Anatomy and Physiology: Joints, Organization, and Bone Structure

Vocabulary flashcards covering foundational concepts of joints, body organization, homeostasis, and bone structure from Chapters 1, 6, and 9.

Joints (articulations)

Locations where two bones meet and body movement occurs, presenting a dynamic tradeoff between strength and mobility.

Synarthrosis

An immovable joint category that includes sutures, gomphoses, synchondroses, and synostoses.

Amphiarthrosis

A slightly movable joint that is stronger than a diarthrosis and weaker than a synarthrosis; can be fibrous (syndesmosis) or cartilaginous (symphysis).

Diarthrosis

A freely movable joint classification, also known as a synovial joint.

Suture

A synarthrotic fibrous joint found only between the bones of the skull, where interlocking bone edges are bound by dense fibrous connective tissue.

Gomphosis

A synarthrotic fibrous joint that binds teeth to bony sockets in the maxillae and mandible via a periodontal ligament.

Syndesmosis

An amphiarthrotic fibrous joint where articulating bones are connected by a ligament.

Symphysis

An amphiarthrotic cartilaginous joint where articulating bones are joined by a pad of fibrocartilage.

Synovial fluid

A viscous fluid with the consistency of egg yolk containing proteoglycans, secreted by the synovial membrane for lubrication, nutrient distribution, and shock absorption.

Meniscus

A pad of fibrocartilage located between opposing bones within a synovial joint that cushions and stabilizes the joint.

Bursae

Small pockets of synovial fluid that cushion areas where tendons or ligaments rub against other tissues.

Flexion

An angular movement in the anterior-posterior plane that decreases the angle between articulating bones.

Extension

An angular movement in the anterior-posterior plane that increases the angle between articulating bones.

Hyperextension

Angular movement that extends a joint past its anatomical position.

Abduction

Angular movement away from the longitudinal axis of the body in the frontal plane.

Adduction

Angular movement toward the longitudinal axis of the body in the frontal plane.

Circumduction

A complex angular motion where the distal end of a bone moves in a circle while the proximal tip remains in position.

Pronation

Rotational movement of the forearm that rolls the radius across the ulna, resulting in the palm facing posteriorly.

Supination

Rotational movement of the forearm that turns the wrist and hand so the palm faces anteriorly.

Opposition

A special movement of the thumb toward the palm or pads of other fingers that enables grasping.

Plane joint

A nonaxial synovial joint with flattened or slightly curved surfaces that permits limited sliding or gliding movements.

Hinge joint

A monaxial synovial joint that permits angular movement in a single plane.

Condylar joint

A biaxial synovial joint featuring an oval articular face nestled within a depression on the opposing bone.

Saddle joint

A biaxial synovial joint with complex articular faces that fit together like a rider in a saddle, each face concave along one axis and convex along the other.

Pivot joint

A monaxial synovial joint that permits rotation only.

Ball-and-socket joint

A triaxial synovial joint where the round head of one bone rests within a cup-shaped depression in another, permitting angular motion, circumduction, and rotation.

Bulging disc

A condition in which the anulus fibrosus bulges laterally into the vertebral canal without complete rupture.

Herniated disc

A condition in which the nucleus pulposus breaks through the anulus fibrosus and compresses spinal nerves or the spinal cord.

Ligamenta flava

Intervertebral ligaments that connect the laminae of adjacent vertebrae.

Osteoarthritis

A non-inflammatory degenerative joint disease caused by wear and tear of joint surfaces or genetic factors affecting collagen formation, typically affecting individuals over age $60$.

Rheumatoid arthritis

An inflammatory autoimmune condition in which the immune system attacks joint tissues.

Gouty arthritis

A joint disease caused by the precipitation of uric acid crystals within the synovial fluid.

Anatomy

The study of internal and external body structures, including their composition, location, and physical relationships.

Physiology

The study of the functions of anatomical structures and how living organisms perform vital biological processes.

Cytology

The microscopic study of the structure and function of individual cells.

Histology

The microscopic study of tissues, which are groups of specialized cells that work together to perform specific functions.

Sign

An objective, measurable indication of a disease or medical condition, such as a fever.

Symptom

A subjective indication of a disease or physical state experienced by a patient, such as tiredness or pain.

Autoregulation

An intrinsic homeostatic response in a cell, tissue, or organ that adjusts automatically to an environmental change.

