physiology exam 1
selective permeability
1. what is it?
2. how is it possible
a characteristic of a plasma membrane where it will allow some substances into the cell but not other substances
2. diffusion, osmosis, transport proteins, and active transport
phospholipid
main building block of a membrane
fluid mosaic model
fluid: the membrane is more fluid than solid because the proteins and phospholipids move laterally
Mosaic: because it is composed of manny different macromolecules
Model:
what molecules will dissolve in the lipid layer?
1. molecules that are hydrophobic (non-polar)
What molecules can get through the lipid layer
examples (2)
Some small/ non-polar molecules
1. O2 and CO2
what molecules will not pass through the lipid layer
large molecules
what molecules cannot pass through the lipid layer?
examples (2)
hydrophilic (polar)
1. Na+ and Cl-
Diffusion
the spontaneous movement of a substance from the regions of higher concentration to regions of lower concentration without the need of energy
in general cells have:
1. outside:
2. inside:
1. high concentration of Na+, Ca2+ & Cl-
2. high concentration of K+
what is a gradient?
a difference in amount of stuff in two different areas
what does the gradient determine?
the direction and rate of diffusion
what are the two types of gradients?
1. chemical concentration gradient
2. electrical concentration gradient
1. the chemical concentration gradient
2. the electrical concentration gradient
1. the concentration of a substance
2. the charge of the substance compared to the charge in the cell
electrochemical gradient
describes both the effects of the electrical concentration gradient and the chemical concentration gradient
motion zero
...
net diffusion
majority of ions come into the cell from outside of the cell
the bigger the gradient the __A__ they move and the __B__ ions that move
A. faster
B. more
some channes are....
specific for certain things
no net diffusion =
equilibrium state
The influence of an electrical gradient
1. opposite charges have...
2. similar charges have...
1. a level of attractive force
2. a level of repelling force

A. look at the charge inside the cell
B. look at how much of that substance is inside the cell
C. which direction will it move
D look at the charge of the ion
E. look at how much of that substance is outside of the cell
Electrochemical equilibrium
the balance between both the gradients
other factors that can influence diffusion (3)
1. types of leaky channes
2. types of transporters
3. number of channels/ transporters
types of channes (2)
1. leaky channels: always open
2. gated channes: could be open or closed
types of channels (4)
1. chemical- gated: opened by chemicals
2. voltage-gated: opened by electrical charge
3. mechanical
4. thermal-gated: opened by temp.

A. Specific non-lipid-soluble molecules or ions
B. non-lipid-soluble molecules
C. lipid-soluble molecules
D. membrane channel
E. concentration gradient
Transport proteins:
1. does not use...
2. this is called
3. example
1. energy
2. facilitated diffusion
3. GLU transporter (Glucose)
what happens when a chemical substance binds to a protein?
the protein changes shape
what is needed to move a substance against their concentration gradient?
- getting these materieals across the membrane uses?
ATP (energy)
- active transport
example of active transport
1. sodium potassium pump
sodium/GLU transporter
A. does this use energy?
B. depends on?
C. this is considered?
D. what is sodium used for?
1. no
2. those that do directly use energy
3. secondary active transport (fake)
4. to help glucose move up its concentration gradient

...
osmosis
diffusion of water across a selectively permeable membrane
1. hypertonic
2. hypotonic
3. isotonic
1. high concentrations of solute (low water)
2. low concentrations of solute (high water)
3. equal concentration of solute on each side
exocytosis
the ejection of cytoplasmic materials by the fusion of a membranous vesicle with the plasma membrane
endocytosis
the movement of extracellular material into the cytoplasm via the formation of a membranous vesicle at the cell surface.

A. dendrites B. nissle bodies C. axon hillock
D. axolemma E. axon F. synaptic terminals
G. nucleus H. nucleolus
what do all cells have?
a membrane potential
membrane potential
the difference in the electrical charge between the inner membrane and the outer membrane
1. excitable cells =
2. nonexcitable cells=
1. changeable membrane potential (neurons and muscle cells)
2. cannot change membrane potential (all other cells)
what creates the electrical charges of a cell?
ions, amino acids, and proteins
resting membrane potential results from..?
differences in charge across a membrane. (different concentrations of + and - charges
what ions are responsible for generating the value of the membrane potential
concentrations of K+, Na+, Cl- and others
1. Intracellular
2. Extracellular
1. inside the cell
2. outside the cell

A. both chemical and electrical gradient influence
B. now just chemical
C. now diffusion is slowed down b/c electrical gradient is getting more and more +

D. now Na+ is stopped diffusing b/c such a high gradient. (no net diffusion = electrochemical equilibrium) => ENa+ = +60mV
E. It is so positive it is now pushing Na+ out of the cell
1. Ena+ =
2. Ek+ =
1. +60 mV
2. -90 mV

1. no more net diffusion => Ek+ = -90mV
the synapse
where a neuron talks to another cell
where are most nerotransmitters synthesized?
where are they reassempled?
the soma
the synaptic terminals
axoplasmic transport
movement to and from a neurons cell body
1. anterograde
2. retrograde
1. movement towards synaptic terminal
2. movement towards soma of neuron
1. slow movement= A => B
2. fast movement= C => D
1. A. slow stream
B. 1-3mm per day
2. C fast stream
D. 5-10mm per hr
1. what do the terms slow stream and fast stream refer to?
2. what do they not refer to?
1. the movement of stuff (NTs)
2. action potentials
Kinesins
motor protein
how can we change the membrane potential of the postsynaptic membrane?
by increasing the permeability of the membrane to allow ions to move across


