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Muscle and cardiovascular phys
p
200
Physiology
Undergraduate 4
02/28/2007

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Term
made of collagen, attaches skeletal muscles to bone
Definition
tendon
Term
end of a muscle attached to a stationary region
Definition
origin
Term
end of bone attached to a mobile attachment
Definition
insertion
Term
this type of muscle brings the center of bones closer together
Definition
flexor
Term
this type of muscle brings center of bones further apart
Definition
extensor
Term
flexor extensor pairs are called
Definition
antagonistic muscle groups
Term
a collection of muscle cells is known as
Definition
muscle fibers
Term
characteristics of muscle fibers
Definition
long, cylindrical cells, largest cells in the body, several hundred nuclei on the surface of each cell, created by fusion of many individual embyonic muscle cells
Term
adjascent muscle fibers that are sheathed in connective tissue unit are called
Definition
fasicles
Term
the cell membrane of a muscle fiber is called
Definition
the sarcolemma
Term
the cytoplasm of a muscle fiber is
Definition
the sarcoplasm
Term
highly organized bundles of contractile and elastic proteins that carry out the work on contraction are called
Definition
myofibrils
Term
modified endoplasmic reticulum in muscle cells that consist of longitudinal tubules thsat sequester and release Ca ions
Definition
sarcoplasmic reticulum
Term
what is the fxn of t-tubules
Definition
to move action potentials from the NMJ into the interior of the fiber
Term
the cytosol of muscle fibers contain many of what for energy and metabolism
Definition
mitochondria and gylcogen granules
Term
name the contractile proteins, the regulatory proteins, and the giant accessory proteins found in the myofibril
Definition
CP=myosin and actin; RP= tropomyosin and troponin, GAP= titin and nebulin
Term
the motor protein of the myofibril whose various isoforms determine contraction speed
Definition
myosin
Term
a G-protein that polymerizes to create the thin filaments of the myofibril
Definition
actin
Term
parallel thick and thin filaments are connected via
Definition
crossbridges
Term
how do crossbridges form?
Definition
when the myosin heads bind loosley to the actin in the thin filament
Term
a repeating pattern of filaments in a myofibril of skeletal muscle
Definition
SARCOMERE
Term
Z disk
Definition
the zigzag structure that are attachment sites for the thin filaments (actin)
Term
I band
Definition
the lightest band of the sarcomere occupied only by thin filaments
Term
A band
Definition
the darkest band of the sarcomere, composed of the whole thick filament
Term
M line
Definition
represent proteins that form the attachment site for the thick filaments
Term
H zone
Definition
is occupied by only thick filaments
Term
what is titin?
Definition
it is a huge protein that stabilizes the position of contractile filaments and its elasticity returns stretched muscles to their resting length
Term
what does nebulin do?
Definition
it is an inelastic protein that attaches to the z disk and helps align actin fibers
Term
Excitation-contraction coupling is
Definition
the process in which muscle action potentials initiate calcium signals that in turn activate contraction and relaxation cycles
Term
what is the sliding filament theory of muscle contraction?
Definition
overlapping actin and myosin filaments slide past one another is an energy requiring process that creates muscle contratcion
Term
how many binding sites are there on the myosin head?
Definition
two; one for ATP and the other for and the other for actin
Term
how is myosin a molecular machine?
Definition
it converts the chemical energy in ATP to the mechanical energy of movement (an ATPase)
Term
what event causes the power stroke of the myosin head?
Definition
the release of an inorganic phosphate
Term
what causes rigor mortis?
Definition
the myosin usually exists with ATP bound to it and the rigor state is short, after death, ATP levels drop and the muscles do not have ATP bound and exists solely in the rigor state
Term
what is the fxn of tropomyosin?
Definition
it is a regulatory protein that covers the actin fillament's myosin binding site
Term
what is the role of troponin?
Definition
it is a calcium binding protein that controls the position of tropomyosin
Term
what are the steps of excitation coupling
Definition
ACh is relased in the NMJ; ACh initiates an action potential in the muscle fiber; the action potential trigers release of Ca from the SR; Ca combines with troponin and initiates contraction
Term
ACh release into the synapse causes what?
