A&P Test 3 Flashcards
1
Q
what is the length tension relationship?
A
a graph that shows how well a muscle stretches out
2
Q
What is active force/tension?
A
the amount of force the muscle is generating when we shock the muscle and an AP goes through the muscle
3
Q
how do you stretch out the muscle without an action potential?
what kind of tension is this?
A
pull on the two ends of the muscle
passive tension
4
Q
what is active tension shown by on the graph?
A
the upside down V graph
5
Q
as the overlap section in a sarcomere decrease in size we have
A
an overstretched muscle
6
Q
what creates more tension? length tension or relaxing tension plus action potential?
A
action potential plus relaxing potential
7
Q
describe length tension relationship:
A
if you have a muscle stretched to it’s optimal stretch using a metal weight and measure the tension, it should be the same as the metal weight.
If you shock this muscle with an action potential it should contract.
However, if you have a muscle being overstretched using too heavy of a weight and try to shock it with an AP, you probably wouldn’t have much if any contraction because the myosin heads aren’t talking to the actin filaments.
8
Q
describe load contraction velocity diagram:
A
The velocity of our skeletal muscles shortening is directly and inversely related to the load on our muscles.
9
Q
if the muscle if lifting a really heavy load, then the velocity of shortening/contraction is
A
slower
10
Q
increased load = ________ muscle contraction speed
A
decreased
11
Q
where is load/contraction velocity important?
A
in the heart
12
Q
what is an example of the heart being effected by the load/contraction velocity
A
if the heart is pumping against a high afterload (BP) it takes the heart longer to eject the blood. This can cause problems in the cardiac cycle. If it’s taking longer to eject blood then it may not have as long to refill.
13
Q
how can the body control how much force is being produced by the skeletal muscle?
A
recruiting more and more motor units when we need more and more force. (quantal regulations/ summation)
14
Q
what is quantal summation?
A
The number of motor units activated.
Recruiting larger and larger motor units and portions of the muscle to recruit more and more force
15
Q
what is temporal summation?
A
force generation in comparison to rate of stimulation in Hz (number of stimuli/second)
16
Q
At a stimulation frequency of less than 10 or 12hz, we have
A
individual contractions with the muscle being able to relax between stimuli
17
Q
after a frequency of 10 or 12 hz, what happens?
A
the contractions become additive. We don’t have complete relaxation before the next action
18
Q
why is a frequency of 10 or 12 hz additive?
A
because calcium is coming out of the SR faster than it can be put into the SR.
19
Q
we can increase the force of contraction of our muscle until we reach what frequency?
A
40hz
20
Q
define tetany:
A
when Ca++ receptors are saturated and the muscle is at the peak amount of force that it can generate.
21
Q
what happens at 40 hz that makes us loose any of the little twitches seen in the measurment?
A
so much calcium inside the cell (outside the SR) that we begin to loose any of the individual twitches. At this point the calcium receptors are saturated and this is the peak of the amount of force that the skeletal muscle can generate.
22
Q
what do you get when you stimulate the muscle at supramaximal stimulation at a really high rate? (tetany)
A
you get 3 times the force.
23
Q
define atrophy:
A
skeletal muscle cells get smaller because they lose myofibrils. If this happens for a very long time, skeletal muscle cells can disappear too.
24
Q
define hypertrophy:
A
having more myofibrils in the skeletal muscle cells. The cells get bigger
25
is the heart cell capable of regenerating heart cells?
yes but it happens at such a super slow rate that it isn't much help when you have a massive MI
26
people with hope for a future cure after a spinal cord injury that paralyzes them can do what?
pay people to come in and stimulate their muscles with electrodes so their muscles don't atrophy.
27
smooth muscles is usually _____ to perform a specific task
specialized
28
on a gram to gram basis, smooth muscle is ____ than skeletal muscle
stronger
29
what is the ultra low cycling rate in smooth muscle called?
what is the benefit?
latch mechanism
the smooth muscle can maintain a contraction for a long period of time using very minimal amounts of energy
30
boa constrictor analogy?
boa constrictors grab and hold on like smooth muscle?
boa constrictors use skeletal muscle though
31
how does smooth muscle look different than skeletal?
*the cells are much smaller
t*hey attach to one another via some type of fascia or connective tissue, or sometimes neighboring cells can share walls like in a gap junction
*actin and myosin arrangements are different than in skeletal muscle
*the places where the actin is anchored
*calcium internal stores
32
what is the ratio of actin to myosin in the sarcomere in the smooth muscle?
