API_Exam 1 Flashcards
what molecules can move easily through the cell membrane
H2O
glucose
ions
urea
CO2
O2
N2
isoflurane
halothane
what is the respiration center of the cell
mitochondria
why can the heart last longer than any other organ without O2
heart muscle has 10x the oxygen
the outside of the lipid bilayer is ___ while the inside is ___
hydrophilic
hydrophobic
what type of drugs cross the cell membrane easily
lipid soluble
non polar
where is Na concentration higher
extracellular 142
intracellular 10
where is K concentration higher
intracellular 140
extracellular 4
where is Ca concentration higher
extracellular 2.4
intracellular 0.0001
where is Mg concentration higher
intracellular
where is Cl concentration higher
extracellular 103
intracellular 4
where are amino acids, cholesterol, phospholipids, protiens, and neutral fats higher in concentration?
intracellular
what do fats, proteins, amino acids, and cholesterol in the cell do
help keep the inside negatively charged
what drives muscle contraction
Na entering the cell
what is a transporter
a protein in the lipid bilayer that facilitates movement in and out of the cell
what type of transporter is electrically stimulated
voltage gated ion channels
what type of transporter is stimulated chemically
ligand gated channel
define diffusion
movement of particles from a higher concentration to a lower concentration
T/F diffusion transports require additional energy
F
facilitated diffusion requires a protein to activate but still going from high to low
what are the two types of diffusion
simple and facilitated
define facilitated diffusion
diffusion from higher concentration to lower concentration using a protien
what is active transport
movement of particles from lower concentrations to higher concentrations using ATP or energy from Na
T or F: active transport requires additional energy?
true
ATP or Na
how does water get in and out of the cell
through aquaporins
true or false: lipid soluble molecules require channels or proteins to cross the cell membrane
FALSE
what molecules require channels or proteins to enter the cells
water soluble or charged particles
define dispersion force
molecules create force against eachother
what is an ungated ion channel
leak channel
allows movement based on diffusion, determined by size shape and charge of the channel and ion
example of voltage gated channels
Na
K
what is an example of a chemical gated channel
nicotinic acetycholine receptor channels
muscarinic
what receptor channels are part of the sympathetic nervous system
alpha
beta
what is the neurotransmitter for the parasympathetic nervous system
acetylcholine
what does troponin I bind to
actin
what does troponin T bind to
tropomyosin
what dose troponin C bind to
calcium
what are two types of excitatory post synaptic potentials
temporal
spatial summation
what do sympathetic mechanisms increase permeability to
Na and Ca
what is the neurotransmitter for the sympathetic nervous system
epinephrine
what do parasympathetic mechanisms increase permeability to
Potassium
what packages vesicles in the cell
golgi apparatus
where does the vesicle release acetylcholine
synaptic cleft
what is a ligand gated channel
a transporter that requires another chemical to attach to it to make it open
what has to attach to ligand before sodium rushes into muscle
acetylcholine
what rushes into the muscle once acetylcholine binds to the ligand
sodium
how long does a ligand gated channel stay open
as long as acetylcholine is attached
what knocks acetylcholine off the ligand
acetylcholinesterase
what happens when acetylcholine is knocked off the ligand channel
the channel closes
sodium cannot get in
what causes contraction of the muscle
sodium rushing in
what is acetylcholinesterase
an enzyme that breaks down acetylcholine
what is acetylcholine broken down into
choline and acetyl coA
what has 20% more mitochondria than other body tissues and why
heart- allows it last longer without oxygen
what gas passes in out of cell easily making induction and recovery quicker
sevoflurane
what is the barrier, integrity of cell, and separates it from extracellular fluid
cell wall
Phospholipid bilayer
what is needed for glucose to get in the cell
a transporter triggered by insulin
what is an action potential
the movement of Na into cell making inside of cell more positive causing it to act
what receptors do muscles fire with and what neurotransmitter
nicotinic
acetylcholine
what receptors do glandular tissues use
muscarinic
what on the potassium pump takes water off the potassium molecule
carbonyl oxygen
what are Na channels lined with and what are they charged
amino acids
negative charge
what pulls water away from Na to allow it to go through the Na channel
amino acids
why is facilitated diffusion slower than simple diffusion
it requires a protein and has limited transporters
another name for facilitated diffusion
carrier mediated diffusion
what causes action potential
moving cell off equilibrium via stimulus
what happens when nerst equilibrium is attained
cell is at resting potential
what two factors influence movement of an ion
concentration
charge
what is the most important transporter in medicine
Na K pump
what is hydrostatic difference
applying pressure on one side results in increased energy available to cause net movement from high to low pressure
where do you see hydrostatic pressure
blood
kidneys
another name for sodium potassium pump
Na K atpase
what combines to form atp
glucose and O2
how does atp give off energy
