Exam 3 Flashcards
what are the different ions that are involved in membrane potential?
K+
Na+
Cl-
Ca2+
what are the two different aspects of membrane potential?
concentration gradient
membrane permeability
what is a concentration gradient?
ions inside versus outside
what is membrane permeability?
K+ is the most permeable
what is influx?
ions into the cell
what is efflux?
ions out of the cell
what are the different ion channels?
mechanical
chemical
voltage-gated
what is a mechanical ion channel?
respond to pressure/stretch
what is a chemical ion channel?
respond to ligands
ex: neurotransmitter
what is a voltage-gated channel?
respond to changes in membrane potential
what is repolarization?
return to the resting membrane potential
neuron = -70mV
-usually the 2nd half of action potential
-K+ enters cell
-K+ channel is slow to open
-Na+ channels close
why are membrane potentials always fluctuating?
due to the influx of Na+ and Cl- and the efflux of K+
only a few ions are needed to cause a change
what is resting potential?
-70mV
what is polarization?
flow of electrical charge carried by an ion is called the ion current
what does the flow create?
polarization
what does polarization create?
an electrical signal
what are the two types of signals?
graded potential
action potential
what are some characteristics of graded potential?
variable-strength signal
travel short distance
what is action potential?
very brief
large depolarization
travel far
what do you need to create action potential?
graded potential
what is graded potential?
change in membrane potential whose size is proportional to the stimulus
where does graded potential occur?
dentrites
cell body
what might graded potential do?
trigger or inhibit action potential
what is hyperpolarization?
becoming more negative than resting potential
- last part of action potential
- final K+ channel closes
what is depolarization?
decreasing the membrane potential difference
generally = more positive mV
-usually at the start of an action potential
-Na+ channels are open
what are the four steps of graded potential?
- ion channels open
- membrane potential changes
- resistance/current causes current flow to decrease over distance
- may reach trigger zone if strong enough and cause action potential
what two things does the strength of potential depend on?
- strength of initial stimulus
2. distance from stimulating point
where is the trigger zone?
at the axon hillocks
there are a lot of __________ at the trigger zone
Na+ channels
what needs to happen for action potential to occur?
graded potential reaches zone and is above the threshold voltage
what is another name for trigger point?
threshold potential
where does threshold potential happen?
near -55 mV
what are the two different types of graded potential additive effects?
spatial summation
temporal summation
what is spatial summation?
graded potentials produce at the same time from different neuron
what is temporal summation?
graded potentials produced in the same neuron and close together in time
what happens when action potential begins?
it proceeds through the entire length to the axon
all-or-none
what is excitability?
ability of a neuron to respond rapidly to a stimulus and fire an action potential
what are the four phases of action potential?
resting
rising
falling
hyperpolarization
what is conduction?
movement of action potential through axon at high speed
how does axon diameter influence conduction speed?
larger is faster than smaller
how does myelination influence conduction speed?
presence of myelin allows salutatory conduction which increase action potential transfer speed
what is a synapse?
anatomical connection between neurons and their targets
-information transmission
what are the three regions of a synapse?
- axon terminal on presynaptic cell
- synaptic cleft
- membrane on post synaptic cell
what are the different kinds of cells that a synapse can be?
neurons
non-neuronal cell
what are the two different types of synapse?
electrical
chemical
what is a electrical synapse?
electrical signal passes directly from cytoplasm of one cell to another
what does an electrical synapse use to pass the electrical signal?
gap junction
where does electrical synapse occur?
in neurons of CNS
-also cardiac and smooth muscle
what is a chemical synapse?
electrical signal of presynaptic cell converted to chemical signal and sent across synapse
what does an chemical synapse use to pass the electrical signal?
neurohormones
neurotransmitters
what are the majority of synapses?
chemical
where does action potential arrive?
axon terminal
what happens after action potential reaches the axon terminal?
voltage gated Ca2+ channel opens
what does Ca2+ trigger?
exocytosis of vesicles
what happens after exocytosis of vesicles is triggered?
