Human Anatomy and Physiology: Somatotypes, Skeleton, and Muscular System

Comprehensive vocabulary flashcards covering human anatomy, including body types, skeletal structure, joint classifications, muscular roles, and the mechanics of muscle contraction.

Somatotype

A category of body type (Endomorph, Ectomorph, or Mesomorph) determined largely by genetics that may affect exercise suitability and physical shape.

Endomorph

A body type characterized by higher body fat, a tendency to gain weight relatively easily, and wider waist and hips.

Ectomorph

A body type characterized as thin and lean with a slender waist, narrow hips and shoulders, and difficulty gaining weight.

Mesomorph

A body type characterized by a higher muscle-to-fat ratio, a muscular physique, and the ability to build and maintain muscle relatively easily.

Skeletal System

A framework consisting of $206$ bones in the human body that provides support, shape, protection, movement, blood cell production, and mineral storage.

Red Marrow

Also known as myeloid tissue, it produces all red blood cells, $60–70$ percent of white cells, and all platelets.

Yellow Marrow

Marrow found in the central cavities of long bones in adults that stores fat tissue.

Osteoporosis

A condition associated with aging or mineral deficiency where bones become porous, thin, and brittle, increasing the risk of fractures.

Epiphysis

The expanded portion located at each end of a long bone.

Epiphyseal growth plate

The cartilaginous region within the metaphysis where growth in the length of a bone occurs.

Diaphysis

The shaft portion of a long bone.

Periosteum

A tough, fibrous fascial sheath that covers the entire bone.

Compact (Cortical) Bone

Bone tissue that is solid, strong, and resistant to bending.

Cancellous (Trabecular) Bone

Bone tissue that provides elastic strength to resist compression forces.

Ossification

The process of bone formation where existing connective tissues are replaced by bony structures.

Intramembranous Bones

Bones that originate between sheet-like layers of connective tissues.

Endochondral Bones

Bones that begin as masses of hyaline cartilage which are later replaced by bone tissue.

Synovial Joint

A freely movable joint containing a cavity with fluid secreted by a synovial membrane, surrounded by an articular capsule.

Fibrous Joint

An immovable joint where bones are held tightly together by fibrous connective tissue, such as sutures in the skull.

Cartilaginous Joint

A slightly movable joint where bones are connected by cartilage, such as intervertebral discs or the pubic symphysis.

Spinal Column

A structure divided into five regions: $7$ cervical, $12$ thoracic, $5$ lumbar, $5$ sacral (fused), and $4$ coccygeal (fused) vertebrae.

Intervertebral Discs

Thick fibrocartilaginous structures between vertebrae that absorb vertical shock and allow movement in the column.

Synovial Fluid

A substance that provides lubrication, nutrient distribution, and shock absorption within a joint cavity.

Ligaments

Tough, white, non-elastic fibrous tissues that connect bone to bone and enhance joint stability.

Tendons

Cord-like fibrous connective tissues that attach muscle to bone and transmit force produced by the muscle.

Hyaline (Articular) Cartilage

A tough, smooth, blue-white cartilage covering bone ends that reduces friction and absorbs shock.

Flexion

A movement that decreases the angle between the anterior surfaces of articulating bones (except for the knee and toes).

Abduction

Movement of a bone or limb away from the midline of the body.

Adduction

Movement of a bone or limb towards the midline of the body.

Supination

A movement of the forearm where the palm is turned anteriorly or superiorly.

Pronation

A movement of the forearm where the palm is turned posteriorly or inferiorly.

Skeletal Muscle

Striated, voluntary muscle tissue attached to bones that is consciously controlled.

Smooth Muscle

Non-striated, involuntary muscle tissue located in the walls of hollow internal structures like blood vessels and the stomach.

Cardiac Muscle

Striated, involuntary muscle tissue that forms the walls of the heart to pump blood.

Agonist

Also known as the 'prime mover,' it is the muscle that contracts most to bring about a desired movement.

Antagonist

The muscle on the opposite side of a joint that decelerates, stops, and reverses a movement initiated by the agonist.

Synergist

Muscles that assist the agonist in performing a desired movement.

Relaxin

A hormone produced during pregnancy that softens pelvic structures to prepare and widen the birth canal.

Sliding Filament Theory

A description of muscle contraction where myosin cross-bridges pull actin filaments toward the center of the sarcomere.

Myofibrils

Thread-like structures within a muscle fiber that contain smaller contractile myofilaments called actin and myosin.

Sarcomere

The functional unit of a myofibril where the shortening and contraction process occurs.

Myosin

Thick contractile protein filaments shaped like two twisted golf clubs.

Actin

Thin contractile protein filaments that resemble two pearl necklaces wound around each other.