Definition
the opening of Na and K channels to create deplolarization
Term
how does an action potential trigger the relases of Ca from the SR?
Definition
ACTION potential moves down the t-tubule and triggers a voltage sensing receptor that is mechanically linked to Ca channels in the SR. these receptors are known as DHP receptors
Term
what causes relaxation in skeletal muscles?
Definition
the SR pumps Ca back into its lumen using a Ca ATPase; this cause as decrease in Ca concentration which alters tropomyosin to block the myosin binding to actin
Term
a single contraction relaxation cycle is known as what?
Definition
a twitch
Term
the short delay between action potential and the beginning of tension is
Definition
called the latent period
Term
acts as an ATP buffer in muscle cells
Definition
phosphocreatine
Term
what is the enzyme responsible for transferring the phosphate to creatine and back?
Definition
creatine kinase (CK)
Term
what are the 2 types of fatigue?
Definition
peripheral and central
Term
differences b/t fast and slow twitch muscle
Definition
fast has faster myosin, fast can remove Ca for cytoplasm faster so faster twitch, fast uses gylcolysis for energy;;;; slow have more mitochondria, slow resist fatigue better, slow are narrower for better oxy absorption, slow have more myoglobin,
Term
what is muscle summation
Definition
multiple action potentials of high frequency can stimulate a more forceful contraction
Term
2 types of tetanus are
Definition
unfused tetanus has stimuli far enough apart to allow partial relaxation, fused tetanus causes the muscle to reach a steady tension with no relaxation
Term
what is a motor unit?
Definition
the basic unit of contraction of skeletal muscles consisting of multiple fibers and a somatic motor neurons
Term
how can muscles create graded contractions of varying force and duration?
Definition
muscles can vary contration by changing the types of motor units that are active or by changing the number of motor units active
Term
what is the process of muscle unit recuitment?
Definition
a weak stimulus activates a few motor units, increasing the stimulus strength recruits successively more fibers until maximum tension is reached
Term
what controls recruiment of muscle fibers
Definition
the CNS
Term
what is asynchronous recruitment of motor units
Definition
the CNS modulates firing rates of motor neurons so that different motor units take turns maintaining tension so as to prevent fatigue
Term
isotonic contraction
Definition
a contraction that creates force and moves a load
Term
concentric vs. centric isotonic contractions
Definition
centric shortens muscles and eccentric is lengthening of muscles to resist the force of gravity
Term
isometric contractions
Definition
create force without moving a load
Term
what elements of muscles allow for isometric contractions
Definition
series elastic elements like tendons
Term
what are the advantages of having a level fulcrum system with insertion points where they are (like in the biceps)
Definition
amplifies both distance of movement of load and the speed of movement
Term
how are the contractile fibers of smooth muscle organized
Definition
into oblique bundles
Term
how many neuclei in smooth muscle cells?
Definition
one
Term
single vs. multi unit smooth muscle
Definition
single unit has all of the fibers of a single unit connected electrically via gap junctions and contract as a unit;;;;;multi unit consist of cells not lectrically linked and each cell must be closely associated with its own axon or varicosity
Term
how is smooth muscle different from skeletal in its components?
Definition
smooth muscle myosin ATPase activity is slower, has longer actin and myosin filaments, and has more plentiful actin
Term
what is the primary Ca release channel in smooth muscle SR?
Definition
it is an IP3-receptor channel (IP3 is a second msgr. in the phosphlipase C pathway)
Term
how does the organization of smooth muscle fibers allow for gradation of tension during contraction?
Definition
the myosin is completely covered by myosin heads, and can move long distances along the actin without encountering the end of a sarcomere
Term
what are the steps of contraction in smooth muscle?
Definition
Ca increase initiates contraction, Ca binds to calmodulin, calmodulin with bound Ca activates myosin light chain kinase (MLCK), MLCK phosphorylates light chains in myosin heads to increase ATPase activity, myosin crossbridges slide along actin
Term
what pumps help in smooth muscle relaxation?
