Neurophys Basics Flashcards by Leslie Vargas

What is the brainstem comprised of?

medulla, pons, midbrain

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The brainstem is where ________ arise

CN 3-12

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Medulla “inner region” of the brainstem

regulate breathing and blood pressure,
swallowing, coughing, and vomiting reflexes

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Pons” bridge” of the brainstem

Balance, posture, breathing

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Mid brain of the brain stem

Auditory and visual

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What is the function of the cerebellum?

Coordination of movement
Planning & execution of mvmt
Posture, head and eye mvmts
Position - integrates info from spinal cord to cerebral cortex and inner ear (vestibular system)

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What is the diencephalon “between brain”?

Thalamus and hypothalamus
Grand central for sensory and motor info b/n cerebral cortex and spinal cord

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What are cerebral hemispheres?

Cerebral cortex,
white matter tracts (all the axons)
3 deep nuclei (BG, Hipp, amyg)

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What are the 4 lobes of the cerebral cortex?

Frontal, parietal, temporal, occipital

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The cerebral cortex is compromised of _______ and ________ systems which provides info encoded neural maps.This ______ coding is preserved at each level of the nervous system. In the cerebral cortex as sensory and motor _________.

Sensory, motor systems,
topographic coding
preserved homunculus

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What does Cerebral spinal fluid bathe and what is it made by?

Brain/spinal cord is bathed in fluid
Made by choroid plexus in ventricles
500 mL/day- Drains into venous system

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The blood brain barrier consists of

capillary endothelial cells and + basement membrane, + neuroglial membrane, + glial end feet (projections of astrocytes from the brain side of the barrier)

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What are the two ways in which the BBB differs from other barriers in tissues?

The junctions between endothelial cells in the brain are so “tight” that few substances can crossbetweenthe cells.
Only a few substances can passthroughthe endothelial cells: Lipid-soluble substances (e.g., oxygen and carbon dioxide) can cross the blood-brain barrier, but water-soluble substances are excluded.

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T/F is there a lymphatic system in the brain?

True

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What are the meninges?

Several connective tissue sheaths
1. pia mater- attached to the brain
2. subarachnoid- between arachnoid and pia- filled with CSF.
3. arachnoid
4. dura mater- thickest, most durable attached to inner surface of skull

Arachnoid and pia are continuous

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What is the most caudal portion of the CNS?

Spinal cord

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What are the two pathways of the spinal cord?

Ascending pathway brings sensory info -> brain
Descending motor commands from brain

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What does the spinal cord communicate with the PNS through?

31 pairs of spinal nerves containing
sensory (Afferent) and Motor (Efferent) nerves.

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Where is the spinal cord located?

Base of skull to 1st lumbar vertebra in adults

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Why does cervical and lumbar have more gray matter than the thoracic?

they have a lot more to take of so they have more gray matter

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Dorsal root ganglion is responsible for ______

sensory

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Ventral root ganglion is responsible for__________

motor

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The spinal cord is divided into segments each segments has a b/l pair of bundled nerve fibers called ____________. The pair= __________ roots and __________ roots accompanied by blood vessels.

roots
ventral, dorsal

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Afferent = ________ and Efferent =__________

arrive, exit

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What are reflexes?

Response between a stimuli and an elicited motor reaction

Reflexes are only between _________, _________, ____ “The reflex Arch”

afferent (sensory) nerve CNS interneuron, an efferent (motor) nerve

There are 3 types of reflexes differing in their complexities. Which one is the simplest reflex?

Stretch(myotatic)reflex is simplest of all- ex: knee-jerk

What is a plexus and what are the 4 plexuses (PNS)?

(branching network) of intersecting nerves. A nerve plexus is composed of afferent and efferent fibers that arise from the merging of the anterior rami of spinal nerves and blood vessels. Cervical, brachial, lumbar and sacral

White matter

the axon with its myelin sheith

What are the supporting cells in the PNS?

Satellite and Schwann cells

More myelin on the neuron increases _______ of the nerve

conduction. more myelin= faster

What are 4th order neuron examples?

last at the stop, more in the brain in the cerebral cortex Hearing- Primary auditory cortex Vision -primary visual cortex

Somatosensory (PNS) has senses related to

touch, position (proprioception), pain, temp

1st order neuron interacts with ___________

external world

What are the somatosensory pathways?

Info from the limbs and trunk share a common class of sensory neurons > dorsal root ganglion neurons the first order neuron Each dorsal root ganglia correspond to a specific region of the body- a strip called the Dermatome

What is the anterolateral (spinothalamic) pathway responsible for?

sensory pathway so tract going up to the brain and it has to do with the pain and cutaneous pain

What is the visceral origin of the Anterolateral (spinothalamic) pathway?

responsible for pain and cutaneous pain Low density of nociceptors compared to skin so considerable divergence within CNS- in other words a single visceral afferent nerve goes to many second order neurons The level where the visceral afferent input occurs with the superficial afferent input results in referred pain

What are the types of receptors in the sensory PNS?

