A&P Exam 4 Flashcards
neurons and muscle cells which communicate with each other through APs
excitable cells
the difference in the amount of electrical charge on the inside of the cell membrane vs. the outside of the cell membrane
membrane potential (MP)
when excitable cells are “at rest” (not conducting APs)
Resting Membrane Potential (r-MP)
the difference in ion concentration between the intracellular vs. extracellular areas
chemical gradient
the difference in charge between the intracellular vs. extracellular areas
electrical gradient
the spread of electrical signal along the membrane of an excitable cell
propagation (conduction)
passive transport with no gates
leak channels (pores)
passive transport with gates
gated channels
what are the three types of gated channels?
voltage, ligand, and mechanical
active transport which requires ATP
ion pumps
leakiest channel
K+ leak channels
plasma membrane is more permeable to ____ than to _____
K+, Na+
channels that respond to MP change and help with generation/propagation of APs
voltage-gated channels
where are voltage gated channels primarily found
on the axon and axon hillock
what element is mostly found going through voltage gated channels
Na+
voltage gated channels are time sensitive, true or false?
true
channels that respond to specific chemical stimulus
ligand gated channels
where are ligand gated channels located?
dendrites, somas, and motor end plate
a molecule that binds to another (usually larger) molecule, usually hormones or neurotransmitters
ligand
channels that respond to mechanical deformation of the cell membrane
mechanically-gated ion channels
where are mechanically-gated ion channels found?
sensory receptor cells/ dendrites of sensory neurons
most important ion pump
sodium-potassium pump
sodium potassium pump pumps out _____ for every _____ it pumps in
3 Na+, 2 K+
resting r-MP value
-70mV
when the inner aspect of the cell membrane is negative compared to the outer aspect
polarized
intracellular cation
K+
extracellular cation
Na+
intracellular anions
phosphorus and proteins
extracellular anion
Cl-
peak millivolts reaches in response to an AP
30mV
axon hillock and initial segment of the axion; contains many voltage-gated Na+ channels
trigger zone
depolarizing on the membrane potential from -70mV to -55mV
threshold value
a rush of Na+ into the cell due to depolarization
Na+ influx
threshold value
-55mV
an AP is always of the same amplitude (+30mV) no matter the strength of the stimulus; stronger stimulus doesn’t equal a larger AP
All-Or-Nothing Principle
the change of the negative membrane potential to become positive
depolarizing phase
the restoring of a r-MP of -70mV for a membrane
repolarizing phase
the brief time after the repolarizing phase where the membrane potential is more negative than -70mV
hyperpolarizing phase
the time during the depolarizing/repolarizing phases when another AP cannot be generated
Absolute Refractory Period
the time during the hyperpolarization phase when an AP can only be generated if it is depolarized more positively than the typical threshold value
relative refractory period
the only type of stimuli which can generate an AP during the relative refractory period
suprathreshold stimulus
the step-by-step depolarization of each adjacent area of the plasma membrane (unmyelinated axons)
continuous conduction
when the AP jumps from node to node (myelinated axons)
saltatory conduction
the propagation speed of an AP which is determined by the fiber diameter and myelination of the fiber
conduction velocity
the membrane is at rest; voltage-gated Na+ channels are resting and voltage-gated K+ channels are closed
resting phase
voltage-gated Na+ channel activation gates are open (absolute refractory period)
depolarization phase
voltage-gated K+ channels are open; Na+ channels are inactivating (absolute refractory period)
repolarization phase
voltage-gated K+ channels are still open; Na+ channels are in the resting state
Hyperpolarization phase
a synapse that is either excitatory or inhibitory; most common type of synapse
chemical synapse
synapses where ionic current spreads directly from cell to cell through gap junctions; allows for faster communication; always excitatory
electrical synapse
a small deviation from the r-MP which makes the membrane either more or less polarized; occurs in the dendrites and somas of the neuron; localized; size based on stimulus strength
graded potential
the difference of electrical charges on the inside/outside of the cell
polarization
another name for graded potentials, because they synapse at the post-synaptic membrane
synaptic potentials
a neurotransmitter that brings that MP closer to threshold
excitatory neurotransmitter
the result of a graded potential which brings the membrane potential closer to threshold; not strong enough to initiate a nerve impulse
Excitatory Postsynaptic Potential (EPSP)
neurotransmitters that open ligand-gated ion channels, resulting in hyper polarization (making the MP more negative)
inhibitory neurotransmitter
the result of a graded potential which makes the MP more negative
Inhibitory Postsynaptic Potential (IPSP)
the process by which postsynaptic potentials are added together
summation
when multiple EPSPs are delivered along the same axon and thus, are staggered in time
temporal summation
when EPSPs come from different neurons and summate together
spatial summation
when the excitatory effect is greater than the inhibitory effect but less than the threshold level of stimulation; does not generate a nerve impulse but does bring the membrane closer to threshold
subthreshold EPSP
there are about _____ known/suspected neurotransmitters
100
amino acid neurotransmitter; chief excitatory neurotransmitter of the CNS
glutamate
amino acid neurotransmitter; chief inhibitory neurotransmitter of the CNS
GABA
monoamine neurotransmitter; “5-HT”
Serotonin
monoamine neurotransmitter; catecholamine; DA
dopamine
monoamine neurotransmitter; catecholamine; Epi
Epinephrine
monoamine neurotransmitter; catecholamine; NE
Norepinephrine
name for dopamine, epinephrine, and norepinephrine
catecholamines
gas neurotransmitter; NO
nitric oxide
misc. neurotransmitter; ACh
acetylcholine
a structure that can respond to a stimulus in the internal or external environment
sensory receptors
graded potentials created by a sensory receptor are also called a…..