Definition
Ca ATPases in SR and in the PM in addition to Ca-Na antiporters in the PM
Term
what enzyme removes the phosphate on myosin to decrease ATPase activity?
Definition
myosin phosphatase
Term
variable amounts of Ca entering smooth muscle cells causes
Definition
graded forces of contraction
Term
what is myogenic contraction?
Definition
when stretch activated Ca channels open to create a contraction
Term
what chemicals regulate smooth muscles contractions?
Definition
NTs, hormones, and paracrines. Note: NTs can be tonic controlled byb graded amounts of NTs
Term
what is hypoxia?
Definition
it means low oxygen, thebrain does everything it can to prevent hypoxia in the brain
Term
the central wall of the heart
Definition
septum
Term
trace path of pulmonary circulation
Definition
right ventricle, pulmonary arteries, lungs, pulmonary veins, left atrium
Term
blood moves how?
Definition
from high pressure to low pressure
Term
what are the two components of a fluids pressure
Definition
the flowing component as kinetic energy, and a lateral component as hydrostatic pressure
Term
what creates the driving pressure of the cardiovascular system?
Definition
the ventricles
Term
fluid flow is (directly or indirectly) proportional to the pressure gradient?
Definition
directly
Term
fluid flow is (directly or indirectly) proportional to resistance?
Definition
indirectly
Term
what three factors influence resistence?
Definition
length*viscosity*1/radius^4
Term
what two factors influence mean arterial pressure?
Definition
cardiac output and peripheral resistance
Term
what two factors determine velocity of flow?
Definition
v= flow rate/ cross sectional area
Term
a tough membranous sac that encases the heart
Definition
pericardium
Term
cardiac muscle is also known as
Definition
myocardium
Term
in what order do the 4 chambers of the heart contract
Definition
first the 2 atria in unison, then the two ventricles in unison
Term
the tubular embryonic heart twists back on itself causing what unique characteristic?
Definition
the ventricles recieve blood at the top and also pump out at the top
Term
in what direction do the ventricles contract?
Definition
from the bottom up to squeeze the blood out
Term
this type of valve seperates the atriums and ventricles
Definition
the atrioventricular valves (AV)
Term
these type of valves seperate the ventricles from arteries
Definition
semilunar valves
Term
tissue that prevent the AV valves from prolapsing
Definition
chordae tendineae
Term
these tissues provide stability for the chordae
Definition
papillary muscles
Term
tri cuspid valve is where? bicuspid?
Definition
right side; left side
Term
name the two semilunar valves
Definition
aortic and pulmonary valve
Term
specialized myocardial cells that create the signals for contraction
Definition
autorythmic cells or pacemakers
Term
how many nuceli in cardiac muscle?
Definition
one
Term
what is an intercalated disk
Definition
it is found in cardiac muscle cells, and they are the cell junctions that connect muscle fibers with desmosomes and gap junctions
Term
cardiac muscle functions like what type of smooth muscle?
Definition
single unit because of the gap junctions
Term
what is the initiating event for cardiac contraction
Definition
action potential from pacemaker opens voltage gated Ca channels in the t-tubules and Ca opens RyR channels in the SR to release more Ca
Term
in skeletal muscles, contraction in a single unit is
Definition
ALL OR NOTHING FOR A GIVEN SARCOMERE LENGTH
Term
how are cardiac muscle contractions graded?
Definition
by how much Ca enters the cell
Term
what are characteristics of the myocardial contraction action potential
Definition
there are two K channel opening stages (one fast and one slow) and an plateau caused by Ca imflux
Term
how is tetanus avoided in cardiac muscle
Definition
the longer action potential means that the AP and the refractory period end at the same time
Term
what property allows autorythmic cells in the heart to generate AP's spontaneuosly
Definition
they have unstable membrane potentials that constantly depolarize towards threshold
Term
what are the steps in autorythmic cells creating AP's
Definition
at -60mv ions channels open to allow Na influx, as the membrane depolarizes Ca channels open and cause steep depolarizations, eventually the Ca channels close and K channels have opened allowing repolarization
Term
How do NT's ,modulate heart rate
Definition
they alter the permeability of certain ions into autorythmic cells
Term
how does sympathetic stimulation affect heart rate
Definition
it speeds it up because norepinephrine and epinephrine increase the If and Ca permeability causing faster depolarization
Term
how do catecholamines exert their affect over ion channels on autorythmimc cells?
