Exam 2 my Qs Flashcards
What kind of signal is contact dependent needs direct surface contact, signal chemical may use CAMs (cell adhesion molecules)
local
What 2 categories do gap junctions fall under
local and electrical
what kind of communication is distant diffuse, hormones are secreted by endocrine glands into blood, only target cells with receptors for hormone respond to the signal
endocrine
What kind of hormone is secreted by a neuron and diffuses across blood
neurohormone
What kind of filaments make the H band/ zone
only thick, no overlap
What is the latent period
The delay between the muscle AP and beginning of muscle tension. Time needed for Ca calcium release and binding to troponin.
What is a multiunit smooth muscle
smooth muscle in which cells are not linked electrically and each muscle fiber is controlled individually
What does nebulin do
inelastic giant protein that aligns filaments of sarcomere
What is phosphocreatine
muscle molecule that stores energy in high energy phosphate bonds
What is ryanodine receptor channel, where is it
ca calcium release channel of sarcoplasmic reticulum in striated skeletal muscles
What is a single unit smooth muscle
smooth muscle fibers that are electrically coupled by numerous gap junctions
What does titin do?
maintains spatial structure of myofibrils
What does tropomyosin do?
blocks the myosin binding site on actin
Troponin
complex of 3 proteins associated with tropomyosin, binds to Ca calcium controls action of tropomyosin
What is a z disk
sarcomere proteins where actin filaments attach
What is a muscle twitch
single contraction/ relaxation cycle in a muscle fiber
What is an isotonic contraction
creates force without movement
What is an isometric contraction
creates force and moves a load
DHP receptor
voltage sensing receptors in t tubules that are liked to ca calcium channels skeletal contraction
creatine kinase
enzyme that transfers a high energy phosphate group from phosphocreatine to ADP
calmodulin
intracellular 2nd messenger that binds ca calcium
What is the A band
striated muscle sarcomere whose length equals that of a thick filament
What causes acetylcholine to be released into synaptic cleft?
action potential arrives at axon terminal
What ions enter and exit the motor end plate after an AP
Na in, small amount of K out
What causes local depolarization of the motor end plate
ion exchange once channels open
What enzyme breaks down acetylcholine?
acetylcholinesterase
Where do Ca calcium ions go after AP
released into cytosol
What are the 4 main characteristics of muscles
excitability, contractibility, extensibility, elasticity
Where are skeletal, smooth and cardiac muscles located
skeletal: attached to bones, a few sphincters close off hollow organs
smooth: form walls of hollow organs and tubes some sphincters
Cardiac: heart
Which of the 3 muscle types does not have sarcomeres?
smooth
which of the 3 muscle types is not striated
smooth
What fiber proteins are in skeletal muscle
action, myosin, troponin and tropomyosin
What fiber proteins are in smooth muscle
actin, myosin and tropomyosin
What fiber proteins are in cardiac muscle
action, myosin, troponin and tropomyosin
What fiber protein does smooth muscles lack that the other two have?
troponin
Which of the 3 muscle types is multinucleate
skeletal
Which of the 3 muscle types has short branching fibers
cardiac
What controls skeletal muscle, fibers and where is ca from
ca and troponin
fibers are independent
ca from SR
What controls smooth muscle
ca and calmodulin
some electrically linked (gap junctions) others independent
Ca from ECF and SR
calcium
What controls cardiac muscle
Ca and troponin
fibers electrically linked gap junctions
ca from ECF and SR
calcium
What type of muscle is not controlled by troponin?
smooth
What type of muscle has only independently functioning fibers
skeletal
What type of muscle gets Ca from SR only
skeletal
What type of muscle can be independent or electrically linked in its fibers?
smooth
What type of muscle does not have graded force of a single fiber twitch
skeletal
What initiates the contraction of skeletal muscle?
acetylcholine
What initiates the contraction of smooth muscle?
stretches, chemical signals from pacemaker cells. sometimes autorythmic
What causes cardiac muscle to contract?
it is autorythmic
What kind of neuron controls skeletal muscles
somatic
What kind of neuron controls cardiac and smooth muscle
autonomic
What hormone influences the contraction of cardiac muscle
epinephrine
What are satellite cells?
PNS glial cells
What glial cell is nonmyelinating
satellite
What are astrocytes?
branched CNS glial cells that communicate with gap junctions
What are microglia
immune cells in the CNS, remove damaged cells and foreign invaders.
What are ependymal cells
create selectively permeable epithelial layer separates fluid from CNS
Where is Ca stored in the myofibril
in the terminal cisternae
What are the non elastic and elastic stabilizers in actin (thin)
nebulin non elastic
titin elastic
What creates the light and dark regions in banding patterns
A dark (thick filaments) I light (thin filaments)
What are the 3 phases of contraction
latent, contraction, relaxation
What ion enters through Ach receptor channel and initiates an AP
Na, sodium
What alters the conformation of DHP receptor
AP in t-tubule
What does DHP receptor open?
Ryr Ca, calcium release channels in SR
What ion binds to troponin to start actin myosin binding?
Ca, calcium
How does Ca get back into SR
Ca ATPase pumps it back in
What causes troponin to release calcium
decrease in free cytosolic ca
When can the power stroke begin?
when tropomyosin moves off banding site
What is released during the power stroke?