generator potential
a specialized special cell that synapses with a sensory neuron
sensory cell
sensory receptors are located on _____ and ______
dendrites of a primary sensory neuron; sensory cell
the process in which the energy of a stimulus is converted into an electrical signal
sensory transduction
mechanoreceptors, thermoreceptors, and nociceptors
somatic sensory receptors
chemoreceptors and baroreceptors
visceral sensory receptors
a type of graded potential where the sensory receptor cell is also the primary afferent neuron and a change in membrane potential spreads along its membrane; only involves one receptor cell to receive and convert the stimulus
generator potentials
a type of graded potentials where the sensory receptor is separate from the afferent neuron; the change in MP of the sensory receptor cell triggers the release of a neurotransmitter, initiating a graded potential, then an AP
receptor potentials
receptors which convey information about the changes in information
dynamic receptors
persistent receptors which convey information about the persistence of a stimulus
static receptors
receptors which respond maximally but briefly to a stimulus; their response decreases if the stimulus is maintained
rapidly adapting
receptors which keep firing as long as the stimulus is present
slowly adapting
nerve endings that have unspecialized terminal branches of their dendrites e.g. nociceptors
free nerve endings
cutaneous receptors which are encapsulated in order to determine the nature of the stimuli which they respond to e.g. pacinian corpuscles
encapsulated nerve endings
receptors that respond to tissue-damaging stimuli such as heat/cold, pinpricks, chemicals/acids, etc.
nociceptors
receptors which respond to normal ranges of temperature
thermoreceptors
receptors which detect mechanical stimuli such as light tough, discriminatory touch, pressure, stretch, and vibration.
tactile mechanoreceptors
what are the four main types of tactile mechanoreceptors?
- merkel’s discs
- meissner’s corpuscles
- ruffini’s corpuscles
- pacinian corpuscles
tactile mechanoreceptor located in the dermal/epidermal junction which responds to sustained light touch; slow adapting
merkel’s disks
tactile mechanoreceptor located in the papillary dermis which responds to fine touch; fast adapting
meissner’s corpuscles
tactile mechanoreceptor located in the reticular dermis which responds to stretch; slow adapting
ruffini’s corpuscles
tactile mechanoreceptor located in the deep dermis/hypodermis which responds to vibration; fast adapting
pacinian corpuscles
receptors in the musculoskeletal system which sense kinesthesia; subcategories: muscle spindles and golgi tendon organs
proprioceptor mechanoreceptors
sense of limb position
kinesthesia
proprioceptors located in the muscle tendon which detect muscle tension
golgi tendon organs
visceral receptors which are responsive to distension (stretch), ischemia, and inflammation but don’t respond to pain such as burning or cutting
nociceptors
visceral receptors which are located in blood vessel walls and sense blood pressure by sensing the tension of the aterial walls
baroreceptors
visceral receptors which detect chemical stimuli such as oxygen, carbon, dioxide, glucose, or AAs
chemoreceptors
visceral receptors which detect changes in osmotic pressure
osmoreceptors
sense which consist of specialized sensory receptor cells that generate an electrical signal; sight, smell, taste, and hearing
special senses
special sense with photoreceptor cells which contain rhodopsin (protein); physical energy –> electrical signals
sight
special sense with odor receptor cells which contains proteins that bind to specific chemicals; chemical signal –> electrical signals
smell
special sense with gustatory receptor cells which bind to chemicals; chemical signal –> electrical signals
taste
special sense with hair cells in the inner ear which detect movement
hearing
somatic receptors which perceive information from the skin and skeletal muscles and relay it to the CNS
somatosensory receptors
when outgoing information is sent to a target cell which is a skeletal muscle; contains upper and lower motor neurons
somatomotor pathway
when outgoing information is sent to a target cell which is a smooth/cardiac muscle cell or gland
autonomic motor pathway
a bundle of axons in the PNS
nerve
a bundle of axons in the CNS
