Medical Terminology PDF

Medical terminology Medical terminology Dr. Abla S. Abdel Aleem 1  Medical terminology Medical terminology Medical terminology is a special vocabulary used by healthcare professionals for effective and accurate communicatio...

Medical terminology Medical terminology Dr. Abla S. Abdel Aleem 1  Medical terminology Medical terminology Medical terminology is a special vocabulary used by healthcare professionals for effective and accurate communication. Every health related field requires an understanding of medical terminology, Word Parts Word components fall into three categories: 1. The root is the fundamental unit of each medical word. It establishes the basic meaning of the word. 2. A suffix is a short word part or series of parts added at the end of a root to modify its meaning. This book indicates suffixes by a dash before the suffix, such as itis (inflammation). 3. A prefix is a short word part added before a root to modify its meaning. This book indicates prefixes by a dash after the prefix, such as pre(before) The simple word learn can be used as a root to illustrate. If we add the suffix er to form learner, we have ―one who learns.‖ If we add the prefix re to form relearn, we have ―to learn again.‖ 2  Medical terminology Not all roots are complete words. In fact, most medical roots are derived from other languages and are meant to be used in combinations. The Greek word kardia, for example, meaning ―heart,‖gives us the root cardi. The Latin word pulmo, meaning ―lung,‖ gives us the root pulm. In a few instances, both the Greek and Latin roots are used for the same structure. We find both the Greek root nephr and the Latin root ren used in words pertaining to the kidney ROOT WHAT IT DESCRIBES EXAMPLE BLAST- germ, immature cell blastoma = a cancer made of immature cells CARCINO- cancer carcinogenic = cancer causing CARDIO- heart cardiotoxicity = toxicity to the heart CYTO- cell cytotoxic = toxic to the cell DERMA- skin dermatitis = inflammation of the skin HISTIO- tissue histology = study of tissue HEPATI- liver hepatoblastoma = liver cancer MALIGN- bad harmful malignant = growing, spreading NEPHRO- kidney nephrotoxic = harmful to the kidneys NEURO- nerves neuroblast = an immature nerve cell ONCO- mass tumor oncology = the study of cancer OSTEO- bone/bony tissue osteosarcoma = bone cancer PAED- child pediatric oncology = study of childhood cancer SARCO- tissue sarcoma = tumor of bone, muscle, or connective tissue TOXO- poison toxicology = study of poisons 3  Medical terminology A compound word contains more than one root. The words eyeball, bedpan, frostbite, and wheelchair are examples. Some examples of compound medical words are cardiovascular (pertaining to the heart and blood vessels), urogenital (pertaining to the urinary and reproductive systems), and lymphocyte(a white blood cell found in the lymphatic system). Combining Forms: When a suffix beginning with a consonant is added to a root, a vowel (usually an o) is inserted between the root and the suffix to aid in pronunciation. A combining vowel may be added between a root and a suffix. Thus, when the suffix –logy, meaning ―study of,‖ is added to the root neur, meaning ―nerve or nervous system,‖ a combining vowel is added: neur + o + logy = neurology (study of the nervous system) SUFFIX WHAT IT DESCRIBES EXAMPLE -AEMIA condition of blood leukemia = cancer of blood cells -ECTOMY excision / removal nephrectomy = excision of a kidney -ITIS inflammation hepatitis = inflammation of the liver -OLOGY study / science of cytology = the study of cells -OMA tumor retinoblastoma = tumor of the eye -PATHY disease neuropathy = disease of the nervous system 4  Medical terminology -OSIS disease /condition necrosis = dying cells Word Derivations As mentioned, most medical word parts come from Greek (G.) and Latin (L.). The original words and their meanings are included in this text only occasionally. However, they are interesting and may aid in learning. For example, muscle comes from a Latin word that means ―mouse‖ because the movement of a muscle under the skin was thought to resemble the scampering of a mouse. The coccyx, the tail end of the spine, is named for the cuckoo because it was thought to resemble the cuckoo’s bill.For those interested in the derivations of medical words, a good medical dictionary will provide this information When you add a suffix to a word ending in x, the x is changed to a g or a c. If there is a consonant before the x, such as yx or nx, the x is changed to a g. For example, pharynx (throat) becomes pharyngeal (fahRINjeal), ―pertaining to the throat‖; coccyx (terminal portion of the spine) becomes coccygeal (kokSIJeal), to mean ―pertaining to the coccyx.