disassociation of phosphate
what does sodium need to get outside of the cell after an action potential
active transport
what is it when molecules are pumped against electrochemical gradient by atp
primary active transport
define secondary active transport
transport driven by energy store in the electrochemical gradient of another molecule
usually Na
what kind of energy does secondary transport use
indirect energy
example of secondary active transport
sodium glucose symporter
how does the cell get sodium out after the action potential
Na K pump
ratio of Na and K leaving/entering cells via Na-K pump
3 Na out
2 K in
what medication inhibits Na K pump to increase sodium in the cells to increase contraction strength
digoxin
what drug class is digoxin
glycoside- inotrope
what are the functions of glycosides
-increase intracellular sodium
-decrease sodium gradient
-decrease sodium/calcium antiporters
-increase intracellular calcium
where are calcium pumps located
cell membrane
sarcoplastic reticulum
what causes microfibrils to shorten and contract
calcium
why can you read an ecg
positive charges fire down ventricles and positive leads pick up causing spike on ecg
what happens when there is nothing to transport H+ ions
metabolic acidosis
what do water and CO2 make
carbonic acid –> breaks off to form bicarb and H+
where are hydrogen pumps important
kidneys
what is a symporter
moves two molecules at the same time and in the same direction
what is the number one transporter that insulin affects
Glut 4
what blocks glut 4/ other glucose binding sites so that insulin cannot activate it
fat
what is an antiporter
transports substances in the opposite direction of the ion
something in, something out
what is transcellular transport
moving through a whole sheet of tissue rather than just the membrane
what is an example of transcellular transport
smooth muscle tissue
what is osmosis
diffusion of water across selectively permeable membrane to area of more substances
what happens when albumin leaks into abdomen and why
ascites due to osmosis
what is tonicity
the combining of cell with fluid
what is osmolarity
measure of concentration
define isotonic
osmotic pressure is same in solution as in the cell or tissue
define hypotonic
osmostic pressure is lower in the solution than in the cell so fluid goes into cell and it swells
define hypertonic
osmotic pressure in the solution is high so water gets pulled out of the cell and it shrinks
what are some causes of hyponatremia
increased water loss
excessive sweat
DM insipidus
decreased secretion/response to ADH
what is voltage
measurement of potential energy generated by separate charges also known as membrane potential
what is a current
the flow of electricity from one point to another
what is the formula for current
voltage/resistance
what is an action potential
initiating the cell to do a function
what molecule has the most leaky channels
potassium
what is nerst equilibrium
when concentration and electrical charge are balanced in the cell
what is a regular resting membrane potential
-70 to-90 mv
why is resting membrane potential so close to the equilibrium of potassium
potassium is more permeable to the cell membrane, gets through quicker/easier
what direction does the resting membrane potential move closer to
towards the molecule with the greatest permeability
always K
what is depolarization
when sodium rushes into the cell to create an action potential
what is the resting membrane potential for skeletal muscle fibers
-90
what is the resting membrane potential for smooth muscle fibers
-50 to -60 mv
what is the resting membrane potential for neurons
-60 to -70 mv
what are glial cells
astrocytes
where are axons and pathways located
white matter
where does action potential occur (neuro)
nucleus of a neuron and sent down axon
what is repolarization
what happens after an action potential when cell becomes negative again and goes back to resting membrane potential
what is is called when the potential goes over 0 mv
overshoot
what is hyperpolarization
moving more negative than the resting membrane potential
“overpolarizing”
what needs to be reached for action potential to occur
threshold
what is a graded threshold
when stimulation occurs but doesnt reach actual threshold for action potential
what are excitatory post synaptic potentials
things that help enhance excitability to help graded threshold get to threshold
what is temporal summation
1 presynaptic neuron stimulating post synaptic multiple times
how does excitatory post synaptic potentials get membrane to threshold
open more Na channels
5 steps to action potential
- stimulus causes sodium channels to open activation gate letting sodium into cell
- once enough sodium is in to get cell to threshold action potential happens, all sodium channels open causing sodium to flood into cell
- once cell hits +30 mv, inactivation gate on sodium channels close stopping na from entering and potassium channels open letting potassium out of cell to help cell become more negative
- once cell gets to rmp, K channels start to close. voltage becomes more negative than rmp which is called hyperpolarization
- sodium potassium pumps gets 3 sodium out of cell and brings 2 potassium in. Leaky channels also aid in balancing cell to bring it back to rmp aka equillibrium
what is spatial summation
multiple presynaptic signals to one post synaptic neuron
where does excitatory summation occur
post synaptic
what do inhibitory post synaptics do
drive potassium out
