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39 Cards in this Set

  • Front
  • Back
What is the connective tissue layer around each muscle cell called?
The endomysium.
What is the connective tissue layer around a fascicle called?
The perimysium.
What is the connective tissue around an entire muscle called?
The epimysium (continuous with the perimysium and also known as the deep fascia).
Where are the nuclei located in muscle cells?
At the periphery.
How do capillaries interact with skeletal muscle?
They form a network around each individual cell.
How do skeletal muscle cells become multinucleated?
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.
The light bands of skeletal muscle are the...
...I bands.
The dark bands of skeletal muscle are the...
...A bands.
I bands contain _____ filaments composed of the protein _______.
thin; actin
A bands contain _____ filaments composed of the protein _______.
thick; myosin
What happens with actin filaments and myosin filaments in muscle contraction?
They are pulled over top of each other.
What is the line down the middle of an I band called? What does it do? How does it move in muscle contraction?
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.
What is a sarcomere?
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.
What are the bands in the middle of A bands called? How do they respond to muscle relaxation and contraction?
They are called H bands. They are widest when the muscle is relaxed and disappear when it is fully contracted.
How are skeletal muscles and tendons attached?
The end of the skeletal muscle and the tendon interdigitate. As well, the endomysium and the connective tissue of the tendon merge.
What path does blood flow take to get to the individual muscle cells?
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.
How are muscle cells innervated?
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.
How does your body control the amount of force needed for a given task?
It activates an appropriate number of muscle fibers (they fire all-or-nothing).
What are some unique physical features of smooth muscle which are visible under a microscope?
Cells are spindle-shaped, nuclei are cigar-shaped and centrally-located, no striations or banding.
Why is banding not visible in smooth muscle cells?
Although the same essential mechanism is used, actin and myosin are not organized into myofibrils, but form seperate structures that interact laterally.
What are reticular fibers? What level of connective tissue is it part of?
They are fibers that form a network around each muscle (in all muscle types) and bind cells together. They are part of the endomysium.
How does the connective tissue structure of smooth muscle differ from that of other muscle types?
It lacks an epimysium; the perimysium is continuous with the connective tissue in which bundles of smooth muscle tissue are embedded.
What characteristics make smooth muscle good at generating perstaltic waves?
It is designed for slow, sustained contractions, which do not require neural input (although neurons can be involved).
Describe the role of smooth muscle cells in the villi.
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.
Describe the role of smooth muscle in blood vessels.
They contract or relax to regulate the diameter of the vessel in response to hormonal and autonomic regulation.
What is mesenchyme?
Embryonic connective tissue.
What do mesenchymal cells secrete to fill the space between the cells? What is this substance composed of?
Ground substance. It is composed of water and hyaluronic acid.
What can mesenchymal cells mature into?
Fibroblasts or adipocytes.
What is contained within the ground substance secreted by fibroblasts?
Elastin and collagen fibers.
Describe the appearance of the nuclei and cytoplasm of mesenchymal cells.
They have roundish nuclei, and many thin cytoplasmic processes that from a network in the tissue.
What are the primary cells of connective tissue?
Why is fibroblast cytoplasm rather hard to see?
It stretches out along collagen bundles, becoming very thin.
Why do fibroblast nuclei tend to stain darkly?
Because they are usually heterochromatic (inactive).
When do fibroblasts become euchromatic?
When they are involved in wound repair.
Do adipocytes usually exist as individual cells, usually exist with others to form adipose tissue, or some of both?
Some of both.
What do adipocytes look like under the microscope?
They look like a big solid mass of lipid with a bit of ctyoplasm and a nucleus on the periphery.
What are the three major macromolecules in connective tissue's extracellular matrix, and what do they each do?
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.
What are the two components of the repeating disaccharide units in glycosaminoglycans?
A uronic acid and an amino sugar.
What structural shape do glycosaminoglycans take?
They are long and unbranched.