Chapter 4 - Communication In The Nervous System Flashcards
What are 3 types of interneurons?
Stellate (star-shaped) cell
• Small; many dendrites extend around the cell body; larger brains contain more (behavioral complexity).
Pyramidal cell
• Has a long axon, a pyramid-shaped cell body, and two sets of dendrites, apical and basal; carries information from cortex to rest of brain and spinal cord.
Purkinje cell
• Is distinctively shape with extremely branched dendrites that form a fan; carries information from cerebellum to rest of brain and spinal cord.
What are glial cells?
What are the 5 classes?
Provides insulation, nutrients and support
Aid in repairing neurons and eliminating waste products
Produced THROUGHOUT an organisms life
5 classes:
- Ependymal cell
- Astrocyte
- Microglial cell
- Oligodendroglial cell
- Schwann cell
What are ependymal cells?
(TYPES OF GLIAL CELLS)
Small, ovoid; found in the walls of the ventricles
Make and secrete cerebrospinal fluid (CSF)
What are astrocytes?
(TYPES OF GLIAL CELLS)
Star shaped, symmetrical
Provide structural support for neurons
Transport substances between neurons and capillaries (blood–brain barrier)
Enhance brain activity by providing fuel to active brain regions
Promote healing of damaged brain tissue
What are microglia?
(TYPES OF GLIAL CELLS)
Originate in the blood as offshoot of immune system
Involved in scavenging of debris (e.g., dead cells); phagocytosis
Monitor the health of brain tissue and play the role of its immune system
Identify and attack foreign tissue
Invade the area to provide growth factors that aid in repair when brain cells are damaged
What are the 2 types of MYELIN-producing glial cells?
- Oligodendroxcytes
- produce myelin in the BRAIN & SPINAL CORD
- 75% glial cells in brain - Schwann cells
- produce myelin in the REST of the nervous system
What is included in a cell membrane?
Phospholipid bilayer
Selectively permeable membrane
Phosphate head, lipid tail
Hydrophobic tail, hydrophilic head
Protein channels
Explain the difference b/w polarization, voltage and resting potential
Polarization: a state in which there is a difference in electrical charge between the INSIDE and OUTSIDE of the NEURON
Voltage: measure of the difference in electrical charge between TWO POINTS
Resting potential: difference in charge between INSIDE and OUTSIDE of MEMBRANE of a neuron at REST
What is a voltmeter?
Device that measures the difference in electrical potential b/w two bodies
Explain ions in terms of (+) & (-) and where they lie on the cell membrane?
(+) = Na+, K+
(-) = Cl-, A- (organic anion)
A- and K+ Ions have HIGHER CONC INSIDE the axon
Cl- ions and Na+ are MORE CONC OUTSIDE the axon
***We are gonna focus more on the +
What is force of diffusion?
Tendency of ions to move through membrane to LESS concentrated side
What is electrostatic pressure?
Force where ions are repelled from SIMILARLY charged, ATTRACTED to OPPOSITELY charged
What is concentration gradient?
Ink dropped into water diffuses
Until it is EQUALLY distributed through-out water
What is voltage gradient?
If salt solution is poured into water
Neg ions will flow down electrostatic gradient
UNTIL + and - is everywhere
What is the sodium potassium pump?
Large protein molecules that move Na+ ions through cell membrane to OUTSIDE, K+ ions back INSIDE
Ion channels can be “____________ gated or ____________ gated, or _____ gated ”
Chemically; electrically; not
CHEMICAL: neurotransmitters/hormones
ELECTRICAL: change in electrical potential of membrane
Explain the process of the sodium potassium pump
- K+ is free to ENTER & LEAVE the cell
- Na+ channels are ordinarily CLOSED to PREVENT entry to Na+
- Na+ - K+ pumps of THREE Na+ for EVERY TWO K+
***Basically FUCK Na+, who even likes them?
What are voltage-activated ion channels?
