unit 3 full

What is the primary function of skeletal muscle regarding the skeletal system?

It produces body movements by moving the skeleton.

How do skeletal muscles contribute to joint stability?

Muscle contractions maintain muscle tone to stabilize joints.

What is the role of postural muscles during wakefulness?

They contract continuously to maintain body positions.

Which muscular structures prevent the outflow of contents from hollow organs?

Sphincters.

Skeletal muscle contractions aid in the flow of lymph and the return of _____.

Venous blood

What is the term for the production of heat by muscular tissue?

Thermogenesis.

How does shivering contribute to thermogenesis?

It dramatically increases the rate of heat production.

As muscle tissue ages, the amount of connective tissue increases while the number of _____ decreases.

Muscle fibers

What is the primary physical result of aging on muscle tissue?

Loss of muscle mass.

Skeletal muscles produce movement by exerting force on _____.

Tendons

Concept: Muscle Origin

Definition: The attachment of a muscle tendon to the stationary bone (usually proximal).

Concept: Muscle Insertion

Definition: The attachment of a muscle tendon to the movable bone (usually distal).

In a lever system, what is the 'fulcrum'?

The fixed point around which a rigid structure moves.

In a lever system, what is defined as the 'effort'?

The applied force exerted by muscular contraction used to move a resistance.

In a lever system, what is defined as the 'load'?

The resistance that opposes movement.

What condition describes a lever operating at a mechanical advantage?

The load is closer to the fulcrum and the effort is farther from the fulcrum.

What condition describes a lever operating at a mechanical disadvantage?

The load is farther from the fulcrum and the effort is closer to the fulcrum.

How does a 'power lever' (mechanical advantage) affect effort and distance?

A small effort can move a large load over a small distance.

How does a 'speed lever' (mechanical disadvantage) affect effort and speed?

A large effort moves a small load at a greater speed.

Which class of lever places the fulcrum between the effort and the load?

First-class lever.

What is the anatomical example of a first-class lever system?

The atlanto-occipital joint (raising the head).

Which class of lever places the load between the effort and the fulcrum?

Second-class lever.

What is the anatomical example of a second-class lever system?

Standing up on the toes (ball of the foot).

Which class of lever places the effort between the fulcrum and the load?

Third-class lever.

What is the anatomical example of a third-class lever system?

The elbow joint (flexing to pick up a glass).

Which lever class is the most common in the human body?

Third-class lever.

How are muscle fibers arranged within a single fascicle?

They are parallel to one another.

What is the fascicle arrangement of the sartorius muscle?

Parallel.

What is the fascicle arrangement of the biceps brachii?

Fusiform.

What is the fascicle arrangement of the orbicularis oculi?

Circular.

What is the fascicle arrangement of the pectoralis major?

Triangular.

What is the fascicle arrangement of the rectus femoris?

Bipennate.

What is the fascicle arrangement of the deltoid muscle?

Multipennate.

Term: Agonist (Prime Mover)

Definition: The leader muscle that contracts to cause a specific action.

Term: Antagonist

Definition: The muscle that stretches and yields to the effects of the prime mover.

Term: Synergist

Definition: A muscle that aids the movement of the prime mover.

Term: Fixator

Definition: A muscle that stabilizes the origin of the prime mover.

How many bones make up the adult human skeleton?

Approximately 206.

The axial skeleton consists of how many bones?

80 bones.

The appendicular skeleton consists of how many bones?

126 bones.

What tissue produces all blood cells (hematopoiesis)?

Red bone marrow (reticular connective tissue).

What type of storage occurs in yellow bone marrow?

Triglyceride storage (adipose connective tissue).

What percentage of bone matrix is organic (collagen, cells, etc.)?

35%

What percentage of bone matrix is inorganic (mineral salts like calcium phosphate)?

65%

Identify the five types of bones based on shape.

Long, short, flat, irregular, and sesamoid.

Term: Diaphysis

Definition: The shaft or long main portion of a long bone.

Term: Epiphyses

Definition: The distal and proximal ends of a long bone.

Term: Metaphyses

Definition: The regions in a mature bone where the diaphysis joins the epiphyses.

What is the name of the membrane lining the medullary cavity?

Endosteum.

Term: Foramen

Definition: A round or oval opening through a bone for the passage of vessels and nerves.

