Skeletal System
Muscle atrophy
lack of muscle activity; reduces muscle size, tone, and power
The space occupied by an osteocyte is called a
lacuna
The carpal bones are examples of ________ bones.
short
Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber
shortens
Which muscle types are voluntary, and which are involuntary?
skeletal muscle is voluntary, and cardiac and smooth muscles are involuntary
Which three organ systems coordinate to maintain normal blood calcium level?
skeletal system, digestive system, urinary system
The structural explanation of how a muscle fiber contracts is called the
sliding filament theory
Small, oddly shaped bones that fill gaps between bones of the skull are called ________ bones
sutural
The narrow space between the synaptic terminal and the muscle fiber is the
synaptic cleft
At each end of the muscle, the collagen fibers of the epimysium, and each perimysium and endomysium, come together to form a
tendon
Identify three sources of stored energy utilized by muscle fibers.
ATP, creatine phosphate, glycogen
The cytoplasm of the neuromuscular synaptic terminal contains vesicles filled with molecules of the neurotransmitter named
Acetylcholine
Excessive growth hormone after puberty could result in
Acromegaly
Identify the six broad categories for classifying a bone according to shape.
Flat, irregular, sesamoid, short, long, and sutural bones.
Describe the function of the medullary cavity.
Forms red and white blood cells and holds bone marrow
Compare gigantism with acromegaly
Gigantism results from an overproduction of growth hormone before puberty, whereas acromegaly results from an overproduction of growth hormone after puberty.
muscle hypertrophy
Muscle growth from heavy training Increases diameter of muscle fibers Increases number of myofibrils Increases mitochondria, glycogen reserves
Motor unit
a motor neuron and its associated muscle fibers
The medullary cavity of bones contains
bone marrow and yellow bone marrow
During the ________ phase of action potential development, voltage-gated sodium channels are open.
depolarization
Individual muscle cells are surrounded by what connective tissue?
endomysium
The lining of the medullary cavity is called the
endosteum
The dense layer of connective tissue that surrounds an entire skeletal muscle is the
epimysium
What structure allows a bone to grow in length?
epiphyseal plate
List the major parts of a long bone.
epiphysis, metaphysis, diaphysis, and medullary cavity
A rounded hole through a bone is termed a
foramen
Excessive growth hormone prior to puberty could result in
giantism
Muscle fibers differ from "typical cells" in that muscle fibers in
have many nuclei
What molecule supplies the energy for a muscle fiber contraction?
ATP
Arrange the order of endochondral ossification process systematically.
1. Cartilage model enlarges 2. Blood vessels grow around the edge of the cartilage model 3. Blood vessels penetrate and enter the central region 4. Growth and remodeling continue 5. Capillaries and osteoblasts migrate into epiphyses 6. Epiphyses fill with spongy bone 7. Bone grows in length at epiphyseal cartilage
List the steps involved in fracture repair, beginning just after the fracture occurs.
1. Fracture hematoma formation 2. Callus formation 3. Spongy bone formation 4. Compact bone formation
How many appendicular bones
126
The adult skeleton contains ________ major bones
206
How many axial skeleton bones
80
Na+ and K+ both use ________ to passively diffuse across the plasma membrane.
ATP
Tendon
Attaches muscle to bone
The skeletal system is made up of the
Axial and appendicular divisions
The most abundant mineral in the human body is.....
Calcium
What is the composition of hydroxyapatite?
Calcium + phosphate
_______(mineral) accounts for almost two-thirds of the weight of bone.
Calcium phosphate
When estrogen is increased in females at puberty, epiphyseal plates becomes
Closed
Where is articular cartilage found, and how is it nourished?
Covering epiphyseal portions of articulating bone and its nutrients diffuse from synovial fluid within the joint
Define depolarization, and describe the events that follow it.
Depolarization is the when the inside of the cell becomes positive due to sodium ions rushing in. After depolarization, repolarization occurs when potassium ions rush out of the cell causing the inside of the cell to become negative again.
What tissue is replaced by bone during intramembranous ossification?
Hyaline cartilage
How would the compressive strength of a bone be affected if the ratio of collagen to hydroxyapatite increased?
If the ratio of collagen to hydroxyapatite in a bone increased, the bone would become less strong (as well as more flexible).
Explain the primary difference between endochondral ossification and intramembranous ossification.
In intramembranous ossification, bone develops from mesenchyme or fibrous connective tissue, whereas in endochondral ossification bone develops from a cartilage model
Compare incomplete tetanus with wave summation.
Incomplete tetanus refers to a muscle producing near-peak tension during rapid cycles of contraction and relaxation. Wave summation refers to the addition of one twitch to another.
Define intramembranous ossification
Intramembranous ossification is bone formation within connective tissue without the prior development of a cartilage model.
What happens to the lactate produced by skeletal muscle during peak activity?
It diffuses out of the muscles into the bloodstream, and then the liver converts it to pyruvate
As a bone increases in diameter, what happens to the medullary cavity?
It grows in length
How does calcitonin act to lower blood calcium?