NT enter the synaptic cleft
what do the NT do after they enter the synaptic cleft?
bind to receptor on post synaptic cell
what happens after NT bind to receptor on post synaptic cell?
there is a cell response
what are the different types of chemicals used for NT?
amines purines gases peptides lipids AA
what are the different types of chemical signals?
paracrine
autocrine
in the CNS how many different kinds of NT are there?
many different kinds
in the PNS what are the different kinds of NT are there?
ACh
norepinephrine
epinephrine
what are the amino acid NT that excite?
glutamate
aspartate
what are the amino acid NT that inhibit?
glycine
GABA
what are the amine NT?
serotonin histamine dopamine norepinephrine epinephrine
what are the peptide NT?
substance P vasopressin somatostatin leu-enkephalin# met-enkephalin# beta-endorphin#
what are the purines NT?
adenosine
ATP
AMP
what are the gases NT?
NO
CO
what are the different methods that can be used to clear NT from that synapse?
removal from ECF
inactivation by enzymes
diffusion
what are some example of removing NT from the ECF of a synapse?
- bring back to the presynaptic cell
- norepinephrine - adjacent neurons/glial cells
- astrocytes
what are some example of inactivating NT by enzymes in a synapse?
ACh
AChE
what are two different ways to integrate neural info transfer?
divergence
convergence
what is divergence?
one presynaptic neuron + many postsynaptic neurons
what is convergence?
many presynaptic neurons + one postsynaptic neuron
what are the division of the nervous system?
central
peripheral
what are the two components of the CNS?
brain
spinal cord
what are the types of the neurons in the PNS?
afferent
efferent
what does an afferent neuron do?
detect stimuli
-sensory
what does an efferent neuron do?
trigger responses
-motor
what is the CNS surrounded by?
meninges
what are meninges?
layers of protective membranes that are specific to the CNS
what is the structure of PNS?
composed of spinal and cranial nerves that carry action potentials toward (afferent) or away from (efferent) the CNS
what is a nerve?
bundles of axons with CT
what is a ganglion?
mass of PNS cell bodies
what is a preganglionic?
occurring before a ganglion
what is a postganglionic?
occurring after a ganglion
what does a ganglion form into?
knots
swelling
what does a ganglion create?
satellite cells form supportive capsule around the cell bodies
what is a plexus?
groups of ganglia
what are the two different types of ganglia?
dorsal root
autonomic
what is the general layout of the PNS and the spinal cord?
afferent enters through dorsal root ganglion
efferent exits through ventral root
what is a root?
end of nerve
what is a dorsal root ganglia?
swellings on root
-cell bodies of sensory neurons
what is a ventral root?
carries info from CNS to muscle/glands
what is gray matter?
unmyelinated nerve cell bodies, dendrites, axon terminals
what does gray matter contain?
contains dorsal, lateral, and ventral horns
what is white matter?
myelinated axons
-bundles of axons known as tracts
what is an ascending tract?
carry sensory info to brain
-dorsal, external lateral
what is a descending tract?
carry efferent (motor) signals from brain to spinal cord -ventral, interior lateral
what are the subdivision of the PNS?
somatic
visceral
what is somatic?
we are consciously aware of these and may have the ability to consciously control
-includes special senses
what is visceral?
responsible for involuntary sensation and control
-associated with the ANS
what does the brain determine for somatic and visceral?
modality
location of stimulus
intensity of stimulus
what do all receptors use?
transduction
what do all receptors require?
stimuli to reach a threshold
what is transduction?
changes to an electrical signal
what happens when you get used to a stimuli?
threshold changes
where does the afferent somatic tract originate?
skin
certain viscera
-receptor activation triggers AP in sensory neuron
what are the four somatosensory modalities?
touch
temperature
nociception
propriocecption
what is touch?
most common receptor: corpuscles
what is temperature?
cold and warm receptors
what is nociception?
pain and itch
respond to noxious stimuli
cause tissue damage
what is proprioception?
awareness of body position in space
what are the special senses of the afferent tract?
olfactory
taste bud
retina
inner ear
what are special senses?
smell taste vision hearing equilibrium
what is a chemoreceptor?
oxygen
pH
various organic molecules such as glucose
what is a mechanoreceptor?
pressure cell stretch vibration acceleration sound
what is a photoreceptor?
photons of light
what is a thermoreceptor?
varying degrees of heat
what is responsible for voluntary motor control?