decrease resting membrane potential (make it more negative)
what do seizure medications do
GABA decreases resting membrane potential(makes it more negative) so that its harder to get to threshold to have an action potential
do action potentials summate
no, constant amplitude
however, initiation to threshold can summate
at what mv does Na channels close and potassium channels open
+30 mv
why does hyperpolarization occur
potassium channels are slow to close until hitting the resting membrane potential
what helps correct cells are hyperpolarization
Na K pump
what ion flows out of the cells to get repolarization
potassium
what gets cells back to equilibrium
Na K pump
how is an action potential initiated
depolarization
what channels do action potentials rely on
voltage gated channels
what changes during action potentials
permeability of cell
what is true about action potentials conduction velocity
it is constant
large diameter= fast conduction
small diameter= slower conduction
which conduct faster: myelinated or unmyelinated
myelinated
what is propagation of action potential
opening of sodium channels that depolarize adjacent membrane that opens more sodium channels
what is propagation
spread of the action potential along the axon
works with depolarization and repolarization
what are schwann cells
they surrond the nerve axon forming a myelin sheath
what is between each myelin sheath
node of ranvier
how does myelin sheath increase conduction velocity
action potential jumps from node of ranvier to node of ranvier rather than cell to cell
need less action potential to move
what is an autoimmune disease where myelin sheath is destroyed
multiple sclerosis
what is excitatory post synaptic potential
part of temporal summation
synapse builds on itself to get to threshold
what are distant synapses whose epsp’s overlap
spatial summation
what is an inhibitor post synaptic potential
temporary hyperpolarization (more neg than RMP) cause by flow of negative ions into post synaptic cells
makes it unlikely that action potential will occur
what are all virtually all neurotransmitters
ligands
list parts of muscle largest to smalled
muscle
fascicles
muscle fiber
myofibrils
what is the outside of lining of the muscle fiber
sarcolema
what muscular structure does contraction occur
myofibril
what are the thin parts of the myofibril
actin
what are the thick parts of the myofibril
myosin
where is actin attached to
z disk
what is the space from one z disk to the next z disk
sarcomere
includes actin and myosin
what are on the twist of the actin filaments
protein receptor attachment sites
“active sites”
what are the molecules on top of actin filament
troponin molecules
what is on the end of myosin molecules
dual head
what is the i band
actin filaments
what happens to the i band during contraction
gets smaller
where does contraction occur
sarcomere
from one z disk to another z disk
what is the A band
actin and myosin
inside of i band on each side
what are myofibrils surrounded by
sarcoplasm
what are characteristics of muscle fibers
single cells
multi-nucleated
surrounded by sarcolemma
what lies between myofibrils
organelles: mitochondria and sarcoplasma reticulum
why are mitochondria important
where respiration occur
respiration to make O2 so it can combine with glucose to form ATP
what is the recoil spring that stabilizes myosin to z band
titin aka connectin
what kind of structure is titin
largest single polypeptide
connective tissue
coile protein in sarcomere
what happens when a sarcomere becomes too big in the heart
dilated cardiomyopathy
myosin and actin dont come in contact with each other
what is troponin complex
another name for the molecules on top on actin
what is braided together to form actin
F actin and tropomyosin
what are the parts of the troponin complex
i= binds to actin
t= binds to tropomyosin
c= binds to calcium
what covers active sites and prevents interaction with myosin
tropomyosin
what part of actin does myosin bind to
active sites ( g actin)
what bind to g-actin
myosin heads
what happens when calcium binds to troponin molecule
causes tropomyosin to uncover active sites on actin allowing myosin to bind
what happens to head of myosin is pulled back
stores energy from ATP
similar to mouse trap
what is rigor mortis
myosin is bound to actin and waiting for ATP to come release it
muscle rigidity
what happens when actin is moved over and myosin reaches z disk
full contraction
what happens to tropomyosin when calcium gets depleted
covers back up receptor/active sites
how is atp involved with power stroke
cocks the myosin head
stored energy
what is active tension and what is an example
cannot be measured
gripping fist
what is passive tension
tension pulled back a flexed muscle
fingers automatically popping back when spread out by other hands
what is the prerequisite to contraction
tension
what does the length of the sarcomere depend on
contraction
when length of the sarcomere is short, what happens to tension developed
decreases
not every myosin is in contact with actin
when is the greatest potential for the most tension developed in contraction
when every myosin head is in contact with actin so it can move further
what happens when you stretch sarcomere too far
you lose contractility of muscle
what in concentric
what muscle is called when it gets short with contraction
what is excentric
what muscle is called when it gets longer/hyperextended
what is isometric
when you can strain and cant shorten or lengthen muscle
