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human phys quizlet cards

The scientific study of living things
How do we know if a thing is a living thing?
Life is a process or function, not a substance
Characteristics of living things
- Organization
- Homeostasis
- Grow
- Adapt/evolve
- Reproduce
- Require energy and nutrients
Process by which organisms maintain
equilibrium or internal constancy (temp, bp,
blood sugar, pH, water balance)
The study of the processes or functions of
Levels of organization
- Atom
- Molecule
- Cells
- Tissues
- Organ
- Organ system
- Organism
Assemble into cell structures, regulate cell
functions, and catalyze cell reactions
Smallest units capable of carrying out the
processes of life
Group of cells with similar structures and
Four types of tissue
1. Epithelial
2. Connective
3. Muscle
4. Nervous
Two or more types of tissue organized to
perform a particular function
Organ system
Collection of organs performing related functions
and interacting to accomplish a common activity
Negative feedback
main regulatory mechanism for homeostasis
- Occurs when a change in a variable
triggers a response that opposes the
- Delayed response
Measures the variable
Compares with set point/ideal
Makes corrective response
Anticipation/feedforward control
Reduces delay and helps overcome fluctuations
Predicts and counters oncoming disturbance
before regulated state is changed
Positive feedback
output is continually enhanced so that the
variable continues to move in the direction of
- occurs when rapid change is needed because
homeostatic set point is no longer appropriate
- eventually a trigger will end the positive
feedback loop
- EX: birth
Whole body systems
Regulate and coordinate homeostasis and other
functions for the good of the whole body
Nervous system
- for activities requiring swift responses
- detects external environment changes
- Coordinates complex "higher" functions like
learning, memory, and consciousness
Endocrine system
- for activities that require duration rather than
- Controls internal environment and reproductive
Support and movement systems
Protect from harm, obtain food, reproduce, etc
Skeletal system
- support and protection for organs
- Enables movement
Muscular system
- enables movement
- Temperature regulation
Maintenance systems
Maintain the internal environment/homeostasis
Circulatory system
Transports nutrients, gases, hormones, etc.
Around the body
Respiratory system
- gas exchange
- Maintains proper ph
Immune system
- defends against foreign invaders and
cancerous cells
- Repairs or replaces injured and old cells
Excretory system
Removes excess water, salts, acids, and wastes
Digestive system
- breaks down food to absorbable nutrients
- transfers water and salts to internal
- Eliminates undigested food
Integumentary system (hair, skin, and nails)
- regulates body temp
- Protective physical barrier keeping out
microorganisms and keeping in internal contents
Reproductive system
- produces gametes
- delivers gametes
- embryo and fetal development
- Produces milk
Cell membrane
- encloses cell
- maintains differences in ion concentrations
inside and out of cells
- permits specific substances to pass in and out
- Provides surface interactions for cell-to-cell
Cell membranes have three components
1. Phospholipids
2. Cholesterol
3. Proteins
Have hydrophobic and hydrophilic regions
(Hydrophobic) repel water
Phospholipid bilayer
Unsaturated fatty acids
Saturated fatty acids
Increase fluidity (more flexible)
Decrease fluidity (stiffer)
Some molecules wiggle through on their own
Some molecules cannot wiggle through on their
Passive transport
Passive transport examples
Simple diffusion
Facilitated diffusion
Cells have watery insides and watery outsides,
so phospholipid tails clump in such a way that
two layers are formed
shape only take their shape because of the
clumping of the tails
- Constantly moving and wiggling around,
exchanging places millions of times per
- This accounts for the membrane's fluidity
- don't line up well
- Makes phospholipids more flexible/fluid
- stack well
- Makes phospholipids stiffer
hydrophobic lipid that animals make
- Wiggles in with the hydrophobic tails to
make the cell membrane less fluid (stiffer)
- use unsaturated fatty acids
- Use no or very little cholesterol
- use saturated fatty acids
- Use plenty of cholesterol
- heat = more fluid
- cold = less fluid
- cold environments use unsaturated fats
- Warm environments use cholesterol
- channels/pores or carriers for transport
- receptors for communication
- enzymes for chemical reactions
- adhesion proteins for anchoring and attaching
