Nervous System Overview

These flashcards cover key terms and concepts from the lecture on the Nervous System Overview.

What structures make up the CNS?

brain and spinal cord

What is the main function of the CNS?

processing information

How is the CNS protected?

with bone=skull and vertebrae

What fluid is crucial for CNS health?

cerebrospinal fluid (CSF)

What structures make up the PNS?

peripheral and mixed nerves are mylinated

What is the function of the PNS?

delivering information without processing

Afferent pathways (PNS)

senory

efferent pathways (PNS)

motor

Meninges

Three layers of connective tissue covering the CNS structures

Dura Mater

Outermost layer of the meninges made of dense fibrous connective tissue with actually 2 layers with dural sinuses of venous blood/old CSF flowing here

Arachnoid Mater

Middle layer of the meninges with spiderweb-like fibers that creates cavern (subarachnoid space) for CSF flow along outside of brain and spinal cord

Pia Mater

Inner layer of the meninges; a thin layer that covers the CNS surface and houses tiny blood vessels

What are gyri and sulci?

folds that increase surface area

What is gray matter?

cortex (outer brain layer)

Cerebrum

The largest part of the brain responsible for complex functions; contains cortex with five lobes.

Frontal Lobe

Responsible for voluntary motor functions and personality.

Parietal Lobe

Somatosensory center processing sensory information.

Occipital Lobe

Visual center of the brain.

Temporal Lobe

Involved in hearing, smell, and high-order thinking.

Insula

Deep brain structure related to communication skills.

Corpus Callosum

A structure of white matter that connects the two brain hemispheres.

Cerebellum function?

motor coordination and proprioception, high density of neurons, white matter = arbor vitae

Hypothalamus

Master controller of the endocrine system (hormones) and autonomic nervous system (autonomic effects)

Thalamus function?

sensory gateway to cortex, filter for afferent information

Brainstem

Connects the spinal cord to the brain; now gray matter on inside/white outside

brainstem location

directly anterior of 4th ventricle and cerebellum

Medulla function?

basic life functions

Pons function?

connects to cerebellum

Reticular formation function?

complex gray matter running vertically, alertness - constant communication with hypothalamus, houses cranial nerves

CNI (one) olfactory

sensory - smell

CN II (two) optic

sensory - vision

CN III (three) oculomotor

motor - eye movement, pupil constriction

CN IV (four) trochlear

motor - moves eye (superior oblique muscle)

CN V (five) trigeminal

both - facial sensation + chewing

CN VI (six) abducens

lateral eye movement

CN VII (seven) facial

both - facial expression, taste (anterior 2/3), salivary glands

CN VIII (eight) vestibulocochlear

sensory - hearing and balance

CN IX (nine) glossopharyngeal

both - taste (posterior 1/3), swallowing

CN X (ten) vagus

both - parasympathetic control of heart, lungs, digestion

CN XI (eleven) spinal accessory

motor - neck/shoulder movement

CN XII (twelve) hypoglossal

motor - tongue movement

Where does the spinal cord begin (brainstem ends)?

foramen magnum

How many spinal nerve pairs?

31 (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)

spinal cord

column in vertebral canal, site of interneurons for signal conduction, both afferent and efferent pathways, site of some reflexes

spinal nerves exit via

intervertebral foramen on both sides of cord

What is a nerve plexus?

network of spinal nerves that redistribute fibers to body regions

cervical plexus

C1-C4

cervical plexus main nerve

phrenic nerve

cervical plexus function

diaphragm (breathing)

brachial plexus

C5-T1 (ARM)

brachial plexus major nerves

axillary, musculocutaneous, median, ulnar, radial

brachial plexus functional compartments

anterior arm - flexion (musculocutaneous)

posterior arm - extension (radial)

lumbar plexus

L1-L4 (ANTERIOR LEG)

lumbar plexus major nerve

femoral nerve

lumbar plexus function

knee extension (anterior thigh)

sacral plexus

L4-S4 (POSTERIOR LEG)

sacral plexus major nerve

sciatic nerve

sacral plexus function

posterior thigh + most of lower leg

Autonomic Nervous System (ANS)