when one myofibril makes a contraction
twitch contraction
what kind of fibers have rapid rates of shortening
fast or white fibers
muscles around the eye
what kind of fibers have slow rates of shortening
slow or red fibers
ex: soleus
what determines if fast or slow muscle fibers are activated
the stimulus sent to them
what muscle fiber has longest sustaining power
slow fibers because they have more mitochondria
what makes slow muscle fibers unique
type 1-
many mitochondria,
oxidative,
smaller diameter,
high myoglobin
high capillary density
low glycolytic enzyme
what makes fast muscle fibers unique
type II
few mitochondria
glycolytic
large diameter
low myoglobin
low capillary density
high glycolytic enzyme
a collection of muscle fibers is innervated by a single ____
neuron
what part of the spinal cord does motor stimuli come from
ventral horn aka anterior horn
how does the brain send a stimuli through spinal cord
synapse on neuron (in gray matter) sends out stimuli out through action potentials
what is frequency summation
results from increase in frequency of contraction of a single motor unit
what is multiple fiber summation
results from an increase in number of motor units contracting at the same time
what is force summation
an increase in contraction intensity as a result of additive effect of individual twitch conditions
what happens when you increase frequency summation
tetany state
full contraction
muscles are always in a state of partial ____
contraction aka tone
what system do you affect for dilation
inhibit sympathetic
what is the formation of new muscle fibers
hyperplasia
what is an increased in shortening capacity and increase in maximum contraction velocity
lengthening
what is an increase in actin and myosin
hypertrophy
what does increase in sarcomeres in a series lead to
faster velocity of shortening because there are more to contract
what are some causes of atrophy
cast on limb
sedentary
tenotomy
neuropathy
what is the difference between tension and contraction
tension is the potential a muscle has to contract
where does an axon going to a muscle come from
anterior horn of the spinal cord
what is between the axon and the target
synaptic cleft
what is the invagination in the subneural cleft aka the motor endplate membrane
synaptic trough
what increases the surface area of post synaptic membrane
synaptic trough in subneural cleft
what is at the top of the subneural clefts
ach gated channels
what is at the bottom of the subneural cleft
voltage gated channels
where are there large amounts of acetylcholinesterase
synaptic cleft
what kind of receptors are ach gated channels
nicotinic
what kind of channels are nicotinic receptors
ligand gated
what are ANS systems, their neurotransmitters and receptor sites
PNS-acetylcholine-nicotinic/muscurinic
SNS-epinephrine- alpha/beta
in what systems do muscles work off of acetylcholine
somatic and PNS
what receptor sites are always tied to muscle
nicotinic
what receptor sites are generally tied to glandular tissues
muscarinic
what are terms for acetylcholine channels
ach channel
ligand gated
nicotinic
Describe how ach is released from the motorneuron
- action potential (sodium floods in making cell positive)
- sodium making cell positive causes calcium channels at terminal endplate of axon to open which lets calcium in
- Calcium causes protein on terminal end and protein on vesicle to bond
- Vesicle is opened by bonding and AcH is released
at subneural cleft, what happens with the different channels to open them
- ACH receptors are opened by ACH that was released from pre-synaptic membrane
- Sodium rushes in through ACH channels
- Cell becoming more positive by sodium opens up voltage gated Na channels letting even more sodium in
- cell/muscle becoming more positive= action potential
how does acetyl choline get deactivated off ligand channel
acetylcholinesterase
what can go through ach gated/nicotinic/ligand gated channel
sodium, potassium, calcium
what does botulinum toxin do
decreases release of ach to decrease muscle contraction
what does curare do
blocks nicotinic ach receptors by competing for binding site
what are some ach like drugs and how do they work
carbachol/nicotine- activate nicotinic ach receptors, NOT DESTROYED BY ACHE= prolonged effect
What are some anti ach inhibitors and how do they work
neostigmine, physostigmine, diisopropyl= block degradation of ach= prolonged effect
what autoimmune disease is characterized by presence of antibodies against nicotinic ach receptor which damages or destroys them creating paralysis
myasthenia gravis
what autoimmune disease results from autoimmune attack against voltage gated calcium channels on presynaptic motor nerve terminal so ach is not released from vesicle
lambert eaton myasthenic syndrome
where does action potential come from to stimulate muscle
anterior horn of spinal cord
what is around sarcoplasmic reticulum
sarcolemma
what are tubes through sarcolemma that penetrate the muscle fiber and are filled with extracellular fluid
t tubules
what transmit action potentials deep into the muscle fiber
t tubule
what are enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules
terminal cisternae
what is the intracellular storage compartment for calcium
sarcoplasmic reticulum
what are the structures of the t tubule/sr system
sarcolemma surrounds sarcoplasmic reticulum which surrounds myofibril
terminal cisternae surrounds transverse tubule which runs through muscle fiber
what is a part of the sarcoplasmic retiuculum
