Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior- PSB3340

Behavioral psych

Two major classes of cells that make up the nervous system are the

neurons and glia

Parts of a neuron

cell body (soma), dendrites, axon, axon hillock, myelin, nodes of Ranvier, axon terminals, synapse

Cell body (soma)

varies in shape and size, contains nucleus, function= synthesis, metabolism, energy

Dendrites

thin branching diners, spiny or aspiny, decreasing diameter, function= input

Axon

single thin extension, usually collateralized (branched), constant diameter, function= transmission

Axon hillock

site where axon exits soma, function= establishing the action potential

Myelin

fatty coating around axon, function= insulation and conduction of AP

Nodes of Ranvier

gaps in myelin, function= facilitate conduction of AP

Axon terminals

swelling at tip of axon branch, function= release neurotransmitters into synapse

Synapse

structure consisting of presynaptic membrane, cleft, and postsynaptic membrane → there is structure matrix in the cleft via proteins, function= transmission of information

How can we classify neurons

based on size of soma + shape and size of neurons

magnocellular

Large soma

parvocellular

Small soma

connicellular/ granule

Small cell body

bipolar interneurons are in

retina

all somatosensory neurons are

unipolar

all spinal motor neurons are

multipolar

pyramidal cells are from which areas

cortex and brain areas like hippocampus

which type of cell has most synapses than any other type in cerebellum and important for organizing motor function

purkinge

3 types of multipolar cells

purkinje, basket, pyramidal

purkinje cell

A type of large nerve cell in the cerebellar cortex.

Basket cell

highly branched axons that form dense, "basket-like" inhibitory synaptic arrangements around the somata, cortex

Pyramidal cell

a type of large nerve cell that has a rough pyramid shape cell body; found in the cerebral cortex and hippocampus

Multipolar neuron

many branches extending from soma, lots of dendrite and single aton

Bipolar neuron

one large dendrite extends and single axon exiting

Unipolar neuron

dendrite/soma and then axon connects on its way past

Interneuron

 neurons that lack the capacity to fire an AP, may have an axon without right machinery or no axon, only capable of communicating over very small distances = short axon if it has one

Synapse?

all communication and all electrochemical activity happens here

Membrane is composed of

a liquid bilayer with hydrophilic on outside and hydrophobic on inside, making it selectively permeable

Cytoplasm

fluid filled compartment of cell, function= medium for chemical reactions

Cytoplasm function

Maintains concentration of enzymes and substrates involved in biochemical reactions

Nucleus

contains genetic material, function= encoding and transcribing mRNA

Ribosomes

ribonucleoprotein molecule, function= translation of mRNA to protein

ER

smooth or rough membranous, function= rough is for protein synthesis and transport v. smooth is fat synthesis and transport

Golgi complex

membranous sculptures, function= packages proteins for transport

Vesicles

membraneous structure of lipid bilayers, function= package for transport, storage, and release of substance, can ectocytosis

Mitochondria

membranous DNA counting structure, function= energy store an release

Microtubules and filaments

tublinc, actin, protein polymers, function= transport structure

anterograde direction

transport system in soma down to axon

Anterograde direction is accomplished by

kinesins

kinesins

protein that hold onto cargo such as vertical or mitochondria and move by them by walking along microtubule

Dynesis

Important for recycle materials, far transport, and status of axon terminals

Retrograde transport

terminal up to soma

Retrograde transport accomplished by

dynesis

Specific organelles are also found in the axon terminal because

it is a site of biosynthesis of neurotransmitters and recycling

Which organelle is NOT found in the axon terminal

ER

Why is the ER not found in the axon terminal

axon is devoid of protein synthesis (v. dendrites that do mRNA synthesis)

Mechanism of protein synthesis

1. Transcription- happens in nucleus, enzyme unwinds DNA to expose gene, mRNA creates complementary based off one strand of DNA template, leaves nucleus to cytoplasm

