Bone and muscle test

Why are calcium ions necessary for skeletal muscle contraction?

A) Calcium ions trigger the binding of myosin heads to actin filaments.

A sarcomere is ________.

A) the contractile unit between two Z discs

Explain how the anatomy of compact bone differs from that of spongy bone.

Compact bone is composed of osteons (Haversian systems). Concentric rings of matrix, called lamellae, are situated around a central (Haversian) canal. The rings and central canal constitute an osteon, or Haversian system. Other canals, called canaliculi, spread outward from central canals to connect to lacunae which house osteocytes. Spongy bone is open, airy, and spiky. It is composed of small, needlelike pieces of bone. Spongy bone lacks osteons and the network of canals visible in compact bone

The H zone, located within the A band, lacks thin filaments and is represented by ________.

D) Label D

What is the unstoppable electrical current that travels down the length of the entire surface of a sarcolemma?

D) action potential

Which movement is opposite to abduction?

D) adduction

Each complex of central canal and matrix rings in compact bone is known as ________.

D) an osteon (Haversian system)

What type of tissue covers the epiphysis of bones and reduces friction in the joints?

D) articular cartilage

The heads of the myosin myofilaments are called ________ when they link the thick and thin filaments together during skeletal muscle contraction.

D) cross bridges

The large hole located in the base of the occipital bone that allows the spinal cord and brain to connect is the ________.

D) foramen magnum

An incomplete bone break, known as a(n) ________ fracture, is commonly seen in children.

D) greenstick

A bone fracture that results in the bone being broken into many fragments is a ________.

E) comminuted fracture

The elbow is classified as a ________.

E) hinge joint

What kind of tissue is the forerunner of long bones in the embryo?

E) hyaline cartilage

The endomysium that wraps individual muscle fibers is indicated by ________.

b

The perimysium wraps a fascicle of muscle cells and is represented by ________.

c

The muscle fiber (cell) is indicated by ________.

d

What is the main function of the quadriceps group?

C) knee extension

The femur, tibia, humerus, and radius are all classified as ________.

C) long bones

Which of these muscles is the prime mover of elbow extension?

C) triceps brachii

Which two bones constitute the forearm?

C) ulna and radius

The area that causes the lengthwise growth of a long bone is indicated by ________.

D) Label E

The patella is indicated by ________.

D) Label I

The mandible is indicated by ________.

D) Label N

What type of bone cell is primarily active when bone growth occurs?

D) osteoblast

The arrangement of bone tissue shown in Figure 5.3 consists of ________.

D) osteons (Haversian systems)

Which muscle helps compress the abdominal contents during defecation or childbirth?

D) rectus abdominis

Which term does NOT describe smooth muscle cells?

D) skeletal

In adults, the function of the yellow marrow is to ________.

D) store adipose tissue

What bones protect the spinal cord?

D) vertebrae

Which of the following could create an open, or compound, fracture?

D) when the broken bone penetrates through the skin

Which muscle group includes the biceps femoris, semimembranosus, and semitendinosus?

B) hamstring group

The process of bone formation is known as ________.

B) ossification

Which of the following is NOT a function of the skeletal system?

B) regulation of blood pressure

What organelle wraps and surrounds the myofibril and stores calcium?

B) sarcoplasmic reticulum

List and explain the steps in the repair process of a simple fracture.

Step 1 is hematoma formation. A hematoma, or blood-filled swelling, forms when bone breaks and blood vessels rupture. Bone cells are deprived of nutrition and die. Step 2 is fibrocartilage callus formation. The site of damage experiences growth of new capillaries into the clotted blood and disposal of dead tissue by phagocytes. Connective tissue cells of various types form a mass of repair tissue called fibrocartilage callus. This fibrocartilage callus contains several elements: some cartilage matrix, some bony matrix, and collagen fibers. This fibrocartilage callus acts to splint the broken bone, closing the gap. Step 3 is bony callus formation. As more osteoblasts and osteoclasts migrate into the area and multiply, fibrocartilage is gradually replaced by a callus of spongy bone (the bony callus). Step 4 is bone remodeling. Over the next few months, bony callus is remodeled in response to the mechanical stresses placed on it, so that it forms a strong, permanent patch at the fracture site.

The I band within a skeletal muscle fiber is indicated by ________.

B) Label B

The diaphysis is indicated by ________.

B) Label C

The myofilament composed of actin is indicated by ________.

C) Label C

The area that contains glassy hyaline cartilage that provides a smooth slippery surface which decreases friction is indicated by ________.

C) Label D

The carpals are indicated by ________.

C) Label T

The canal that runs through the core of each osteon (Haversian system) contains ________.

C) blood vessels and nerve fibers

The presence of an epiphyseal plate indicates that ________.

C) bone length is increasing

Discuss the role of the myosin heads in sliding filament theory.

of the myofilaments and causes a muscle cell contraction. 72) The myosin heads attach to binding sites on the actin filaments to form cross bridges and to begin the process of sliding. The myosin heads swivel toward the center of the sarcomere, attaching and detaching several times which generates tension that helps pull the thin filaments toward the center of the sarcomere. This "walking" of the myosin heads along the thin filaments allows the thin filaments to slide past the thick filaments. As a result, the Z discs are pulled closer together. Since this event occurs simultaneously in sarcomeres throughout the cell, the muscle cell shortens.