It inhibits the activity of osteoclasts, which are the cells responsible for breaking down bone. ... Therefore, the inhibition of the osteoclasts by calcitonin directly reduces the amount of calcium released into the blood.
How would denaturing collagen from the bone matrix affect the physical properties of a bone?
It would cause it to become brittle
How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?
It would cause muscles to stay contracted.
During the Cori cycle, in the liver
Lactate is converted to glucose and sent to the bloodstream
Describe the functions of osteocytes.
Maintain protein and mineral content of surrounding matrix and occupy lacunae and repair bone
If osteoclast activity exceeds osteoblast activity in a bone, how will bone mass be affected?
Mineral content decreases and weakens the bone
What is the ratio of organic compounds to inorganic components in the composition of bone?
Organic compounds: 33% of bones Inorganic compounds: 67% of bones
Describe the functions of osteogenic cells and osteoblasts.
Osteoblasts form new bones, synthesize and secrete osteoids, and calcify and become osteocytes. Osteogenic cells have high mitotic activity, are the only bone cells that divide, and develop into osteoblasts.
Identify the hormone that stimulates the release of calcium ions from bone matrix. Explain its mechanism of action.
Parathyroid hormone; it blocks reabsorption of phosphate in the proximal tubule while promoting calcium reabsorption in the ascending loop of Henle, distal tubule, and collecting tubule.
Name the clinical condition affecting skeletal muscle, which is caused by a virus
Polio
Why is pituitary growth failure less common today in the United States?
Synthetic growth hormone treatment is now an option
What causes calcium to be released from the sarcoplasmic reticulum?
The action potential in the sarcolemma travels along the T tubules to the triads, where it triggers the release of Ca2+ from the terminal cisternae of the sarcoplasmic reticulum
Define appositional growth
The enlargement of a bone by the addition of bone matrix at it's surface.
Membrane potential is
The voltage across a cell's plasma membrane.
The interconnecting struts and plates found in spongy bone are called
Trabeculae
Name a bone that is classified as "irregular" in shape.
Vertebrae/Facial bone
When do muscle fibers produce lactate?
When deprived of oxygen; anaerobic metabolism
During appositional growth, bone grows
Wider and is replaced by cartilage
The most important factor in decreasing the intracellular concentration of calcium ion after contraction is
active transport of calcium into the sarcoplasmic reticulum
During the recovery period, the body's need for oxygen is increased because
additional oxygen is required to restore energy reserves consumed during exercise.
A resting muscle generates most of its ATP by
aerobic metabolism
In endochondral ossification, what is the original source of osteoblasts?
cells of the inner layer of the perichondrium
When a muscle is stimulated repeatedly at a high rate, eliminating a relaxation phase, the amount of tension gradually increases to a steady maximum tension. This is called
complete tetanus
Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for
contraction
The muscle weakness of myasthenia gravis results from
loss of acetylcholine receptors in the end-plate membrane.
The Na+/K+ ion pump is responsible for
maintaining the sodium/potassium concentration gradients constant.
Cellular membrane potential is measured in
millivolts
During activities requiring aerobic endurance
most of the muscle's energy is produced by the mitochondria
Receptors for acetylcholine are located on the
motor end plate
Neurons and ________ have electrically excitable membranes that propagate action potentials.
muscle cells
Skeletal muscle fibers are formed from embryonic cells called
myoblasts
________ are stem cells located between the endomysium and sarcolemma that function in the repair of damaged muscle tissue.
myosatellite cells
The opening in the diaphysis through which blood vessels provide oxygen to osteons is named the ________ foramen
nutrient
During the process of ________, an existing tissue is replaced by bone.
ossification
Cells that secrete the organic components of the bone matrix are called
osteoblasts
_______ are stem cells that develop into osteoblasts.
osteogenic cells
The structural units of mature compact bone are called
osteons
Blood is distributed from the surface of a bone to deeper central canals through channels known as
perforating canals
The advantage of having many nuclei in a skeletal muscle fiber is the ability to
produce large amounts of the muscle proteins needed for muscle contraction and produce enzymes
neuromuscular junction
region where a motor neuron comes into close contact with a skeletal muscle cell
Define endochondral ossification.
replacement of a cartilage model with bone
After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as
rigor mortis
The plasma membrane of skeletal muscle is called the
sarcolemma
The repeating contractile unit of a skeletal muscle fiber is the
sarcomere
The type of bone that is adapted to withstand stresses that arrive from many directions is ________ bone.
spongy
_______ bone does not contain capillaries, but receives nutrients through its canaliculi.
spongy
Aponeurosis
strong and broad sheet of tissue that acts as a tendon to broadly attach muscles to bone
Osteon
structural unit of compact bone
Oxygen debt
the amount of oxygen required after physical exercise to convert accumulated lactic acid to glucose
The large proximal projection on the femur is termed the
trochanter
The rapid rise and fall in force produced by a muscle fiber after a single action potential is a(n)
twitch
If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called
wave summation
What part of bone stores fat?
yellow bone marrow
Axial skeleton
•Bones of skull, thorax, and vertebral column •Form longitudinal axis of body
Appendicular skeleton
•Bones of the limbs and girdles that attach them to the axial skeleton