Smooth Muscle

1. 1Smooth muscle is found in the walls of the hollow organs, including all the blood vessels.

   1. ATrue
   2. BFalse
2. 2Smooth muscle is not striated.

   1. ATrue
   2. BFalse
3. 3Smooth muscle is regulated by which division of the nervous system?

   1. AAutonomic
   2. BSomatic
   3. CMotor
4. 4Hormones can regulate smooth muscle.

   1. ATrue
   2. BFalse
5. 5What is the function of the dense bodies in smooth muscle?

   1. AAnchor actin filaments
   2. BAnchor myosin filaments
   3. CStore lipids for oxidation to release energy
   4. DStore glycogen
6. 6Intermediate filaments such as vimentin and desmin span the smooth muscle cells to form the cytoskeleton. What do they attach to?

   1. ADense bodies
   2. BPhospholipid heads of cell membrane
   3. CNuclear envelope
   4. DTransmembrane proteins
7. 7Which is the true comparison between smooth and striated muscle?

   1. ASmooth muscle has a higher ratio of actin to myosin
   2. BSmooth muscle has a higher ratio of myosin to actin
8. 8Fill in the blanks to label this diagram of a smooth muscle cell.

   

   1. ASarcoplasmic reticulum
   2. BDensy body
   3. CIntermediate filaments
   4. DNucleus
9. 9How do the actin and myosin filaments shorten smooth muscle cells?

   1. APull the dense bodies together when they contract
   2. BPull the microtubules together when they contract
   3. CShorten the intermediate filaments when they contract
   4. DPull the nucleus closer to the cell membrane when they contract
10. 10Fill in the blanks below to describe the regulation of the smooth muscle of the intestines.
    The smooth muscle cells have [blank_start]gap[blank_end] junctions with the [blank_start]interstitial[blank_end] cells of [blank_start]Cajal[blank_end]. These cells are [blank_start]depolarised[blank_end] in a rhythmic fashion. This causes the membrane potential of the smooth muscle cell to [blank_start]oscillate[blank_end] and thus the smooth muscle cells to [blank_start]contract[blank_end] rythmically.

    1. Ainterstitial
    2. BCajal
    3. Cgap
    4. Ddepolarised
    5. Eoscillate
    6. Fcontract

11. 11This is a cross section of the wall of a muscular artery. Label it,

    

    1. AEndothelial cells
    2. BTunica intima
    3. CTunica adventitia
    4. DSmooth muscle
    5. EBlood vessel
    6. FCollagen
    7. GSympathetic nerve
    8. HGap junctions
    9. ITunica media
    10. JBasal lamina
    11. KFibroblast
12. 12What component of a muscular artery prevents it from expanding too much in changes in blood pressure?

    1. ACollagen
    2. BElastin
    3. CFibroblasts
    4. DBasal lamina
13. 13Why do some muscular arteries require their own blood vessels within their walls?

    1. ATheir walls are too thick to rely on diffusion alone
    2. BThese blood vessels branch into other tissues
    3. CTo supply blood to the nerves innervating the artery
    4. DFor fun
14. 14Which cells in the muscular artery wall can differentiate into smooth muscle cells?

    1. AFibroblasts
    2. BChondroblasts
    3. CMyoblasts
    4. DEpiblasts
15. 15What is meant by unitary smooth muscle?

    1. ANot all cells have synaptic input - excitation is spread through tissue via gap junctions
    2. BAll cells have their own synaptic input from an independent motor neuron
    3. CAll cells have their own synaptic input from fibres of the same motor neuron
    4. DSmooth muscle cells are not connected by gap junctions in the tissue
16. 16What is meant by multi-unit smooth muscle?

    1. AEach smooth muscle cell has synaptic input
    2. BNot all smooth muscle cells have synaptic input - excitation is spread through tissue by gap junctions
    3. CSmooth muscle cells in the tissue are not connected by gap junctions
    4. DSmooth muscle cells in the tissue are connected by gap junctions
17. 17U[blank_start]nitary[blank_end] smooth muscle allows for co-ordinated contraction of many cells, for example in the GI tract and respiratory system.
    M[blank_start]ulti-unit[blank_end] smooth muscle allows for finer control of muscle, for example in the iris and piloerector muscles of the skin.

    1. Anitary
    2. Bulti-unit
18. 18What is vascular tone?

    1. AThe degree of constriction of a muscular blood vessel
    2. BThe threshold of calcium influx required to initiate vasoconstriction in a muscular blood vessel
    3. CThe number of action potentials required to maintain a muscular blood vessel at vasoconstriction
    4. DThe time it takes for a muscular blood vessel to change from vasoconstriction to resting diameter
19. 19Which of these stimuli cause a muscular blood vessel to dilate?

    1. ATissue metabolites
    2. BNitrogen oxide
    3. CLocal hormones
    4. DAngiotensin II
    5. EAdrenaline
    6. FNoradrenaline
20. 20Which of these stimuli cause a muscular blood vessel to constrict?

    1. ATissue metabolites
    2. BNitrogen oxide
    3. CLocal hormones
    4. DNoradrenaline
    5. EAdrenaline
    6. FAngiotensin II
21. 21Fill in the blanks below to describe the process of
    hormone-mediated vascular smooth muscle contraction.
    1. Noradrenaline binds to an a1 [blank_start]adrenergic[blank_end] receptor.
    2. This activates a [blank_start]G[blank_end] protein which in turn activates phospholipase [blank_start]C[blank_end].
    3. Phospholipase [blank_start]C[blank_end] cleaves [blank_start]PiP2[blank_end] into D[blank_start]AG[blank_end] and I[blank_start]P3[blank_end].
    4. IP3 binds to calcium channels on the s[blank_start]arcoplasmic reticulum[blank_end], causing them to open.
    5. DAG opens Na+/Ca2+ [blank_start]symport[blank_end].
    6. The combined action of IP3 and DAG increases the concentration of [blank_start]calcium[blank_end] within the cell, [blank_start]depolarising[blank_end] the membrane.
    7. This depolarisation opens [blank_start]L-type[blank_end] Ca2+ channels in the membrane causing further influx of calcium.
    8. Depolarisation spreads throughout the tissues via [blank_start]gap junctions[blank_end].