Discuss the importance of calcium ions in skeletal muscle contraction.

shortens. 73) Calcium ions are necessary for myosin heads to attach to binding sites on actin filaments. As the action potential travels into the muscle cell, it stimulates the sarcoplasmic reticulum surrounding each myofibril to release its stored calcium ions into the sarcoplasm. The calcium ions trigger the binding of myosin heads to actin filaments and the initiation of the sliding of filaments. 14

Explain the five functions of the skeletal system.

1. SupportNthe skeletal system forms the body's internal structural framework. The bones of the legs act as pillars to support the body trunk when we stand, and the rib cage supports the thoracic wall. 2. MovementNthe skeletal muscles, attached to bones by tendons, use the bones as levers to move the body and its parts. 3. ProtectionNbones, such as the skull, thorax, and pelvis, protect the enclosed soft body organs. 4. StorageNfat is stored in the internal cavities of bones. Bones also serve as a storehouse for minerals, the most important being calcium and phosphorus. 5. Blood cell formation-hematopoiesis occurs within the red marrow of certain bones.

The A band within a myofibril is indicated by ________.

A) Label A

The epimysium is represented by ________.

A) Label A

The parietal bone is indicated by ________.

A) Label A

The area that serves as a storage area for fat in adults is indicated by ________.

A) Label H

The manubrium and xiphoid process fuse to form the bone indicated by ________.

A) Label O

The fibula is indicated by ________.

A) Label W

According to the sliding filament theory, how does muscle contraction occur?

A) Myosin heads form cross bridges and pull thin filaments, causing them to slide.

What is released by axon terminals into the synaptic cleft to stimulate a muscle to contract?

A) acetylcholine

Striated involuntary muscle tissue is classified as ________ muscle.

A) cardiac

Striated involuntary muscle tissue found in the heart is ________.

A) cardiac muscle

A fracture that is common in osteoporotic bones is a(n) ________.

A) compression fracture

Which of the following consists of two large, flat muscles that cover the lower back?

A) latissimus dorsi

The sternum is the result of fusion of three bones called the ________.

A) manubrium, body, xiphoid process

51) The plasma membrane of a skeletal muscle cell is called the ________.

A) sarcolemma

Describe the events that occur from the time that a motor neuron releases acetylcholine at the neuromuscular junction until muscle cell contraction occurs.

Acetylcholine (ACh) is released from the axon terminals of a motor neuron, which diffuses across the synaptic cleft and attaches to receptors in the sarcolemma. ACh binds and opens channels that allow the simultaneous passage of sodium ions into the muscle fiber and potassium ions out of the muscle fiber. Since more sodium ions enter the muscle fiber than potassium ions leave, a local area of depolarization develops. As more channels that only allow sodium entry open, an action potential is initiated and sweeps over the entire sarcolemma. Calcium ions are released from storage areas inside the sarcoplasmic reticulum of the muscle cell. They attach to the myofilaments, which triggers the sliding of the myofilaments and causes a muscle cell contraction.

You have lost the labels to your muscle tissue slides in laboratory. Explain the characteristics that allow you to distinguish among skeletal muscle, smooth muscle, and cardiac muscle tissue.

Although cells in both skeletal muscle tissue and cardiac muscle tissue are striated, look for intercalated discs and branched cells in the cardiac muscle cells to distinguish between these two tissues. Furthermore, skeletal muscle cells are multinucleate while cardiac muscle cells are uninucleate. Cells in smooth muscle tissue lack striations, making it easy to distinguish from skeletal and cardiac muscle tissues. Like the cells in cardiac muscle tissue, smooth muscle cells are uninucleate. However, smooth muscle tissue cells do not branch nor do they possess intercalated discs.

What condition results if muscles are not used, such as when immobilized in a cast for healing a broken bone?

B) atrophy

Small canals that connect osteocytes in their lacunae to the central canal are known as ________.

B) canaliculi

Which muscle forms the curved calf of the posterior leg?

B) gastrocnemius

The physician knew her patient was most likely a child before she walked into the examination room because the X-ray revealed a(n) ________.

B) greenstick fracture

Which of these events must occur first to trigger the skeletal muscle to generate an action potential and contract?

E) Acetylcholine (ACh) binds to receptors on the sarcolemma and allows passage of sodium ions into the cell.

The proximal epiphysis is represented by ________.

E) Label B

The periosteum, a connective tissue covering on the diaphysis, is represented by ________.

E) Label F

The radius bone is indicated by ________.

E) Label Q

Which method of regenerating ATP during muscle contraction can produce lactic acid?

E) anaerobic glycolysis

What must rush into a muscle cell to promote its depolarization?

E) sodium ions

Plane, hinge, and pivot joints are examples of ________.

E) synovial joints