Muscle Histology

Question 1

Skeletal Muscle

Answer 1

four characteristics: voluntary, striated, not branched, and multinucleated

usually attached to one or more bones; composed of numerous skeletal muscle fibers, blood vessels, and nerves, and connective tissue sheets that surround the muscle fibers and connect muscle to bone

Question 2

Myofiber (l.s)

Answer 2

Elongated, multinucleated,
cylindrical fiber (cell); contains
myofibrils, separated from
other fibers by layer of areolar
connective tissue; exhibits
striation

Question 3

Myofiber (x.s)

Answer 3

Elongated, multinucleated,
cylindrical fiber (cell); contains
myofibrils, separated from
other fibers by layer of areolar
connective tissue; exhibits
striation

Question 4

Nucleus (l.s) (skeletal muscle)

Answer 4

located on periphery of cell

Question 5

Nucleus (x.s) (skeletal muscle)

Answer 5

located on periphery of cell

Question 6

Striations: A-Band (l.s) (skeletal muscle)

Answer 6

Dark band in the middle of
the sarcomere; composed
of entire thick filaments
and on its lateral end
regions of overlapping thin
filaments

Question 7

Striations: I-Band (l.s) (skeletal muscle)

Answer 7

Light band containing
thin filaments only and
connectin proteins

Question 8

Endomysium (l.s)

Answer 8

innermost connective tissue layer; it is a delicate, areolar CT layer that surrounds and electrically insulates each muscle fiber

Question 9

Endomysium (x.s)

Answer 9

innermost connective tissue layer; it is a delicate, areolar CT layer that surrounds and electrically insulates each muscle fiber

Question 10

Perimysium (x.s)

Answer 10

located around the fascicles; dense irregular CT sheath of the perimysium contains extensive arrays of blood vessels and nerves that branch to supply each individual fascicle

Question 11

Epimysium (x.s)

Answer 11

a layer of dense irregular CT that surround the whole skeletal muscle

Question 12

Fascicle (x.s)

Answer 12

A bundle of muscle fibers
separated from other bundles
of fibers by a dense irregular
connective tissue covering

Question 13

Type 1 Fibers (x.s)

Answer 13

Slow oxidative fibers; appear dark red because of presense of large amount of myoglobin; cells produce contractions that are slower and less powerful, however can contract over long periods of time without fatigue because ATP is supplied primarily thorugh aerobic cellular respiration.

Question 14

Type 2 Fibers (x.s)

Answer 14

Split into fast oxidative fibers (Type IIA) and fast glycodytic fibers (Type IIB);

Fast oxidative fibers: least numerous of skeletal muscle fiber types; produce a fast, powerful contraction with ATP provided primarily through aerobic respiration; appear a lighter red than slow oxidative fibers

Fast glycolytic fibers: most prevalent skeletal muscle fiber type; provide both power and speed but can only contract for short bursts because ATP is provided primarily through anaerobic cellular respiration.

Question 15

Cardiac Muscle

Answer 15

individual muscle cells arranged in thick bundles within the heart wall; branch and are both shorter and thicker than skeletal muscle fibers

Question 16

Cardiocyte

Answer 16

myocytes of the heart;

Cardiomyocytes, also known as cardiac muscle cells, usually contain one elongated nucleus that lies in the centre, which is a distinguishing feature from skeletal muscle. By examining the ultrastructure, it becomes apparent that the myofibrils separate as they approach the nucleus, pass around it and re-assemble in their original pattern on the other side

Question 17

Nucleus of cardiac muscle

Answer 17

Question 18

Striations: A-bands (Cardiac muscle)

Answer 18

Dark band in the middle of
the sarcomere; composed
of entire thick filaments
and on its lateral end
regions of overlapping thin
filaments

Question 19

Striations: I-band (Cardiac muscle)

Answer 19

Light band containing
thin filaments only and
connectin proteins

Question 20

Intercalated discs

Answer 20

unique to cardiac muscle; they are composed of desmosomes and gap junctions; only one or two nuclei; junctions where individual cells are joined to adjacent muscle cells

Question 21

Smooth Muscle

Answer 21

composed of short muscle cells that have a fusiform shape (widest at the middle of the cell and tapered at each end); single, centrally located nucleus; have both thick and thin filaments but not precisely aligned, so no visible striations or sarcomeres

Question 22

Nucleus (smooth muscle)

Answer 22

Question 23

Non-striated (smooth muscle)

Answer 23

What is a significant difference between the appearance of this cell compared to that of other muscles?

Question 24

Endomysium (smooth muscle)

Answer 24

layer of areolar connective tissue that ensheathes each individual myocite

for what muscle type is this image of?

Question 25

What is the tissue type of tendons?

Answer 25

it is composed of dense fibrous connective tissue made up primarily of collagen fibers

Question 26

What is the difference between a relaxed sarcomere and fully contracted sarcomere?

Answer 26