Chapter 1 and 2 of Neurology

where was the seat of intelligence according to Ancient Egyptians

the heart

what did aristole propose about the brain

cool the blood

Gall- phrenology

behavioral traits could be inferred from bumps on the skull reflecting brain enlargements

Dr. Broca (1861)

studied patients unable to speak but they could understand language

why were patients unable to speak but understand language have.

had a legion in the same part of the brain (now coined as the Broca area)  which is important for language

Dr. Wernickle (1891)

studied patients that could speak but could not understand language

what is wrong with patients that can speak but cannot understand language

they had legions but just in a different part of the brain (Wernickle’s area)

what did Galen discover

the brain’s fluid filled ventricles

What does Galen propose?

Proposes that the nervous system operates via hydraulics.

connection with the nervous system and electricity

Electricity is discovered→ Luigi Galbani demonstrated this is how nerves and muscles work via electricity.

Debate between Golgi and Ramon y Cajal

is the nervous system a continuous reticulum or cells?

Golgi

argues that nervous system is a continuous reticulum like the circulatory system

Ramon y Cajal

argues that it is made of cells that communicate via contact.

how does cajal prove his hypothesis

used silver nitrate stain (Golgi stain) that Golgi developed to prove he was right.

Who was right in debate between Golgi and Cajal?

Cajal; settled with the help of an electron microscope in the 1950s

neuron doctrine

the fact that the nervous system is a selection of cells called neurons

sparks

information travels down nerve cells with electricity. This is how neurons communicate—> how gap is closed

soups

information travels down nerve cells with electricity. But the connection is cross via chemicals.

which is correct, sparks or soups

soups

dominant framework of neuroscience

genes—> proteins—> neurons—> circuits (brain activity)—> mind and behavior

genes

code for proteins that are used to form and operate neurons. They then form a network of circuits to communicate info which is called brain activity, which dictate mind/behavior.

how does problems in the molecular level lead to problems?

it leads to problems at the highest level

type of brain cells

neurons and glia

size of neurons and glia

10-50 micrometers

brain tissue is…

very flappable and must be hardened using formaldehyde.

nissil stain

stains neurons, not glia.

where does the nissil stain stain?

stains the cell body

who created the silver chromate solution

Camillo Golgi

other name for silver chromate solution

Golgi stain

parts of neurons

soma and neurites

neurites

axon and dendrites

cell theory applies to

neurons

basic job of neuron

sense changes in the environment, communicate them to other neurons and command the body’s response to the stimulus

properties of neurons

Morphologically heterogeneous in size and shape each has a unique size/shape

Conduct bioelectric signals across long distances with no toss of signal strength 

Possess specific connections with other nerve cells and with muscles and glands

soma

cell body; contains nucleus and other organelles, and performs most metabolic functions

dendrites

projections from the soma that receives information

axon

extension that sends information- via electrical signals from the cell body to the terminal buttons

axon collaterals

side branches that grow from the main axon allowing the neuron to contact multiple other neuron targets

nucleus

contains chromosomes which are multiple amounts of DNA.

gene expression

DNA is transcribed to mRNA. mRNA is translated into a protein

alternative splicing

the cutting of some exons which lead to multiple types of proteins

nucleus structure

spherical, double membrane, contains small pores. DNA is condemned into chromatin threads which contains genes that each ocode for specific proteins.

ribosomes

important for protein translation.

where are bound ribosomes located

Rough endoplasmic reticulum (ER)

bound ribosomes

Nissl bodies: membrane with attached ribosomes (bound ribosomes)

Translated proteins inserted into plasma membrane or are exocytosed (ion channels)

