Chapter 2 The Human Body in Health and Disease

● Anatomic Reference Systems ○ Used to describe the locations of the structural units of the body. ○ Anatomy and Physiology Defined ■ Anatomy = study of the structures of the body ■ Physiology = study of the functions of the structures of the body (physi → nature or physical) ■ Anatomic position → describes body standing in the standard position ● Standing up straight so that the body is erect and facing forward ● Holding the arms at the sides with hands turned so palms face toward the front ○ The Body Planes ■ Body planes → imaginary lines (vertical and horizontal) used to divide the body into sections for descriptive purposes. ■ Vertical plane = up and down plane that is at a right angle to the horizon. ■ Sagittal plane = vertical plane that divides the body into unequal left and right portions. ■ Midsagittal plane (midline) = sagittal plane that divides the body into equal left and right halves. ■ Frontal plane (coronal plane) = vertical plane that divides the body into anterior (front) and posterior (back) portions; located at right angles to the sagittal plane. ■ Horizontal plane = flat, crosswise plane, such as the horizon. ■ Transverse plane = horizontal plane that divides the body into superior (upper) and inferior (lower) portions; can be at the waist or at any other level across the body. ● Body Direction Terms ○ Ventral = front (belly side) of organ or body (ventr → belly side of body) ○ Dorsal = back of the organ or body (dors → back of the body) ○ Cephalic = toward the head (cephal → head) ○ Caudal = toward the feet (caud → tail or lower part of body) ○ Anterior = situated in the front (anter → front or before) ○ Posterior = situated in the back (post → back or toward the back) ○ Superior = uppermost, above, toward the head ○ Inferior = lowermost, below, toward the feet ○ Proximal = situated nearest the midline or beginning of a body structure ○ Distal = situated farthest from midline or beginning of a body structure ○ Medial = the direction toward, or nearer, the midline ○ Lateral = the direction toward, or nearer, the side of the body, away from the midline ● Major Body Cavities ○ Dorsal Cavity → located along the back of the body and head, contains organs of the nervous system ■ Cranial cavity = located within the skull; surrounds and protects the brain. ■ Spinal cavity = located within the spinal column; surrounds and protects spinal cord. ○ Ventral Cavity → located along the front of the body, contains organs that sustain homeostasis → process through which the body maintains a constant internal environment (home/o → constant; -stasis → control) ■ Thoracic cavity (chest cavity or thorax) = surrounds and protects the heart and the lungs ● Diaphragm → muscle that separates the thoracic and abdominal cavities. ■ Abdominal cavity = contains major organs of digestion; referred to simply as the abdomen. ■ Pelvic cavity = space formed by the hip bones and contains the organs of the reproductive and excretory systems. ■ Abdominopelvic cavity = two cavities as a single unit (abdominal and pelvic) ■ Inguinal = relating to the groin; refers to the entire lower area of the abdomen ● Groin → crease at the junction of the trunk with the upper end of the thigh. ○ Regions of the Thorax and Abdomen ■ Right and left hypochondriac regions = covered by lower ribs (hypo- → below, chondr/i → cartilage); below the ribs. Also, hypochondriac describes a person with an abnormal concern about his/her health. ■ Epigastric region = located above the stomach (epi- → above) ■ Right and left lumbar region = located near the inward curve of the spine (lumb- → lower back); lumbar = part of the back between ribs and the pelvis ■ Umbilical region = surrounds the umbilicus (belly button/navel); navel marks the point where the umbilical cord was attached before birth ■ Right and left iliac region = located near the hip bones (ili- → hip bone) ■ Hypogastric region = located below the stomach ○ Quadrants of the Abdomen ■ Right upper quadrant (RUQ) ■ Left upper quadrant (LUQ) ■ Right lower quadrant (RLQ) ■ Left lower quadrant (LLQ) ○ The Peritoneum ■ Peritoneum = multilayered membrane that protects and holds organs in place within the abdominal cavity. ● Membrane → thin layer of tissue that covers a surface, lines a cavity, or divides a space or region. ■ Parietal peritoneum = outer layer of the peritoneum that lines the interior of the abdominal wall. ● Parietal → cavity wall ■ Mesentery = fused double layer of the parietal peritoneum that