skeletal muscle
what are some examples of involuntary motor control?
cardiac muscle
smooth muscle
exocrine muscle
what is the efferent visceral also called?
autonomic nervous system
what are the two different parts of the autonomic system?
sympathetic
parasympathetic
what is parasympathetic?
rest and digest
routine
day to day
what is sympathetic?
fight or flight
stressful, threatening situation
what is antagonistic control?
one action opposes the other
what are some examples of tonic control?
sweat glands
blood vessels
what are neurons connected by?
synapses
what is the origin of the sympathetic nervous system?
thoracolumbar region of the spinal column
what is the thoracolumbar region?
- begins with 1st thoracic vertebra
- ends with 3rd/4th lubar vertebra
where do ganglia lie for the sympathetic nervous system?
close to the spinal cord
pre for sympathetic nervous system
short
post for sympathetic nervous system
long
what is the purpose of the parasympathetic nervous system?
to regulate normal body function during periods of reduced stress
what are some example of associated responses for the parasympathetic nervous system?
increased exocrine gland secretions
GI smooth muscle contractions
decreased heart rate
increased gut & pancreas enzyme secretion
what is the origin of the parasympathetic nervous system?
craniosacral region
what does the craniosacral region include?
- cranial nerves: III - oculomotor VII - facial IX - glossopharyngeal X - vagus 75% - nerves of the sacrum are included as well
where do ganglia lie for the parasympathetic nervous system?
close to the target tissue
pre for parasympathetic nervous system
long
post for parasympathetic nervous system
short
what is DEF?
synapse between postganglion and target
what does the axon end have?
varicosities
what are varicosities filled with?
NT
what are sympathetic preganglionic autonomic neurotransmitters?
acetylcholine
what are parasympathetic preganglionic autonomic neurotransmitters?
acetylcholine
what are sympathetic postganglionic autonomic neurotransmitters?
norepinephrine
epinephrine
what are parasympathetic postganglionic autonomic neurotransmitters?
acetylcholine
what are the two different pathways for PNS & SNS?
cholinergic
adrenergic
what is cholinergic?
uses ACh
muscarinic - parasympathetic
nicotinic - preganglion only
what is adrenergic?
norephinphrine or epinephrine
what is alpha adrenergic?
the most common - norephinphrine
how many different kinds of beta adrenergic are there?
three
B1
B2
B3
what is beta 1 adrenergic?
heart
kidney
epinephrine = norepinephrine
what is beta 2 adrenergic?
blood vessels
smooth muscle of organs
epinephrine
what is beta 3 adrenergic?
adipose tissue
norepinephrine
what is the adrenal medulla also known as?
modified ganglion
what are chromaffin cells?
modified postganglion neuron
what does the chromaffin cell do?
secretes epinephrine
what is muscle?
excitable, contractile tissue
what does muscle respond to?
electrical stimuli
what does electrical stimuli begin?
muscle contraction
what does it mean to be contractile?
shortens in response to an electrical stimulus
what are the three different types of muscle?
skeletal
smooth
cardiac
what % of the body is skeletal muscle?
40%
what % of the body is smooth and cardiac muscle?
10%
what are the characteristics of skeletal muscle?
highly organized
fast contractions
for skeletal muscle where does the source of Ca2+ come from?
intracellular
what are the different fiber types for skeletal muscle?
Type 1
Type 2A
Type 2B
what is type 1 skeletal muscle fiber?
slow twitch (ST) highly oxidative
what does it mean to be oxidative?
high endurance
low power
what is type 2A skeletal muscle fiber?
fast twitch (FOG) oxidative-glycolytic
what does it mean to beoxidative-glycolytic?
moderate endurance
moderate power
what is type 2B skeletal muscle fiber?
fast twitch (FG) glycolytic
what does it mean to be glycolytic?
low endurance
high power
what are the different colors of the skeletal muscle fibers?
type 1: lots of myoglobin - very dark red
type 2A: light red
type 2B: pale pink
what is a different name for muscle cell?
muscle fiber
what is an example of type 1 skeletal muscle fiber?
posture
low power endurance
what is an example of type 2A skeletal muscle fiber?
jogging
movement
what is an example of type 2B skeletal muscle fiber?