- Recognition proteins
- Small molecules (water, co2, o2)
- Hydrophobic molecules (lipophilic
molecules, caffeine, alcohol, hormones,
- Hydrophilic molecules (sugars, salts)
need transport proteins
- Large molecules (polysaccharides) need
vesicular transport
the movement of substances across a cell
membrane without the use of energy by the cell
- Move down high to low
- Simple diffusion
- Facilitated diffusion
- Osmosis
movement of a solute from an area of high
concentration to an area of low concentration
- O2 in, CO2 out
- Wiggle across phospholipids
the transport of substances through a cell
membrane along a concentration gradient with
the aid of transport proteins
Isotonic solution
Hypertonic solution
Hypotonic solution
Isotonic solution
Energy-requiring transport
Active transport
Vesicular transport
Cell-to-cell communication
Direct cell communication
Surface markers
Messenger ligands
- Take up salts and electrolytes
Diffusion of water through specialized
The relative concentration of solutions that
determine the direction and extent of osmosis
Has the same concentration of nonpenetrating
solutes as normal cells
A solution in which the concentration of solutes
is greater than that of the cell that resides in the
A solution in which the concentration of solutes
is less than that of the cell that resides in the
No net flow
Water flows out, cell shrinks
Water flows in, cell expands
movement of substances either against their
concentration gradient (low to high) or using
- Energy required
Use of a protein and energy (ATP) to move
molecules against their concentration gradients
Allows large things to enter (endocytosis) or
leave (exocytosis) the cell
Communicate through direct contact or indirectly
through extracellular chemical messengers
gap junction tunnels that bridge two cells
- Allow small molecules and ions to be
- Especially important for electrical signals
(ions) in excitable cells (like neurons)
allow for direct linkup between cells
- Allows for recognition
- Especially important for immune system
to recognize and destroy cells that aren't
our own
cytoskeletal extensions that allow transfer of
molecules and also whole organelle
- Found between developing mammalian
immune cells
- paracrines
- neurotransmitters
- hormones
- neurohormones
- pheromones
- Cytokines
local chemical messengers that only affect cells
in immediate environment
- Rely on diffusion
Intracellular cascades
Lipophilic molecules
Lipophobic molecules
Nuclear receptors
Three means of signal transduction upon
Opening or closing chemically/ligand gated
membrane channels
Activation of an enzyme that in turn activates a
Transferring signal to an intracellular chemical
molecules used by neurons (brain/nerve cells) to
communicate directly with their very close,
specific target cells
- Released in response to electrical signals
- Targets can be other neurons, muscles,
or glands
long-range messengers secreted into circulation
by glands to effect cells at a distance
- Only target cells will have appropriate
receptors/receive the message
Released by neurons in response to electrical
signals (like neurons) but are released into blood
stream to affect distant target cells (like
released into the external environment and
travel through air or water to sensory cells in
another animal
- Often used for social interactions such as
sexual activity and marking territory
can have local or distant effects but are not
produced by glands
- Made by almost anybody cell, generally
involved in development and immunity
when activated, receptors trigger a biochemical
chain of events inside the cell called signal
- 2 mechanisms: lipophilic and lipophobic
Enter the cell by moving through the membrane
Cannot enter the cell and must bind to receptors
on the cell surface
Receptor recognizes a particular promoter
sequence and starts transcription (building new
proteins/changing gene expression)
1. Opening or closing chemically/ligand
gated membrane channels
2. Activation of an enzyme that in turn
activates a protein
3. Transferring signal to an intracellular
chemical messenger - "second
regulates movement in and out of the cell
- Especially important for ion movement,
which causes electrical conduction in
brain muscle cells
some receptors have a protein kinase enzyme
associated which activates other proteins
- Common molecules that use this pathway
= insulin and growth factors
this in turn triggers a cascade of events
Second messenger
Amplification of a second-messenger pathway
Two categories
Membrane potential
The majority of the ICF and ECF is electrically
neutral and the membrane itself is not charged