‖ If a vowel comes before the x, such as ax or ix, you change the x to a c. Thus, thorax (chest) becomes thoracic (thoRASik), to mean ―pertaining to the chest‖; and cervix (neck) becomes cervical (SERvihkal), to mean ―pertaining to a neck.‖ SUFFIXES BEGINNING WITH rh 5  Medical terminology When you add a suffix beginning with rh to a root, the r is doubled. For example: hem/o (blood) + rhage (bursting forth) = hemorrhage (a bursting forth of blood) men/o (menses) + rhea (flow, discharge) = menorrhea (menstrual flow) Forming Plurals Many medical words have special plural forms based on the ending of the word. TABLE 1-4 gives some general rules for the formation of plurals along with examples. The plural endings listed in the second column are substituted for the word endings in the first column. Note that both singular endings on and um change to a for the plural. You have to learn which singular ending to use for specific words when converting a plural word ending in a to the singular. Singular Plural Alveolus Alveoli Bronchi Bronchus Canaliculi Canaliculus Glomeruli Glomerulus Homunculi Homunculus Microvilli Microvillus Nevi Nevus Nuclei Nucleus 6  Medical terminology Nucleolus Nucleoli Plexus Plexi Stimulus Stimuli Thrombus Thrombi Villus Villi Ampulla Ampullae Bursa Bursae Word endings Singular form Plural Form Consonants other contusion contusions than s, h, or y s, ch, sh virus viruses y allergy allergies General Guidelines in Forming Plurals of Nouns with Special Endings Singular Plural Examples Examples (Plural) Ending Ending (Singular) is es diagnosis, diagnoses, anastomosis anastomoses *Some words ending in is take on their plural form by omitting the is and adding ides, as in arthritis and arthritides um a atrium, ostium atria, ostia us i bronchus, alveolus bronchi, alveoli *Some words ending in us take on their plural form by omitting the us and adding era or ora, as in viscus to viscera and corpus to corpora. a ae cava, vertebra cavae, vertebrae ix ices appendix, cervix appendices, cervices ex ices apex apices 7  Medical terminology ax aces thorax thoraces ma s or mata condyloma condylomas or condylomat on a spermatozoon spermatozoa *Some words ending in on take on their plural form by adding s, as in chorio to chorions nx nges phalanx phalanges PREFIXES Meaning a-/an- Not, without pre- before post- after hypo- Under, below hyper- over PREFIXES Meaning a-/an- Not, without pre- before post- after hypo- Under, below hyper- over sub- Under, below epi- above inter- Between, among intra- Within, inside micro- small macro- large dys- Bad, painful, difficult ROOTS 8  Medical terminology neur/o Nerve, nervous system ophthalm/o Eye, vision ot/o Ear, hearing dermat/o skin cardi/o heart pulmon/o lung hepat/o liver nepgh/o kidney gastr/o stomach oste/o bone my/o Muscle, m SUFFIXES -ac,-ic,-al,-ous,-tic Related to or pertaining to -itis Inflammation of -logist Specialist in the study of -logy Study of -oma Tumor mass -osis Abnormal condition -pathy Disease, disease condition -scope Lack, observe -scopy Visual examination -gram To record -graphy Process of recording 9  Medical terminology MEDICAL SPECIALISTS AND THEIR SPECIALTIES SUFFIXES: MEDICAL SPECIALISTS AND THEIR SPECIALTIES Medical Specialists Medical Specialties Suffix Meaning Example Suffix Meaning Example -er, -ist one who internist -ac, -al, pertaining to obstetrical -ic, ical -iatrician practitioner pediatricia -logic, - pertaining to psychological n logical the study of -logist one who pulmonolo -iatrics, - medical pediatrics stud- ies, gist iatry profes- sion specialist or treatment -logy study or gynecology science of The following table lists some of the most common combining forms associated with medical specialties and specialists Combining Meaning Medical Medical Form Specialty Specialist cardi/o heart cardiology cardiologist dermat/o skin dermatology dermatologist esthesi/o feeling or anesthesiology anesthesiologist sensation gynec/o female gynecology gynecologist immune/o immune immunology immunologist ne/o, nat/o new, birth neonatology neonatologist ophthalm/o eye ophthalmology ophthalmologist path/o disease pathology pathologist 10  Medical terminology radi/o radiation or radiology radiologist radius ur/o urinary tract or urology urologist urine SURGICAL PROCEDURES A significant number of medical terms refer to surgical procedures. Generally, the suf- fixes used will give you an idea about the type of surgery or procedure performed. For instance, the suffix -ectomy means surgical removal. Polypectomy and adrenalectomy refer to the excision or removal of