Classified based on type of stimulus it receives Mechanoreceptors Photo- Chemo- Thermo- Nocio- they are 1st order neurons and they are designed to pick up these types of stimuli. The environmental stimulus causes a change in the receptor membrane> action potential> to next neuron along sensory pathway

What is a motor unit?

single motoneuron + muscle fibers it innervates. Large motoneuron> many muscle fibers> bigger contraction

The motor system of the PNS is directed by the upper motor neurons in the ________

primary motor cortex (motor homunculus)*sz via descending pathways

The motor system conducts ________ movements

voluntary (execution)

In the motor system of the PNS motor movement is complex, what are the structures involved?

BG, thalamus, Cerebellum, premotor cortex

A resting potential is

-70 mv

What is synaptic transmission?

How one neuron communicates with another cell

What are the different types of synaptic transmissions?

1. electrical-gap junctions. Current travels from one neuron to another 2. Chemical- most common -Presynaptic (neuron 1) and postsynaptic (neuron 2) -Excitatory (causing an action potential) or inhibitory chemical released (hyperpolarization thus refractory) -Slow -Axodendritic, axosomatic, axoaxonic, etc… -Chemicals are neurotransmitters, neuromodulators, and neurotrophic (growth) -Neurotransmitter types- amino acids, neuropeptides, monoamines

3 ways to clear the neurotransmitter

1. reuptake 2. diffusion 3. metabolite to help break it down into something else so it doesn't bind to the receptors

Cell body of motoneuron is the presynaptic neuron which releases ________ which activates the _____________located on motor end plate of a skeletal muscle.

acetylcholine, nicotinic receptors

Overall, what is the somatic nervous system in charge of?

voluntary movement

Overall, what does the autonomic system do?

controls functions of visceral organs- BP, temp, digestion

Where does the preganglionic neuron originate?

CNS

Where does the postganglionic neurons reside in?

ganglia outside of CNS

Postganglionic axons travel via ______ to ______

synapse on visceral organs: Heart, bronchioles, vascular smooth mm, GI tract, bladder, genitalia

All PREganglionic cells used neurons to release_______. POSTganglionic cells release _____ or _______ or _______.

1. acetylcholine 2. acetylcholine or norepinephrine or neuropeptides

Sympathetic nervous system: Where do the preganglionic neurons originate and how do they exit?

Preganglionic neurons originate In spinal cord (thoracolumbar) leave via the ventral motor roots to paraveterbral ganglia or prevertebral ganglia

Parasympathetic nervous system: preganglionic neruons are in the _______ and ________ segments.

brainstem and sacral

Preganglionic neurons are always _________. They release ________ on ___________ of postganglionic neurons.

cholinergic, aCh, nicotinic receptors

Postganglionic neurons releases ________ to act on __________ receptors.

Norepiniephrine, adrengeric

Cranial nerves are where the sensory and motor efferent terminate/emerge are nuclei found in the _______ and ________

cerebrum, brainstem.

Internal carotid supplies blood to most of the __________

cerebrum

Vertebral arteries supplies blood to the __________ and ________

brainstem and cerebellum

The internal carotid artery ascends through the neck and it goes through temporal bone through sinus to reach the base of the brain. At the _________ then bifurcates into _______ and _________ cerebral arteries.

1. optic chiasm 2. middle, anterior

The vertebral arteries are between the medulla and pons and they fuse to form _________. Then at the midbdrain it bifurcates into the ________ cerebral arteries after giving off branches to the _________ arteries.

1. basilar artery 2. posterior 3. cerebellar arteries.

What is the circle of willis?

An arterial polygon connecting: anterior cerebral internal carotid posterior cerebral arteries Usually little blood flow through posterior communicating arteries but great back-up collateral!

Cerebral veins empty into the ______ and ultimately the ________

dural venous, internal jugulars

The nerve roots fuse at the _________ forming a ______ nerve. After emerging from the vertebral column, divided into ______, _______, > mix together > skin and muscles

1. intervertebral foramen 2. mix 3. rami, form plexuses

Neuroglial cells

give neurons protection and metabolic support

Astrocytes

help form blood brain barriers, in CNS

Oligodendrocytes

produces myelin in the CNS

Schwann cells

produces myelin in the in the PNS

What is myelin

lipid blanket around nerve helps conduction – known as white matter

What are the supporting cells in the CNS

1. Oligodendendrocyte- form myelin in the CNS (aka schwann in PNS) 2.Astrocytes: 1. lots in gray matter 2. many roles esp repair and scar formation called gliosis. 3. Microglia: phagocyte- cleans up debris. 4. Ependymal: lines ventricular system- have to with producing CSF