Chapter 46: Skeletal, Muscular, and the Integument 46-1 The Human Body Plan 46-2 Skeletal System 46-3 Muscular System 46-4 Integumentary System
46-1 The Human Body Plan I. Body Tissues (FOUR types) • (1) Muscle, (2) Nervous, (3) Epithelial, (4) Connective
(A) Muscle Tissue (THREE types) • CONTRACTILE tissue regulated by voluntary AND involuntary control.
(1) Skeletal Muscle (VOLUNTARY muscle, striated) • Movement of BONES in trunk, limbs, and facial muscles.
(2) Smooth Muscle (INVOLUNTARY muscle tissue, spindle-shaped) • Regulates movement of FOOD material through gastrointestinal tract.
(3) Cardiac Muscle (INVOLUNTARY muscle tissue, striated) • Regulates BLOOD FLOW through heart, systemic, AND pulmonary loops.
(B) Nervous Tissue • Neurons COMMUNICATE between glands, organs, muscles and BRAIN.
(1) Neurons • Receive AND transmit ELECTROCHEMICAL messages to ORGANS, MUSCLES, and other NEURONS.
(C) Epithelial Tissue • LAYER(S) of cells LINE or COVER all internal and external SURFACES.
Critical Thinking (1)Why are third-degree burns, which destroy the epidermis AND dermis of the skin, often fatal if covering large regions of the body?
Critical Thinking (2)Oil glands secrete an oily substance that helps keep the skin soft and flexible. They ALSO secrete fatty acids, which help KILL bacteria. How might their function be affected if you wash your skin TOO frequently?
(D) Connective Tissue (i.e., bone, cartilage, tendons, fat, blood, lymph) • Binds, SUPPORTS, and protects structures in body.
(1) Matrix (solid (bone), semisolid (fat), or liquid (blood)) • Intercellular SUBSTANCE that SURROUNDS connective tissue.
II. Organs and Organ Systems • Organs RARELY work alone; RATHER, organs interact in organ SYSTEMS, regulated by NERVOUS system. Ex: Skeletal, Muscular, Integumentary, Cardiovascular, Respiratory, Immune, Digestive, Excretory, Nervous, Endocrine, and Reproductive.
(A) Integration of Organ Systems • Organ tissues are interconnected; for example, STOMACH below.
III. Body Cavities (FOUR main HUMAN cavities) • Cavities PROTECT organs from injuries and from WEAR and TEAR of movement. (1) Cranial Cavity • Encases BRAIN and CRANIAL NERVES. (2) Spinal Cavity • Extends from FORAMEN to base of spine SPINAL CORD. (3) Thoracic Cavity • Contains HEART, ESOPHAGUS, and RESPIRATORY organs. (4) Abdominal Cavity • Contains DIGESTIVE, REPRODUCTIVE, and EXCRETORY organs.
46-2 Skeletal System I. The Skeleton (206 bones, TWO parts) • SUPPORT and PROTECTION, store MINERALS (Ca, P), and site of RBC (and some WBC) synthesis.
Critical Thinking (3)What may be an advantage of a cartilaginous skeleton during PRENATAL development?
(1) Axial Skeleton • Bones of SKULL, RIBS, SPINE, and STERNUM.
(2) Appendicular Skeleton • Bones of ARMS and LEGS, AND scapula, clavicle, pelvis.
II. Bone Structure • Bone is MOIST, living tissue LESS than 20% of body’s MASS. (1) Periosteum • Tough, vascular membrane on BONE SURFACE ~ supplies nutrients and nerve signals to BONE CELLS.
(2) Compact Bone (UNDER the periosteum) • THICK layer enables bones to endure large amounts of PHYSICAL stress.
(3) Haversian Canals (narrow CHANNELS in bone) • Allow room for BLOOD VESSELS to circulate through living bone tissue.
(4) Osteocytes (LIVING bone cells) • Embedded in gaps surrounding Haversian canals (TWO TYPES OF CELLS).
(5) Spongy Bone (INSIDE compact bone) • Arranged along points of PRESSURE or stress, making bones both LIGHT and STRONG.
(6) Bone Marrow (soft tissue, RED or YELLOW) • Blood cell synthesis (RED); FAT as NRG reserve and can be CONVERTED to RED if blood loss occurs (YELLOW).
(A) Injury and Repair (osteoclasts AND osteoblasts) • If CIRCULATION is maintained and PERIOSTEUM survives, healing will occur to DAMAGED bones.
(1) Fracture • A CRACK in BONE due to sudden blunt force.
III. Bone Development • Osteocytes RELEASE minerals into spaces BETWEEN cartilage cells, turning CARTILAGE to BONE.
(1) Ossification • Cartilage slowly HARDENS into BONE due to deposition of MINERALS. • (NOTE: Some cartilage REMAINS, lending flexibility to areas between bones, at the nose, ears, and areas inside the trachea).