    1. Aadrenergic
    2. BG
    3. CC
    4. DC
    5. EPiP2
    6. FAG
    7. GP3
    8. Harcoplasmic reticulum
    9. Isymport
    10. Jdepolarising
    11. Kcalcium
    12. LL-type
    13. Mgap junctions
22. 22What effect does stretch have on vascular smooth muscle?

    1. AOpens stretch-activated Na+ cells to exacerbate depolarisation of cell
    2. BOpens L-type Ca2+ channels on the cell membrane
    3. COpens Ca2+ channels on the sarcoplasmic reticulum
    4. DActivates Ca2+ sensitisation
23. 23What enzyme, activated by the binding of adrenaline to an a1 adrenergic receptor, activates Ca2+ sensitisation?

    1. ARho kinase
    2. BProtein kinase C
    3. CMAPK
    4. DMAPKK
24. 24FIll in the blanks below to describe nitrous oxide-mediated vasodilation.
    1. Nitrous oxide activates [blank_start]guanylate cyclase[blank_end] enzyme.
    2. [blank_start]Guanylate cyclase[blank_end] uses GTP to form cGMP ([blank_start]cyclic[blank_end] GMP).
    3. gCMP activates protein kinase [blank_start]G[blank_end] which opens [blank_start]potassium[blank_end] channels in the membrane.
    4. Resulting efflux of [blank_start]potassium[blank_end] from cell results in [blank_start]hyperpolarisation[blank_end].
    5. Proteins pump calcium out of cytosol back into sarcoplasmic reticulum via [blank_start]SERCA[blank_end] or out of the cell entirely via [blank_start]plasma membrane[blank_end] Ca2+ ATPase (PMCA).

    1. Aguanylate cyclase
    2. BGuanylate cyclase
    3. Ccyclic
    4. DG
    5. Epotassium
    6. Fpotassium
    7. Ghyperpolarisation
    8. HSERCA
    9. Iplasma membrane
25. 25Fill in the blanks below to describe the crossbridge cycle with respect to calcium.
    1. Activation of smooth muscle cell causes an increase in sarcoplasmic [blank_start]calcium[blank_end].
    2. Calcium binds to [blank_start]calmodulin[blank_end] protein.
    3. Calmodulin can then bind to myosin [blank_start]light chain kinase[blank_end] - this forms an active complex.
    4. The active complex [blank_start]phosphorylates[blank_end] myosin, allowing the crossbridge cycle to begin.

    1. Acalcium
    2. Bcalmodulin
    3. Clight chain kinase
    4. Dphosphorylates
26. 26Which of the two light chains of myosin can be phosphorylated?

    1. AEssential light chain (closer to the head)
    2. BRegulatory light chain (further from the head)
27. 27What enzyme do we need to stop the crossbridge cycle?

    1. AMyosin phosphatase
    2. BMyosin light chain kinase
    3. CMyosin hydrolase
    4. DATP hydrolase
28. 28What effect does rho kinase have on myosin phosphatase?

    1. AInhibits it to promote contraction
    2. BActivates it to promote relaxation
    3. CInhibits it to promote relaxation
    4. DActivates it to promote contraction
29. 29How does rho kinase increase calcium sensitivity?

    1. AInhibits myosin phosphatase so less dephosphorylation occurs so more light chains are phosphorylated without an increase in calcium
    2. BOpens all calcium channels on the sarcoplasmic reticulum and the sarcolemma of the smooth muscle cell
    3. CActivates guanylate cyclase
    4. DActivates phospholipase C
30. 30Nitrogen oxide activates myosin phosphatase via cGMP, promoting relaxation by desensitising the cell to calcium.

    1. ATrue
    2. BFalse
31. 31Smooth muscle increases in exerted [blank_start]force[blank_end] following a stimulus. You would expect that
    myosin [blank_start]phosphorylation[blank_end] would increase in parallel because phosphorylation drives the [blank_start]cross-bridge[blank_end] cycle. However, myosin phosphorylation decreases following the stimulus. This means that myosin can be [blank_start]dephosphorylated[blank_end] when bound to actin in a cross-bridge - it therefore cannot detach and becomes a [blank_start]latch[blank_end]-bridge. This means that smooth muscle cells don't need to use as much [blank_start]ATP[blank_end] - they're stuck in their shortened state.

    1. Aphosphorylation
    2. Bcross-bridge
    3. Cforce
    4. Ddephosphorylated
    5. Elatch
    6. FATP
32. 32What are the spontaneous oscillations in smooth muscle cell membrane generated by the cells themselves or by pacemaker cells?

    1. AAction potentials
    2. BSlow waves
    3. CDepolarisations
    4. DWide waves
33. 33Which ion causes the upstroke of an action potential in smooth muscle due to its influx into the sarcoplasm?

    1. ANa+
    2. BCa2+
    3. CH+
    4. DK+

Description

Principles of Physiology and Pharmacology Quiz on Smooth Muscle, created by Charlotte Jakes on 17/12/2019.

Author

Charlotte Jakes

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