2. Translation- happens in cytoplasm and ribosomes, mRNA attaches to a ribosome and tRNA brings amino acids to start AUG codon, makes peptide bond chain until stop codon

3. Proetin folding- polypeptide chain folds into unique 3d stucture becoming a functional protein

primary structure

Amino acids assembled into chains

secondary structure

pleated sheets and alpha helixes

tertiary structure

placed together in 3d stucture

quaternary structure)

final folding of proteins

Glia cells

important multifunctional cells for activity (such as insulation, structural support, transport of nutrition, removal of waste, implicit information exchange)

Type of glia in CNS

ependymal, oligodendrocute, astrocytes, micro, radial

Ependymal cell

line the ventricles and central canal and help with synthesis and circulation of cerebrospinal fluid (CSF)

Oligodendrocyte

myelin sheath in CNS neurons, has cell body with numerous dendrites that wrap around axon(s)

Astrocytes

formation of blood CNS barrier, trophic support for neurons, insulation for synapses and Nodes of ranvier

Microglia

recognize abnormalities in brain via long extensions, and remove damage materials, act as immune defense of brain and spinal cord

Radial glia

extend from inner core of brain to outer surface, function as a scaffold for new neurons to crawl out of core, mature into astrocytes

Types of cells in PNS

satellite and schwan

Satellite cells

imilar to astrocytes but in PNS, surround cell body and support and insulate soma

Schwann cells

form myelin of PNS by wrapping around myelin and squeezing out cytoplasm, different because they only wrap around a single axon on a single site (different than oligodendrocytes), also more flexible

Neuraxis

extends from top down which has a 90^o inflection

rostoral or anterior

front

caudal or posterior

bottom

dorsal

back

ventral

stomach

lateral

side

medial

middle

ipsilateral

same side where original

contralateral

different side input than originati

proximal

close

distal

distant

afferent

to spinal cord

efferent

away from spinal cord

Frontal/ transverse plane

section along short legnth of brain

Sagital plain

section across longitude

Horizonal plane

like cutting a baguette

Transverse

cross section

Nervous system is made up of what two other systems

PNS and CNS

PNS is made up of which 2

somatic and automatic

Somatic system made up of

sensory and motor

CNS made up of

spinal cord and brain

Brain made up of

forebrain, midbrain, and hindbrain

Brain’s 3 layers

dura matter, anachoid matter, pia matter

Dura matter

closest to skull, hard

Anachnoid matter

middle layer, spiderlike web structure

Pia matter

you wont see ya pia because it is on the inside

ventricular system

A system of fluid-filled cavities inside the brain

lateral ventricle

A complexly shaped lateral portion of the ventricular system within each hemisphere of the brain

choroid plexus

A highly vascular portion of the lining of the ventricles that secretes cerebrospinal fluid

third ventricle

The midline ventricle that conducts cerebrospinal fluid from the lateral ventricle to the fourth ventricle

fourth ventricle

The passageway within the pons that receives cerebrospinal fluid from the third ventricle and releases it to surround the brain and spinal cord

Meninges

The three protective sheets of tissue—dura mater, pia mater, and arachnoid—that surround the brain and spinal cord

blood-brain barrier

The mechanisms that make the movement of substances from blood vessels into brain cells more difficult than exchanges in other body organs

Hydrocephalus

inability of CFS to drain into bloodstream, if not pressure will build and head expands and damage will eventually occur

Cortex/ forebrain

higher cognitive functions, goal directed behaviour, object recognition

Subcortical structures of the forebrain

thalamus, geniculate nucleus, basal ganglia, limbic system

Thalamus

 bilaterally symmetrical position, critical for sensory and motor function, motor signaling between cerebellum and motor cortex, sensory signaling to cortex and reciprocal inputs from cortex), sleep

Geniculate nucleus

a key thalamic relay center for the visual pathway, situated in the posteroventral region of the thalamus