10 - Muscular Tissue

Question 0

What does “striated” mean?

Answer 0

Describes muscle that has alternating light and dark protein bands (striations), visible when the tissue is examined under a microscope.

Question 1

What are the 4 primary functions of muscular tissue?

Answer 1

Producing body movements, stabilizing body positions, storing and moving substances within the body, and generating heat.

Question 2

Which muscle tissues are striated?

Answer 2

Skeletal muscle tissues and cardiac muscle tissues

Question 3

Which muscle tissue is striated and involuntary?

Answer 3

Cardiac muscle tissue

Question 4

Which muscle tissue is striated and voluntary?

Answer 4

Skeletal muscle tissue

Question 5

Which muscle tissue is nonstriated and usually involuntary?

Answer 5

Smooth muscle tissue

Question 6

What is the opposite of striated?

Answer 6

Smooth

Question 7

What is the built-in (intrinsic) rhythm of the heart, helped by several
hormones and neurotransmitters that adjust heart rate by speeding up
or slowing down the pacemaker?

Answer 7

autorhythmicity

Question 8

As muscular tissue contracts, it also produces heat - what is this process called?

Answer 8

thermogenesis

Question 9

What is the purpose of involuntary contractions of skeletal

muscles, known as shivering?

Answer 9

They can dramatically increase the rate of heat production.

Question 10

What are the 4 special properties of muscular tissue?

Answer 10

Electrical Excitability, Contractility, Extensibility, Elasticity

Question 11

What is this property of both muscle and nerve cells, the ability to respond to certain stimuli by producing electrical signals called action potentials (impulses)?

Answer 11

Electrical Excitability

Question 12

What are the two main types of stimuli that trigger action potentials in muscle cells?

Answer 12

Electrical stimuli and chemical stimuli. Autorhythmic electrical signals arise in the muscular tissue itself, as in the heart’s pacemaker. Chemical stimuli, such as neurotransmitters released by neurons, hormones distributed by the blood, or even local changes in pH, can also trigger action potentials in muscle cells.

Question 13

These can travel along a cell’s plasma membrane due to the presence of specific ion channels.

Answer 13

Action potentials (muscle action potentials & nerve action potentials)

Question 14

The ability of muscular tissue to contract forcefully when stimulated by an action potential.

Answer 14

Contractility

Question 15

The ability of muscular tissue to stretch, within limits, without being damaged.

Answer 15

Extensibility

Question 16

The ability of muscular tissue to return to its original length and shape after contraction or extension.

Answer 16

Elasticity

Question 17

True or False? Each skeletal muscle is a separate organ.

Answer 17

True. Each skeletal muscle is a separate organ composed of hundreds
to thousands of skeletal muscle cells, also called muscle fibers
because of their elongated shapes.

Question 18

What is the name for the thousands of skeletal muscle cells that have elongated shapes and make up each skeletal muscle?

Answer 18

Muscle fibers

Question 19

The reddish or meatlike appearance that we associate with muscular tissue arises from the large population of well-vascularized muscle cells in the __________ of the organ.

Answer 19

muscle belly (body) [The belly of the muscle can be an elongated, thick, rounded mass, a triangular shape, a thick rectangular mass, or a thin, flat sheet of muscular tissue.]

Question 20

Tough, glistening white dense regular connective tissue structures that attach the muscle belly to the bones, are minimally vascular, lack muscle cells, and consist primarily of parallel arrangements of collagen fibers.

Answer 20

tendons (Like the muscle belly, tendons display a great variety of shapes: Some are long, ropelike structures, while others are arranged in flat sheets called aponeuroses.)

Question 21

Tendons arranged in flat sheets are called __________.

Answer 21

aponeuroses (An example of an aponeurosis is the epicranial aponeurosis on top of the skull between the occipital and frontal bellies of the occipitofrontalis muscle.)

Question 22

Surrounding each muscle fiber is a thin wrapping of mostly reticular fibers called the __________. This surrounding connective tissue helps to bind the muscle fibers together, yet it is loose enough to allow them to move freely over one another. In addition, it carries small blood vessels that supply the fibers with nutrients.

Answer 22

endomysium (en -doˉ-MI¯Z-eˉ-um; endo- within)

Question 23

Groups of muscle fibers form bundles wrapped in a thicker layer
of connective tissue. This muscle fiber bundle is a ________.

Answer 23

fascicle (FAS-i-kl little bundle), also called a fasciculus

Question 24

The dense irregular connective tissue covering a muscle fiber bundle is called the ___________.

Answer 24

perimysium (per -i-MI¯Z-eˉ-um; peri- around). The perimysium also allows a certain degree of freedom of motion between neighboring fascicles and transmits blood vessels.

