NSCI 2101 Exam 1

Axon ("nerve fibers")

- carry nerve impulse (action potential)
- Myelin speeds up conduction

axon terminal

release neurotransmitters into synaptic cleft and onto other neurons at synapse.

dendrites

- receive synapses from axon terminal

Synaptic Cleft

The narrow gap that separates the presynaptic neuron from the postsynaptic cell.

Cerebral cortex

- sparse branching dendrites
- emerge from apex and base of cell soma

Cerebellar cortex

- extensive branching
- emerging only from peripheral half of cell

cell

-surrounded by cell membrane (lipid bilayer)
-require metabolic energy

types of cells in the nervous system

neurons and glial cells

parts of neuron

cell body, axon, axon terminal, myelin sheath, dendrites

cell soma

-contains nucleus
- synthesizes macromolecules/organelles
- integrate electrical activity

Types of Glia cells

astrocytes, oligodendrocytes, microglia, ependyma

function of glia

- slow, local modulation (not rapid or over long distances)
- create myelin around axon
- scavenge dead cells
- line ventricles
(NO AXONS = SLOW) Glia have no axons

Division of the nervous system

central nervous system and peripheral nervous system

Central nervous system

Brain, spine

peripheral nervous system

-sensory neurons (from skin, bone, viscera to CNS0
-Motoneurons (from CNS to muscle)

Division of the Peripheral Nervous System

somatic (sensory/moto), autonomic

autonomic nervous system

controls vasculature and viscera

Division of autonomic nervous system

sympathetic and parasympathetic, enteric

sympathetic nervous system

"fight or flight" - arises from thoracic spinal cord

parasympathetic nervous system

"rest and digest" - arises from brain or sacral spinal cord

enteric nervous system

secretions and motility of the gut (as many neurons as spinal cord)

tract

bundle fibers of axon (cns) example is corpus callosum.

Nuclei

group of neurons outside cortex (CNS)

Cortical Layers

Group of Neurons within cortex (CNS)

ganglia

group of neuronal somata (PNS)

nerves

bundle of axons (PNS)

Ventral

Toward the belly

Dorsal

toward the back

Rostral

toward the beak

Caudal

towards the tail

coronal plane

divides body into front and back

horizontal plane

flat crosswise plane

parasagittal plane

not on midline - divides left to right

medulla oblongata

- between bottom of skull and top of spine
- most caudal part of brain stem

pons

bridge over brain stem connecting cerebellum
- between midbrain and medulla

Inferior/Superior pontine sulcus

rostral and caudal sulcus around pons

cerebellum

large, rigid masses on either side of pons

Midbrain

rostral from pons

Cranial Nerve 3: Oculomotor

- emerges from the midbrain
- controls ocular movement

Cranial Nerve 4: Trochlear

emerges from dorsal border of pons and midbrain

Diencephalon

thalamus, hypothalamus, and pineal gland

Cranial Nerve 2: Optic Nerve

ventral surface of diencephalon

Telencephalon

cerebral cortex and basal ganglia, amygdala, putamen, caudate nucleus

lateral sulcus/fissure

location of pons/medulla

medial longitudinal fissure

separates hemispheres

Purpose of gyri/sulcus

increase surface area of the cortex

sulcus/fissure

groove in brain surface. Fissure is a deep groove.

gyrus

bump or ridge on brain surface

pre-central gyrus

movement/motor

post central gyrus

(touch)/sensory

central sulcus

separates frontal and parietal lobes

Lobes of the cerbral cortex

limbic is deep medial, surrounding corpus callosum

Fertilized egg

zygote, after the sperm and the egg unite

Morula

A solid ball of cells that makes up an embryo; in humans, this stage occurs within four days of fertilization. zygotes divides 2-3 days after fertilization

inner cell mass

forms embryo

embryonic age

time after fertilization (used by Biologist and us)

gestational age

time after last menstruation (embryonic + 2 weeks)
*used by clinicians

embryo invades uterus

day 6-15
develops into embryonic disk

embryonic disk

- composed of ectoderm and endoderm
- part of the inner cell mass

Primary germ layers

ectoderm, mesoderm, endoderm

primitive streak

- defines 2 sides
-first midline
-develops in embryonic disk

cephalic fissure

curve in midbrain of the embryo that positions the forebrain ventrally

mesoderm

- bone, muscle, and organs
-develops after other primary germ layers
- forms from cell migration from the ectoderm

ectoderm

skin and nervous system

Endoderm

gut, glandular organs, liver

primary germ cell layers forms from...

cell migration

neural plate formation

cell migration from ectoderm forms mesoderm, forming neural plate

Neurulation

formation of the neural tube
( neural plate -> neural groove -> neural tube)

neural groove

before closure - hallow inside

formation of neural crest

fusion above neural tube/groove
- will become the PNS

nueral tube

will become the CNS
- hollow tube that is inside

basal plate

motor (output)
ventral plate on neural tube

alar plate

sensory (input)
dorsal plate on neural tube

neural tube defects

spina bifida and anencephaly

spina bifida

- neural tube defect
- failure of closure at the caudal end of neural tube
- results in meninges forming outside the body
- prevented by B-12 during pregnancy

Anencephaly

failure of fusion of neural tube on rostral end

formation of the nervous system relies on

mitosis (cell division), cell migration

Mitosis allows

Growth
Differentiation

cell migration

cells move to their destinations

Cell Cycle

neurons terminally differentiate and enter Go

PNS forms from

neural crest (spinal column) and neurogenic placodes (developing head)

neural crest forms...

sensory ganglia
autonomic ganglia
schwann cells
enteric NS
melanocytes

Neurogenic placodes form...

-sensory ganglia (nerves)
-olfactory epithelium
-hair cells in ear
-anterior pituitary gland
-lens of eye

Formation of CNS relies on

migration and mitosis

spinal cord develops from

neural tube

2 important functions of placodes

1- cells can source important cells and tissue
2 - can induce changes in neighboring cells/tissues (lens)

neural vesicles

hallow swelling that occur around 26 days

primary vesicles

prosencephalon, mesencephalon, rhombencephalon

secondary vesicles

telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon
*divide around 40 days

pontine flexure

-between the mete- and myelen-
-opens the fourth ventricle

sulcus limitans

separates alar and basal plates

Development of cerebellum

Rhombic lip - divides and grows into..
around 20 weeks

development of forebrain

-telencephalon enlarges most
- outward expansion results in C-shape

Temporal lobe grows over

insular cortex

function of meninges

protect brain and spinal cord - suspension system

3 layers of meninges

dura mater, arachnoid mater, pia mater

Dura Mater

adheres to inside of skull
- has one blood supply (meningeal arteries)
-has pain sensing nerve fibers

arachnoid trabeculae

little beans between pia and arachnoid

dural folds

falx cerebri
- stabilizes brain from forces from sides