Muscle

Question 1

Skeletal Muscle (Striated, Voluntary)

Answer 1

Each skeletal mm fiber is long, cylindrical with the nuclei located peripherally.
- longitudinal arrays of cylinder-shaped myofibrils.
This ordered parallel arrangement of the myofibrils is responsible for the crossstriations of light and dark banding that is characteristic of skeletal muscle.

Question 2

Red muscle fibre

Answer 2

Red fibers are small with much myoglobin, many mitochondria, oxidative enzymes and represent slow twitch fibers adapted to slow repetitive contractions.

Question 3

white muscle fibre

Answer 3

White fibers are large with less myoglobin, fewer mitochondria, poor in oxidative enzymes and represent fast twitch fibers adapted to rapid short-lived forces.

Question 4

Intermediate fibers

Answer 4

Intermediate fibers have features of both types. Most muscles have a mixture of the 2 types.

Question 5

Smooth Muscle (Non-Striated, Involuntary)

Answer 5

Locations: e.g. the walls of blood vessels and hollow organs (digestive, respiratory, urinary, etc)
-The cells are surrounded by a fine collagen and
reticular fiber network (endomysium). There are no cross striations

Question 6

Motor Nerve Ending (Motor end plate, Neuromuscular Junction)

Answer 6

A specialized region on skeletal mm fibers where a motor nerve terminates.
Function: transmit a stimulus from the nerve fiber to the muscle cell via the release of neurotransmitters from the nerve terminal vesicles across the synaptic cleft.

Question 7

Cardiac Muscle (Striated, Involuntary)

Answer 7

Location: found only in the heart (myocardium).
Myocardium consists of a network of branching cardiac mm cells arranged end to end. The fibers are separated from each other by CT sheets.
Heart mm differs from skeletal and smooth mm in that
it possesses an inherent rhythmicity as well as the ability to contract spontaneously.
Each cell has a single, oval and centrally placed nucleus, occasionally two nuclei are present

Question 8

Intercalated Discs

Answer 8

formed by cardiac mm cells at the site of a Z line. Intercalated discs have areas of low resistance allowing the rapid spread of an impulse from cell to cell.

Question 9

Purkinje Conducting Fibers

Answer 9

Are large modified muscle cells filled with glycogen and mitochondria. They function as specialized conducting cells of the AV bundle in the heart. The cells can have 2 or more nuclei.