Human Anatomy & Physiology Quotes

“Only about 40% of the energy released during muscle contraction
is converted to useful work (still, this percentage is significantly
higher than that of many mechanical devices).”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Once exercise stops, the
repayment process begins.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“■ATP and creatine phosphate reserves must be resynthesized.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“■Glycogen stores must be replaced.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“■
The accumulated lactic acid must be reconverted to pyruvic acid.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“■Its oxygen reserves in myoglobin must be replenished.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Whether or not fatigue occurs, vigorous exercise alters a muscle’s chemistry dramatically. For a muscle to return to its resting
state, all the following must occur:”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Availability of ATP declines during contraction, but it is abnormal for a muscle to totally run out of ATP. So, lack of ATP is not
a fatigue-producing factor in moderate exercise.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Muscle fatigue is a state of physiological inability to contract
even though the muscle still may be receiving stimuli.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Muscle cells also give off large amounts
of metabolic wastes that must be removed through veins if contraction is to remain efficient.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Skeletal muscle has a rich blood supply. This is understandable because contracting muscle fibers use huge amounts of
energy and require almost continuous delivery of oxygen and
nutrients via the arteries.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Its role is to force fluids and other substances through internal body
channels. Like skeletal muscle, smooth muscle consists of elongated
cells, but smooth muscle has no striations”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Smooth muscle tissue is found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Cardiac muscle tissue occurs only in the heart (the body’s
blood pump), where it constitutes the bulk of the heart walls.
Like skeletal muscle cells, cardiac muscle cells are striated (see
Figure 4.9b, p. 139), but cardiac muscle is not voluntary. Indeed,
it can and does contract without being stimulated by the nervous system. Most of us have no conscious control over how fast
our heart beats.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“■Skeletal and smooth muscle cells (but not cardiac muscle
cells) are elongated, and for this reason, they are called muscle fibers.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Muscles are distinguished by their ability to transform chemical energy (ATP) into
directed mechanical energy. In so doing, they become capable of exerting force.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Skeletal muscles are described as voluntary, but even relaxed
muscles are almost always slightly contracted, a phenomenon
called muscle tone.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“muscle stretching that occurs during eccentric contractions causes microtears in the muscles.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“As
the primary ossification center enlarges, osteoclasts break
down the newly formed spongy bone and open up a medullary cavity in the center of the diaphysis.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“The diaphysis elongates and a medullary cavity forms.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“The entering osteoclasts partially erode the calcified
cartilage matrix, and the osteogenic cells become osteoblasts and secrete osteoid around the remaining calcified
fragments of hyaline cartilage, forming bone-covered cartilage trabeculae. In this way, the earliest version of spongy
bone forms in a developing long bone.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“which contains a nutrient artery and vein, nerve fibers, red marrow elements, osteogenic cells, and osteoclasts.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“In month 3, the forming cavities are
invaded by a collection of elements called the periosteal
bud,”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“The periosteal bud invades the internal cavities and
spongy bone forms.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“This
deterioration opens up cavities, but the bone collar stabilizes the hyaline cartilage model.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Cartilage in the center of the diaphysis calcifies and then
develops cavities.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“It is more complex than intramembranous ossification because the hyaline cartilage must
be broken down as ossification proceeds.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Beginning late in the second month of development, this process uses hyaline cartilage “bones” formed earlier as models,
or patterns, for bone construction.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“Except for the clavicles, essentially all bones below the base of
the skull form by endochondral ossification (en0do-kon9dral).”
― Elaine Nicpon Marieb, Human Anatomy & Physiology

“The beauty of using flexible structures (membranes and cartilages) to fashion the embryonic skeleton is that they can accommodate mitosis. Were the early skeleton composed of calcified
bone tissue from the outset, growth would be much more difficult.”
― Elaine Nicpon Marieb, Human Anatomy & Physiology