10-20 actin: 1myosin
33
the structure that actin is anchored to is called
dense bodies
34
which has more calcium: smooth or skeletal muscle?
skeletal
35
how does Smooth muscle cells get calcium?
leaky channels
VG calcium channels
Ligand gated ion channels
36
smooth muscle is dependent on _______ calcium
outside
37
if you have a patient with a blood calcium of 0 you aren't going to have ________
the calcium induced calcium release that it does every time the heart beats
probably the more important reason is that: tone in your vessels to create blood pressure
38
how are smooth muscle cells aranged?
cells are functionally linked to one another via gap junctions.
39
what is another term for visceral smooth muscle?
unitary smooth muscle (act as one unit)
40
where is visceral/unitary muscle founds?
in the internal lining of our hollow organs
41
what goes through gap junctions in the smooth muscle?
Na+ and Ca++
42
what is a multiunit smooth muscle?
a smooth muscle without any gap junctions. this allows for much more delicate control of how much the smooth muscle is squeezing.
43
If a smooth muscle isn't connected via gap junctions, what are they dependent on to produce an action potential?
neurotransmitters
44
what are examples of multiunit Smooth Muscle?
ciliary muscles in the eye
iris muscles in the eye
45
most the body has what type of smooth muscle?
visceral
46
What is the only hybrid muscle in the body?
esophagus
47
esophagus is a hybrid of what 2 muscles?
skeletal muscle and visceral smooth muscle
48
what are the 3 types of muscles in the body?
skeletal
smooth
cardiac
49
what are the shape of the smooth muscles cells around the blood vessel?
diamond or triangular
50
what is layer of connective tissue next to smooth muscle cells that are there for structural support?
adventitia
51
what type of cells are 1 layer thick that layer the inside of the circulatory system?
endothelial cells
52
the only Blood vessels that are exclusively endothelial cells and does not have smooth muscle is the
capillaries
53
what are the 3 layers of the smooth muscle?
inner: tunica intima
middle: tunica media
outer: tunica adventitia/externa
54
the smooth muscle layer and endothelial layers talk to each other with
gasses
neurotransmitters
55
how is myosin set up in skeletal muscle?
in the middle there is a gap because all of the myosin heads are orientated at an angle spreading out from the middle of the molecule
the left and right side are differentiated by the gap and heads pointing in different directions.
56
because of the way that the myosin and actin are oriented in the smooth muscle, smooth muscle can contract__________ shorter
a lot
57
if you have a 2 micrometer smooth muscle and you contract it strongly, it can shorten to
vs a big skeletal muscle will only shorten about
half it's length
a couple of centimeters.
58
in a smooth muscle the neurotransmitter is always_____ however depending on where it is it may have a different action
ACh
59
the ACh receptors that are expressed in vascular beds typically
mediate vascular relaxation
60
what do we need on the inside of the cell to get a contraction?
actin
regulatory light chain of the myosin head
61
how is actin different in the smooth muscle than the skeletal muscle?
the active sites are always exposed in the smooth muscle
62
in smooth muscle the regulatory light chain is not always _____ it requires
turned on
phorphorylization
63
what regulates the activity of the smooth muscle?
myosin light chain kinase
64
what is a kinase?
an enzyme that phosphorolyates
65
when MLCK is really active, you should have a lot of
activity
66
what plays a role in the activity of MLCK?
Ca++
67
what does calmodulin do?
wraps itself around the MLCK which activates it.
68
what does calmodulin require to change shape?
Ca++
69
where does Ca++ come from in the smooth muscle?
ECF
Some in the SR
70
What is a really important Ca++ channels in the smooth muscle?
VG L type calcium channels (slow)
71
If we want a smooth muscle to relax what has to happen?
myosin head ATPase activity has to decrease to do this we have to remove phosphate from the myosin heads.
They can fall off but it takes a long time so we use the enzyme MLCP to speed up this process.
AND/OR
get rid of Ca++ (3 ways)
72
A&P: what is the process to get a contraction of the smooth muscle
* Ca++ comes into cell via leak or L type channels
* Ca++ binds with calmodulin
* Calmodulin phosphorylates MLCK.
* MLCK increases the cycling rate of the myosin head
= contraction
73
where can Ca++ exit the smooth muscle sarcoplasm?
SR via SERCA pump
plasma membrane Ca++ ATPase pump PMCA
main way: NCX 3 Na+ in 1 Ca++ out
Na+/K+ pump cleans up the extra Na+
74
after protein kinase g is activated by cGMP in the smooth muscle, what does protein kinase G do?
it sticks phosphates on things.