1. what happens when you increase the flow of ions across the membrane of a neuron?
2. what does that cause
3. what does that lead to
4. what happens to those ions that entered the cell
1. you generate a current
2. that changes the membrane potential
3. creation of a graded potential
4. move to regions of lower concentrations
graded potential
a. more ions =
b. less ions =
a temporary slight change in the memb. potential
a. bigger change
b. smaller change
action potentials
how neurons send the message along the axon to communicate to the next neuron
only what kind of cells can generate an action potential?
- ex? (2)
excitable cells
- muscle membranes and neuron membranes
what is an action potential
- a brief "transient" change in the membrane potential in response to a stimulus
what does a stimulus do?
causes a change in the permeability of the membrane
what must the stimulus reach to trigger an Action potential
threshold
what is the purpose of the stimulus?
to cause enough of an increase in the permability of the cell membrane to significantly change the RMP of that fart of the membrane to initiate action potentials
changes in permeability results in...
changes in ion flow




refractory periods (2)
1. absolute refractory periods
2. relative refraxtory
1. absolute refractory period
2. relative refractory period
1. not able to start AP
2. can start an AP if big enough

A. absolute refractory
B. end of relative refractory
C. resting membrane potential

A. may be able to send AP if enough stimulus
B. can't send an AP
hoe to affect the information of an action potential (3)
1. influence the membrane potential at the initial segment
2. influence the release of neurotransmitters
3. influence the duration of the NTs at the synapse
1. influence the membrane potential at the initial segment
a. NTs can do what to a postsynaptic neuron
b. what types of summations are there?
a. inhibit or excite
b. temporal and spatial




what happens in an excitatory synapse
we excited the postsynaptic memb. so that it didn't exactly reach threshold (-55mV) but it did have a little more + charge (could be -69, -60, etc)
what happens in an inhibitory synapse
- either introduce a - charge or a + charge ion
- GABA could land on a Cl gated channel which lets in Cl-
-Cl- could attract + charged ions making initial segment more negative
temporal summation
rapidly repeated stimulation from one synaptic knob
spatial summation
2 or more synaptic knobs simultaneously stimulating


2. influence the release of neurotransmitters
they can do what do the presynaptic neuron
facilitate or inhibit




what happens in presynaptic facilitation
serotonin influencing Ca2+ channels make it so that they are open, so more exocytosis, so more NT release
what happens in presynaptic inhibition
GABA influences Vg Ca2+ channels making it so that Ca2+ cant get in, so no exocytosis, so not much NT release
1. where do you find chemical channels?
2. where do you find voltage gated
1. only on somas and dendrites
2. only on synaptic terminals
how to end the effects of NTs (2)
1. degredation of NTs
2. Reuptake
Degredation of NTs-
1. how?
enzynmes break down the NTs
reuptakes-
1. what happens
NTs are taken back up into the presynaptic neuron
how to prolong the effects of NTs (2)
1. enzyme activity
2. preventing reuptake
Enzyme activity examples for prolonging the effects of NTs (2)
1. MAOs
2. MAOIs = monoamine oxidase inhibitors
1. MAOs
2. MAOIs
1. breaks down NTs
2. stops the break down of NTs
preventing reuptake examples (2)
1. medications that are general (TCA=tricyclics)
2. medications that are specific (SSRIs = serotonin selective reuptake inhibitors)
1. TCAs
2. SSRIs
1. affects 3-4 NTs
2. only affects serotonin so that serotonin can stay in the cleft longer
a change in the membrane potential creates...
a signal
1. graded current =
a. travels ___ distances
b. speed?
c. lotation?
1. changes in membrane potential that gets weaker as it travels away from the source
a. short
b. slowly
c. in dendrites and somas
2. action potentials
a. travels ___ distances
b. speed?
c. lovation
2. keep their same strength no matter how far they travel
a. great
b. very fast
c. axon hillocks to axon terminals
how are axons classified?
-examples (3)
based on diameter or velocity
1. type A fibers
2. type B fibers
3. Type C fibers
type A fibers
1. ____ diameter
2. velocity =
3. is this myelinated?
4. these are for what?
1. largest
2. very fast - 268mph
3. myleinated
4. sensory input- reflexes
Type B fibers
1. ____ diameter
2. velocity
3. is this myelinated
1. smaller diameter
2. 40 moh
3. myelinated
Type C fibers
1. ____ diameter
2. velocity
3. is this myelinated
4. these are for what?
1. smallest in diameter
2. very low 2 mph
3. unmyelinated
4. pain signals
types of nerve fibers based on NT released (2)
1. cholinergic fibers
2. adrenergic fibers
1. cholinergic fibers
2. adrenergic fibers
1. fibers that release acetylcholine
2. fibers that release norepinephrine or epinephrine
categories of receptors that recieve the NT
1. cholinergic receptors for Ach
2. adrenergic receptors for norepinephrine
cholinergic receptors for Ach (2)
1. nicotinic receptors
2. muscarinic receptors
1. nicotinic receptors
a. types
b. example
1. many different types
2. skeletal muscle tissue
2. muscarinic receptors
a. types
b. examples
a. 5 different types
b. cardiac tissue
2. adrenergic receptors for norepinephrine(2)
a. alpha
b. beta


Sympathetic dividision uses what kind of NT
both Ach and norepinephrine
parasympathetic division uses what kind of NT
only Ach


how many synapses could you have on a single soma?
up to 50,000