Definition
they bind to Beta adrenergic receptors and use a cAMP second messenger system
Term
what is the effect of parasympathetic stimulation of the autorythmic cells?
Definition
acetylcholine activates muscarinic cholinergic receptors that increase K permeability and decrease Ca permeability to decrease heart rate
Term
where does the heart contraction signal begin?
Definition
in the sinoatrial node (SA) in the right atrium
Term
a group of autorythmic cells at the floor of the right atrium
Definition
the atrioventricular node (AV)
Term
what is the pathway from SA firing to ventricular contraction
Definition
SA node, internodal pathway, AV node, AV bundle, bundle branches, purkinje fibers
Term
why is it important that the ventricles do not recieve electrical signals from the atria?
Definition
because the ventricles need to contract from the bottom up
Term
what is the function of the AV node delay?
Definition
to allow the atria to finish contracting before before ventricular contraction begins
Term
complete heart block
Definition
when the AV node's transmission of signals is blocked and the ventricles pump slower than the atria
Term
p wave corresponds to what on an EKG
Definition
depolarization of the atria
Term
the QRS complex represents what?
Definition
the successive depolarization of the ventricles
Term
what does the t wave represent
Definition
repolarization of the ventricles
Term
what does an EKG represent?
Definition
it is the sum of multiple action potentials taking place in the heart; represents electrical events not mechanical events
Term
what three things can an EKG show
Definition
heart rate, heart rhythm, and order of waves (to diagnose heart blocks)
Term
this is the cause of the first heart sound S1
Definition
closing of the AV valves
Term
what causes the S2 sound of the heart
Definition
closing of the semilunar valves
Term
what do the axises represent in a pressure volume curve
Definition
y=pressure x=volume
Term
where is EDV and ESV on the p-v curve
Definition
B and D
Term
what represents isovolumetic contraction and relaxing?
Definition
contraction=bc and relaxing=da
Term
where on the p-v curve is the stroke volume determined
Definition
cd
Term
what is stroke volume?
Definition
EDV-ESV=Stroke volume
Term
how is cardiac output determined?
Definition
CO= heart rate X stroke volume
Term
what are the two ways that the autonomic nervous system can alter heart rate?
Definition
can change the frequency of the autorythmic cells, and can change the conduction through the AV node
Term
what part of brain controls heart rate?
Definition
medulla
Term
how does sympathetic control alter heart rate
Definition
increase rate of depolarization and increasse conduction through AV node
Term
what is the preload on the heart?
Definition
the degree of myocardial stretch before contraction
Term
as stretch of the ventricular wall increases....
Definition
stroke volume increases as well
Term
what are the axes on a starling curve
Definition
x-axis is the volume (stretch of sarcomere length) and the y-axis is the force of contraction
Term
the frank-starling law of the heart states....
Definition
the heart pumps all the blood that returns to it
Term
what three factors affect venous return to the heart?
Definition
the skeletal muscle pump, the respiratory pump, and sympathetic innervation of vasculature
Term
contractility increases how?
Definition
by altering the amt. of Ca available
Term
a chemical that alters contractility is called....
Definition
an inotropic agent
Term
how do catecholamines increase contractility?
Definition
they bind to beta drenergic receptors that use cAMP to phosphorylate voltage gated Ca channels
Term
what is phospholamban
Definition
it is regulatory protein that is activated by catecholamines by phosphor. They increase Ca ATPase activity of the SR
Term
how do cardiac glycosides work?
Definition
they shut down Na K ATPases and there fore prevent the Ca Na ATPase from working. This causes an increase in cytosolic Ca and increase contractility
Term
what causes an increase in afterload?
