week 1 lecture 2 neuron

neuron (nerve cell)

excitable cell in the nervous system that processes and transmits information by electrochemical signaling

axon

sends messages to other neurons by making connections

synapses

junction between 2 nerve cells

how do neurons talk to each other

releasing chemicals called neurotransmitters at the synapse

about how many neurons are in the brain

86 billion

how many connections could the brain neurons have

over 10000

camillo golgi

developed staining pattern called golgi stain

golgi stain

took tissues, placed in potassium dichromate then did the same with silver nitrate to get staining to various tissues. stains only a few cells at a time making them visible under the microscope

reticular theory

nervous system is a single network (turned out to be wrong)

santiago ramon y cajal

used golgi stain with parts of brain, drawing all the different types of cells noticing similar structural components, proposed the neuron doctrine

neuron doctrine

nervous system is made up of discrete individual cells, which shifted framework from thinking about the nervous system as a continuous network to a cellular circuit-based network

sensory neuron

neuron that detects changes in the external or internal environment and sends information about these changes to the central nervous system

motor neuron

neuron located within the central nervous system that controls the contraction of a muscle or the secretion of a gland

interneuron

neuron located entirely within the central nervous system

membrane function

encloses the cell in a double layer of lipid

cytoplasm function

fluid inside the cell

nucleus function

cell center that contains DNA

mitochondria function

supplies energy from nutrients

ribosomes function

protein synthesis

lysosomes function

recycling center

smooth ER function

produces lipids

rough ER function

has ribosomes for making proteins

golgi apparatus function

packaging and storage

microtubules function

protein filaments for transporting substances within the cell

why do neurons care about mitochondria more than other cells

high energy demand for ion gradients and neurotransmitter release

why do neurons care about cytoskeleton more than other cells

axonal transport over long distances

why do neurons care about rough ER more than other cells

neurotransmitter receptor synthesis

neuroglia

nerve glue, supporting cells of the central nervous system

functional types of neurons

sensory, motor, inter

types of glial cells

schwann cell, oligodendrocyte, astrocyte, microglia

schwann cell

cell in peripheral nervous system that is wrapped around myelinated axon, providing one segment of its myelin sheath

oligodendrocyte

forms myelin sheaths

most abundant cell of human brain, contributes to the blood-brain barrier

astrocyte

microglia

specialized immune cells of the brain and spinal cord acting as the central nervous system’s resident immune cells to monitor the brain’s environment, defend against pathogens, clear cellular debris through phagocytosis, support neural development, prune unnecessary neuronal connections

Oligodendrocytes vs. Schwann Cell

One oligodendrocytes can myelinate many axons; one Schwann cell myelinates one axon segment

blood-brain barrier

semi-permeable barrier between the blood and the brain produced by the cells in the walls of the brain’s capillaries

how is blood-brain barrier formed

endothelial tight junctions

how is blood-brain barrier regulated

astrocytic end-feet

blood-brain barrier function

protect the brain, tightly regulates what substances can pass from the blood to the brain

what can pass through the blood-brain barrier

glucose, fat-soluble molecules, oxygen, carbon dioxide, anesthetics, alcohol, viruses, amino acids

what can’t pass through the blood-brain barrier

most large hydrophobic molecules, proteins, ions, bacteria, antibiotics

epilepsy

blood-brain barrier breaks down which trigger chronic or acute seizures

multiple sclerosis

an autoimmune and neurodegenerative disorder in which the immune system attacks the myelin. blood-brain barrier breaks down allowing T-lymphocytes to cross and attack the myelin

A

dendrites

B

nucleus

C

cell body (soma)

D

glial cell

E

axon

F

axon terminal

A

node of ranvier

B

myelinated axons

C

mitochondrion in axoplasm

D

node of ranvier

E

microtubule

F

soma of oligodendrocyte

what is this structure

oligodendrocytes (central nervous system)

what is this structure

neuron

what are the major intracellular organelles relevant to neurons

nucleus, mitochondria, ribosomes, lysosomes, ER, golgi apparatus

soma

central region of the neuron containing the nucleus

dendrites

neurite specialized to receive synaptic inputs from other neurons

dendritic spine

small sac of membrane that protrudes from the dendrites of some cells and receives synaptic input

axon hillock

swelling of the axon where it joins the soma

terminal bouton

axon terminal, end region of an axon usually a site of synaptic contact with another cell

synapse

region of contact where a neuron transfers information to another cell

neurotransmitter

chemical released by a presynaptic element upon stimulation that activates postsynaptic receptors

presynaptic neuron

nerve cell that sends a signal to the postsynaptic neuron across a synapse

postsynaptic neuron

nerve cell that receives signals from the presynaptic neuron at a synapse

myelin

membranous wrapping or sheath around axons provided by oligodendroglia in the central nervous system and Schwann cells in the peripheral nervous system

node of Ranvier

space between two consecutive myelin sheaths where an axon comes in contact with the extracellular fluid

extracellular fluid

all the fluid in the body outside of cells

extracellular fluid function

crucial internal environment for cells, deliver nutrients, remove waste, transport substances like oxygen, hormones, and electrolytes

intracellular fluid

water and dissolved substances found inside every body cell

ion channel

membrane-spanning protein that forms a pore that allows the passage of ions from one side of the membrane to the other

concentration gradient

difference in concentration from one region to another. Ionic concentration gradients across the neuronal membrane help determine the membrane potential

electrical gradient

separation of positive and negative charges across the cell membrane

resting membrane potential

membrane potential or membrane voltage maintained by a cell when it is not generating action potentials; also called resting potential. Neurons have a resting membrane potential of about -65 mV