terminal cisternae
what is stored in the sarcoplasmic reticulum and terminal cisterne
calcium
where does action potential go through sr system
through t tubule
what is the cork that fill the holes on the terminal cisterne
ryanodine channel
what does the protein connect the ryanodine with on the t tubule
dihydropyridine
what is a voltage channel on t tubule
dihydropyridine
what happens when action potential comes down t tubulein SK muscle
sodium from action potential causes dhp to open which pulls ryanodine out of terminal cisterne which release calcium out of terminal cisterne
where does calcium that comes from terminal cisterne go to
troponin receptor site on skeletal muscle
what is the large calcium attracting protein in terminal cisterne/sarcoplasmic reticulum
calsequestrin
why is calsequestrin important
draws calcium back into sarcoplasmic reticulum to stop muscle contraction
what are the events of ec coulpling in the cardiac muscle
-ap moves through t tubule
-calcium DHP receptors are activated releasing a small amount of Ca into fiber
-Ca binds to ryanodine receptors directly, releasing large amounts of Ca from terminal cisternae
-Calcium goes to troponin molecules to activate muscle contraction
-Calcium is attracted to calsequestrin to come back into terminal cisterne and contraction is terminated
what are the events of ec coupling in skeletal muscle
-ap moves through t tubule
-Na from action potential causes voltage DHP receptor to open which pulls ryanodine cork with it which releases calcium from terminal cisternae
-Calcium goes to troponin to activate muscle contraction
-Calsequestrin attracts calcium to come back into terminal cisterne and ryanodine shuts it in
Why do you need to give calcium slow
could give a heart attack, opens ryanodine receptors causing lots of contractions
What drives cardiac muscle vs skeletal muscle ec coupling
calcium vs na (voltage)
what is ca release proportional to in skeletal muscle
membrane voltage
what is ca release proportional to in cardiac muscle
calcium entry into ryanodine receptor
what has decreased cases of malignant hyperthermia
sevoflurane
what triggers malignant hyperthermia
inhaled anesthetics isoflurane and halothane
what causes malignant hyperthermia
constant leak of SR calcium through ryanodine receptor–causes uncontrollable muscle contractions
what system drives smooth muscle contractions
autonomic nervous system
name some places where smooth muscles are found
vasculature, intestines
what are sheets of smooth muscles working together with one nerve innervation that stimulates all cells/muscles
unitary/visceral
what are tissues made of discrete bundles of cells which are densely innervated. They each have their own nerve that stimulates them
multiunitary
what is an example of multiunitary smooth muscle
iris
what is an example of unitary smooth muscle
small intestine
what are some characteristics of smooth muscle
operates over large lengths, energy efficient, maintain force for long periods, myogenic, calcium action potentials, poorly developed sr
is smooth muscle striated
no, but skeletal muscle is
what is a dense body in a smooth muscle equivalent to in a skeletal muscle
z disk
what connects dense bodies in smooth muscle and is a thick fibrinous cord
intermediate filament
what connect intermediate filaments in smooth muscle
dense bodies
what brings tissue together when a smooth muscle contracts
dense bodies
where do actin and myosin lay in smooth muscle
between dense bodies
what is a latch state in smooth muscle
maintaining force for long periods of time- hours, days, weeks
what is myogenic in smooth muscle
being spontaneously active
what is delayed during a latch state
phosphorylation
what provides electrical coupling in smooth muscle
gap junction
what is a vesicle comparable to in smooth muscle
varicosity
what would a parasympathetic (ACH) release have on intestinal smooth muscle
increases digestive activity
does smooth muscle have troponin
No, calcium binds to calmodulin instead
what phosphorylates the light chain
myosin light chain kinase
what is myosin light chain kinase
enzyme that breaks down ATP, initiates contraction
describe ec coupling of smooth muscle
-stimulus comes to smooth muscle
-calcium pump calcium from ECF/SR to inside cell
-calcium binds to calmodulin which stimulates myosin light chain kinase (MLCK)
-MLCK phosphorylates (takes 1 ATP) MLC which is on myosin head which activates myosin head causing powerstroke (contraction)
-released by having myosin light chain phosphatase (MLCP) knocks of phosphorus = relaxation
-ATP is used to drive calcium out of cell into ECF or back into SR
where is myosin light chain located
myosin head
what activates vs deactivates myosin in smooth muscle
activate= MLCK
deactivate= MLCP
how many atp are needed in smooth muscle vs skeletal muscle
smooth= 2, skeletal=1
what does calcium bind to in smooth muscle vs skeletal muscle
calmodulin vs troponin
what are endocrine hormones
hormones released into blood stream to stimulate activity elsewhere
what are paracrine (exocrine) hormones
only effects neighboring cells, doesn’t get in blood
what are the four things that control smooth muscle
endocrine, paracrine, local nervous system (ans)
what are the three types of tissue in the heart
atrial, ventricular, conductive
what tissue separates the atria and ventricle
fibrinous tissue
why is the fibrinous band of tissue between atrium and ventricle important
- allows independent contraction of each other