Term: Fossa

Definition: A shallow, basin-like depression in a bone, often serving as an articular surface.

Term: Condyle

Definition: A large, round protuberance with a smooth articular surface at the end of a bone.

Term: Tuberosity

Definition: A large, rounded, usually roughened projection for muscle attachment.

Term: Trochanter

Definition: A very large, blunt, irregularly shaped process found only on the femur.

Which bone cells are considered bone stem cells?

Osteoprogenitor cells.

Which bone cells secrete organic extracellular matrix (osteoid)?

Osteoblasts.

Which bone cells maintain bone tissue and are 'trapped' in the matrix?

Osteocytes.

Which bone cells function in bone resorption (breakdown of matrix)?

Osteoclasts.

What are the structural and functional units of compact bone?

Osteons (Haversian systems).

Which structures in compact bone contain the cell bodies of osteocytes?

Lacunae.

Which tiny channels contain the processes of osteocytes and connect lacunae?

Canaliculi.

Which canals connect blood vessels of the periosteum to the central canals of osteons?

Perforating (Sharpey's or Volkmann's) canals.

Spongy bone tissue is composed of a latticework of thin columns called _____.

Trabeculae

In spongy bone, where do osteocytes receive their nutrients?

From capillaries in the endosteum surrounding the trabeculae.

Growth in the length of a long bone is called _____ growth.

Interstitial

Growth in the thickness (diameter) of a bone is called _____ growth.

Appositional

Identify the four zones of the epiphyseal plate from the epiphysis to the diaphysis.

1. Resting cartilage, 2. Proliferating cartilage, 3. Hypertrophic cartilage, 4. Calcified cartilage.

In which zone of the epiphyseal plate do chondrocytes divide and secrete ECM?

Zone of proliferating cartilage.

In which zone of the epiphyseal plate do osteoclasts dissolve calcified chondrocytes so osteoblasts can lay down bone?

Zone of calcified cartilage.

In appositional growth, which cells deposit new bone on the outer surface?

Osteoblasts.

In appositional growth, which cells destroy bone tissue lining the medullary cavity?

Osteoclasts.

What two processes are involved in bone remodeling?

Bone resorption and bone deposition.

How does mechanical stress from exercise affect bone tissue?

It stimulates osteoblasts to increase mineral salt deposition and collagen fiber production.

What is the primary effect of aging on bone extracellular matrix?

Demineralization (loss of calcium and minerals).

Why does bone become more brittle with age?

The production of collagen fibers slows down.

Term: Articulation (Joint)

Definition: A point of contact between two bones, bone and cartilage, or bone and teeth.

What are the three structural classifications of joints?

Fibrous, cartilaginous, and synovial.

Term: Synarthrosis

Definition: An immovable joint.

Term: Amphiarthrosis

Definition: A slightly movable joint.

Term: Diarthrosis

Definition: A freely movable joint.

What type of connective tissue holds articulating bones together in a fibrous joint?

Dense irregular connective tissue.

A joint where articulating bones are connected by hyaline cartilage or fibrocartilage is a _____ joint.

Cartilaginous

What is the defining feature of a synovial joint?

The presence of a synovial (joint) cavity.

Identify the two layers of the articular capsule in a synovial joint.

An outer fibrous membrane and an inner synovial membrane.

What are the primary components of synovial fluid?

Hyaluronic acid and a filtrate of blood plasma (interstitial fluid).

What are the two types of accessory ligaments found in synovial joints?

Extracapsular and intracapsular ligaments.

Term: Articular Discs (Menisci)

Definition: Fibrocartilage structures that divide the synovial cavity into two smaller cavities.

What is the function of a labrum in a ball-and-socket joint?

It is a fibrocartilaginous lip that extends from the edge of the joint socket to deepen it.

What are bursae?

Sac-like structures filled with fluid that alleviate friction between skin, tendons, muscles, or ligaments and bone.

Which bones articulate to form the elbow joint?

The humerus (trochlea and capitulum), the ulna (trochlear notch), and the radius (head).

The hip joint is formed by the articulation of the head of the femur and the _____.

Acetabulum of the hip bone

Which type of joint is the knee joint structurally?

A hinge joint.

Which bones articulate to form the ankle joint?

The tibia and fibula (malleoli) and the talus.