Definition
increase in arterial blood pressure
Term
two hormones released from hypothalamus
Definition
oxytocin:eject milk, stimulate contraction of uterus and ADH: water reabsorption (both released in posterior pituitary)
Term
differences bt the anterior and posterior pituitary glands
Definition
anterior is a true endocrine gland, and he posterior is an extension of the hypothalamus and secretes hormones made in the hypo
Term
a hormone that controls the secretion of another hormone is ??
Definition
a trophic hormone
Term
what is the fxn. of the hypothalamic-hypophyseal portal system?
Definition
prevents the dilution of trophic from the hypothalamus to anterior pituitary
Term
what are the hormones of the anterior pit.?
Definition
prolactin, thyrotropin, adrenocorticotropin, growth hormone, follicle-stimulating hormone, and leutinizing hormone
Term
hormones released form the hypothalamus
Definition
PRH, TRH, CRH, GHRH and GHIH, GnRH, and dopamine to inhibit Prolactin
Term
what is synergism or potentiation
Definition
the combination of two or more hormones are more than additive in their effects
Term
six basic steps of muscle contraction
Definition
tight binding in rigor state (45 degrees), ATP binds to myosin causing dissociation, ATPase activity hydro ATP, myosin head swings to 90 degrees,release of Pi causes power stroke back to 45 degrees, loss of ADP causes rigor state binding again
Term
what happenens when AP gets into t-tubule?
Definition
DHP receptors sense the change in voltage and mechanically open ryanodine receptors in SR to let Ca in, ca binds to troponin which moves tropomyosin
Term
what is the bicuspid valve?
Definition
vavlve bt the left atrium and ventricle
Term
how does cardiac muscle form graded contractions?
Definition
it varies the force it generates based on the # of cross bridges which is linked to the amt. of Ca bound to troponin
Term
this para. NT slows the the heart rate by increasing K permeability
Definition
ACh on muscarinic
Term
this symp. NT speeds up heart contr. by increasing Ca and If perm.
Definition
epinephrine on B1 adrenergic receptors
Term
pathway of AP through heart
Definition
SA node==>internodal pathway to AV node===>AV bundle==>apex of heart===>purkinje fibers
Term
what happens if a pacemaker is injured?
Definition
the next fastest pacemaker sets the pace
Term
what are the 2 ways that the autonomic system can regulate heart rate
Definition
by altering the depolarization of autorythmic cells and also by altering conduction through the AV node
Term
two factors that influence the stroke volume
Definition
contractility and the length of the muscle fibers
Term
what determines the stretch of the heart?
Definition
the end diastolic volume (pre-load)
Term
what is afterload?
Definition
the combined effects of EDV and arterial resistance in the arteries
Term
what are matarterioles?
Definition
they offer the passage directly from arterial to venous circulation if the precapillary sphicters are contracted leading to caps.
Term
what causes a pulse?
Definition
the pressure increase after LV ejection
Term
what is pulse pressure?
Definition
it is the pressure exerted by a pulse PP = Syst.Pressure-diastolic Pressure
Term
why does blood not flow backwards in veins?
Definition
some veins have one way valves
Term
what is arterial blood pressure? how is it defined?
Definition
reflects the driing pressure created by the heart's pumping action. MAP=diastolic P+.3333*pulse pressure
Term
how is a sphygmomanometer
Definition
the pressure at which a korotkoff sound appears is the systolic pressure, where it disappears again is the diastolic
Term
what is peripheral resistance
Definition
it is the resistane offered by the arterioles against blood draining from arteries
Term
how is MAP influenced by peripheral resistance?
Definition
MAP= CO*Rarterioles
Term
what two properties of blood can influence MAP?
Definition
blood's distribution in the circulation, and its volume
Term
which part of the circulation is lrager volume?
Definition
the venous side, if blood loss==>constriction of veins returns more blood to arterial side
Term
what are the four general determinants of MAP
Definition
blood volume, blood distribution bt arterial and venous, reistance in arterioles, and cardiac output
Term
how does smooth muscle regulate an increase of pressure in arterioles?
