia)

\*what constitutes gray matter?

cell bodies of neurons (neurons, dendrites, synapses, protoplasmic astrocytes, microglia, kinds of oligodendrocytes)

Does gray or white matter do more processing?

Gray

\*What space is the cerebrospinal fluid surrounds in the brain?

subarachnoid space

\*What is the epidural space?

This is the space between dura (thickest part) and the skull. It is the potential space between periosteum and calvaria in the cranium or the space between the dura and vertebral periosteum

\*the cns consists of

the brain, brain stem, and spinal cord

What happens if the epidural space is affected?

an epidural hematoma, which is a pooling of blood between dura and the skull. Pressure is put on the soft brain rather than the skull potentially leading to damage.

What can cause migraine headaches?

the vasodilation is the epidural space and pressure on the dura matter, which results in trigeminal pain

What is the subdural space?

the thin space between dura and arachnoid layers. it is one cell thick

What happens when the subdural space is affected?

subdural hematoma, which is bleeding in the subdural space

How do we define the CNS?

brain, brain stem, and spinal cord. Cell bodies\=nucleus and myelinated axons are known as tracts

How do we define the PNS?

everything that is not the brain, brain stem, and spinal cord. Cell bodies\=ganglia and myelinated axons are known as nerves

\*What is the fundamental task of the nervous system and its neurons?

signaling

Ganglion and nerves are a part of which nervous system?

PNS

Nuclei and tracts are a part of which nervous system?

CNS

\*in the cns, collections of myelinated axons are called

tracts

\*in cns, collections of cell bodies are called

nuclei

\*in the pns, collections of cell bodies are called

ganglia

\*in the pns, collections of myelinated axons are called

nerves

\*At what level of the vertebrae/spinal nerve trunks do sensory and motor neurons of the spinal cord enter and exit across both the superior and inferior surface of the same segment of the vertebral segment and only across the inferior/bottom surface thereafter?

After/at C7 (before c7, only on top)

\*What do we call C1?

atlas

\*What do we call C2?

axis

\*Which space is larger than the subdural space, contains CSF, and subarachnoid cisterns?

subarachnoid space

\*what is the space between the middle most and innermost protective covering of the brain

subarachnoid space

\*the space found between the outermost and middle most protective covering of the brain is called

subdural space

\*What makes up the fibrous septa?

\-Falx cerebri

\-Falx cerebelli

\-Tentorium cerebelli

\*what is the fibrous septa

supports the brain, separates the two hemispheres

\*what separates the two cortical hemispheres

falx cerebri

this extends into and fills the cerebral longitudinal fissure and is the medial matrix of support for the two cerebral hemispheres. It is also sickle shaped

Falx cerebri

Continuous with the falx cerebri, this part continues posteriorly to separate the two cerebellar hemispheres. Barely anatomically signficant

Falx cerebelli

\*what separates the two cerebellar hemispheres

falx cerebelli

\*where is the tentorium cerebelli located

horizontally in the transverse fissure

This runs horizontally and continuous with the falx cerebri and falx cerebelli (leading to a bisection of these). It separates the occipital lobe and cerebellum. It also fills in the transverse fissure.

Tentorium cerebelli

What do the fibrous septa do?

Provide a support matrix to the brain.

\*the surface vasculature is contained/held in place by what?

the innermost covering of the brain, the pia mater, which is one cell thick

Which of the 3 meningeal layers holds the vasculature directly to the brain's surface and follows the brain’s contours?

Pia mater

\*Where is CSF located?

subarachnoid space

\*What is the purpose of CSF?

to moisten/lubricate and protect the brain/brainstem/spinal cord (decreases forces like gravity and maintains the shape of the brain and helps transport neurochemicals)

\*What manufactures the CSF?

the choroid plexus in the ventricles. It is made by glial cells called ependymal cells

Is the CSF compressible? Is it protective?

It is not compressible or protective, but it does support the shape of the brain

\*the grooves/indentations on the brain surface are convolutions called

fissures or sulci

What is a sulcus?

fissures or furrows that are found on the cerebral cortex in convoluted brains

\*What is a gyrus?

bumps or raises areas found on the cerebral cortex in convoluted brains

\*What is contralateral?

opposite side

\*What is ipsalateral?

same side

\*Where is the lateral sylvian fissure?

located on the superior surface of the temporal lobes

\*a fissure that represents a type of incomplete transverse cut is called the

lateral sylvian fissure

\*What is the fissure of Rolando/central sulcus?

runs vertically, it separates motor (frontal lobe; precentral gyrus), from sensory cortex (parietal lobe; postcentral gyrus)

\*The major blood supply to the brain is provided by?

vertebral arteries and the internal carotid arteries

\*What is the circle of willis and what are its components?

Vascular anastomosis formed by posterior communicating and cerebral, and anterior communicating and cerebral. the vessels encircle the optic chiasm

the circle of willis is named after

sir thomas willis

\*what is the circle of willis

a system that ensures constant blood flow, but only in the case of a severe vascular blockage

\*the venous sinuses of the brain are formed by a separation of 2 layers of the dura mater. What are these layers?

the meningeal and periosteum layers of the dura mater

\*If damaged, what major cerebral artery will cause left homonymous hemianopsia?

posterior cerebral artery

\*What is homonymous hemianopsia?

loss of half the same hemiretina field, which means the opposite visual field of each eye. For example, if the LEFT occipital pole is damaged, it will result in LEFT hemiretina damage and RIGHT field of vision damage

\*the fibrous septa are formed by the meningeal layer of which of the major layers that protect the brain?

dura mater

\*how many pairs of cranial nerves are there?

12 pairs

\*How many pairs of spinal nerves are there?

31 pairs

\*Which motor system is excitatory and involved in direct and voluntary actions?

pyramidal motor system

Which motor system is not voluntary and is primarily involved in inhibition?

extrapyramidal motor system

What is the pathway of the anterior cerebral artery and what does it cover?

\-Front, middle, top

\-It covers areas of the optic tract, optic chiasm, superior and posterior surfaces of corpus callosum, anterior hypothalamus, medial, orbital, and dorsal medial frontal lobe

\*What is the pathway of the middle cerebral artery and what does it cover?

\-Passes laterally along the inferior surface of the brain, across the most anterior pole of the temporal lobes.

\-passes through the dorsolateral surfaces of the temporal lobe, most of the pre and post central motor and sensory strips, and also travels through the lateral sylvian fissure

\-Covers lateral sides, temporo-occipital, angular gyral areas, lateral frontal, anterior temporal lobes, Broca's area and Wernicke's area