Extrinsic regulation

Homeostatic regulation controlled from the outside by the nervous or endocrine system to adjust activities across multiple organ systems.

Homeostasis

The physiological state of internal stability maintained by bodily systems responding to internal and external changes.

Receptor

A homeostatic sensor sensitive to a specific stimulus or environmental change.

Control center

The homeostatic integration center that receives and processes information from a receptor and sends commands to an effector.

Effector

A cell or organ that responds to commands from the control center to oppose or enhance a stimulus.

Negative feedback

A homeostatic control mechanism in which the response of the effector negates or opposes the original stimulus, maintaining variables within normal limits.

Positive feedback

A homeostatic control mechanism in which an initial stimulus produces a response that exaggerates or enhances the original change in conditions.

Viscera

The internal organs contained within the thoracic and abdominopelvic cavities.

Retroperitoneal space

The area posterior to the peritoneum and anterior to the muscular body wall containing the pancreas, kidneys, ureters, and parts of the digestive tract.

Sutural bones (Wormian bones)

Small, flat, irregularly shaped bones found between the flat bones of the skull.

Irregular bones

Bones with complex shapes featuring short, flat, notched, or ridged surfaces, such as vertebrae and pelvic bones.

Short bones

Boxlike bones with roughly equal dimensions, such as carpal and tarsal bones.

Flat bones

Thin bones with parallel surfaces that provide protection and extensive muscle attachment areas, such as the cranial roof, sternum, ribs, and scapulae.

Long bones

Relatively long and slender bones found in the limbs, palms, soles, fingers, and toes.

Sesamoid bones

Small, round, flat bones that develop inside tendons near joints of the knees, hands, and feet, such as the patellae.

Diploë

The layer of spongy bone sandwiched between two layers of compact bone in flat cranial bones.

Hydroxyapatite

The hard, insoluble matrix crystal formed by the reaction of calcium phosphate, $Ca_3(PO_4)_2$, and calcium hydroxide, $Ca(OH)_2$, given by the chemical formula $Ca_{10}(PO_4)_6(OH)_2$.

Osteogenic cells (osteoprogenitor cells)

Mesenchymal stem cells located in the endosteum and inner layer of the periosteum that divide to produce osteoblasts.

Osteoblasts

Immature bone cells that secrete organic osteoid matrix during osteogenesis.

Osteoid

The uncalcified organic matrix produced by osteoblasts prior to mineral deposition.

Osteocytes

Mature bone cells occupying lacunae that maintain the protein and mineral content of the bone matrix and assist in repair.

Osteoclasts

Large, multinucleate cells derived from monocyte/macrophage stem cells that secrete acids and protein-digesting enzymes to dissolve matrix during osteolysis.

Osteon

The basic structural and functional unit of mature compact bone, consisting of concentric lamellae surrounding a central canal.

Trabeculae

The strut and plate meshwork that forms the structural framework of spongy bone.

Periosteum

A two-layer membrane covering the outer surface of bones, composed of an outer fibrous layer and inner cellular layer.

Endosteum

An incomplete cellular layer lining the medullary cavity, trabeculae, and central canals, active in bone growth and remodeling.

Endochondral ossification

The process of bone development in which a hyaline cartilage model is replaced by bone tissue.

Epiphyseal closure

The event at puberty when epiphyseal cartilage production slows and osteoblast activity accelerates, closing the epiphyseal plate into an epiphyseal line.

Appositional growth

The increase in bone diameter accomplished by adding circumferential lamellae to the outer bone surface.

Intramembranous ossification (dermal ossification)

The direct formation of bone within mesenchyme or fibrous connective tissue, producing dermal bones such as the mandible and clavicles.

Parathyroid hormone (PTH)

A hormone produced by parathyroid glands that increases blood calcium ion levels by stimulating osteoclast activity, enhancing calcitriol secretion, and decreasing renal calcium excretion.

Calcitonin

A hormone secreted by thyroid C cells that lowers blood calcium ion levels by inhibiting osteoclasts and promoting calcium excretion by the kidneys.

Osteopenia

Inadequate ossification resulting in a non-pathological reduction in bone mass, typically starting between ages $30$ and $40$.

Osteoporosis

A severe reduction in bone mass that compromises normal function, affecting $29\%$ of women and $18\%$ of men over age $45$.