ADP
What causes tension in skeletal muscle
fatigue, fiber length, previous contractions rate of stimulation, thickness of fibers
What type of twitch fiber is fast but fatigues easily
fast twitch white
What type of twitch fiber has moderate Ca ATPase activity
slow twitch
What type of twitch fiber has the longest contraction period
slow twitch
What type of twitch fiber can become more oxidative with endurance training
fast twitch red
What type of twitch fiber uses aerobic oxidative metabolism
slow twitch
Put twitch fibers in order of capillary density
high: slow twitch
medium: fast twitch red
Low: fast twitch white
What type of twitch fiber has numerous mitochondria
slow twitch
What makes fast twitch glycolytic white muscle white?
the low capillary density
What colors are the 3 twitch fibers
slow: dark red
fast oxidative glycolytic: red
fast twitch glycolytic: white
put twitch fibers in order of diameter size
slow: small
fast twitch red: medium
fast twitch white: large
What type of twitch fiber has slow myosin ATPase activity
slow twitch
What type of muscle has torpedo shaped cells
smooth
What are the differences between smooth and skeletal muscle
smooth has longer actin and myosin, more actin, no sarcomere arrangement less endoplasmic reticulum
What is the major role of smooth muscle ?
homeostatic: control fluid flow, sphincters, tonic contractions
What does the contractile response of a multi unit smooth muscles depend on?
number of fibers stimulated
What signals the contraction of smooth muscle
cytosolic ca calcium
What does calcium bind to in smooth muscle contraction
CAM calmodulin
what does the ca-calmodulin complex activate
myosin light chain kinase (smooth muscle only)
What does MLCK myosin light chain kinase do?
phosphorylates light chains in myosin heads and increases myosin ATPase activity, smooth muscle
What is the first step in smooth muscle relaxation
removal of ca from cytosol
What causes muscular dystrophy
mutation on x chromosome
What test diagnosis muscular dystrophy
creatine kinase
What is myasthenia gravis
abnormal fatigue in muscle, antibody against acetylcholine receptors.
how is myasthenia gravis treated?
Ach esterase inhibitors, removal of thymus gland
What helps avoid tearing in cardiac muscle?
desmosomes in intercalated disks
What restrains the heart valves
chordae tendineae and papillar muscles
What prevents blood from flowing backwards?
semilunar valves
What are the 2 blood flow circuits?
pulmonary and systemic
What are the components of pulmonary circuit
RA and RV to (deoxy) from (oxy) lungs
What are the components of systemic circuit
LA LV vessels to from body except lung
Blood flow pressure in order of most to least
aorta–> arteries–> arterioles –> capillaries –> venules –> veins –> vena cavae
What happens to pressure as blood moves across a vessel
pressure drops when fluid is flowing
What kind of pressure does the movement of blood depend on?
pressure difference, not absolute
what makes flow faster
the narrower the vessel, the faster if flow is constant
Where does an Ap in cardiac muscle contraction come from
adjacent cell
What happens to Ca after Ap in cardiac contraction
back into SR or exchanged with Na by NCX antiporter
How is sodium gradient maintained in cardiac contraction
na-k-atpase
What causes tension in cardiac muscle
calcium levels in cytoplasm
muscle length at start of contraction as muscle stretches, more force created
Who is more flexible skeletal or cardiac muscle
cardiac
What percentage of cardiac muscles are contractile and how many are autorythmic
contractile: 99%
autorythmic (pacemakers) 1%
During AP in pacemaker
Net Na in (if opens) –> Ca in (if close) –> Ca in –> K out –> if open k channel closed funny
The cardiac cycle between contraction and relaxation: 1) Late Diastole
both sets of chambers are relaxed and fill passively
a. Atrial diastole
b. Ventricular diastole
c. Blood moves from A into V because AV valves are open
2) Atrial systole
atrial contraction forces a small amount of additional blood into ventricles
a. Heart sound 1
b. Atria contract add 20% more blood to ventricles
c. Atrial systole
d. Ventricular diastole
3) Isovolumic ventricular contraction
a. First phase of ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves.
b. Max blood volume in ventricles = end diastolic volume (EDV)
c. AV valve closes (lub sound), builds pressure allows valve to open later
d. Valves between A and V are closed to avoid backward flow
e. Ventricular systole
f. Atrial diastole
4) Ventricular ejection
a. As ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected
b. Open because pressure in V will be greater than the pressure in blood vessels, pulmonic trunk and aorta
c. Heart sound 2
d. Ventricular diastole starts again
5) Isovolumic ventricular relaxation
a. As ventricles relax, pressure in ventricles falls
b. Blood flows back into cusps of semilunar valves and snaps them closed
c. AV valves open allowing blood back in, restarting cycle
d. Minimum blood in ventricles = end systolic volume (ESV)
Time in cardiac cycle
o Time for complete cycle depends on heart rate
o Rate = 60 beats ( 1 min 60 s) = 1 s per complete beat cycle
o Rate = 75 beats ( 1 min = 0.8 s/ beat cycle)
o Ventricles in diastole 0.5 sec
o In systole 0.3 s
o Total 0.8 s
cardiac output
blood pumped per ventricle per unit time
P wave
QRS
T wave
P: atrial depolarization
QRS: ventricular depolarization and atrial repolarization
T: ventricular repolarization
stroke volume
blood pumped by one ventricle during one contraction