Controls involuntary bodily functions and balances between sympathetic and parasympathetic systems

hypothalamus as master control center

brainstem integral for homeostasis

Parasympathetic Nervous System

Part of the ANS responsible for 'rest and digest' functions

vagus nerve huge player, also CNs (III, IX)

necessary to lower most vital signs in time of decreased movement/relaxed mood

PNS cholinergic pathways

Ach used along entire pathway

PNS digestive system enhanced

increased blood supply for digestion and absorption of nutrients (store for more active times/use proteins for manufacturing and repairing body)

Sympathetic Nervous System

Part of the ANS associated with 'fight or flight' response.

SNS adrenergic pathways

Ach used first and then path ends with NE at target

SNS increased blood supply

to vital organs to anticipate skeletal muscle movement; associated with emotional stress

most vital signs increased to deal with increased body activity (exception is digestion)

Limbic System

Deep brain structures involved in emotional responses and memory creation.

how we deal with environment, neurotransmitters powerful to mental health (dopamine, serotonin)

amygdala

helps with development of an emotional response

hippocampus

helps to formulate memories

Cerebrospinal fluid = CSF

crucial for health of CNS

balance: production=disposal of fluid each day

Where is CSF produced?

choroid plexus (from blood)

What is the pathway of CSF?

1. lateral ventricles

2. interventricular foramina

3. third ventricle

4. cerebral aqueduct

5. fourth ventricle

6. subarachnoid space

7. arachnoid granulations

8. venous blood (dural sinuses)

What happens if CSF flow is blocked?

hydrocephalus (fluid buildup in ventricles - tubes in between chambers)

Neuron

excitable, conductive, and secretory

does not undergo mitosis: they age! (except olfactory)

nerve

bundles of nerve fibers (axons) wrapped in connective tissue

neuron classes

afferent (sensory), efferent (motor), interneurons

neurosoma

cell body

nissl body

dark-stained regions of rough ER

dendrite

receives signal (1-1,000s per neuron)

axon

start of nerve fiber (1 per neuron)

synaptic bulb

terminal arborization at end of axon

forms junction=synapse with next cell

neurotransmitter

chemical released in vesicle into synapse to help spread signal

acetylcholine (Ach)

receptors that use this are called cholinergic

used at neuromuscular junction between neuron and skeletal muscle cell

where is Ach used in ANS pathways

at first and final synapses along the parasympathetic path

at first synapse along the sympathetic path

norepinephrine = NE

receptors that use this are called adrenergic

very similar to epinephrine and adrenaline made by other parts of body (adrenal glands)

where is norepinephrine used

final synapse in sympathetic path

dopamine and serotonin

associated with limbic system

helps with pleasure pathways

involved in addictive patterns and positive reward systems

Action Potential

An electrical impulse that enables neuronal communication.

1. resting membrane potential

inside negative (-70 mV)

maintained by Na+/K+ ATP pump

2. stimulus/local potential

dendrites receive signal

if threshold reached action potential begins

3. depolarization

Na+ channels open

Na+ rushes in

membrane becomes positive

4. repolarization

K+ channels open

K+ exits cell

membrane becomes negative again

5. hyperpolarization

K+ leaves too much

membrane temporarily more negative

6. return to resting

pump restores ion balance

role of Ca2+

triggers neurotransmitter release at synapse

role of myelin

speeds conduction (saltatory conduction)

local potential at dendrite vs. full-blown action potential at axon

local - graded, decremental input signals

action - all-or-none, propagated output signals

ligand-gated vs. voltage gated channels

ligand - open upon binding chemical signals (neurotransmitters)

voltage - open in response to changes in membrane potential

neuroglia

supportive cells for nervous system

neuroglia roles

protection, help with function, bind neurons together, avoid undesirable neuron contact

replenish throughout life (cells able to continue to divide)

White Matter

Regions of the nervous system containing myelinated axons.