All cells have a slight excess of positive charges
outside and negative charges inside
Some excitable cells (brain and muscle) can
produce rapid changes in membrane potential
when excited
Equilibrium potential for K+
G-protein coupled receptor, g protein,
second messenger (most common =
camp), protein kinase, designated protein
1. cAMP
2. Ca+2 (through DAG and IP3 pathways)
3. cGMP
It only takes a small amount of the original
messenger to bring about dramatic effects
1. Antagonists
2. Agonists
block a step or receptor in a signaling pathway
- EX: Viagra blocks the second messenger
pathway that restricts blood flow (allowing
more blood flow)
enhance a step or activate a receptor
- EX: heroin and morphine are agonists of
opioid receptors (mimicking endorphins)
separation of charges across the membrane
- Measured in millivolts (mv)
- Opposite charges attract each other,
causing them to line up against
- Na+ and Cl- ions = high outside in ECF
- K+ ions = high inside in ICF
the magnitude of the membrane potential
depends on the number of charges separated
- As more separated charges are lined up,
the membrane potential rises
- Resting membrane potential is negative
- Main ions: Na+, K+, and A- A- is a negatively charged intracellular
- A- too large to cross membrane, but Na+
and K+ can move through channels if
- K+ is extremely permeable (crosses
- The opening of ion channels (transport
proteins for ions) to allow Na+ and K+ to
flow will quickly alter the resting
membrane potential
- -90mv
- Inside negative relative to outside
- If membrane was fully permeable to K+, it
would flow out of the cell down concentration
- Cell would become more negative because
of A- Now K+ is attracted to negative inside and
starts to flow back inward down the electrical
Nernst equation
When the electrical and concentration
gradients counterbalance, no net movement
occurs = equilibrium potential for K+
eion= 61/z log co/ci
Equilibrium potential for Na+
61 = a constant
Z = ion's valence
Co = concentration outside
Ci = concentration inside
Equilibrium potential for Na+
If membrane was fully permeable to Na+, it
would flow into the cell down concentration
- Outside becomes more negative because
of Cl-
But now Na+ is attracted to negative outside and
starts to flow back out down the electrical
Goldman-hodgkin-katz equation
Vm =
Counterbalancing passive leaks and active
Resting potential is not at K+ or Na+ equilibrium,
pumping at resting membrane potential
so both leak
- Continually, K+ leaks out, Na+ leaks in
- K+ more because it's so permeable
- Na+ more slowly because it's less
Excitable cells
Undergo rapid, short-lasting changes in
membrane potential
Two main types of excitable cells
1. Neurons
2. Muscle cells
Use change in potential to receive, process,
initiate, and transmit signals
Use change to contract
Membrane potential other than 0 mv
Decrease in potential; membrane less negative
Return to resting potential after depolarization
Increase in membrane potential; membrane
more negative
Two main techniques of measuring membrane
1. Microelectrodes
2. Patch clamping
Can be inserted into a neuron with little damage;
can directly measure voltage
- Can also be paired with a voltage clamp
technique: membrane potential is held at
a constant and specific value
Patch clamping
Electric signaling
Leak channels
Gated channels
Four types of gated ion channels
Voltage-gated channels
Ligand-gated (chemically gated) channels
Mechanically-gated channels
Thermally-gated channels
Channel opening results in one of two forms of
electrical signals
Graded potentials
Stronger event
Longer duration of event
Graded potentials are
Allows researchers to measure which
ions move in which direction at any given
A single tiny pipe gets attached to membrane
with gentle suction
- Allows measurement of a single ion
- Can also add substances to pipe the (to
block or activate receptors and channels)
Generated by ion movement across the
- Changes in ion movement are brought
about by changes in membrane
permeability in response to a triggering
Non-gated and open all the time
- Contribute to resting potential
Opened or closed in response to a stimulus;
changes membrane potential
1. Voltage-gated
2. Ligand-gated
3. Mechanically-gated
4. Thermally-gated
Open and close in response to changes in
membrane potential; crucial for neural signaling
Open or close in response to a specific chemical
messenger; also crucial for neural signaling
Open or close in response to stretch or touch;
important for sensory transduction
Respond to local changes in temperature; also
important for sensory transduction
1. Graded potentials
2. Action potentials
