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106 terms

Scientific Investigation Lab

STUDY
PLAY
descriptive statistics
measures of central tendency (mean, median, mode) + measure of dispersion (range, variance, standard deviation, standard error)
normal distribution
parameter vs. frequency... 68, 95, 99% within tha +/- 1, 2, 3 standard deviations (delta/ s) of the mean.
95% CI
if the 95% CI overlap, the groups are not different from one another.
t-test
compare the means of 2 populations/ distributions
ANOVA
compare the means of more than 2 populations
regression
"r2"... ANOVA. cause-and-effect relationship???... mathematical equation
correlation
"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...
P-value
=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
variable>>variates
characteristic>>scores
accuracy & precision
nearness of a measurement to the actual value of the variable & closeness of repeated measurements of the same quintity
Homeostasis
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
Negative feedback
responses are in the "opposite" from the initial stimulus/ disturbance in homeostasis... keeping the right body temp.
Positive feedback
responses are in the "same" as the initial stimulus/ disturbance in homeostasis... blood clotting & the enhancement of labor contractions during birth
Positive feedback
inherently unstable and always move the system farther away from homeostasis
Solution
a uniform mixture of solute and solvent (liquid)
diffusion
movement of molecules
net diffusion
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.
active transport
osmosis
net movement of water = solvent from an area of low solution conc. to an area of high solute conc.
osmotic pressure
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...
Na+ Cl-
Osmolarity
# of particles (such as Na+) that will generate osmotic pressure
molarity
mol/ L
osmolarity
ex) mol/L Na+ + mol/L Cl-
Tonicity
"relative" differences in osmotic pressure/ conc. among different solutions
hypotonic solution
lower conc. of solutes ex) swimming pools
hypertonic solution
higher conc. of solutes ex) seawater
isotonic solution
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.
Conc. 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
Electrical gradient
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-
Gldman-Hodgkin-Katz eq.
resting m.p = -70 for a nerve cell
Nernst eq.
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...
depolarization
both the electrical and conc. gradients of Na+ move Na+ into the cell... -70 to +30
repolarization
both the electrical and conc. gradients of K+ move K+ out of the cell
hyperpolarization>>afterhyperpolarization
overshoot of the resting membrane potential by K+ efflux
threshold voltage
-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...
all-or-none principle
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
refractory period
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.
Reflex
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!
unlearned response times using an auditory cue
reflex arc
sensory receptors -- sensory/ afferent neurons (dorsal root) -- synapses in the spinal cord -- motor/efferent neurons (ventral root) -- effector
reflexes occur in...
(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.
Ipsilateral reflex
reflex occurring on the same side as the stimulus
Contralateral reflex
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!!
Reciprocal inhibition
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.
def. transduction
process by which stimulus energy is transformed to an electrical response
Meissner's corpuscle, Merkle's corpuscle, Pacinian corpuscle, and ruffini corpuscle
are mechanoreceptors
Free nerve ending
some are nociceptros, some are thermoreceptors, andsme are mechanoreceptors
modality
= 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
sound wave conduction through...
air, fluid, solids (=bone)... compression & rarefraction
frequency -->
pitch of the sound
amplitude-->
loudness of the sound
how do sound waves get transmitted?
external auditory canal -- tympanic membrane -- ossicles (malleus, incus, and stapes) -- cochlea (sterocilia of hair cells transduce mechanical stimulus of sound pressure waves into nerve impulses)
Cornea and lens
focus light rays onto the retina
rods
low light perception, black-and-white vision
cones
less sensitive to light, color vision
fovea centralis
area of highest visual acuity
blind spot
where the optic disc occurs
accommodation
process of keeping an object in focus as it is moved closer to the eye
At the infinite distans = 20 ft.
the light entering the eye from an object are parallel and naturally focused on the fovea centralis and the lens is in its RELAXED state
presbyopia
age-related decline in the ability to accommodate for near vision
hyperopia = farsightedness
short eyeball/ images of near objects converge at a point behind the retina... corrected with a convex/ converging (+) lens
myopia = nearsightedness
long eyeball/ images of far objects focus at a point before the retina.. corrected with a concave/ diverging lenses (-)
visual acuity
ability of the lens to refract the light to focus an image on the retina
diopter
=1/ focal length (from lens to the focal point on the retina) in meters... measures refractive power of a lens... visual acuity
the snellen eye chart is based on
a visual angle of one minute!
conduction deafness
hearing inability due to impaired conduction of sound waves in the middle ear/ cochlea
sensorineural deafness
hearing inability due to impaired transduction from the cochlea to the auditory complex
Weber's test detects...
sound perceived by the damaged ear due to bone conduction is not dampened and seems louder --> conduction deafness
Rinne's tests are used to distinguish
the cause of conduction deafness...bone is more efficient at conducting sound waves than the middle ear --> conduction deafness due to middle ear damage