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