"r from -1.0 to +1.0"... assumes no cause-and-effect relationship b/w the variables... association??... measures the direction and strength of the linear relationship...
=probability. If P < 0.05, the individuals are significantly different from each other.
Null hypothesis (H0)
A statement of no difference
Population vs. Sample
N vs. n
parameter vs. statistic
Population vs. Sample
accuracy & precision
nearness of a measurement to the actual value of the variable & closeness of repeated measurements of the same quintity
dynamic internal constancy... Claude Bernard "an organism remains constant despite changes in the external environment surrounding the organism"
The body maintains homeostasis with a set of sensors and physiological mechanisms that can be activated or inhibited accordingly.
Any deviations from the set point will be detected by the sensors which will stimulate mechanisms to return the body to the set point.
Feedback mechanisms = feedback loops... response becomes the stimulus!
(stimulus) -- sensors (single cells/ multiple cells in a gland or organ) --integrating center--effectors -- response
responses are in the "opposite" from the initial stimulus/ disturbance in homeostasis... keeping the right body temp.
responses are in the "same" as the initial stimulus/ disturbance in homeostasis... blood clotting & the enhancement of labor contractions during birth
inherently unstable and always move the system farther away from homeostasis
a uniform mixture of solute and solvent (liquid)
movement of molecules
net movement of molecules from an area of high conc. to an area of low conc.
Rate of diffusion is dependent upon...
(1) conc. gradient (2) permeability & thickness of the semipermeable membranes (3) surface are of the semipermeable membranes (4) size of the molecules diffusin (5) temperature
Diffusion with no energy required from high conc. to low conc.
diffusion, osmosis (MW of water = 18g/mol) , facilitated diffusion (protein transporter)
Diffusion with energy required, from low to high conc.
net movement of water = solvent from an area of low solution conc. to an area of high solute conc.
tendency of a solution to elicit osmosis... # of molecules (such as NaCl) i.e. 1 Molar of anything contains 6.02*10 to the 23 molecules
1 M glucose solution has the same osmotic pressure as a 0.5 M NaCl solution...
# of particles (such as Na+) that will generate osmotic pressure
ex) mol/L Na+ + mol/L Cl-
"relative" differences in osmotic pressure/ conc. among different solutions
lower conc. of solutes ex) swimming pools
higher conc. of solutes ex) seawater
same solute conc.
Action potential is caused by...
the movement of ions, particularly Na+ and K+
How does the nervous system communicate?
through action potentials
ion gradients across the human cell membranes are established by...
active solute pumps using ATP... ex) Na+/K+ pump that moves both ions against their conc. gradients
Na+/K+ pump moves...
3 Na+ out of the cell and 2K+ into the cell for every 1 ATP molecule... maintains both a conc. gradient AND an electrical gradient.
relative diff. in the # of Na+ and K+ present in the intra- and extracellular fluids... more K+ inside the cell and more Na+ out side the cell
Na+/K+ pump --> separations of electrical charges (ions)
resting membrane potential
-70 mV for a nerve cell. V across the cell membrane while the cell is at rest.
Resting membrane potential is created because of...
(1) diff. in the ion concentrations on the O vs. I of the cell membrane (2) relative permeability of the plasma membrane to Na+ and K+ ions (3) conc. gradient of Cl-
resting m.p = -70 for a nerve cell
equilibrium potential (= electrical potential needed to balance an ionic conc. gradient so that the net flux of that ion is 0) for each ion such as Na+
voltage-gated Na+ and K+ channels
when a neuron receives an electrical stimulus, it induces voltage-gated Na+ and K+ channels in the cell membrane to open
K+ channels are
slower than Na+ channels
Na+ channels have
a faster rate of response to voltage changes across the membrane and an extra intracellular structure known as an inactivation gate which limits the influx of Na+ ions into the cell by blocking the channel shortly after depolarization opens it...
both the electrical and conc. gradients of Na+ move Na+ into the cell... -70 to +30
both the electrical and conc. gradients of K+ move K+ out of the cell
overshoot of the resting membrane potential by K+ efflux
-55mV... If the stimulus opens enough voltage-gated Na+ channels to depolarize a neuron to its threshold voltage then an action potential can be generated.
An action potential is an...
amplitude of depolarization
does not depend on the stimulus strength/duration but the chemical properties of the voltage-gated ion channels & the conc. and electrical gradients of the cell
def. action potential
a brief all-or-none depolarization of the cell membrane... has a refractory period and a threshold
def. threshold potential
membrane potential at which an action potential is initiated
def. resting membrane potential
steady transmembrane potential of a cell that is not producing an electric signal
time during which an excitable membrane does not respond to a stimulus that normally causes response
def. equilibrium potential
at the eq. potential for an ion, there is no net movement of the ion because the opposing fluxes are equal, and the potential will undergo no further change...
absolute refractory period
time period following an action potential during which a second action potential cannot be generated, no matter how strong the stimulus
relative refractory period
a second potential may be generated, but it requires a stimulus stronger than the one that generated the first action potential
compound action potential
sum of the all the action potentials... voltage change across the nerve rather than a single axon
EPSP (excitatory postsynaptic potential)
electrical response in the postsynaptic cell at an excitatory synapse
IPSP (inhibitory postsynaptic potential)
electrical response in the postsynaptic cel atan inhibitory synapse
Action potentials are generally initiated by...
the temporal and spatial summation of many EPSPs.
the postsynaptic cell's potential is the result of...
temporal and spatial summation of the EPSPs and IPSPs at the many active excitatory and inhibitory synapses on the cell.
an involuntary and stereotypic response to a stimulus to maintain homeostasis
learned responses are
NOT innate reflex responses
As the experiment is repeated enough times, the unlearned response will become a learned response!
(1) somatic nervous system (2) autonomic nervous system
Effectors of somatic reflexes are skeletal muscles which are usually under voluntary control and the effect is always
excitatory = causing a muscle contraction...ex) patellar tendon reflex
autonomic nervous system reflexes assist in regulating the activity of physiological systems such as endocrine, cardiovascular, repiratory, urinary, and digestive systems which are NOT under voluntary control and the effect is
either stimulatory OR inhibitory, depending on the neurotransimitter released by the efferent neuron and the receptor type present on the effector.
Autonomic reflexes occus in...
(1) SNS (2) PNS sym and para.
Reflec occur very quickly in response to a stimulus because...
processing by higher brain centers is not required for the reflexive action.
reflex occurring on the same side as the stimulus
reflex occurring on the opposite side of the stimulus
The patellar tendon stretch reflex is...
an ipsilateral monosynaptic reflex, in which the sensory neuron synpases DIRECTLY onto the motor neuron... no interneurons!!
in stretch reflexes, the antagonistic muscle group is simultaneously inhibited from contracting.
In the patellar tendon stretch reflex, some afferent neurons synapse on inhibitory interneurons... this part of a stretch reflex is
polysynaptic!! includes interneurons.
process by which stimulus energy is transformed to an electrical response
Meissner's corpuscle, Merkle's corpuscle, Pacinian corpuscle, and ruffini corpuscle
Free nerve ending
some are nociceptros, some are thermoreceptors, andsme are mechanoreceptors
= type of sensory stimulus... ex) heat, cold, sound, pressure...
Sensitivity of a certain area depends on...
(1) density (2) receptive fields of somatic sensory receptors