Serve as short distance signals
- Usually produced in only one region of
- Result in depolarization with a magnitude
directly related to the magnitude of the
triggering event
More channels open = larger graded potential
Longer duration of graded potential
A flow of electric charge
- Once a graded potential is produced in
one area, the current spreads in both
directions due to neighboring voltagegated channels
- Called passive conduction
Decremental: they gradually die out over short
- This is because of leaks in the current
(membrane has no good insulators here)
Graded potentials generate
Action potentials
Triggering an action potential
Explosive depolarization
Action potential
Voltage-gated ion channels
Two types of channels important for action
Voltage-gated Na+ channels
Voltage-gated K+ channels
Changes in permeability underlying an AP
This is why they are only useful at
signaling over short distances
- Postsynaptic potentials (neural function)
- Receptor potentials (sensory/neural
- End place potentials (muscle function)
- Pacemaker potentials (cardiac function)
- Slow wave potentials (muscle and cardiac
Brief, rapid, large changes in membrane
potential during which the cell becomes more
positive than the outside
- Involved only a portion of membrane
- But APs are nondecremental
- Great for long distance signaling
- Graded potentials in a cell create currents
that depolarize portions of the cell
- These can summate, causing even more
depolarization, eventually reaching
- Usually, ~+10 or 15 mv above resting
+30 to +40mv
- Just as rapidly, the membrane repolarizes
dropping to resting, but the forces behind
this push too far, causing a transient
hyperpolarization (~-80mv)
The entire rapid change from threshold to peak
and then back to resting
- An AP is an all-or-none event: if threshold isn't
reached, an AP doesn't fire
Responsible for permeability changes during the
action potential
1. Voltage-gated Na+ channels
2. Voltage-gated K+ channels
Have two gates
- Activation gate guards the channel
- Inactivation gate blocks the channel (ball
and chain)
Both gates must be open to allow Na+ through
Only has one gate
• Hinge
- Unlike Na+ channels, which open rapidly
at threshold, K+ have a delayed onset to
1. At rest, all voltage-gated channels are
2. At threshold, Na+ activation gate opens
and Na+ moves in
After an AP
Anatomy of a neuron
Cell body
Axon hillock
Axon terminals
Contiguous conduction
3. Na+ moving in causes explosive
4. At peak of AP, Na+ inactivation gate
closes, ending movement in. At same
time, K+ activation gate finally opens and
K+ starts moving out (down it's
concentration gradient)
5. Positive K+ flows out, repolarizing the cell
(making it more negative)
6. On return to resting potential, Na+
activation gate closes and inactivation
gate opens. Does not cause a change in
Na+ flux here but allows it to reset for the
next threshold.
7. K+ keeps moving out, causing a brief
8. K+ gate closes and resting potential
- The resting potential is restored by the
closing of na and K channels but ion
concentration is altered slightly.
- The cell can fire another AP right away
but it will eventually reach equilibrium
- Needs Na+/K+ pump
A single AP involves only a small membrane
portion of an excitable cell, but it must travel in
order to serve as a long-distance signal
- Plus, there must be a way for the signal
to be transmitted from one cell to the next
- Neurons and muscle cells = excitable
Houses the nucleus and organelles of a normal
cell, but has unique offshoots: dendrites and
Project like antennae to increase surface area
for receiving signals from other neurons
- Dendrites and cell body = "input zone"
because they receive and integrate
incoming signals
- Also, where graded potentials occur in
response to triggering events
"Conducting zone"
A single extension that conducts APs away from
the cell body and communicates with other cells
"Trigger zone"
Site where APs is triggered by a graded
"Output zone"
Branch at the end of the axon where they pass
on information to other cells
- Involves spread of AP down every patch
of membrane along the axon
Refractory period
Absolute refractory period
Relative refractory period
Coding the strength
Stronger stimulus = frequency of APs
Saltatory conduction
Schwann cells
Nodes of ranvier
Increasing speed by increasing axon diameter
AP cycle repeats in a chain reaction until
it has spread to the end
Time during which a new AP cannot fire in a
region that just fired an AP
- The refractory period prevents
"backward" current flow. During an AP
and slightly after, an area cannot be
restimulated to undergo another AP,
