Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Physiology > Smooth muscle > Flashcards

Smooth muscle Flashcards

1
Q

Smooth muscle fibers are larger or smaller than skeletal muscle fibers?

A

Smaller (thinner and shorter)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Does smooth muscle contain striations?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

True or false: all smooth muscle is largely the same

A

False- differs in innervation, packaging, organization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where are nuclei found in smooth muscle?

A

Centrally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are multi-unit smooth muscle?

A

discrete smooth muscle fibers that contract independently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are unitary smooth muscle?

A

a group of fibers that contract together as a single unit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which type of smooth muscle utilizes gap junctions?

A

Unitary smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which type of smooth muscle is utilized for small movements?

A

multiunit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which type of smooth muscle are organized into sheets or bundles that contract together?

A

Unitary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which type of smooth muscle utilizes the ANS primarily?

A

Multiunit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which type of smooth muscle utilizes hormones?

A

Unitary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Do smooth muscles express troponin?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the difference in the myosin head in smooth muscle? What does this allow for?

A

that the myosin heads are not all arranged in the same direction. This allows for multi-directional contraction or force generation can in multiple in multiple planes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the function of the dense bodies found dispersed throughout smooth muscle cells?

A

Like z discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What replaces Z discs in smooth muscle?

A

Dense bodies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the function of the dense bodies?

A

Allow for force of contraction to be transmitted from one cell to the next

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the arrangement of myosin in smooth muscle?

A

Arranged in multiple planes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which attaches to the dense bodies: actin or myosin?

A

Actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the primary source of Ca in smooth muscle?

A

the extracellular fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How much Ca does the sarcoplasm contribute to smooth muscle cell contraction

A

Very little

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the point of regulation for Ca in smooth muscle? (What does Ca bind to? What enzyme is affected? What does this cause?)

A

Binds to calmodulin, and activates myosin light-chain kinase (MLCK). This then phosphorylates the regulatory chain of myosin ATPase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

In skeletal muscle ATPse is always on. Is this the case for smooth muscle? How?

A

No, must be activated by myosin light chain kinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What forms the cross bridge between myosin head and actin?

A

Phosphorylation by from ATP, from myosin phosphorylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Decreased MLCK activation and myosin phosphatase activity can lead to what?

