Exam 2 Flashcards
intracellular
inside cell
intercellular
outside cell
agonist
encourages rxn
antagonist
blocks rxn
up-regulation
increase response to stimulus
down-regulation
decrease response to stimulus
what changes can receptor activation lead to?
-transport properties
-permeability
-electrical state of plasma membrane
-metabolism
-secretory activity
-proliferation and/or differention
-contraction
cessation of activity
-decrease in receptor activation
-decrease in first messenger
-decrease in receptor #, affinity or activity
how does a decrease in first messenger occur
-enzymes
-taken up by adjacent cells
-diffuses away
how does a decrease in receptor #, affinity, or activity occur
-receptor phosphorylation decreases affinity for 1st messenger and prevents g protein binding
-receptor endocytosis
what coordinates functions of the body?
both nervous (fast) and endocrine (slow) systems
what do nervous and endocrine systems do?
-regulate internal functions
-organize and control behavior
what system controls ALL behavior?
nervous system
what do nerve cells do?
coordinate organs, mediate sensation, control movements, encode the ‘mind’
central nervous system contains..?
brain, spinal cord
peripheral nervous system..?
peripheral nerve
dendritic spines purpose
increase surface area for a neuron to receive signals from other neurons
what does myelin normally contain?
-20 to 200 layers of oligodendrocytes
or
-Schwann cell plasma membrane surrounding portions of axons
what does anterograde use?
kinesins
what does retrograde use?
dyneins
anterograde
moving along an axon away from neuronal cell body
retrograde
moving from axon terminal back towards neuronal cell body
where does afferent go
towards region of brain
where does efferent go
away from region of brain
where do interneurons project?
they project within the nucleus
ganglion
group of neuronal cell bodies outside of CNS
nerve
group of axons outside of CNS
tract
group of axons inside the CNS
amount of glial cells in human CNS
at least 50%
what do glial cells do?
-provide physical and metabolic support to neurons
-retain capacity to divide throughout life
what do oligodendrocytes do?
-form myelin of CNS
-one oligodendrocyte provides several segments of myelin for several neurons
astrocyte functions (5)
-regulate interstitial fluid composition of CNS by removing neurotransmitters, ammonia, and excess potassium from extracellular fluid
-stimulate blood/brain barrier
-provide glucose or ketones to neuron for metabolism
-guide and stimulate neuronal growth during development
-may play note in brain signaling
Microglia
phagocytic immune-like cells
Ependymal cells
regulate flow + production of cerebrospinal fluid
Schwann cells
-myelinated axons in PNS
-each provides one segment of myelin for one axon
electrical force
-increase with quantity of charge
-increases with distance of separation between charges decreasing
current
-rate of movement of change
-positive in direction of positive charge movement
Ohm’s Law
I= V/R
I- current
V- electrical potential (voltage)
R- resistance
is the inside of a cell more + or - ?
negative
when is equilibrium (steady-state) reached?
when diffusion driving forces pulling potassium out of cell is exactly matched by electrical driving force pulling the potassium back into cell.
how does flow of cation (+) into cell affect membrane potential
leads to positive membrane potential
what do miniscule changes in ionic concentration lead to?
large changes in membrane potential
ionic driving force
ions are driven across the membrane at a rate proportional to the difference between the membrane potential and equilibrium potential
Nernst Equation
(1/ion charge)(61.54mV)log [ion o]/[ion i]
what uses 70% of all ATP used by the brain?
Na/K pump
concentration/electrical gradients in brain
-Na/K pump
-calcium pump
-calcium binding proteins
-large number of anionic proteins contribute to negative membrane potential
-potassium
-sodium
potassium and sodium leakiness
potassium- leaky
sodium- not leaky
can determine permeabilities with goldman equation
look up and double check because too much work to write out lol
what flows out of a cell
Na
what flows into a cell
K
what does Na flow with
flows in with both concentration and electrical gradient
what does K flow with
flows in with electrical and out with concentration gradient
how is concentration difference for Cl ion determined?
-by electrical difference across the membrane
what does increasing chloride permeability do to membrane potential?
makes membrane potential more negative
how is extracellular potassium concentration regulated in the brain?
-blood/brain barrier regulates K entry
-astrocytes take up excess potassium from around neurons
excitable cells
-can change membrane potentials
-use this to transmit info quickly from one part of membrane to another
most common types of cells to display excitability
all muscle cells and neurons
how to muscle cells use excitability
to coordinate contraction
how to neurons use excitability
to transmit info as to whether or not to release neurotransmitter
types of changes in membrane potential
-graded
-action potential
graded potential
-caused by the openings of an ion channel in the dendrites or soma of a neuron
-can depolarize or hyperpolarize cell
vary in amplitude (depending on # of channels open and duration of opening)
-can be localized or decremental
depolarize cell
make less negative (Na in)
hyperpolarize cell
make inside more negatively charged (K out)
action potentials
-how a neuron can transmit a signal from the dendrites or soma to the axon terminal
-wave of depolarization that moves down length of axon
-has a characteristic size and shape that is always the same for a given neuron
-retains size + shape down entire axon length
-all-or-none
initial depolarization
Na goes in
how are action potentials triggered
-triggered by graded potentials that reach a threshold depolarization at the axon hillock (trigger zone)
5ms after depolarization
K goes in
only time action potential can generate
-when depolarizing stimulus of sufficient intensity is generated
-either stimulus is not great enough to open any of the voltage-gated sodium channels, or it opens all
how do Na channels work
Na channels open and inactivate very rapidly
how to K channels work
K channels open and close slowly
