Introduction to the Human Body

Overview of Anatomy and Physiology
Anatomy: scientific study of the body's structures Physiology: scientific study of the chemistry and physics of the strucutres of the body and the ways in which they work together to support the functions of life
 * Gross anatomy (macroscopic anatomy): study of the larger structures of the body, those visible without the aid of magnification
 * Microscopic anatomy: study of structures that can be observed only with the use of a microscope or other magnification devices
 * Regional anatomy: study of the interrelationships of all the structures in a specific body region
 * Systemic anatomy: study of the structures that make up a discrete body system

Homeostasis: state of steady internal conditions maintained by living things

Structural Organization of the Human Body
Cell: smallest independently functioning unit of a living organism Tissue: group of many similar cells that work together to perform a specific function
 * Cytoplasm: water-based cellular fluid
 * Organelle: variety of tiny functioning units within a cell

Organ: anatomically distinct structure of the body composed of two or more tissue types

Organ system: group of organs that work together to perform major functions or meet physiological needs of the body Organism: living being that has a cellular structure and that can independently perform all physiologic functions necessary for life
 * Integumentary system:
 * encloses internal body structures
 * sites of many sensory receptors
 * Skeletal system:
 * supports the body
 * enables movement (with muscular system)
 * Muscular system:
 * enables movement (with skeletal system)
 * helps maintain body temperature
 * Nervous system:
 * detects and processes sensory information
 * activates bodily responses
 * Endocrine system:
 * ​​​​​​​secretes hormones
 * regulates bodily processes
 * Cardiovascular system:
 * ​​​​​​​delivers oxygen and nutrients to tissues
 * equalizes temperature in the body
 * Lymphatic system:
 * ​​​​​​​returns fluid to blood
 * defends against pathogens
 * Respiratory system:
 * ​​​​​​​removes carbon dioxide from the body
 * delivers oxygen to blood
 * Digestive system:
 * ​​​​​​​processes food for use by the body
 * removes wastes from undigested food
 * Urinary system:
 * ​​​​​​​controls water balance in the body
 * removes wastes from blood and excretes them
 * Male reproductive system:
 * produces sex hormones and gametes
 * delivers gametes to female
 * Female reproductive system:
 * ​​​​​​​produces sex hormones and gametes
 * supports embryo/fetus until birth
 * produces milk for infant

Functions of Human Life
Metabolism: sum of all anabolic and catabolic reactions that take place in the body Responsiveness: ability of an organism to adjust to changes in its internal and external environments
 * Anabolism: process whereby smaller, simpler molecules are combined into larger, more complex substances
 * utilizes energy
 * Catabolism: process by which larger, more complex substances are broken down into smaller, simpler molcules
 * releases energy
 * Adenosine triphosphate (ATP): chemical compound used to store and release energy

Development: all of the changes the body goes through in life Growth: increase in body size
 * Differentiation: unspecialized cells become specialized in structure and function to perform certain tasks in the body

Reproduction: formation of a new organism from parent organisms

Requirements for Human Life
Oxygen Nutrient: substance in foods and beverages that is essential to human survival Temperature Pressure: force exerted by a substance that is in contact with another substance
 * brain cells are especially sensitive to lack of oxygen due to their requirement for a high and steady production of ATP
 * brain damage likely within 5 minutes without oxygen
 * death likely within 10 minutes
 * Water
 * ​​​​​​​can only survive a few days without water
 * makes up 70% of an adult's body mass
 * helps regulate internal temperature and cushions, protects, and lubricates joints and other body structures
 * Macronutrients
 * ​​​​​​​energy-yielding nutrients are primarily carbohydrates and lipids
 * proteins mainly supply the amino acids
 * can survive without energy-yielding nutrients for several weeks
 * Micronutrients
 * ​​​​​​​vitamins and minerals
 * some can be stored, thus can survive without them for a few days or weeks
 * other cannot be stored, so they must be consumed every day or two
 * chemical reactions in the body can only take place just above/below 37 degrees Celsius
 * sweating is body's response to heat
 * adequate water intake required when sweating
 * less effective in humid environments since sweat cannot evaporate
 * shivering is body's response to cold
 * increased breakdown of stored energy
 * when energy reserve is depleted, core temperature significantly drops and RBC's lose ability to give up oxygen
 * causes confusion, lethargy, loss of consciousness, death
 * body reduces blood flow to extremities
 * can lead to frostbite and gangrene
 * altitude sickness results from less pressure at high altitudes, reducing exchange of gases
 * causes dyspnea, confusion, headache, lethargy, and nausea

