chapter 13-15

What are the 2 anatomical subdivisions of the nervous system.

CNS & PNS

CNS

• Consists of brain and spinal chord

• integrating, processing and coordinating

• Intelligence, memory, learning, and emotion.

NOTE: There are no nerves at the brain or spinal chord

PNS

• Neural tissue outside the PNS

• Provides sensory info to the CNS

• Carries motor commands to peripheral tissues

• 2 divisions (afferent and efferent)

Ending to the spinal chord:

1. ends at L1/L2

2. Has carrot-tip like end (Conus medullaris)

3. The horse tail of nerves (caudal equina) —> enter or exit through the anterior and posterior sacral foramina

Afferent vs. efferent

Afferent: Sensory information INTO the CNS.

Efferent: motor commands OUT to muscle and glands.

(SAME DAVE)

Is there more neurons or neuroglia within neural tissue?

there is more neural glial

Main functions of neuroglial

• provides framework for neural tissue 

• Maintain the intercellular environment 

• Acts as phagocytes 

Neuroglial found in PNS vs CNS

PNS:

1. Satellite cells 

2. Schwann Cells 

CNS: 

1. Ependymal cells 

2. oligodendrocytes 

3. astrocytes 

4. microglial (macrophages)

Schwann Cells

• surrounds ALL axons of PNS regardless of being unmyelinated or not

• participates in repair processes after injury —>  in deep injury to a nerve, Schwann cells that remain can form a structure described as a "tube" like a straw and this tube allows an axonal bud to grow down it, guided by chemotaxis (a chemical information flow from the target)

PNS

Satellite cells

• regulates O2, CO2, nutrient, and NT levels in the ganglia

• PNS

If one were to put a pin through the PNS and hit Schwann cells, would they be able to hit both myelinated and unmyelinated axons

YES!!!

Astrocytes

• Largest and most numerous glial cells

• located in CNS 

• maintain the BBB

• form scar tissue after injury

Microglia 

removes cell debris, wastes and pathogens via phagocytosis. (CNS)

Ependymal cells

• line the ventricles and the central canal of the spinal chord

• assist in the production, circulation, and monitoring of CSF

Name the 3 receptors monitored by the sensory neurons 

1. exteroceptors 

2. proprioceptors

3. interoceptors

exteroceptors

• receives info from external environment

• touch, temp, and pressure sensations 

• special senses of sight, smell, and hearing

proprioceptors

• receives info from internal environment

•  position and movement of skeletal muscles and joints 

• information carried into somatic sensory neurons 

interoceptors

• receives info from internal environment

• digestive, respiratory, cardiovascular, urinary, and reproductive systems

• sensations of deep pressure as well as taste.

What type of pathway of neural circuits regulates homeostasis?

reverberation

Neural cortex

Gray matter on the surface of the brain

Centers

• collections of the neuron cell bodies in the CNS; each have specific function

• Gray matter org

Higher Centers

the most complex centers of the brain

(gray matter org)

nuclei

collection of neuron cell bodies in the interior of the CNS

(gray matter org)

Tracts

Bundles of CNS axons that share a common origin and destination (white matter org)

Columns

• white matter org

• several tracts that forms an anatomically distinct mass (think of white columns in the spinal cord. 

T or F: does the spinal chord and the brain have functional independence 

T

Which part of the spinal chord are lateral horns present?

T1 - L2

Filum Terminale

• is a pia mater structure

• keeps the spinal cord in its dural sac

What does Filum Terminale and denticulate ligament have in common

the both originate from the pia mater

Name the 3 meningeal layers

1. dura mater (tough mother)

2. arachnoid mater

3. pia mater (innermost layer)

Which structures in the spinal cord include CSF

• Subarachnoid area 

• Central canal

What do the lateral gray horns of the spinal cord include

Visceral motor neurons

Ascending vs Descending tracts

Ascending: relays info from spinal cord to the brain

Descending: relays info from the brain to spinal cord

The brachial plexus separates what two structures?

the anterior and middle scalenes (muscle)

Name nerves from lateral to medial that make up the brachial plexus.

musculocutaneous, axillary, radial, median, and ulnar nerves

“my aunt raced my uncle)

Sciatic Nerve

• huge nerve located inferiorly

• for most people, exits from the inferior border of the piriformis muscle

General steps for a reflex arc

1. stimulus. stretching of muscle stimulates muscle spindles

2. activation of a sensory neuron

3. information processing at moter neuron 

4. activation of motor neuron

5. response. contraction of muscle

Cingulate Gyrus

1. the emotional gyrus (overwhelming emotion)

2. note that our most powerful visceral memories come from smell: olfaction goes directly into the cingulate gyrus rather than the thalamus

What to remember about the ventricles

• in a midsagittal cut, the 3rd ventricle would be destroyed 

• if you put a pin through the 3rd ventricle; you are in the thalamic nuclei 

• on either side of the 3rd ventricle, you have the thalamus 

• FILLED WITH CSF

Choroid Plexus

• includes epitomal cells

• main function is to produce CSF

Define anastomosis:

natural connection between structures that create alternate ways to get blood to go where it needs to go. (think of circle of willis)

Claustrum

1. a structure involved in subconscious processing

2. act like a conductor of an orchestra, letting things happen at certain times

3. associated with when time seems to move slowly during a state of emergency, gives person time to think and do things that may not be possible in a regular time frame

Lentiform nucleus

• includes putamen and globus pallidus

• DA-ergic 

What is the amygdala’s function centered around?

sex, fear and aggression 

Brain regions (5)

1. telencephalon (cerebrum)

2. Diencephalon

3. Mesencephalon 

4. Metencephalon (cerebellum and pons)

5. myelencephalon (medulla oblongata)

Telencephalon

• cerebrum

• It is primarily associated with consciousness

Diencephalon

• connects the cerebrum to the brain stem (both functionally and structurally) 

• functions are almost exclusively subconscious

• Includes: epithalamus, thalamus, and hypothalamus

Epithalamus

• includes pineal body

• responsible for converting serotonin into melatonin

Thalamus

• the relay center or all sensory and motor information flowing through the brain. —> only exception is olfactions (goes through the cingulate gyrus)

• Located on either side of the 3rd ventricle

Hypothalamus

• center for satiety

• This refers to the control of the four biological imperatives: eating, sleeping, drinking, and sexual behavior

• Suprachiasmatic Nucleus or SCN: Located above optic chiasm, responsible for generating our circadian rhythm

What to know on exam about the SCN

• Suprachiasmatic Nucleus

• generation of the circadian rhythm.  

Mesencephalon

• also known as the midbrain 

• Corpora quadrigemina: superior and inferior colliculi (visual and auditory)

• Reticular Formation: automatic processing of incoming sensations and outgoing motor commands; can initiate motor responses responses to stimuli; helps maintain consciousness

Metencephalon

• pons: respiratory activities —> within gray matter

• cerebellum: coordinating movement beneath the level of consciousness —> adjusts postural muscles of the muscle to maintain balance + programs and fine-tunes voluntary and involuntary movements

myelencephalon

• medulla oblongata

• connects the brain with the spinal cord

• relation station, house for cranial nerve nuclei and controls visceral functions like blood pressure, and heart rate.