A

Relaxation or tonic contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
When intracellular [Ca] falls, what happens?
Prevents further MLCK activation,
26
Where can multi-unit smooth muscle be found?
Ciliary and iris muscle of the eyes, piloerector muscles
27
What is the action of MLCK?
Phosphorylate the regulator chain of myosin ATPase
28
What state is the myosin head in (in smooth muscle) when ADP + Pi is bound to it?
Actin and myosin are bound
29
What happens when myosin loses the ADP +Pi?
Power stroke
30
What is the chemical change in smooth muscle that allows myosin to detach?
ATP binds to the myosin head
31
How many molecules of ATP are needed for smooth muscle contraction?
2--One ATP molecule is needed for the phosphorylation of the regulatory chain of myosin and the second ATP molecule is needed for the cross bridge cycling.
32
What brings about relaxation of smooth muscle?
A decrease in [Ca], leading to a decrease in MLCK activation
33
What is the primary innervation of multiunit smooth muscles?
Autonomic
34
What is the primary innervation of unitary muscles?
Autonomics, as well as environmental factors
35
Which type of smooth muscle cells have gap junctions, unitary or multiunit?
Unitary
36
Where are unitary muscles primarily found?
GI tract, bile ducts, ureters, uterus, blood vessels
37
Is ATPase regulated in skeletal muscle? How about in smooth muscle? What is the regulator in each (if any)?
No regulation in smooth muscle Calmodulin/Ca complex turn it on for smooth muscle
38
How many inorganic phosphates are bound to myosin in skeletal muscle? Smooth muscle?
One is skeletal Two in smooth
39
What causes the power stroke in smooth muscle?
The loss of ADP and one of the Pi
40
What recocks the myosin head in smooth muscle?
Binding of a new ATP
41
What must happen to the ATP on the myosin head to allow for attachment of the head to actin?
must be hydrolyzed to ADP
42
What are the two ways in which smooth muscles can relax?
1. Lower [Ca] | 2. Dephosphorylation of myosin by myosin phosphatase
43
What are the two chemical changes that can lead to the "latch bridge" state?
Low MLCK and myosin phosphatase activity Low ATPase activiy
44
What is the chemical state of myosin in the latch state?
ADP and Pi can be bound, but the regulatory Pi is not.
45
How many ATP molecules are needed for contraction in smooth muscle? What is the reason for this?
2-One ATP molecule is needed for the phosphorylation of the regulatory chain of myosin and the second ATP molecule is needed for the cross bridge cycling.
46
Which type of muscle can have rapid contraction and relaxation? Opposite?
Skeletal Opposite = smooth
47
Which cross bridge cycling is fast: skeletal or smooth? Which is slow?
``` Fast = Skeletal Slow = Smooth ```
48
What is the max force that skeletal muscle can generate?
3-4 kg/m^2
49
What is the max force that smooth muscle can generate?
4-6 kg/m^2
50
Which type of muscle is able to under a latch mechanism?
Smooth
51
Which type of muscle has stress-relaxation?
Smooth
52
Which muscle type exerts more energy for fast twitches? Slow?
Fast, smooth uses more Slow, skeletal uses more
53
Why can smooth muscle require less energy to produce the same tension over an extended period of time, when it require more ATP per cycle of myosin movement?
Far less cycles occur to maintain contracted state
54
During smooth muscle relaxation, ATPase activity is relatively (large or small)? What is the consequence of this?
Small The actin-myosin cross bridge is not formed
55
There are no neuromuscular junctions in smooth muscle. How, then, is smooth muscle innervated?
Via diffuse branches of nerve fibers that lay over sheets of smooth muscle
56
What accounts for the slow onset of an action potential activating a smooth muscle?
There is more physical space between the neuron varicosities compared to a neuromuscular plate
57
What are the bodies along an axon terminal that innervate smooth muscles?
Varicosities
58
What are the primary neurotransmitters in smooth muscle control? Which is usually excitatory, and which is usually inhibiting?
Norepi =inhibiting | Acetylcholine = excitatory
59
True or false: when acetylcholine plays an excitatory role in smooth muscle innervation, norepi always plays the exact opposite, and vice versa
True
60
"In some cases of (BLANK) smooth muscle, nerve fiber does contact the smooth muscle, forming a 'contact junction'".
Multiunit
61
What is electro-mechanical stimulation? How could this occur?
a change in membrane permeability that results in a depolarization of smooth muscle. This could occur if membrane sodium or calcium channels were opened.
62
What is electro-mechanical inhibition? How could this occur?
change in membrane permeability that results in a hyperpolarization of smooth muscle. This could occur if membrane sodium or calcium channels were closed or if potassium channels were opened.
63
What is pharmacomechanical stimulation? How could it occur?
stimulation of smooth muscle contraction by signaling molecules. For example, some hormones will activate the phospholipase C (PLC) pathway through their respective receptor.
64
What is pharmacomechanical inhibition? How could it occur?
as the inhibition of smooth muscle contraction mediated by signaling molecules. For example, some hormones will activate the protein kinase A (PKA) pathway, causing MLCK to be phosphorylated/deactivated
65
What are the three different regulator categories of smooth muscle?
Neurotransmitters Chemical/physical factors Hormones
66
What are the two roles of [Ca] in smooth muscle contraction?
Can cause action potential Activates MLCK
67
What are the two types of action potentials in smooth muscles?
Spike potentials ACtion potentials ith plateaus
68
What is the resting membrane potential of smooth muscles? How does this compare to skeletal?
around -60 mV. Lower (absolute value) compared to skeletal muscle (~-90 mV)
69
What is responsible for the prolonged phase action potential (the pone with a plateau)?
Ca (channels are slower to open and close)
70
What is the slow wave potential? What is the consequence of this?
a basoelectrical rhythm of membrane potential that occurs at rest. This means that a smooth muscle cell is more likely to be depolarized at peaks in the baseoelectric rhythm
71
What are the 9 hormones that affect smooth muscle function? | PO-HEAVENS
``` Norepi Epi Angiotensin Endothelin Vasopressin Oxytocin Serotonin Histamine Prostaglandins ```

Physiology (75 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions