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Histology 2018 > Lecture 14 > Flashcards

Lecture 14 Flashcards

1
Q

What are the 2 components of the perimysium of skeletal muscle?

A

fibroblasts and type I collagen fibers

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2
Q

What is the cell membrane of a skeletal muscle cell called?

A

the sarcolemma

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3
Q

How is Desmin involved in the molecular structure of skeletal muscle cells? what is the name for the region of the sarcolemma where desmin is anchored?

A

desmin is an intermediate filament that extends from one myofibril to the other and is anchored in the sarcollema

Costameres are where desmin inserts into the sarcolemma

(desmin filaments span across several myofibrils)

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4
Q

how is plectin involved in the molecular structure of skeletal muscle cells?

A

plectin links adjacent desmin filaments to each other

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5
Q

name the 2 components AND their contents, of an intercalated disc in cardiocytes

A

Transverse component: desmosomes and fascia adherentes

Longitudinal component: gap junctions

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6
Q

Name the type of muscle tissue with the following characteristics: voluntary and striated

A

Skeletal muscle

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7
Q

Name the type of muscle tissue with the following characteristics:

Single mononucleated cells w/ central nuclei

No sarcomeric arrangement

Innervated via the ANS or enteric system

Do not respond in the “all or none” fashion

Cells connected via gap junctions

A

Smooth muscle

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8
Q

Name the type of muscle tissue with the following characteristics: single mononucleated cells that are often branched, and feature a centrally positioned nuclei.

A

Cardiac muscle

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9
Q

There is a type of muscle cell that is not directly innervated. name the type of muscle and why it is not directly innervated

A

Cardiac muscle

They communicate via gap junctions (intercalated discs).

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10
Q

What type of myofiber fits the following characteristics?

(Dark or Red fibers) intense staining for oxidative enzymes (NAD)

Rich in NADH transferase, myoglobin, and have many mitochondria

Primarily use oxidative phosphorylation for ATP production

Slow/continuous contraction speed

A

Type I

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11
Q

What type of myofiber fits the following characteristics?

Intermediate NAD staining

Uses both aerobic and anaerobic respiration for ATP production

Medium contraction speed

Resistance to fatigue

A

Type IIA

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12
Q

What type of myofiber fits the following characteristics?

Light NAD staining

Primarily anaerobic respiration for ATP production

Rich in ATPase ( bc they contract very rapidly)

Fatigue quickly

A

Type IIB

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13
Q

What is another name for Type IIB myofibers?

A

white/light muscle fibers

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14
Q

List, from largest to smallest, the “muscle units” of a skeletal muscle

A

Muscle to fascicle

to bundle of myofibers

to bundle of myofibrils(which are a linear array of sarcomeres)

A sarcomere is made up of thin (actin) and thick (myosin) filaments

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15
Q

List, from largest to smallest, the “CT units” of a skeletal muscle

A

Epimysium (sheet on outside)

to perimysium (surrounds fascicles)

to endomysium (surrounds myofibers)

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16
Q

what are the 2 components of the endomysium? how does this effect the distribution of the force of the muscle contraction?

A

Endomysium consists of basal lamina and reticular collagen fibers

Basal lamina is secreted by muscle cells and anchors muscle fibers to one another so the force of the contraction can be distributed evenly

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17
Q

What are the 2 components of the Perimysium?

A

The perimysium consists of fibroblasts and type I collagen fibers

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18
Q

Sarcomeres are separated from one another by transverse discs called ___ _________.

A

Z discs

19
Q

What makes up A bands? what is their length equal to?

A

A bands consist of overlapping actin and myosin filaments

their width/length is equal to the length of the bundle of myosin filaments

20
Q

Describe I bands in terms of the overlapping myosin and actin filaments in skeletal muscle. what happens to I bands during contraction?

A

I bands are the portion of actin filaments that is NOT overlapping the myosin filaments and shrinks during contraction

21
Q

Describe H bands in terms of the overlapping myosin and actin filaments in skeletal muscle. Where are they located and what happens to H bands during contraction?

A

H bands consists of ONLY the myosin filaments that aren’t overlapping

are located in the middle of the sarcomere and they shrink (or even disappears completely) during a contraction

22
Q

describe the molecular structure of tropomyosin and it’s function (Per molecule) in muscle cells

A

2 nearly identical alpha-helical polypeptides twisted around each other

1 tropomyosin molecules covers the binding sites on 7 actin monomers

23
Q

Describe troponin and it’s subunits (I,C, and T)

A

Troponin is a complex of 3 molecules (listed below)

Troponin I: inhibits binding between actin and myosin

Troponin C: binds to Ca2+

Troponin T: Binds to tropomyosin

24
Q

Define the function of αB-crystallin

A

Hsp that protects desmin from mechanical stress

25
Q

Define the function of Dystrophin

A

one of the proteins that links alpha-actinin/desmin complexes to the cytoplasmic side of the sarcolemma (which serves to anchor actin to the sarcolemma and reinforce the sarcollema during contraction

26
Q

Define the function of dystroglycan complex

A

Links dystrophin (intracellular) to laminin-2 (extracellular)

27
Q

Define the function of α-actinin

A

attaches thing filaments to the z line

28
Q

Define the function of Nebulin

A

extends from the z disc to the end of the actin filament and serves as a template in order the regulate the length of actin filaments

29
Q

Define the function of Titin

A

large fibrous protein that extends from the Z-disc to the middle of the H band and connects the ends of thick filaments to Z-line

Provides myosin elasticity and centers thick filaments in the sarcomere

30
Q

Describe the role of Satellite cells

A

attach to myotubes before basal lamina is laid down, and function as stem cells

31
Q

C-Met receptors are the binding site of what type of growth, when they are associated with skeletal muscle tissue satellite cells?

A

hepatic growth

they play a role in hematopoiesis

32
Q

Describe what is happening during the regeneration of muscle cells (assisted by satellite cells)

A

the already present muscle cells are being “built up”

more muscle cells are NOT generated

33
Q

compare and contrast extrafusal and intrafusal muscle fibers. include what motor neurons they are associated with

A

extrafusal: “within the fusiform portion” are thicker, normal skeletal muscle
associated with alpha motor neurons

Intrafusal: “outside of the fusiform portion” are thinner
associated with gamma motor neurons

34
Q

Extrafusal fibers, intrafusal fibers, alpha motoro neurons, gamma motor neurons, primary afferent fibers, and secondary afferent fibers all all components of what?

A

the neuromuscular spindle

35
Q

Compare the T tubule system differences between skeletal and cardiac muscle cells

A

In cardimyocytes the t tubule system is not as extensive as it is in skeletal muscles

each T-tubule interacts with just one cisterna (diad as opposed to the triads in skeletal muscle)

36
Q

List the source and functions of ANP (atrial natriuretic peptide)

A

Source: secreted by cardiac muscle cells located in the atria (makes sense bc its called Atrial Natriuretic Peptides)
This prohormone is cleaved when it is released upon stretching of the atria

Functions:
Regulate fluid electrolyte balance

Relax vascular smooth muscle (this reduces blood volume and pressure)

37
Q

what is the function of dense bodies in smooth muscle tissue? (2 of them)

A

To Anchor actin filaments to each other and to the cell membrane

to Communicate force of contraction to cytoskeleton and cell membrane

38
Q

in smooth muscle tissue, where are actin and myosin bundles found?

A

Actin and myosin bundles are found throughout the cytoplasm, except in the nuclear area

39
Q

Where are dense bodies in smooth muscle found and what do they contain?

A

Found in the cytoplasm and in the cell membrane

Contain alpha-actinin

40
Q

Compare utilization of calcium by smooth muscle cells with cardiac and skeletal muscle cells.

A

In smooth muscle cells, all of the Ca2+ needed for contraction comes from the extracellular environment (they don’t have a T-tubule system or extensive SR bc of this)

Smooth muscle cells have pinocytotic vesicles that may transport Ca2+ from extracellular fluids to the SR

Cardiac and smooth muscles use t tubule cisternae to provide Ca2+

41
Q

Define Caveolae

A

Caveolae: permanent depression of the cell membrane that binds to the cholesterol in the lipid rafts, and forms vesicles that participate in vesicular trafficking

42
Q

Define the composition and location within the cell of Lipid rafts

A

Lipid rafts: a collection of cholesterol and sphingolipids in the PM

43
Q

What are caveloae and lipid rafts both involved in?

A

fluid and electrolyte transport

Histology 2018 (20 decks)

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