- allows atrium to full empty into ventricle
what is a group of tissues working together
syncytium
what are part of the conductive tissues of the heart
sa/av node, purkinje fibers, bundle of his
What muscles have striations
skeletal and cardiac
what initiates action potential in cardiac muscle and what stimulates troponin
sodium, calcium
what are bands on cardiac muscle that are similar to z disk of skeletal muscle
intercalated disks
what is the role of intercalated disks of cardiac muscle
contracts from one intercalated disk to another
what makes another cell fire without having action potential in cardiac and smooth muscle
gap junction
what type of smooth muscle has gap junctions
unitary smooth muscle
where are gap junctions located in cardiac muscle
intercalated disks
why do atrium and ventricle contract at the same time
gap junctions
what is resting membrane potential of cardiac muscle
-90mv
how long does plateau last in ventricular muscle
0.2-0.3 seconds
why does a plateau occur in ventricular muscle
calcium that initiates ryanodine
what initiates stimulus to beat the heart
sa node- pacemaker of the heart
explain ventricular muscle action potential route
-fast sodium channels open raising membrane potential
and then slow calcium channels begin to open
-potassium channels open at peak so potassium can leave
-a few more calcium channels then open which allows more calcium in
-potassium channels open more letting out more potassium and calcium channels close causing repolarization
-resting membrane potential
what is happening during plateau of resting membrane potential***
calcium is going in and potassium is coming out
what are characteristics of calcium channels in ventricular action potential
slow to open, slow to close
in what phase can cardiac muscle cannot be re-excited
refractory period
what causes rhythmicity of the heart
refractory period- no action potentials
whats the difference between skeletal muscle action potential and cardiac muscle action potential
plateau, calcium is associated with cardiac, voltage is associated with skeletal
what happens when there is no refractory period
a fib or v fib
what is ventricular muscle stimulated by action potential and contracting
systole
what is ventricular muscle reestablishing sodium, potassium, and calcium gradient and is relaxing
diastole
what does p corresond to in heartbeat
atrial contraction
what does qrs correspond to in heartbeat
ventricular contraction
what does t on ekg correspond to in the heartbeat
ventricular repolarization
when does contraction occur
depolarized state
where on ekg does s3 occur
between t and p wave
trace the flow of blood through the heart
- surperior/inferior vena cava, 2. right atrium, 3. tricuspid valve, 4. right ventricle, 5. pulmonary valve, 6. pulmonary arteries, lungs, 7. pulmonary veins, 8. left atrium, 9. mitral valve, 10. left ventricle, 11. aortic valve, 12. aorta
during ventricular diastole, how does blood get from the atrium to the ventricles and how much
75% through gravity and 25% through atrial contraction
when ventricles first start to contract, what does blood do to mitral and tricuspid valves
closes them off
what is the time after ventricles have first started to contract, shutting the bicuspid and tricuspid valves, but haven’t built up enough pressure to open aortic and pulmonary semilunar valves
isovolumetric contraction
what is it called when semilunar valves are both shut but there hasn’t been enough pressure yet to open bicuspid or tricuspid valves
isovolumetric relaxation
how long does ventricle contract for on ekg
qrs through the end of t wave
what is a measure of action potential beginning with contraction on ekg
qrs
when do av valves open on ekg
end of t wave
what is s3 sound
heard during early diastole when blood starts filling ventricle by gravity
what is the dicrotic notch
brief rise in aortic pressure as blood hits off closed valve
what occurs during ventricular diastole in the cardiac cycle
isovolumetric relaxation, av valves open, atrial systole
what happens during ventricular systole
isovolumetric contraction, bicuspid/tricuspid valves close, aortic valve opens, ejection, aortic valve closes
what is a normal end diastolic volume and what is that
120 ml- capacity of blood available in ventricle before systole
what is a normal end systolic volume
50ml- amount of blood left in ventricle after it has contracted
what is a normal ejection volume aka stroke volume
70ml
how do you calculate ejection fraction
ejection volume/end diastolic volume
- 70/120ml= 58%
what are the four factors effecting cardiac output
- Heart rate
- contraction (ef)
- preload (volume)
- afterload
what is afterload
resistance left ventricle must overcome to circulate blood
what is preload and how can you increase it
volume of blood in ventricle and end of diastole- IV fluids
what is amount of blood ejected with each ventricular beat
stroke volume
what is the equation for cardiac output
heart rate x stroke volume
normal = 70/min x 70ml= 4900 ml/min or 5L/min
if Hr=100, edv= 180ml, esv= 20 ml, what is cardiac output
stroke volume= 180-20= 160ml per ejection
100 bpm x 160ml= 16000ml/min
how do you calculate ejection volume
end diastolic volume - end systolic volume
what can cause an increase in afterload
aortic stenosis (calcium buildup in semilunar valves), hypertension
what is frank starling law
The greater the stretch on the myocardial fibers, the greater the force with which they will contract. (ex. stretching a rubber band).