ensuring it can be propagated forward
along the axon
Membrane is completely incapable of firing
another AP no matter how much it is stimulated
by a triggering event
- When channels are already open, they
can't be stimulated to open again
Membrane can only be stimulated by a strongerthan-usual triggering event
- Some lingering inactivation of Na+
channels and the slowness to close of K+
channels = fewer channels in resting
potential and ready
If a stimulus is too weak to get the membrane to
threshold, no AP fires
- Helps to not clutter up the nervous
A stronger stimulus doesn't cause a stronger
AP, but it does cause more APs per second
- Stronger stimulus will also cause more
neurons to reach threshold, thus
increasing total amount of info sent
The spread of APs jumps from node to node
AP conduction down insulated axons where AP
only happens at nodes instead of along entire
~ 50 times faster than contiguous
A lipid made by cells that tightly wrap around the
Myelin in CNS
Myelin in PNS
The bare spaces between myelinated regions
- Voltage-gated Na+ and K+ channels are
at nodes, so this is where current flows
and APs can fire
When axon diameter increases, inner resistance
decreases allowing for faster conduction
Region where info transfer takes place
- Info is transferred across the synapse
from presynaptic cell to postsynaptic cell
When an AP signal reaches the end of an axon,
it must transmit information to the next cell
Two types of synapses
1. Electrical
2. Chemical
Electrical synapse
APs are transmitted across electrical synapses
unperturbed, as if the synapse wasn't present
- The cytoplasm of both cells is in contact
via gap junctions
- Ions flow right through continuing the
- Negligible time delay
Chemical synapse
Pre- and postsynaptic cells don't actually make
contact at chemical synapses
- The gap, called the synaptic cleft, is too
large for electrical impulses to travel past
- Instead, chemical messengers called
neurotransmitters carry the message
Chemical diffusion advantages
• Operate in one direction only
• Allow for signaling other than just
excitatory APs
Synapses can occur between two neurons or
In neuron-to-neuron signaling, usually an axon
between a neuron and a muscle cell
terminal synapses onto the dendrite or cell body
of the postsynaptic neuron
- Axon-to-axon synapse is far less common
- Most neurons receive thousands of
synaptic inputs from the axon terminals of
other neurons
Synaptic knob
Swollen end of nerve fiber
Synaptic vesicles
Store neurotransmitter
An AP triggers neurotransmitter release from the NTs bind to receptors on the postsynaptic cell,
presynaptic cell
usually opening ion channels
Synaptic delay
Converting the signal from electrical
(presynaptic) to chemical (synapse) to electrical
(postsynaptic) takes time
Each presynaptic neuron usually releases only
one NT
Each NT-receptor combo always produces the
same excitatory or inhibitory response
~0.5 - 1 msec
Different NTs cause different changes in the
postsynaptic cell
Cause Na+ channels to open, generating an
excitatory post-synaptic potential (EPSP)
Cause K+/Cl- channels to open, generating an
inhibitory postsynaptic potential (IPSP)
- IPSPs cause slight hyperpolarization of
the postsynaptic cell
- EX: glutamate + glutamate receptor =
- EX: GABA + GABA receptor = inhibitory
- Some NTs bind to several different types
of receptors though, so can excite or
Three ways NTs lose power in the synapse
Some NTs simply diffuse out of synapse
Fast synapses
Slow synapses
Slow synapses ar enot quite as common
Neuromuscular synapses
Terminal bouton
Motor end plate
Acetylcholine (ACh)
ACh receptors
Signal transduction at a neuromuscular synapse
inhibit depending on the postsynaptic
1. Neurotransmitters can be returned to
axon terminals for reuse or transported
into glial cells
2. Enzymes inactivate neurotransmitters
3. Neurotransmitters can diffuse out of the
synaptic cleft
Cariers can pump certain NTs back into
presynaptic cell
Removed by blood stream
Can inactivate NTs
- Acetylcholinesterase (AChE) inactivates
and destroys acetylcholine (ACh)
Where NT opens ion channels
Where NT binds to a receptor that sets off 2nd
messenger cascade in postsynaptic cell
- Can sometimes trigger long-term
- Useful for neuronal growth and
development, plus learning and memory
Junctions between neurons (“motor neurons”)
and muscle cells
- Muscle cells or “fibers” = long and
- The axon terminal enlarges into the
terminal bouton, forming chemical
synapses with muscle fibers
Bulge at the end of an axon from which the axon
releases a neurotransmitter
The area that the terminal bouton synapses onto
The terminal bouton is loaded with vesicles