Definition
stretch activated Ca channels open if increased pressure, this causes constriction of smooth muscle, this causes increase in resistance and causes decrease in bllod flow
Term
what is active hyperemia?
Definition
the metabolic needs of a cell can cause dilation of vessels via paracrines. Ie- decrease of O2 or increase CO2 cause dilation to get more blood flow
Term
what are some paracrines that affect blood vessel diameter
Definition
adenosine, heart dilation, NO, somatic dilation; serotonin, constriction due to wound
Term
what NT tonically controls moygenic tone of arterioles
Definition
norepinephrine on alpha receptors
Term
sympathetic stimulation of vessels during fight or flight event causes what?
Definition
binding to beta 2 receptors causes vasodilation to get blood to important organs, and binding to alpha receptors causes vasoconstriction to divert blood away from less needed organs
Term
what is a fenestrated capillary?
Definition
it is a capillary that has large pores in its epithelium that allows bllod to freely diffuse
Term
why is velocity of flow so slow through capillaries?
Definition
because the total cross sectional area of all capillaries together is so large
Term
what are the names of the two types of bulk flow associated with capillaries called?
Definition
absorption and filtration
Term
what two fluid factors influence the movement of fluid into capilarires?
Definition
hydrostatic pressure and colloid osmotic pressure
Term
what is the function of the lymphatic system
Definition
return fluid and filtered proteins to circulation, move fat from intestine to circ., and to filter pathogens for immune
Term
how does lymph system flow
Definition
from lymph capillaries to lymmph vessels to lymph nodes and then to circ., have one way valves, and rely on smooth muscle contraction for movement
Term
what is edema? where does it come from?
Definition
swelling due to accumulation of fluid in interstitial space, loss of plasma proteins causes disruption bt colloid pressure and hydrostatic pressures
Term
where is the main cardio control center?
Definition
medulla
Term
what is the baroreceptor reflex?
Definition
tonically active baroreceptors that sense pressure change are on the walls of the carotid artery and aorta. when there is increased pressure, AP firing increases to the medulla and then autonomic regulation of CO or resistance can change
Term
what is the baroreflex action of increased blood pressure
Definition
decrease in symp. output causessmooth muscle dilation (alpha receptor), decrease in force of contraction and heart rate (beta 1)
Term
decrease in BP upon standing
Definition
orthostatic hypotension
Term
nephron
Definition
functional unit of the kidneys
Term
bowman's capsule
Definition
initial segment of the nephron that surrounds the glomerulus
Term
proximal tubule
Definition
where most reabsorption takes place
Term
loop of henle
Definition
portion of the nephron that creates an osmotic gradient to control conc. of urine
Term
collecting duct
Definition
recieves fluid from distal tubules of 8 nephrons and drains into the renal pelvis
Term
afferent capillarie, efferent
Definition
afferent deliver blood to glomerulus, efferent collects blood leaving glomerulus
Term
peritubular capillaries
Definition
recieve blood from the efferent arterioles and surround nephron
Term
glomerulus
Definition
ball like mass of capillaries, forms the renal corpuscle together with the bowman capsule
Term
what three forces affect glomerular filtration?
Definition
hydrostatic pressure-colloiid osmotic pressure-hydrostatic pressure of bowman's
Term
what three forces affect glomerular filtration?
Definition
hydrostatic pressure-colloiid osmotic pressure-hydrostatic pressure of bowman's
Term
what happens to GFR if resistance of efferent arterioles is increased?
Definition
GFR increases
Term
what is tubuloglomerular feedback?
Definition
at the juxtaglomerular apparatus, theflow in the distal tubule of the nephron can be detected via macula densa, if an increased GFR, then granular cells secrete renin to cause afferent arteriole constriction
Term
angiotensin
Definition
a potent vasoconstrictor hormone that can affect filtration
Term
aldosterone/adh
Definition
ald is made in adrenal cortex, makes more Na/K pumps so K excreted, ADH more porins so better water reabsorption
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