University Of Alberta Medicine Histoquest

Front 1

What is the connective tissue layer around each muscle cell called?

Back 1

The endomysium.

Front 2

What is the connective tissue layer around a fascicle called?

Back 2

The perimysium.

Front 3

What is the connective tissue around an entire muscle called?

Back 3

The epimysium (continuous with the perimysium and also known as the deep fascia).

Front 4

Where are the nuclei located in muscle cells?

Back 4

At the periphery.

Front 5

How do capillaries interact with skeletal muscle?

Back 5

They form a network around each individual cell.

Front 6

How do skeletal muscle cells become multinucleated?

Back 6

They begin as myoblasts, which then join with other myoblasts to form long, multi-nucleated cells. These then proceed to mature into mature skeletal muscle cells.

Front 7

The light bands of skeletal muscle are the...

Back 7

...I bands.

Front 8

The dark bands of skeletal muscle are the...

Back 8

...A bands.

Front 9

I bands contain _____ filaments composed of the protein _______.

Back 9

thin; actin

Front 10

A bands contain _____ filaments composed of the protein _______.

Back 10

thick; myosin

Front 11

What happens with actin filaments and myosin filaments in muscle contraction?

Back 11

They are pulled over top of each other.

Front 12

What is the line down the middle of an I band called? What does it do? How does it move in muscle contraction?

Back 12

It is called the Z-band or Z-line. It anchors the thin actin filaments of the I band. In muscle contraction, it is pulled towards the center of an A-band.

Front 13

What is a sarcomere?

Back 13

It is the basic unit of striated muscle, the area between 2 Z-bands. It therefore consists of an A band in the middle, with a half I-band and Z-line on either side.

Front 14

What are the bands in the middle of A bands called? How do they respond to muscle relaxation and contraction?

Back 14

They are called H bands. They are widest when the muscle is relaxed and disappear when it is fully contracted.

Front 15

How are skeletal muscles and tendons attached?

Back 15

The end of the skeletal muscle and the tendon interdigitate. As well, the endomysium and the connective tissue of the tendon merge.

Front 16

What path does blood flow take to get to the individual muscle cells?

Back 16

The major artery travels along the epimysium, then down into the perimysium, then down into the endomysium, and finally becomes a network of capillaries around the cell.

Front 17

How are muscle cells innervated?

Back 17

A branch of an axon innervates every muscle cell. The terminal butts up against the plasma membrane, and an action potential results in a contraction of the cell.

Front 18

How does your body control the amount of force needed for a given task?

Back 18

It activates an appropriate number of muscle fibers (they fire all-or-nothing).

Front 19

What are some unique physical features of smooth muscle which are visible under a microscope?

Back 19

Cells are spindle-shaped, nuclei are cigar-shaped and centrally-located, no striations or banding.

Front 20

Why is banding not visible in smooth muscle cells?

Back 20

Although the same essential mechanism is used, actin and myosin are not organized into myofibrils, but form seperate structures that interact laterally.

Front 21

What are reticular fibers? What level of connective tissue is it part of?

Back 21

They are fibers that form a network around each muscle (in all muscle types) and bind cells together. They are part of the endomysium.

Front 22

How does the connective tissue structure of smooth muscle differ from that of other muscle types?

Back 22

It lacks an epimysium; the perimysium is continuous with the connective tissue in which bundles of smooth muscle tissue are embedded.

Front 23

What characteristics make smooth muscle good at generating perstaltic waves?

Back 23

It is designed for slow, sustained contractions, which do not require neural input (although neurons can be involved).

Front 24

Describe the role of smooth muscle cells in the villi.

Back 24

Individual or small groups of smooth muscle cells exist in the villi to generated localized contractions, stirring the small intestine contents and helping lacteals empty into larger lymph vessels.

Front 25

Describe the role of smooth muscle in blood vessels.

Back 25

They contract or relax to regulate the diameter of the vessel in response to hormonal and autonomic regulation.

Front 26

What is mesenchyme?

Back 26

Embryonic connective tissue.

Front 27

What do mesenchymal cells secrete to fill the space between the cells? What is this substance composed of?

Back 27

Ground substance. It is composed of water and hyaluronic acid.

Front 28

What can mesenchymal cells mature into?

Back 28

Fibroblasts or adipocytes.

Front 29

What is contained within the ground substance secreted by fibroblasts?

Back 29

Elastin and collagen fibers.

Front 30

Describe the appearance of the nuclei and cytoplasm of mesenchymal cells.

Back 30

They have roundish nuclei, and many thin cytoplasmic processes that from a network in the tissue.

Front 31

What are the primary cells of connective tissue?

Back 31

Fibroblasts.

Front 32

Why is fibroblast cytoplasm rather hard to see?

Back 32

It stretches out along collagen bundles, becoming very thin.

Front 33

Why do fibroblast nuclei tend to stain darkly?

Back 33

Because they are usually heterochromatic (inactive).

Front 34

When do fibroblasts become euchromatic?

Back 34

When they are involved in wound repair.

Front 35

Do adipocytes usually exist as individual cells, usually exist with others to form adipose tissue, or some of both?

Back 35

Some of both.

Front 36

What do adipocytes look like under the microscope?

Back 36

They look like a big solid mass of lipid with a bit of ctyoplasm and a nucleus on the periphery.

Front 37

What are the three major macromolecules in connective tissue's extracellular matrix, and what do they each do?

Back 37

1) Glycosaminoglycans, which are long polysaccharide chains, and usually linked to proteins to form proteoglycans. They bind and order water to form the extracellular substance.
2) Fibers composed of collagen and elastin, which are in the ground substance and provide strength and resiliency.
3) Structural glycoproteins, which help link all the components together.

Front 38

What are the two components of the repeating disaccharide units in glycosaminoglycans?

Back 38

A uronic acid and an amino sugar.

Front 39

What structural shape do glycosaminoglycans take?

Back 39

They are long and unbranched.