Chapter 1

Anatomy

• Anatomy is the study of structure and shape of the body and its parts
• Observation is used to determine sizes and relationships of parts
• Gross anatomy studies large structures that are easily observable
• Microscopic anatomy studies structures too small to be seen with the naked eye, like cells and tissues

Physiology

• Physiology is the study of how the body and its parts work or function
• Structure directly relates to function
• Examples are the air sacs in the lungs, which have thin walls allowing for gas exchange

Principle of Complementarity

• Function always reflects structure
• What a structure can do is dependent on its form

Levels of Structural Organization

• Six levels of structural organization
• Atoms
• Cells
• Tissues
• Organs
• Organ systems
• Organisms

Structural Units

• Atoms/Chemical: Made up of atoms, molecules, and organelles
• Cells: Smallest units of life, perform all life activities including metabolism, assimilation, digestion, excretion, and reproduction. Cells have common functions, but vary in shape and size
• Tissues: Groups of cells with common function, every organ comprised of multiple tissue types
  • Epithelial - covers and protects
  • Connective - binds and supports other tissues
  • Muscle - movement and heat production
  • Nervous - connects sensory structures to motor structures; found only in nervous systems

Structural Units (continued)

• Organs: Cells are integrated into tissues, serve a common function; complex functions.
• Systems: Made up of organs to meet the needs of the body.
• Human Body: The highest level of organization.

Organ System Overview

• Integumentary: Forms external body covering (skin), includes hair and fingernails, waterproofs and protects, produces Vitamin D, helps regulate temperature, contains nerve receptors
• Skeletal: Consists of bones, cartilages, ligaments, and joints; provides muscle attachment, protects vital organs, site of blood cell formation, stores minerals
• Muscular: Skeletal muscles contract. Produces movement of bones, smooth muscles and cardiac muscles
• Nervous: Fast acting control system, consists of brain, spinal cord, nerves, and sensory receptors; responds to internal and external stimuli, sends messages to the central nervous system which assesses information and activates effectors.

Organ System Overview (continued)

• Endocrine: Secretes chemical molecules (hormones) into the blood, works with the nervous system; functions include growth, reproduction, use of nutrients
  • Includes specific glands: pituitary, thyroid, parathyroids, adrenal, thymus, pancreas, pineal, ovaries (females), testes (males)
• Cardiovascular: Includes heart and blood vessels, heart pumps blood, vessels transport blood to tissues, blood transports oxygen, carbon dioxide, nutrients, hormones, contains white blood cells for protection.

Organ System Overview (continued)

• Lymphatic: Includes lymphatic vessels, lymph nodes, and lymphoid organs; complements cardiovascular system by returning leaked fluids to the bloodstream; lymph nodes cleanse blood; houses white blood cells for immunity.
• Respiratory: Includes nasal passages, pharynx, larynx, trachea, bronchi, and lungs; gases are exchanged with blood through air sacs; supplies body with oxygen and removes carbon dioxide.
• Digestive: Includes oral cavity, esophagus, stomach, small and large intestines, rectum, and accessory organs; breaks down food, allows for nutrient absorption, eliminates indigestible material as feces.

Organ System Overview (continued)

• Urinary: Includes kidneys, ureters, urinary bladder, and urethra; eliminates nitrogenous wastes, maintains acid-base balance, regulates water and electrolyte balance, helps regulate blood pressure.
• Reproductive: For males includes testes, scrotum, penis, accessory glands, and duct system; testes produce sperm, duct system carries sperm to exterior; For females includes ovaries, uterine tubes, uterus, and vagina; ovaries produce eggs, uterus provides site of development for fetus.