Homeostasis
Set point: physiological value around which the normal range fluctuates

Normal range: restricted set of values that is optimally healthful and stable

Negative feedback: mechanism that reverses a deviation from the set point Positive feedback: mechanism that intensifies a change in the body's physiological condition rather than reversing it
 * Sensor (receptor): component of a feedback system that monitors a physiological value
 * Control center: component in a feedback system that compares the value to the normal range
 * Effector: component in a feedback system that causes a change to reverse the situation and return the value to the normal range
 * examples include blood glucose and sweating
 * example includes childbirth and penetrating wounds

Anatomical Terminology
Anatomical position: body standing upright with the feet at shoulder width and parallel, toes forward; upper limbs are held out to each side, and the palms of the hands face forward

Prone: face-down orientation

Supine: face-up orientation

Directional terms Body planes Body cavities Abdominal regions Abdominal quadrants Membranes
 * Anterior (ventral): front or direction toward the front of the body
 * Posterior (dorsal): back or direction toward the back of the body
 * Superior (cranial): above or higher than another part of the body
 * Inferior (caudal): below or lower than another part of the body
 * Lateral: direction toward the side of the body
 * Medial: direction toward the middle of the body
 * Proximal: position on a limb that is nearer to the point of attachment or the trunk of the body
 * Distal: position on a limb that is further from the point of attachment or the trunk of the body
 * Superficial: closer to the surface of the body
 * Deep: farther from the surface of the body
 * Sagittal plane: plane that divides the body or an organ vertically into right and left sides
 * Midsagittal (median) plane: plane that runs directly down the middle of the body
 * Parasagittal (longitudinal) plane: plane that divides the body into unequal left and right sides
 * Frontal (coronal) plane: plane that divides the body or an organ into a front and rear portion
 * Transverse plane (cross section): plane that divides the body or an organ horizontally into upper and lower portions
 * Dorsal (posterior) cavity: contains the brain and spinal cord
 * ​​​​​​​Cranial cavity: contains the brain
 * Vertebral (spinal) cavity: contains the spinal cord
 * Ventral (anterior) cavity: abdominal and thoracic cavities
 * ​​​​​​​Thoracic cavity: superior subdivision
 * ​​​​​​​Superior mediastinum
 * Pleural cavity
 * Pericardial cavity
 * Abdominal cavity: abdomen
 * Pelvic cavity: most inferior part of the abdomen
 * Serous membrane: one of the thin membranes that cover the walls and organs in the thoracic and abdominopelvic cavities
 * Parietal layer: lines the walls of the body cavity
 * Visceral layer: lines the organs
 * Pleura: serous membrane surrounding the lungs
 * Pericardium: serous membrane surrounding the heart
 * Peritoneum: serous membrane surrounding organs of the abdominopelvic cavity

Medical imaging
X-ray: form of high energy EM radiation with a short wavelength capable of penetrating solids and ionizing gases Computed tomography (CT): noninvasive imaging technique that uses computers to analyze several cross-sectional X-rays in order to reveal minute details about bodily structures Magnetic resonance imaging (MRI): noninvasive medical imaging technique based on a phenomenon of nuclear physics in which matter exposed to magnetic fields and radio wavees was found to emit radio signals Positron emission tomography (PET): medical imaging technique involving the use of radiopharmaceuticals Ultrasonography: imaging technique that uses the transmission of high-frequency sound waves into the body to generate an echo signal that is converted by a computer into a real-time image
 * best used to visualize hard structures
 * can damage cell and cause cancer
 * especially useful for soft tissue scans
 * exposes patients to a high dose of radiation
 * malignant tissue gives off different signals
 * higher costs, patient discomfort
 * can illustrate physiologic activity
 * least invasive of all techniques