Also they are packet in lysosomes 

Lots in neurons

free ribosomes

translates proteins that are released into the cytosol

does the smooth er have ribosomes

no

smooth er

folds proteins giving them 3d structure

regulates internal Ca 2+ concentration

Golgi apparatus

sorts protein destination, “post translational” modification of proteins

mitochondria

site of cellular respiration

neurons and ATP

• Neurons require large amounts of ATP

  • Mitochondria are especially abundant where energy needs are greatest

    • Concentrated at synapses- neurotransmitter synthesis

structure of rough ER

Network of tubular membranes enclosing fluid filled sacs called cisternae each

1-1.5 um 

Contains receptors to which ribosomes attach

ribosome structure

Made of rRNA 2 subunit (1 small 1 big) contains peptidyl site, amino site and E site

structure of smooth ER

more tubular than RER. modifies and transports lipid and helps 3’ folding of proteins

what does the smooth er do in muscle cells

it regulates Ca2+ in muscle cells—> sacroplasmic reticulum

structure of golgi apparatus

stacks of flattened fluid filled sacs called cisternae

convex

forming face where vesicles containing materials to modify enter

concave

maturing face, when vesicles with modified material are sent off

structure of mitochondria

double membrane envelope; inner membrane folded cristae which increases SA for phosphorylation; impermeable to ions to set up electrochemical gradient for ATP synthesis.

contains ciricular DNA for binary fission not enclosed in a nuclear membrane, free in the matrix , not associated with histone 70s ribosomes for protein synthesis.

structure of neural membrane

selectively permeable phospholipid bolayer controls exchange of materials between cell and environment

contain protein channels carriers and pumps (Na/K)

Many of the protein channels carriers and pumps are voltaged gated which help to set of action and resting potential for transmitting impulses.

size of microfilaments

small- 5nm

neurofilaments (intermediate filaments)

medium- 10 nm

microtubules

large- 20 mm

function of microfilaments

dynamic involved in growth and movement

enriched in spin—> dendrite

function of neurofilaments

controls thickness of neurites. Enriched in axons Rope like.

function of microtubules

composed of tubulin. Runs down the length of neurites to give basic shape. Acts as a “railroad” for transport

what is unique about axons?

no rough ER or free ribosomes.

axon hillock

beginning; where axons tanners away from soma

axon proper

contains collaterals (branches) to increase surface area

nerve terminal (synaptic bulb)

used for communication

recurrent axon collaterals

Axon collaterals that branch and then return to communicate with original neurons

where is the axon terminal located

pre synaptic side

axon terminals

presence of synaptic vesicles (with neurotransmitter)

large number of mitochondria (high demand)

synaptic bulb heavily coated in proteins

innervation

when a neuron makes contact with another neuron

presynaptic membrane

filled with NT vesicles

postsynaptic membrane

NT receptors inserted into membrane

has the synaptic cleft where synaptic transmission happens

synaptic cleft

the space between, this is where neurotransmitters are released into

synaptic transmission

transfer of information at the synapse. Goes from electrical to chemical to electrical: transfer of info at the synapse

axoplasmic transport

proteins made in the soma must be transported to the axon

is protein translation in the axon?

no

where is all protein made

soma

cytoskeleton and axoplasmic transport

axoplasmic transport happens with the help of the cytoskeleton. Microtubules form the track along which packets of proteins travel by the action of motor proteins

motor proteins

kinesin and dynein

anterograde

away from the soma. Soma to axon terminal and uses kinesin

retrograde

back to soma. Axon terminal to soma and uses dynein

dendrites

receive information

dendritic tree arborization

collective= dendritic tree, 1 branch= dendrite

dendrites are covered with what

neurotransmitter receptors

do dendrites have a high ribosome content

yes

why do dendrites have a high ribosome content

to make a lot of proteins quickly!

why do some dendrites have spines

to increase surface area

ways to classify neurons

based on number of neurites, based on connections, based on dendritic or somatic morphology, axonal length, axonal length, neurotransmitter type

motor neurons

direct output to muscles

primary sensory neurons

they have directions with receptors. convert physical stimuli (i.e. light/sound/pressure ) into electrical signals

interneurons

connections only with other neurons in brain and spinal cord.

stellate cells

can be spiny or aspinous

pyramidal cells

always spiny

golgi type 1

long axons—> projection neuron—> axon extend from 1 side of brain to other. They are pyramidal cells.

golgi type 2

short axons—> axon doesn’t extend beyond—> stellate cells

glutamatergic

release glutamate at synapses