Question 25

Around the periphery of the muscle is a somewhat thicker covering of dense irregular connective tissue called the ___________, which binds all the fascicles together to form the muscle belly.

Answer 25

epimysium (ep -i-MI¯Z-eˉ-um; epi- upon)

Question 26

Why are tendons white?

Answer 26

This continuing mass of collagenous connective tissue takes on a glistening whitish appearance, resulting from highly ordered collagen fibers, reduced numbers of blood vessels, and an absence of muscle.

Question 27

A chronic, painful, nonarticular rheumatic disorder that affects the fibrous connective tissue components of muscles, tendons, and ligaments.

Answer 27

Fibromyalgia (fı¯-broˉ-mı¯-AL-jeˉ-a; algia painful condition). A striking sign is pain that results from gentle pressure at specific “tender points.” Even without pressure, there is pain, tenderness, and stiffness of muscles, tendons, and surrounding soft tissues. In addition to muscle pain, people suffering from fibromyalgia report severe fatigue, poor sleep, headaches, depression, irritable bowel syndrome, and inability to carry out their daily activities. There is no specific identifiable cause. Treatment consists of stress reduction, regular exercise, application of heat, gentle massage, physical therapy, medication for pain, and a low-dose antidepressant to help improve sleep.

Question 28

The various skeletal muscles of the body are further grouped together and protected by large dense irregular connective tissue sheets, called _______, which wrap around groups of muscles much like a sock encircles your foot.

Answer 28

fascia (FASH-eˉ-a bandage)

Question 29

Nerves typically enter the muscle along with the main blood vessels of the muscle as a unit called a ___________.

Answer 29

neurovascular bundle (noo-roˉ-VAS-ku¯-lar)

Question 30

____________ enter the muscle body near the stable tendon attachment (tendon of origin) and then spread through the muscle via the connective tissue channels formed by perimysium and endomysium as they wrap the muscle cells.

Answer 30

neurovascular bundles

Question 31

The _______ fibers initiate the contractile function of muscle cells, while the _______ fibers provide feedback to the nervous system to regulate motor function.

Answer 31

motor; sensory

Question 32

The neurons (nerve cells) that stimulate skeletal muscle fibers to contract are called ___________.

Answer 32

somatic motor neurons

Question 33

A somatic motor neuron has a threadlike extension, called an ______, which travels from the neuron cell body in the brain or spinal cord to a group of skeletal muscle fibers in a muscle of the body.

Answer 33

axon

Question 34

Microscopic blood vessels called __________ are plentiful in muscle tissue; each muscle fiber is in close contact with one or more of these blood vessels (Figure 10.1), which bring oxygen and nutrients to the muscle fibers and remove heat and the waste products of muscle metabolism.

Answer 34

capillaries

Question 35

The dramatic muscle growth that occurs after birth occurs by enlargement of existing muscle fibers, called __________. It is due to the production of myofibrils, mitochondria, sarcoplasmic reticulum, and other organelles. It results from very forceful, repetitive muscular activity, such as strength training.

Answer 35

hypertrophy (hı¯-PER-troˉ-feˉ; hyper- above or excessive; -trophy nourishment)

Question 36

An increase in the number of muscle fibers.

Answer 36

hyperplasia (hı¯-per-PLAˉ-zeˉ-a; -plasis molding)

Question 37

The replacement of muscle fibers by fibrous scar tissue.

Answer 37

fibrosis

Question 38

The multiple nuclei of a skeletal muscle fiber are located just beneath the ___________, the plasma membrane of a muscle fiber.

Answer 38

sarcolemma (sar -koˉ-LEM-ma) sarc- flesh; -lemma sheath)

Question 39

Thousands of tiny invaginations of the sarcolemma, called _____________, tunnel in from the surface toward the center of each muscle fiber. Because they are open to the outside of the fiber, they are filled with interstitial fluid.

Answer 39

transverse tubules (T tubules)

Question 40

Muscle action potentials propagate along the sarcolemma and through the transverse tubules, quickly spreading throughout the muscle fiber. Why?

Answer 40

This arrangement ensures that all the superficial and deep parts of the muscle fiber become excited by an action potential almost simultaneously.

Question 41

The sarcolemma surrounds the _____________, the cytoplasm of a muscle fiber. It includes a substantial amount of glycogen, a storage molecule that consists of a chain of linked glucose molecules.

Answer 41

sarcoplasm (SAR-koˉ-plazm)

Question 42

True or False. The NMJ usually is near the midpoint of a skeletal muscle fiber.

Answer 42

True. This arrangement permits nearly simultaneous activation (and thus contraction) of all parts of the muscle fiber.