what happens in dilated cardiomyopathy
myofibrils have been stretched too far, actin isn’t touching myosin, muscle becomes thin and weak
the higher the afterload_______________
the lower the cardiac output
what can increase/decrease afterload
vasoconstrictor/vasodilators to increase/decrease resistance
what causes the incisura/dicrotic notch
aortic valve closing causing increased pressure
what are chordae tendinae attached to and why
papillary muscles and bicuspid/tricuspid valves- keeps the valves from prolapsing
do a-v valves or semilunar valves have higher velocity
semilunar- smaller openings
how can increased heart rate decrease cardiac output
beating too fast to allow for filling during diastole
what does excess potassium cause in the heart contractility
decreased contractility
what does increased/decreased calcium cause in heart
increase=spastic contraction
decrease= cardiac dilation
what induces action potential in smooth muscle
calcium induced
why is it important that smooth muscle has a poorly developed sarcoplastic reticulum
it means it has to get calcium from extracellular sources
where are varicosities located
terminal axons
what is the difference between vesicle and varicosity
varicosities can hold more than one neurotransmitter
what system drives skeletal muscle activation
somatic
what drives cardiac and smooth muscle activation
autonomic
what is an activator of enzymes in smooth muscle
calmodulin
how does myosin become energized in smooth muscle
phosphorylated first so then it can break down ATP
what is simple diffusion dependent on
lipid solubility and concentration gradient
how do water soluble molecules get into the cell
transport channels via transport proteins
ion channels
what allows glycerol, urea, and ammonia across the cell membrane
aquaglycerporins
what strips water molecules from potassium molecules
carbonyl oxygens
located in selective channels
why is the Na K pump important
-pumps Na ions out and K ions in (3Na:2K ratio)
-plays critical role in regulating osmotic balance by maintaining NA-K balance
-pump is activated by an increase in CELL VOLUME
where are Ca ATpase located
cell membrane and sarcoplastic reticulum
maintains a low cytosolic Ca concentration
where are H ATPase found
kidneys, GI
concentrates ions up to 1 million fold
tonicity vs osmolarity
tonicity depends on the properties of both the membrane and the solute
osmolarity expresses the concentration of a solution
why is the cell so permeable to K ions?
because of carbonyl oxygen
what does an increase in extracellular K concentration cause?
increases the excitability of the cell because the resting membrane potential is closer to the threshold potential
what is the effect of low plasma calcium on threshold potential
threshold potential becomes more negative
this causes more excitability in the cell
which ion(s) manipulates resting membrane potential
Na and K ions
which ion(s) manipulates threshold potential
calcium ions
how does low Ca levels cause tetany
Low Ca causes excitability of nerve axons causing Na channels to open following a very small increase in the Vm
how do Ca ions affect Na channel
bind to the exterior surfaces of voltage gated Na channel
a decrease in # of Ca ions reduces the voltage level (threshold) required to open the Na gate
the threshold potential is more negative and more excitable
what is one of the deadliest electrolyte disorders and why
HYPERkalemia
bc of deadly cardiac arrhythmias
how does HYPERkalemia affect the cell
High K makes the resting membrane potential less negative (raises the resting membrane potential) making it closer to the threshold for depolarization
what are some basics of the action potential
-all or nothing event
-constant amplitude
-initiated by depolarization
-involves changes in permeability
-relies on voltage-gated ion channels
what is the function of action potentials
-deliver sensory information to CNS
-information encoding
-rapid transmission over distance (nerve cell APs)
-AP initiate various cellular responses
what fibers conduct pain sensations
nonmyelinated c fibers
during the upstroke of the AP what are the changes in the cell permeability
Na permeability increases due to opening of Na channels
what changes in the cell permeability in the downstroke of the AP
Na permeability decreases and K permeability increases
this is due to Na channel inactivation and opening of K channels
why does hyper polarization occur
there is a delay in K channel closure
what determines the permeability of the axon membrane
the permeability of axon membrane to ions is determined by the number of open channels
define absolute refractory period
AP not possible due to voltage inactivation of Na channels
define relative refractory period
greater than normal stimulus required to elicit AP
what is myelination
Schwann cells surround the nerve axon forming a myelin sheath
which ions are involved with excitatory post synaptic potentials
cation channels
Na channels
which ions are involved with inhibitory post synaptic potentials
K or Cl
inhibitory post synaptic potential
post synaptic cell is hyper-polarized, depresses excitability
Label each phase of ventricular action potential
0: depolarization; Na floods in
1: (early repolarization) K out
2: plateau; Ca in, decreased K out
3: repolarization; outward flow of K
4: resting membrane potential
name the phases of SA node action potential
0: depolarization; inward Ca current
3: plateau; outward K current
4: slow depolarization; inward Na current
parasympathetic mechanism increases permeability to what
K
SNS mechanism increases permeability to what
Na and Ca
name order of muscle organization
Muscle
fascicles
muscle fiber
myofibril