carrying the NT ACh
Motor end plate loaded
1. An AP in motor neuron travels to terminal
2. Triggers Ca+2 channels to open; Ca+2
3. Ca+2 triggers release of ACh from
4. ACh diffuses across synaptic cleft and
binds to ACh receptor channels on the
motor end plate
5. Binding causes channels to open: Na+
moves in, K+ moves out causing current
6. Current flow = end-plate potential (EPP)
which flows to nearby membrane too
7. Na+ channels in nearby membrane open
8. Na+ entering brings cell to threshold
causing an AP (the AP spreads
Two types of summation
Temporal summation
Spatial summation
Modulating neural pathways
Presynaptic facilitation
Presynaptic inhibition
Retrograde messengers
Many external agents affect neural transmission
Tetrodotoxin (TTX)
throughout muscle cell in contiguous
fashion (no myelin), causing contraction)
9. ACh is destroyed by AChE, terminating
the muscle contraction
The basis of decision making for an excitable
- Graded potentials can be of varying
magnitudes and can be EPSPs or IPSPs
- Not all-or-none like APs, can be summed
1. Temporal summation
2. Spatial summation
The same input causes de- or hyper-polarization
very close in time
- No refractory period for graded potentials
Several inputs cause de- or hyper-polarization
- EPSPs summate to depolarize cell
- IPSPs summate to hyperpolarize cell
- Both can cancel each other out
Chemical messengers that bring about longterm changes to a synapse
- Do not cause EPSPs/IPSPs
- Often activate 2nd messenger cascades
that can alter sensitivity of cell or alter
enzyme levels
Sometimes a 3rd neuron influences activity at a
Messages generally travel in one direction
Altering so that more NT is released
Altering so that less NT is released
Diffuse backward (B to A) and modify synapse
A neuron will often have many other neurons
synapsing onto it
Neuron will often synapse onto several other
Drugs, toxins, pollutants, medicines, diseases,
temperature, and even pressure
Comes from a tree
- Blocks the Na+/K+ pump
- Can be lethal
Comes from blowfish
- Blocks Na+ channels, thereby blocking
- Very potent and very lethal
Chemicals that block an effect
- Symptoms: convulsions, muscle
spasticity, and death
Chemicals that enhance an effect
- Symptoms: lowered inhibitions, memory
loss, difficulty with movement,
unconsciousness, eventually death
Lead exposure
Multiple sclerosis (MS)
Black widow venom
Myasthenia gravis
Even temperature and pressure can alter
Whole-body regulation
Nervous system
Organized into two different systems
Central nervous system
Peripheral nervous system
Afferent neurons
Antagonist of an inhibitory NT (adenosine)
Blocks the dopamine reuptake pump, increasing
dopamine (reward signaling) in synapse
Selective serotonin reuptake inhibitors
- Increase synaptic serotonin, involved in
sleep, sexual behavior, appetite, memory,
mood, etc.
Breaks down the myelin sheath, preventing
proper communication
Disease with unknown cause that also leads to
- Problems with memory, development,
sensation, coordination, muscle
weakness, digestion, etc.
Agonist, causing huge release of all ACh:
muscles can’t relax
- No relaxed muscles = respiratory
paralysis (need contract/relax diaphragm
cycle to breathe)
An autoimmune disease in which ACh receptors
are blocked
- No ACh signaling = extreme muscle
Extreme pressure and cold temps can make
membranes too rigid, plus proteins open and
close too slowly
- Cold also slows diffusion in synapse
Extreme heat can make membrane too fluid and
thus far more permeable, and speeds up
1. Nervous
2. Endocrine
Allows rapid responses, detects the external
environment, and coordinates complex functions
such as memory and consciousness
1. Central nervous system
2. Peripheral nervous system
Brain and spinal cord
Nerve fibers extending to other parts of the body
Carry information to the CNS from sensors
- The afferent division carries info about
the external and internal environment
Carries information from CNS to organs,
muscles, glands, etc.
Have a distinct shape with a sensory receptor
instead of dendrites
- Cell body lies in PNS while axons reach
into CNS
Efferent neurons
Interneurons have two main roles
Skeletal muscles controlled by
Autonomic nervous system
Enteric nervous system
Sympathetic nervous system
Parasympathetic nervous system
Central nervous system
Glial cells
Have cell bodies in the CNS, but axons reach
into PNS to affect organs and muscles
- Match typical neuronal anatomy
- Lie entirely in CNS
- 99% of neurons are interneurons
1. Integrate peripheral info and responses
2. Responsible for abstract phenomena
such as planning, memory, creativity,
intellect, etc.