tract
pathways containing 1st, 2nd, and 3rd order neurons
somatosensory pathway
location of primary somatosensory cortex
postcentral gyrus
somatosensory input travel along _______ to the postcentral gyrus
ascending tracts
location of 1st order neuron somas
dorsal root ganglion
1st order and 2nd order neurons synapse in the ____
CNS
2nd and 3rd order neurons synapse in the _____
thalamus
2nd and 3rd order neurons are _____ neurons
multipolar
2nd and 3rd order neurons are called _______, even tough they’re carrying afferent/sensory information
interneurons
1st order neurons can also be called
primary afferent neuron
3rd order neurons synapse in the ______
postcentral gyrus
location of 3rd order neuron somas
thalamus
both ATs lead to and through the
thalamus
located in the posterior white column of the spinal cord and carries info about proprioception and 2-point discrimination
posterior column AT
tract carrying information regarding pain, temperature, itch, and tickle (“emotionally loaded” sensation)
spinothalamic AT
location of the primary motor area
precentral gyrus
neurons located in the brain and spinal cord and decussate in the medulla oblongata
UMN (upper motor neuron)
“crossing” such as in the medulla oblongata
deussation
paralysis resulting from damage to the UMNs which results in tense, continually contracting muscles
spastic paralysis
neurons whose somas are in the CNS but their axons extend to the skeletal muscles; “motor” neurons
LMN (lower motor neuron)
paralysis due to damage to the LMNs which results in limp, uncontrollable muscles
flaccid paralysis
a representation of a small human being based on what percent of the cerebral cortex each part of the body takes up
homunculus
nervous system which regulates visceral activities by stimulating/inhibiting activities of cardiac/smooth muscle and glands; can’t be consciously controlled; includes the S-ANS, P-ANS, and ENS
ANS (autonomic nervous system)
when a tissue is innervated by both S-ANS and P-ANS neurons
dual innervation
primary ANS regulating centers are the ______ and ______
hypothalamus, medulla oblongata
neurons whose somas are in the CNS and the axon extends out as a cranial/spinal nerve
preganglionic neurons
S-ANS neurons extend out of the _______ ________
thoracic region
P-ANS neurons extend out of the ____ _____ and ______ _______
brain stem and sacral region
what do preganglionic neurons always release
ACh
second neuron in the autonomic pathway; entirely outside the CNS; synapse with effector organ; unmyelinated; release ACh or NE; “ganglionic neurons”
postganglionic neurons
postganglionic neurons release ________ or ________
ACh, NE
found either in the sympathetic trunk or prevertebral ganglia and synapse with chromaffin cells
sympathetic ganglia
a vertical row of ganglia on the left and right of the vertebral column
sympathetic trunk
ganglia located anteriorly to the vertebral columnb
prevertebral ganglia
ganglia found in the terminal ganglia or the intramural ganglia
parasympathetic ganglia
ganglia located very near the effector organ
terminal ganglia
ganglia located within the wall of the effector organ
intramural ganglia
tangled networks of efferent ANS neurons; primary ones are the cardiac and pulmonary plexuses
autonomic plexuses
release ACh; preganglionic neurons (S-ANS and P-ANS), P-NS postganglionic neurons, and somatic motor neurons
cholinergic neurons
cholinergic neurons release _____
ACh
release Epi or NE; S-ANS postganglionic neurons (release NE)
Adrenergic Neurons
bind ACh, nicotinic receptors and muscarinic receptors
Cholinergic Receptors
cholinergic receptors bind _____
ACh
somatic receptors which cause excitation of the postsynaptic cell
nicotinic receptors
visceral receptors which cause either excitatory or inhabitation depending on the cell
muscarinic receptors
bind Ne or Epi; alpha-1, alpha-2, beta-1, beta-2
adrenergic receptors
adrenergic receptors bind _____ or ______
Epi, NE
receptor that causes vasoconstriction
Alpha-1 Receptor
receptor that causes inhabitation of NE release
Alpha-2 Receptor
receptor that causes tachycardia
beta-1 receptor
receptor that causes vasodilation
beta-2 receptor
a substance that binds to and activates a receptor, mimicking a natural neurotransmitter or hormone
agonist
a substance that binds to and blocks a receptor, preventing a natural neurotransmitter or hormone from working
antagonist