jumping
what are the characteristics of smooth muscle?
unorganized contractile protein structure
slow contractions
hormonal influence
for what organs and tubes does smooth muscle form walls for?
blood vessels
GI tract
repro tract
specialized organs
for smooth muscle where does the source of Ca2+ come from?
extracellular
what does smooth muscle also have?
gap junctions
what doe gap junctions allow for?
for skeletal muscle where does the source of Ca2+ come from?
what are the characteristics of cardiac muscle?
similar to skeletal & smooth muscle organized intermediate contractions epinephrine influence exclusive to the heart
what are the shared features between cardiac and smooth muscle?
extracellular Ca2+ needed
cells connected by gap junctions
where are gap junctions found?
intercalated discs
what are some similarities with all the types of muscle?
- muscle contractions always begin through some form of excitation-contraction coupling
- Ca2+ plays a role in ALL muscle contraction
- actin & myosin are the primary contractile proteins
what is fascicle?
bundle of adjacent muscle fibers
what is myofibril?
intracellular bundles of contractile and elastic proteins
what is sarcolemma?
cell membrane
what is sarcoplasmic reticulum?
modified ER
releases Ca2+
what are T-tubules?
allow action potential to move rapidly into fiber & release Ca2+ from sarcoplasmic reticulum
what is epimysium?
connective tissue wrapped around skeletal muscle
what is perimysium?
connective tissue around fascicle
what is endomysium?
cell membrane/sarcolemma
what are myofibrils?
contractile structures
what are contractile proteins?
actin
myosin
what are giant accessory proteins?
titin
nebulin
what are regulatory proteins
tropomyosin
troponin
what is actin?
smaller protein
forms thin filaments
what are the two subtypes of actin?
g-actin
f-actin
what is g-actin?
globular
what is f-actin?
filament
what is myosin?
very large protein
forms think filament
what is tropomyosin?
wrapped around actin filament
blocks binding sites for myosin on the actin filaments
what does troponin connect to?
connects tropomyosin to actin filaments
binds to start tropomyosin movement
what is troponin responsible for?
moving tropomyosin during excitation-contraction coupling
what is titin?
largest protein (25,000 AA)
stabilizes position of contractile filament
elastic
what is nebulin?
inelastic
lies along actin
attaches to z-dish
what does nebulin allow for?
allow proper alignment of filaments within sarcomere
what is an origin?
end of muscle that attaches to more stationary bone
proximal
what is an insertion?
muscle attached to more mobile, distal bone
what is a tendon?
bone to muscle attachment
what is a flexor?
muscle that brings bones closer together
what is an extensor?
muscle that moves bones away from each other
what are flexor-extensor pairs known as?
antagonistic muscle groups
ex: biceps brachii & triceps brachii
where does the z-line move?
toward m-line
where does actin move?
toward m-line
what happens to i-band?
gets smaller
what happens to h-zone
gets smaller
what are contractions?
creation of tension in a muscles
what does the active process of contractions require?
ATP
what is relaxation?
release of tension created by contractions
what is muscle tension?
force created by a contracting muscle
what is a load?
weight/force that opposes contractions
what are the three major steps in muscle contractions?
- events at neuromuscular junctions
- excitation - contraction coupling
- contraction - relaxation: sliding filament theory
what is the sliding filament theory?
a band does not change length with contraction
- myosin shortening does not occur
- instead, actin & myosin slide past each other
why can muscles create force without movement?
actin and myosin slide past each other
what are some characteristics of somatic motor division?
always excitatory
cell bodies in ventral horn
no ganglion
branching of axon terminals (clusters)
what are neuromuscular junction?
synapse of neuron on muscle fiber
what is the autonomic system?
lateral
what is the motor end plate?
ligand-gated Na+ channel
what does a somatic motor neuron release?
ACh at neuromuscular junction
what does the net entry of Na+ through ACh receptor channel initiate?
muscle AP
what does muscle AP lead to?
excitation - contraction coupling
what is excitation - contraction coupling?
muscle APs initiates Ca2+ signals that activates muscle contractions
what is AP conduction?
similar to AP in axon but slower
how is the release of Ca2+ from SR initiated?
AP moves down T-tubules