Motor neurons in the somatic nervous system
- Often thought of as the voluntary system
Part of the efferent division and sends info to
three possible systems
1. Enteric nervous system
2. Sympathetic nervous system
3. Parasympathetic nervous system
Governs the walls of the digestive tract (which
are also influenced by stimuli within the tract)
Dominates in fight-or-flight responses and others
that prepare us for stress
Dominates in rest-and-digest actions
Only ~10% of human brain cells = excitable
- Other 90% of cells are glial cells
Serve as connective tissue and support neurons
- Do not branch as extensively, so only
take up about half the volume of neurons
The most abundant glia and have many
- Hold neurons together
- Establish blood-brain barrier (BBB)
- Transfer nutrients to neurons
- Repair brain injuries and form neural
- Serve as scaffold and guide during fetal
- Take up NTs (halting/reducing neural
- Take up excess K+ from ECF, helping to
maintain proper ECF concentration for
APs to fire
- Enhance synapse formation physically
and chemically through released
- Have gap junctions between neurons and
other astrocytes – allows communication
- Have glutamate (NT) receptors, allowing
for further communication and synapse
Form myelin sheaths around axons in the CNS
Ependymal cells
Cerebrospinal fluid (CSF)
Blood-brain barrier (BBB)
Somatosensory information
Somatosensory cortex
Motor homunculus
Most cortical areas are equally distributed
across the right and left hemispheres
Research suggests each hemisphere is
somewhat specialized
Two forms of memory
Declarative/explicit memory
Done by Schwann cells in PNS
Line the ventricles of the brain and central
canal of the spinal cord
- Form and distribute cerebrospinal fluid
- Serve as neural stem cells, forming new
glial cells, and new neurons
- Release some nerve growth factor,
helping neurons and glia survive
- Serve as immune system in brain,
migrating to infection or injury sites to
destroy invaders and help with healing
Bone that encases the brain
Three nourishing membranes between skull and
Cushioning fluid the brain “floats” in
Highly selective barrier that only allows some
blood-borne material into vulnerable brain tissue
The ability to change in response to demands;
when an area is destroyed, other areas of the
brain can often assume the responsibilities
Body feelings: touch, pressure, body position,
heat, cold, pain
Receives sensory input from a specific area of
the body
“Little man”
Largest portions represent proportion of motor
cortex devoted to controlling muscles in each
- Exception = language areas
- The dominant hemisphere for fine motor
control is usually the left side, thus most
humans and other primates are righthanded
- In humans, the left hemisphere excels in
logic, math, language, and philosophy
- The right excels in spatial perception, art,
and music, plus big picture, holistic things
Acquisition of abilities or knowledge as a result
of experience or instruction
- The ability to learn is made possible by
the nervous system, the more complex
the learning allowed for
The storage of acquired knowledge or abilities
for later recall
1. Declarative/explicit memory
2. Procedural/implicit memory
Events, places, pieces of information, etc.
- Often split into semantic (facts) and
episodic (events)
Procedural/implicit memory
Episodic (declarative)
Semantic (declarative)
Skill learning (procedural)
Priming (procedural)
Conditioning (procedural)
Working memory
Short-term memory
Long-term memory
Memory trace
Where in the brain does memory trace occur?
How does memory trace occur?
Sleep is a universal phenomenon in all
Restoration and recovery
Plasticity and memory processing
Stage 1
Stage 2
Stage 3 and 4
REM sleep
Skilled motor movements, conditioning, etc.
Remembering your first day of school
Knowing the capital of France
Knowing how to ride a bicycle
Being more likely to use a word you heard
Salivating when you see a favorite food
Immediate perceptual and linguistic processing
It lasts seconds to hours and has a limited
Retained days to years and has a vastly larger
- Info lost from short-term is often lost
forever, but info from long-term is often
lost only temporarily
The neural change responsible for retention and
There is not one center, it’s distributed through
several regions: hippocampus, limbic system,
temporal lobes, prefrontal cortex, cerebellum,
- The molecular mechanisms underlying
memory differ for short- vs. long-term
- Short-term memory is caused by
temporary modification to pre-existing
- Long-term memory is caused by relatively
permanent functional or structural
changes between neurons, which
requires changes in gene expression and
formation of new synapses
Characterized by several features
- Periods of minimal movement
- Reduced responsiveness to external
- Rapid reversibility
Restore biochemical processes that degrade
during wakefulness, repair damage caused by
free radicals, restore receptor sensitivity
Sleep aids in memory consolidation and brain
Light sleep, brain waves start to slow
Slower waves and “sleep spindles”; conscious
awareness disappears
“Slow-wave” or “deep” sleep
- Thought to be most restful portion
- When sleeping, walking and night terrors
can occur
- Recently combined into just stage 3 sleep
Rapid eye moment sleep
1 full sleep cycle
Heart rate, breathing, and body temp no
longer well-regulated
- “Paradoxical” sleep because EEG looks
like waking, though hardest to arouse in
- Most vivid dreams here
- Likely important for memory consolidation
- 90 mins
- S1, S2, S3, S2, REM, repeat with S3
lessening and REM increasing as cycles
Subjective awareness of the external world and