Gated protein channels that OPEN OR CLOSE only at SPECIFIC membrane voltages
CLOSED at membranes resting potential
Na+ channels are MORE SENSITIVE than K+ channels, these OPEN SOONER
***Na+ sensitive bc everyone HATES them
What is depolarization?
What is local potential?
If local potential EXCEEDS the threshold for activating electrically gated channels, then an ACTION POTENTIAL occurs
- usually due to an influx of sodium ions
Local potential:
- partial depolarization
- graded potential (varies in magnitude depending on strength of stimulus)
What is the action potential?
Abrupt DEPOLARIZATION of membrane that ALLOWS neuron to COMMUNICATE
Is UNGRADED = (all-or-none law: occurs at FULL strength or NOT AT ALL)
Is NONDECREMENTAL (travels down axon w/out any decrease in size, propagate at each successive point)
Who was Camilo Gogi?
Staining tissue showed and “interconnected net of fibres”
Called it a NERVE NET
Who was Ramon y Cajal?
Staining embryonic cells showed discrete cells of many sizes
Neurons are the nervous systems FUNCTIONAL UNITS
NEURON HYPOTHESIS
Todays accepted theory of brain organization
Explain the 3 basic structures of a neuron?
- Cell body (soma):
- core region of cell
- contains organelles
- INTEGRATES INFO - Dendrites:
- branching extensions
- COLLECTS INFO - Axon:
- main projection from soma
- CARRIES INFO
What is an axon hillock?
JUNCTION of the soma & axon
Where the ACTION POTENTIAL BEGINS
What is an axon collateral?
BRANCHES of an axon
What is a telodendria?
END BRANCHES of an axon
What is terminal button?
KNOB at the tip of an axon
CONVEYS info to other neurons
Aka end foot
What is the dendritic spine?
PROTRUSION from dendrite
Greatly INCREASES surface area
Usual point of contact w/ axons of other cells
What is the synapse?
GAP b/w one neuron and the text
Usually between an end foot of the axon of one neuron and a dendritic spine of another neuron
What is hyperpolarization?
INCREASE in electrical charge across a membrane (MORE NEGATIVE)
DUE to inward flow of CL- or outward flow of K+ ions
What is an absolute refractory period?
Na+ ion channels are UNRESPONSIVE to FURTHER stimulation
New action potential CANNOT occur
What is an relative refractory period?
Na+ ion channels COULD support another action potentional, but Na+ K+ channels are STILL OPEN
Only will occur if the stimulation is sufficiently STRONG enough to OVERCOME the charge
What is a rate law?
Axon encodes stimulus intensity NOT in the size of its a action potential
BUT in its FIRING RATE
What are excitatory postsynaptic potentials? (EPSP)
When receptors open Na+ channels to produce a PARTIAL DEPOLARIZATION of the dendrites and cell body
What are inhibitory postsynaptic potentials? (IPSP)
Receptors open K+ channels, Cl- channels, or BOTH to produce a HYPERPOLARIZATION of the dendrites and cell body
What is spatial summation?
COMBINES potentials occurring stimultaneously at DIFFERENT locations on the dendrites and cell body
What is temporal summation?
COMBINESv potentials arriving a SHORT TIME APART, from either the SAME or SEPARATE inputs
Tay-Sachs disease results from a “__________” allele being expressed, Huntington disease results from a “__________” allele
Recessive; dominant
What is gene (DNA) methylation?
EPIGENETIC mechanism that either enables or blocks transcription
What distinguishes Mendelian genetics from epigenetics?
Mendelian: focuses on inheritance patterns
Epigenetics: study on how enviro & experience can affect the inherited genome
How can the genome of your brain cells change throughout a lifetime?
- W/in and in the cells environment: epigenetic mechanisms (histone mod., gene methylation, mRNA mod.)
- Environmental experiential factors: stress/reduction in stress, changes in brain
Glial cells that participate in neuronal growth and repair in the “______” NOT the “_______”
PNS; CNS
A map of the physical wiring of the entire human brain is called what?
Connectome
Sensory neurons are the “___________” neuron
Simplest