Maintaining Life: Necessary Life Functions

• Maintaining boundaries: Boundaries separate the "inside" from the "outside"
• Movement: Locomotion, movement of substances
• Responsiveness (irritability): Ability to sense changes and react
• Digestion: Breakdown and absorption of nutrients

Necessary Life Functions (continued)

• Metabolism: Chemical reactions within the body, breaks down complex molecules into smaller ones, builds larger molecules from smaller ones, produces energy (ATP); regulated by hormones
• Excretion: Eliminates waste from metabolic reactions; wastes can be removed in urine, feces, or sweat
• Reproduction: Occurs on cellular or organismal levels. New cells are used for growth and repair, or the reproductive system handles the task on an organismal scale.
• Growth: Increases in cell size or body size, increasing the number of cells; hormones play a major role

Survival Needs

• Nutrients: Chemicals used for energy and cell building, include carbohydrates, proteins, lipids, vitamins and minerals
• Oxygen: Required for chemical reactions; made available by the respiratory and cardiovascular systems.
• Water: 60-80% of body weight, most abundant chemical; provides fluid base for secretions and excretions
• Normal body temperature: 37°C (98.6°F), below this chemical reactions slow down & stop; above body temp. chemical reactions proceed too rapidly
• Atmospheric pressure: Must be appropriate for gas exchange

The Language of Anatomy

• Uses special terminology to prevent misunderstandings, using exact terms for position, direction, regions and structures.
• Anatomical position is used for reference: standing erect, feet parallel, arms hanging at the sides, palms facing forward, thumbs pointing away from the body.

Directional Terms

• Superior (cranial/cephalic): Toward the head; above
• Inferior (caudal): Away from the head; below
• Anterior (ventral): Toward the front; in front of
• Posterior (dorsal): Toward the back; behind
• Medial: Toward the midline of the body; on the inner side of
• Lateral: Away from the midline of the body; on the outer side of
• Intermediate: between a more medial and a more lateral structure
• Proximal: Close to the origin of the body part, or the point of attachment of a limb to the body trunk
• Distal: Farther from the origin of a body part, or the point of attachment of a limb to the body trunk
• Superficial (external): Toward or at the body surface
• Deep (internal): Away from the body surface; more internal

Regional Terms

• Anterior (ventral) body landmarks: Specific anatomical references on the front of the body
• Posterior (dorsal) body landmarks: Specific anatomical references on the back of the body

Body Planes and Sections

• Dividing the body (or organ) for visualization of internal structures
• Sagittal: Divides body into left and right parts
  • Median (midsagittal): Divides body into equal left and right parts
• Frontal (coronal): Divides body into anterior and posterior parts
• Transverse (cross): Divides body into superior and inferior parts

Body Cavities

• Dorsal: Cranial (houses the brain) and spinal (houses the spinal cord)
• Ventral: Thoracic (superior to the diaphragm, contains heart and lungs), abdominopelvic (inferior to the diaphragm, contains organs). The abdominopelvic cavity has four quadrants:
• Right upper, right lower, left upper, left lower
• Abdominopelvic cavity has nine regions:
• Right hypochondriac, epigastric, left hypochondriac;
• Right lumbar, umbilical, left lumbar
• Right iliac (inguinal), hypogastric (pubic), left iliac (inguinal)

Body Cavities (continued)

• Other body cavities exist, including oral, digestive, nasal, orbital, and middle ear cavities.

Homeostasis

• Maintaining a relatively stable internal condition, a dynamic state of equilibrium necessary for normal body functioning
• Main controlling systems are nervous and endocrine systems
• Homeostatic imbalance results in disease

Maintaining Homeostasis

• Receptor responds to changes in the environment, sends information to control center along the afferent pathway
• Control center determines the set point, analyzes info, and determines an appropriate response
• Effector provides a means for the response to the stimulus; information flows from control center to effector along the efferent pathway

Feedback Mechanisms

• Negative feedback: Includes most homeostatic control mechanisms, shuts off the original stimulus or reduces its intensity, works like a household thermostat
• Positive feedback: Rare in the human body, increases the original stimulus to push the variable further, happens during blood clotting and childbirth.