attaches parts of the intestine to the interior abdominal wall. ■ Visceral peritoneum = inner layer of the peritoneum that surrounds the organs of the abdominal cavity. ● Visceral → relating to the internal organs ■ Retroperitoneal = located behind the peritoneum (retro- → behind; periton → peritoneum) ■ Peritonitis = inflammation of the peritoneum ● Structures Of The Body ○ Cells → Tissues → Organs → Organ (Body) Systems ● Cells ○ Cells = basic structural and functional units of the body. ■ Cytology = study of the anatomy, physiology, pathology, and chemistry of the cell (cyt → cell) ■ Cytologist = specialist in the study and analysis of cells. ○ The Structure of Cells ■ Cell Membrane = tissue that surrounds and protects the contents of a cell from the external environment. ■ Cytoplasm = material within the cell membrane that is not part of the nucleus (-plasm → formative material of cells) ■ Nucleus = structure within the cell surrounded by a nuclear membrane; it controls activities of the cell, and helps the cell divide. ○ Stem Cells ■ Stem cells = unspecialized cells that are able to renew themselves for long periods of time by cell division; other types of cells have a specialized role and die after a determined life span. ● Under certain conditions, stem cells can be transformed into cells with special functions. ■ Adult stem cells (somatic stem cells) = undifferentiated cells found among differentiated cells in a tissue or organ; primary role is to maintain and repair the tissue in which they are found; undifferentiated → not having a specialized function/structure; differentiated → having a specialized function/structure. ● Graft-versus-host disease → when the stem cells do not match between the donor and recipient, and it rejects. ■ Embryonic stem cells = undifferentiated cells that are unlike any specific adult cell; however, they have the ability to form any adult cell (embry/o → fertilized ovum) ● These cells can grow rapidly indefinitely in a lab and could provide a source for adult muscle, liver, bone, or blood cells. ● These cell transplants do not require as perfect a match between the patient and donor. ● Comes from cord blood (umbilical cord) and placenta of newborn infant; can be harvested at the time of birth without danger to mother or baby; cells are kept frozen until needed for treatment purposes. ● Can also be obtained from surplus embryos produced by in vitro fertilization. ● Genetics ○ Gene = fundamental physical and functional unit of heredity. ○ Genetics = study of how genes are transferred from parents to their children and the role of genes in health and disease (gene- → producing) ○ Dominant and Recessive Gene ■ Dominant gene → if inherited from either parent, offspring will inherit that characteristic. ■ Recessive gene → if inherited from both parents, offspring will have that condition; if inherited from only one parent, and a normal gene from other parent, offspring will not have the condition. ○ The Human Genome ■ Genome = the complete set of genetic information of an organism. ○ Chromosomes ■ Chromosome = genetic structure located within the nucleus of each cell; made up of DNA molecules containing the body’s genes. ● Each individual has 46 chromosomes; 23 pairs of chromosomes ● Chromosome 23: female → XX ; male → XY ■ Somatic cell = any cell in body except gametes (sex cells) ■ Gamete (sex cell) = egg (ovum) or sperm; each has 23 single chromosomes ○ Genetic Disorders ■ Genetic disorder = pathological condition caused by an absent or defective gene. ■ Cystic fibrosis = present at birth and affects respiratory and digestive systems. ■ Down syndrome = genetic variation associated with a characteristic facial appearance, learning disabilities, developmental delays, and physical abnormalities such as heart valve disease. ■ Hemophilia = hereditary bleeding disorder where blood-clotting factor is missing; can have spontaneous hemorrhages or severe bleeding following an injury. ■ Huntington’s disease = passed from parent to child; causes nerve degeneration with symptoms that most appear in midlife (degeneration → worsening condition); eventually results in uncontrolled movements and loss of some mental abilities. ■ Muscular dystrophy = progressive weakness and degeneration of the skeletal muscles that control movement. ■ Phenylketonuria (PKU) = essential digestive enzyme phenylalanine hydroxylase is missing; can be detected by blood test performed on infants at birth; without treatment → causes severe intellectual disability ● Tissues ○ Tissue = group or layer of similarly specialized cells that join together to perform certain specific functions. ○ Histology = microscopic study of the structure, composition, and function of tissues (hist → tissue) ■ Histologist → non-physician specialist who studies the microscopic structure of tissue. ○ Epithelial Tissue ■ Epithelial tissue = forms a protective covering for all of the internal and external surfaces of the body; also form glands. ■ Epithelium = tissue that forms the epidermis of the skin and the surface layer of mucous membranes. ■ Endothelium = tissue that lines the blood and lymph vessels, body cavities, glands, and organs. ○ Connective Tissue ■ Connective tissue = support and connect organs and other body tissues; there are 4 types: ● Dense connective tissue = form the joints and framework of the body (ex: bone and cartilage) ● Adipose tissue (a.k.a. fat) = provides protective padding, insulation, and support (adip- → fat) ● Loose connective tissue = surrounds various organs and supports both nerve cells and blood vessels. ● Liquid connective tissue = blood and lymph; transport nutrients and waste products throughout the body. ○ Muscle Tissue = contains cells with the specialized ability to contract and relax. ○ Nerve Tissue = contains cells with the specialized ability to react to stimuli and to conduct electrical impulses. ○ Pathology of Tissue Formation ■ Incomplete Tissue Formation ● Aplasia = defective development, or congenital absence, of an organ or tissue (a- → without; -plasia → formation) ● Hypoplasia = incomplete development of an organ or tissue usually due to a deficiency in the number of cells (hypo- → deficient) ■ Abnormal Tissue Formation ● Anaplasia = change in the structure of cells and in their orientation to each other (ana- → backward); characteristic of tumor formation in cancers. ● Dysplasia = abnormal development or growth of cells, tissues, or organs (dys- → bad) ● Hyperplasia = enlargement of an organ/tissue because of an abnormal increase in the number of cells in the tissue (hyper- → excessive) ● Hypertrophy = general increase in the bulk of a body part or organ that is due to an increase in the size, but not in the number, of cells in the tissues (-trophy → development); enlargement is not due to tumor formation. ● Glands ○ Gland = group of specialized epithelial cells that are capable of producing secretions (substance produced by a gland); 2 types of glands: ■ Exocrine gland = secrete chemical substances into ducts that lead either to other organs or out of the body, such as sweat glands (exo- → out of; -crine → to secrete) ■ Endocrine gland = produce hormones, do not have ducts (endo- → within); secreted directly into bloodstream and are then transported to organs and structures throughout the body. ○ Pathology and Procedures of the Glands ■ Aden = a gland ■ Adenoids = mass of gland-like lymphoid tissue at the back of the upper pharynx. ■ Adenitis = inflammation of a gland ■ Adenocarcinoma = malignant tumor that originates in glandular tissue (carcin → cancerous; -oma → tumor) ● Malignant → harmful, capable of spreading and potentially life threatening ■ Adenoma = benign tumor that arises in or resembles glandular tissue ● Benign → not life threatening ■ Adenomalacia = abnormal softening of a gland ■ Adenosis = any disease or condition of a gland ■ Adenosclerosis = abnormal hardening of a gland ■ Adenectomy = surgical removal of a gland ● Body Systems And Related Organs ○ Organ = somewhat independent part of the body that performs a specific function. ● Pathology ○ Pathology = study of disease nature and causes as well as the produced changes in structure and function. ○ Pathologist = a physician who specializes in the laboratory analysis of diseased tissue samples to confirm or establish a diagnosis (path- → disease); these tissue specimens can be removed in biopsies, during operations, or in postmortem examinations. ○ Table 2.1 : Major Body Systems ■ Etiology = study of the causes of diseases (eti- → cause) ○ Disease Transmission ■ Pathogen = disease-producing microorganism such as a virus ● Transmission = spread of a disease ● Contamination = a pathogen is possibly present ■ Communicable disease (contagious disease) = any condition that is transmitted from one person to another either directly or by indirect contact with contaminated objects. ● Communicable = capable of being transmitted ■ Indirect contact transmission = situations in which a susceptible person is infected by contact with a contaminated surface.