More cGMP=more activity of protein kinase G=more MLCK being phosphorylated=reduce the amount of activity=relax
75
A target other than MLCK for protein kinase G is the
calcium entry pathways:
phosphorylates calcium channels which closes them = relax
76
where do nitrates come from in the smooth muscle of a healthy person?
endothelial cells
77
what is the result of L-arginine being converted by endothelial nitric oxide synthase (eNOS)
Nitric Oxide
78
what happens when ACh binds to the mACh receptor in the endothelial cells?
this causes Ca++ release from the endothelial cell's endoplasmic reticulum.
When Ca++ comes out it talks to calmodulin. Calmodulin changes shape and this increases activity of eNOS. eNOS acts on L-arginine to form NO.
NO freely diffuses outside of the endothelial cell and interacts with targets(soluble guanylyl cyclase) on the vascular smooth muscle cell.
Soluble guanylyl cyclase turns GTP into cGMP.
cGMP can upregulate protein kinase G which phosphorylates targets that inhibit contraction including MLCK and the Ca++ entry channels
79
what is eNOS?
endothelial nitric oxide synthase
80
what is a phosphodiesterase inhibitor example?
sildenafil
81
what does a inhibitor of phosphodiesterase do? inhibitor of the inhibitor.
prolonging the life of cGMP. increased activity of protein kinase G= relaxed vascular smooth muscle
82
what was sildenafil intended for?
pulmonary htn
83
why is pulmonary htn so bad?
most people don't realize they have it until they've had it for 30-40 years and by then it is end stage
84
a couple months in the the sildenafil trial, they didn't like the results so they halted the experiment and asked for the drugs back, but no one gave any of the drugs back. Why?
the drug was really good for "other stuff"
85
alpha 1 receptor activation on vascular smooth muscle causes what?
contraction of the smooth muscle
86
what is the pathway of an agonist binding to an alpha 1 receptor in the vascular smooth muscle?
IP3 mediated vascular smooth muscle constriction
* Phospholipase C cleaves PIP2 into IP3(inositol triphosphate) and DAG (diacylglycerol)
* IP3 releases Ca++ from the SR
* Ca++ binds with calmodulin
* Calmodulin phosphorylates MLCK.
* MLCK increases the cycling rate of the myosin head
= contriction
87
phospholipase 3 cleaves PIP2 into
DAG and
IP3
88
IP3 does what in the vascular smooth muscle?
increase ca++ in the cell which binds to calmodulin and phosphorylates MLKC which increases the cycling rate of the myosin head.
89
what does DAG do in the vascular smooth muscle?
It increases the activity of protein kinase C which (skip a few steps) increases the vascular constriction of the vascular smooth muscle.
90
serotonin is also something that can constrict smooth muscle vasculature via the same pathway as
alpha one agonist in the smooth muscular vasculature
91
what is weird about serotonin?
only neurotransmitter than can constrict brain blood vessels
92
Why would you not want Norepinephrine and epi to be released and constrict blood Vessels in the brain?
if you're trying to run from a tiger and the Sympathetic nervous system is stimulated, you wouldn't want your vessels to be constricted or you wouldn't be able to run very well.
93
why are SSRI good for headaches in some people?
increases the vascular tone which decreases the amount of pressure in the head that creates a headache
94
Smooth muscle doesn't require an action potential because there is
enough leaky Ca++ channels that the amount of Ca++ coming into the cell can cause the muscles to start tensing up but it isn't enough to cause an action potential so they are independent of an action potential.
95
Ca++ isn't necessarily required for contraction of smooth muscle, there are some oddball instances where we can have some
intercellular signaling machinery working with the phosphorylation levels of the myosin head to generate a contraction
96
Action potentials in smooth muscle is sometimes appear
periodic
as a single short lived spike
as a long drawn out action potential
97
the long action potential is probably d/t
L-Type Ca++ channels
98
what is the oscillation of smooth muscle?
pacemaker activity. when the membrane potential is just changing all on its own, going up and down in a rhythm.
99
smooth muscle in our small intestine function in what way?
oscillating, generating pacemaker activity that generates an action potential every 10-20 seconds. This helps to mix the food in our small intestine as well as pushing it forward through the system.
100
stomach cramps come and go, why?
pacemaker activity
101
how does Ca++ get into the heart cell?
L-type ca++ channels (slow)
T-type Ca++ channels (faster)
102
majority of the Ca++ that comes into the heart cells is from the
internal stores of the heart cell
SR
103
what do you need to release Ca++ from the sr in the heart?