describe muscle fibers
single cells
multinucleated
surrounded by sarcolemma
describe myofibrils
contractile elements
surrounded by the sarcoplasm
what is a sarcomere
smallest contractile unit of a muscle fiber
z disk to z disk
what is the largest protein in the body
titin
what is the functional unit of a muscle
sarcomere
what is a sarcomere made up of
complete A band
2 halves of the I bands
what is unitary/visceral smooth muscle
sheets of electrically coupled cells which acts in unison, often spontaneously active
Ex: blood, bowel
multiunitary muscles
tissue made of discrete bundles of cells which are densely innervated and contract only in response to its innervation
ex: iris, piloerectors, vas deferens
what does latch state mean
maintain force of contraction for long periods of time (hours, days, weeks)
what forms the structural backbone of the smooth muscle
intermediate filament
connects dense bodies together
what smooth muscle structure is the membrane dense area that is similar to z discs
dense bodies
major points about smooth muscle
-less complex than skeletal
-ANS fibers branch and “diffuse junctions” with underlying smooth muscle fibers
-has varicosities in the terminal axons that contain NT
-NT is secreted into the matrix coating and diffuses to muscle cells
-excitation is transmitted by Ca AP or simple diffusion of Ca into fiber
-Ca can be released from SR but has poorly formed SR
Smooth muscle EC coupling
-contraction occurs by the same actin-myosin interactions as in striated muscle (sliding filament)
-the troponin complex is absent (calmodulin is very similar in structure)
-regulation is myosin (not actin) based
-myosin does not hydrolyze ATP ( to become energized) unless it is first phosphorylated (on the regulatory light chain)
-the enzyme myosin light chain kinase (MLCK) phosphorylates the light chain
-MLCK is active only in the presence of a small Ca- binding protein, calmodulin (and only when it has Ca bound)
Contraction-relaxation (myosin based regulation
-initiated by calcium from ECF or SR
-Ca binds to calmodulin (instead of troponin in SKM)
-Ca-calmodulin-MLCK complex leads to phosphorylation of MLC (requires 1 atp)
-MLC is part of the myosin head
-phosphorylated myosin head binds to actin and power stroke occurs automatically
-a second ATP is required to release myosin head from actin
-cross-bridge cycling requires both MLCK and MLCP
-MLCP activity is regulated and can change calciium sensitivity (ex: if MLCP activity is high, contraction will be attenuated in the face of high Ca)
what systems control the smooth muslce
endocrine, paracrine, local nervous system, ANS
features of cardiac muscle
-has actin and myosin filaments
-has low resistance intercalated disks (1/400 the resistance of cell membrane)
-contraction is similar to skeletal muscle but longer
AP of cardiac muscles
-resting membrane potential is -85 to -95 mV
-plateau lasts 0.2-0.3 sec in ventricular muscle
why is there a plateau in cardiac muscles
Ca channels are very slow to open and even slower to close
name the phases of cardiac action potential
0: Fast Na channels open then slow Ca channels
1: K channels open
2: Ca channels open more
3: K channels open more
4: resting membrane potential
what initiates repolarization
Ca channels closing
at what voltage does the Na channels close
+20mV
what are the results of cardiac AP
-Ca release from T tubules, which are large, and a very important source of Ca
-T tubule Ca depends strongly on EXTRACELLULAR Ca concentration
-hearts T-Tubule are bigger than those in SKM (carries a lot more Ca in it) and is rich in mucopolysaccharides
-mucopolysaccharides bind and store Ca (work similar to calsequestrin)
-Ca release from sarcoplasmic reticulum (after stimulation of ryanodine receptors)
systole in the cardiac cycle
ventricular muscle stimulated by action potential and contracting
diastole in the cardiac cycle
ventricular muscle re-establishing Na/K/Ca gradient and is relaxing
What is the P wave
atrium contraction
QRS is what in the cardiac cycle
ventricular contraction
lasts through the end of the T wave
what does the diachronic notch represent
Aortic valve closing
what represents the “lub” sounds
AV valves closing
what represents the “dub” sound
aortic valve closing
what happens during diastole
-isovolumic relaxation
-AV valves open
-rapid inflow of blood
-Diastasis- slow flow into the ventricle
-atrial systole- extra blood in and follows p wave
-accounts for 10-25% of filling
what happens during systole
-isovolumic contraction
-av valve closes (ventricular pressure > atrial pressure)
-aortic valve opens
-ejection phase
-aortic valve closes
During the latter part of the ejection phase, how can blood still leave the ventricle if pressure is higher in the aorta?
total energy of blood leaving the ventricle is greater than in the aorta
what are the four factors that impact CO
HR
Contraction
preload
afterload
ejection fraction equation
ejection volume= end diastolic vol- end systolic volume
ejection fraction=ejection volume/ end diastolic volume
CO equation
CO= HR x stroke volume
Autonomic effects on the heart
-SNS stimualtion causes increased HR, increased contractility, and increased vascular tone
-PNS stimulation decreases HR and Decreases cardiac contractility slightly
vagal fibers go mainly to the atria
what is the function of subneural clefts
-increases surface area of post-synaptic membrane
-ach gated channels at top of subneural cleft
-voltage gated Na channels at the bottom of subneural clefts
where does the AP begin in the motoneuron
in the ventral horn of the spinal cord
what is the function of gap junctions
allow cells to communicate to cells next to them
