chapter one Flashcards
What do the glia do
Provide support to neurons
How many neurons are there
86 billion
cajal was the first to demonstrate what about cells in the nervous system? What did he use to demonstrate this?
The individual cells comprising the nervous system remain separate and don’t merch he did this using a Golgi stain a silver staining to visualize nervous tissue under microscope
What is the neuron hypothesis
That cells are discreet and not interconnected fibres
What part of the cell acts like a gatekeeper
Membrane
What part of the celll contains chromosomes and genes of the cell
nucleus
What part of the cell make proteins
Ribosomes
What is the Endo plasmic reticulum
Folded layers of membranes where proteins are assembled
What is the main difference between regular cells and neurons
Neurons all have a distinctive shape
Blank collect information from other cells and send it toward the cell body while blank get info from the cell body and carries messages to other cells
dendrites, axons
What is the core region of a neuron
Cell body or Soma
Give three descriptors of dendrites
Branching fibers, their surface are lined with synoptic receptors, they have done dendritic spines
What are dendritic spines? what is their function?
Protrusions that further branch out and further increase surface area of dendrites. the greater the surface area of the dendrite the more information the cell can receive
What is the cell body responsible for?
Metabolic work of the neuron
What is the axon hillock
Juncture of soma and axon where axon potential begins
Does an axon hillock branch into one or multiple axon collaterals?
It could do either
The end of an axon is like a blank that is called the blank
knob, presynaptic terminal
The interruptions along the axon that are not covered in Myelin are called
Nodes of Ranvier
Blank neurons are known as multipolar neurons, while blank neutrons are known as bipolar neurons
motor, sensory
Describe a motor neuron..where are they
extensive dendritic networks, large cell bodies, long axons that connect to muscles…..in lower brain steam nd spinal cord
describe sensory neurons
really simple compared to motor, bring sensory from body into spinal cord, sometimes really long distance, dendrite connected directly to the axon
Describing interneuron
Dendrites and axons completely contained within a single structure
What are the four main types of Glia cells
Astrocytes, microglia, oligdendocytes/schwann, radial glia
Describe the astrocytes
Star shaped glia cells help synchronize activity of axon by wrapping around presynaptic terminal and take up chemicals released. They dilate blood vessels which allows more nutrients to come into brain tissues that have heightened activity
Describe microglia
very small, remove waste material, removing virus and fungus, remove dead, dying damaged neurons, you find them a lot in areas of brain damage
describe oligdendocytes and Schwann cells
both responsible for building myelin sheath that arounds axons…olig are in CNS and schwann are in PNS
describe radial glia
guide migration of neurons and growth axon and dendrite in embryonic development
what nutrient can cross blood brain barrier?
glucose: its the neurons food source
why can oxygen and carbon dioxide cross blood brain barrier
very small
why can antidepressants and illegal drugs pass blood brain barrier
fat soluble
Explain astrocytes role in the blood brain barrier
The end of astrocytes attached to blood vessels causing the vessels to bind closely together and therefore prohibit entry to a bunch of substance
Describe the neuron at rest and the charge if the inside of the membrane
The membrane maintains electrical gradient known as polarization. Inside a slightly negative with respects outside at about -70 mV
How do you measure a neurons electrical activity
Use two microelectrodes one intracellular electrode and one extra cellular electrode when both of them are on the outside the electrical difference is zero when the intracellular penetrates the neuron the potential jumps to -70 mV
What are the four charged particles that take part in producing resting membrane potential
Sodium, potassium, chloride, large negative charged protein particles
which particles are on the in and outside of the cell?
potassium and protein on inside, sodium and chloride
Which particle is voltage gated
Sodium
what is the pump that sits on the membrane?
protein that sits on the membrane, its a sodium potassium pump..pumps 3 sodium ions out and 2 potassium ions in
what does the sodium potassium pump require
active tranport
describe the difference between the electrical gradient and the concentration gradient
the electrical gradient is the difference in charge across a membrane. the positive ions want in the cell because it is negatively charged. the cocentration gratin is the relative abundance of a substance in space. ions with high concentration want to diffuse to a place with lower diffusion so potassium wants to go outside and sodium wants to come inside
generally the concentration results in what for potassium and sodium and why? what’s the result?
potassium does leak out becausse its undated, sodium doesn’t because its gated. the sodium potassium pump restores the order to maintain the resting membrane potential
how much more potassium inside cell
about 20x
how much more sodium outside
about 10x
does chloride contribute to potentials? why or why not?
not really, the concentration gradient and voltage gradient are pretty equal
an action potential is a ____ impulse
nerve
the electric current rises, and when it reaches a certain threshold opens the _________ because it was _____ dependant
sodium gate, voltage
describe the ionic basics of the action potential
depolarizing current comes into cell, the electrical current rises, if it reaches the threshold at axon then the sodium gates open. the sodium ions flow in and subsequent nerve pulse occurs, propagating down. after the action potential occurs, the sodium gates quickly close…it returns to resting state by opening of potassium …the sodium potassium pumps later restores the original distribution of ions
what is the main point of all or none law
the action potential amplitude and velocity are independent of the stimulus that initiated …all action potentials intensity and speed are the same
describe absolute refractory period vs relative refractory period
absolute is the first part the membrane absolutey cannot reproduce another action potential…..relative it takes a stronger than usual stimuli
the state of the inside of the cell during the refractory period is known as _____ and is down to ….why does this happen
hyper polarization, -90….the potassium gate is slow to close
________ refers to when a nerve impulse jumps from node to node
salatory conduction
why is there a refractory period
to keep the propagation traveling one way, away from the initial stimulation
what causes multiple sclerosis? what happens in brain as result? how does this manifest in behavior?
damage of myeline….the autoimmune system innapropriatley attacks the CNS and destroys the myelin….nerve impulses can then be slowed or blocked all together. results in fatigue, lack of coordination, sensory, cognitive and motor impairments
describe local neurons
very short axons that only exchange information with neighbours, don’t produce action potential they produce graded potential
to use glucose the body needs _____
thiamine
metabolizing glucose requires _____ so neurons need a steady supply of it
oxygen
active transport is a ____ mediated process
protein
chemicals that require active transport to get into the brain include
amino acids, purines, choline, a few vitamins and iron
describe the basis of alzimers disease
cells lining the brains blood vessels shrink, allowing harmful chemicals into the brain
how fast a drug works is heavily dependant on what
how readily it dissolves in fats
describe viruses that pass the blood brain barrier
rabies, syppillis,
chickenpox: which remain there after being exterminated from rest of the body and may emerge from spinal cord later causing shingles, virus responsible for genital herpes hides in nervous system periodically emerging