ECF ca++ (trigger ca++)
calcium induced calcium release
104
what is the trigger for L and T type ca++ to open?
Action Potential dependent on Na+ flooding in through VG Na+ channels
"Na+ induced Action Potential" starts off the Action potential in the heart. it then turns into a Ca++ dependent action potential by T type and then L type Ca++ channels opening
105
in the heart we have very _____ t-tubules
large
106
a lot of the Ca++ that comes into the heart is parked near the
t-tubules
this is where most of the ECF Ca++ comes into the cell
107
How is Ca++ removed from the Heart cell?
SERCA pump (80%)
NCX 3Na+ in 1 Ca++ out
Plasma Membrane Ca++ ATPase PMCA
108
what does PMCA stand for?
Plasma Membrane calcium ATPase
109
what is calsequestrin?
found in the SR of all muscle cell.
sequestering protein that takes Ca++ out of the circulation and binds to it in the SR
110
what helps the SERCA pump?
Calsequestrin.
It concentrates a lot of calcium in the SR. It helps us hold a lot more Ca++ in the SR
111
SR in the heart vs smooth muscle and skeletal muscle
heart has a modulator of the SERCA called the phospholamban- inhibitor of the SERCA pump
112
what does a phospholamban inhibitor do?
inhibits the inhibitor and increases activity of the SERCA pump
Ca++ tucked back into the SR faster=shorter length of contraction
opportunity to reset the cell faster
this is what speeds up the heart rate. Drug target.
113
what type of signaling compounds do heart cells respond to?
ACh
adrenergic receptors
114
the more catecholamine activity the heart
faster the HR and strong the contractions
115
the more cholinergic the heart
slower the HR and weaker the contraction
116
cAMP dependent relationship beta activity
stimulation of adenylyl cyclase (similar to guanylyl cyclase)
ATP to cAMP
in the heart cAMP has effects on the activity of protein kinases
when PKA activity increases you have stronger strength of contraction
117
higher beta activity
higher PKA activity
118
mACh activation in the heart does what?
adenylyl cyclase slows down
decreases cAMP
reduces PKA
relaxes
119
most heart cells are programed to talk to both
ACh and beta agonists
120
Where in the heart does mACh agonist open potassium channels and slow the HR?
nodal conduction tissue where the heart pacemakers are
121
what produces a strong force, quantal or temporal summation?
temporal (3X)
122
What do motor neurons do to increase force of contraction?
sending waves of action potentials down the motor neuron in a way that it can't reset between the different the contractions
123
dense bodies can be shared between neighboring muscle cells. This acts as an
anchor to provide force
124
how are the myosin set up in the smooth muscle sarcomere?
there is no middle gap, and the myosin heads are arranged in an alternating pattern
125
when stimulated, ACh receptors in the small intestine
contract
126
what is phospholamban
why is it used?
inhibitor of the SERCA pump only found in cardiac muscle
it allows Ca++ to stick around in the sarcoplasm for longer period of time = longer contraction of the heart
127
what is the ratio of calcium coming into the heart cells from the SR and the ECF?
1:4 ratio
80% from SR
20% from ECF
128
How is the cardiac muscle set up?
similar sarcomere to skeletal muscle
129
cGMP is kind of unstable and will fall apart on its own, but if it doesn't fall apart fast enough, what enzyme speeds up this process?
phosphodiesterase
130
what is a stimulator for endothelial cells to use eNOS to convert L-arginine into NO?
signaling compounds/ Neurotransmitters
ACh
bradykinin
131
what is myosin light chain phosphatase?
the enzyme that dephosphorolates MLCK
132
what is one of the signal transduction pathways that can affect the activity level of MLCK?
nitrates hitting tissue and increasing cGMP.
cGMP changes the level of kinases.
133
How is the SR in the smooth muscle?
not well developed
134
what is the ratio of actin and myosin in the sarcomere in the skeletal muscle?
actin 2: myosin 1
135
why is smooth muscle more efficient?
cross bridge cycling is slower than in skeletal muscle
136
define hyperplasia:
Exercising an awful lot for a very long period of time. (generating new muscle cells)
this happens really slow.
137
what are the first thing that disappears in an atrophy person
the internal cylinders (myofibrils)
138
the downside of anything that increases cell division is that it
increases the chance of cancer
139
if you have really healthy muscles that get a bunch of use all the time, the vascular bed will
increase and grow. This adds to you muscle mass.
140
what percent of body mass is smooth muscle?
10%
