Muscular System Histology and Physiology

Which of the following is NOT a function of skeletal muscle

body movement
maintenance of posture
constriction of organs
production of heat

Which of the following is true

Skeletal muscle is capable of spontaneous contraction.
Smooth muscle is found in the walls of hollow organs.
Cardiac muscle cells have multiple nuclei.
Smooth muscle cells are long and cylindrical.
There is a small amount of smooth muscle in the heart.

Which type of muscle tissue has cells that branch

skeletal muscle
smooth muscle
cardiac muscle
both skeletal and cardiac muscle
both cardiac and smooth muscle

Hypertrophy of skeletal muscles from weight lifting is caused by an increase in the

number of muscle fibers.
size of muscle fibers.
number of striations.
number of nuclei within the muscle fibers.
number of muscle cells.

Actin myofilaments

resemble bundles of minute golf clubs.
contain both myosin and tropomyosin.
are held in place by the M line.
contain strands of fibrous actin.
are the thickest proteins in muscle.

When an action potential reaches the presynaptic terminal,

calcium ions diffuse into the presynaptic terminal through voltage-gated ion channels.
acetylcholine moves into the presynaptic terminal.
a local potential is generated in the presynaptic terminal.
ligand-gated ion channels in the presynaptic terminal are opened.
nothing else happens.

In excitation-contraction coupling,

calcium ions must bind with myosin to expose active sites on actin.
myosin heads bind to exposed active sites on actin.
cross-bridges form between myosin heads and calcium ions.
movement of the troponin-tropomyosin complex causes actin myofilaments to slide.
ATP binds to actin myofilaments.

Which of the following helps explain the increased tension seen in multiple wave summation

increased motor unit recruitment
increased concentration of calcium ions around the myofibrils
exposure of more active sites on myosin myofilaments
the breakdown of elastic elements in the cell
decreased stimulus frequency

An isotonic contraction is described as

action potential frequency is high enough that no relaxation of muscle fibers occurs.
a muscle produces constant tension during contraction.
a muscle produces an increasing tension during contraction.
a muscle produces increasing tension as it shortens.
a muscle produces tension, but the length of the muscle is increasing.

Which type of respiration occurs in the mitochondria

anaerobic respiration
aerobic respiration
both anaerobic and aerobic respiration

Muscular System Gross Anatomy
The sternocleidomastoid muscle extends from the mastoid process of the temporal bone to the sternum and medial clavicle. When both sternocleidomastoid muscles contract, the head is flexed. The end of the muscle that connects to the sternum is the


Which of the following represents a class I lever system

crossing your legs
hyperextension of the head
standing on your tiptoes
flexion of the elbow to elevate the hand
lifting weight with your arm

In order to stabilize the hyoid so that the larynx can be elevated in swallowing, the _____ muscle group is used.


If abdominal muscles are contracted while the vertebral column is fixed this will aid in

All of these choices are correct.

Which muscle will depress the scapula or elevate the ribs

levator scapulae
serratus anterior
pectoralis minor
rhomboideus major

Which of the following muscles extends the forearm and has its insertion on the ulna

biceps brachii
triceps brachii

The gluteus maximus

does most of the work in sit-ups.
accounts for a sprinters stance.
allows one to sit cross-legged.
is used in the knee-jerk reflex.
is a common site for injections.

Label muscle A on the diagram.

orbicularis oculi

Label muscle A on the diagram.

linea alba
serratus anterior
rectus abdominis
external oblique
internal oblique

What does A represent

pectoralis major
biceps brachii
serratus anterior


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