polyps and adrenal glands, respectively. Knowing a familiar word related to the suffix makes it easier to analyze a medical term. This process is known as word association. Take a look at the following table. SUFFIXES: SURGICAL PROCEDURES Suffix Meaning Word Association -centesis surgical puncture to aspirate Paracentesis is a puncture of the or perito- neal cavity to remove fluid for remove fluid diagnostic or therapeutic purposes. -ectomy excision (surgical removal Excision of the appendix is referred to or cutting out) as an appendectomy. -lysis process of loosening, freeing, This suffix can also mean dissolving or or destroying destruction, as in hydrolysis. -pexy surgical fixation (securing Nephropexy is a surgical fixation of a in a fixed position) kidney that descends when the patient stands up. -plasty surgical repair Rhinoplasty is a plastic surgery of the nose and is done for several reasons. 11  Medical terminology -rrhaphy suture (fusing a wound by Herniorraphy is surgical repair of the stitches) hernia with suture of the abdominal wall. -scopy visual examination with the Colonoscopy is a means of use of a lighted instrument visualizing the colon with the use of a fiber-optic instrument. -stomy creation of an opening Colostomy is a surgical procedure that creates an opening for the colon or large intestine through the abdomen. -tome an instrument used for cutting A microtome is used to cut thin sections of tissue. -tomy incision (cutting into tissue) Sternotomy is an incision of the sternum usually performed during heart surgery. -tripsy surgical crushing, breaking, Lithotripsy is the surgical crushing of a or pulverizing renal calculus or stone. Four Techniques in Physical Examination Physical examination is a means of gathering clinical data from the client using the exam- iner’s senses, namely the senses of sight, hearing, and touch. Technique Sense Skill Example Involved Inspection sight Eyes are used to Checking for skin observe. color Palpation touch Hands are used to Feeling for lumps feel for the texture, size, con- sistency, 12  Medical terminology and location of body parts. Percussion hearing The fist or fingertips Performing are used to tap the “kidney punch” body part to determine the size, borders, and consistency of body organs. Auscultation hearing A stethoscope is used Listening for breath to listen for sounds sounds within the body. BODY STRUCTURES Some of the combining forms for body structures have already been introduced when naming medical specialists. In this section, you’ll be presented with additional combining forms and the most frequent word associations used. Hepat/o is one of the most common combining forms used 13  Medical terminology in the medical field. Note that hepat/o means liver; hence, hepa- titis refers to an inflammatory condition of the liver. More examples are presented in the following table COMBINING FORMS FOR A NUMBER OF BODY STRUCTURES Combining Meaning Word Association Form aden/o gland Adenopathy refers to the enlargement of the g angi/o vessel Angioplasty is a procedure used to rees- tablis flow through partially or fully blocked blood bi/o life or living Biopsy is a procedure used to extract cells or t for examination. blephar/o eyelid Blepharitis is an infection of the eyelids. cerebr/o, brain Cerebrospinal fluid is a clear, colorless fluid f encephal/o the brain and the spinal cord. Encephalopathy is a general term that refers to disorder or disease of the brain. col/o colon or large Colitis is an inflammation of the colon’s intestine inner lining. faci/o face Facial relates to the face. hepat/o liver Hepatomegaly is enlargement of the liver. mamm/o, breast Mammogram is an x-ray of the breast. mast/o Mastitis is an infection of the breast tissue. muscul/o, my/o muscle The musculoskeletal system is an organ system responsible for movement and activity. Myosin is one of the muscle proteins. myel/o bone marrow or Myelogram is a means of examining the spin spinal cord using a combination of dye and x-ray. oste/o bone Osteoporosis is a disease that weakens the bo thereby increasing the risk for fractures. 14  Medical terminology pulm/o, lungs Pulmonary refers to the lungs. pulmon/o, Pneumatic refers to gas or air. pneum/o, pneumon/o Pneumothorax is the accumulation of air or ga chest. tonsil/o tonsil Tonsillectomy is the surgical removal of the to trache/o trachea Tracheitis is an inflammation of the (windpipe) trachea. vas/o vessel Widening of the blood vessels is known as vasodilation. MISCELLANEOUS WORD PARTS These word parts aren’t categorized under a specific group, but note that they’re fre- quently used in medical terminologies. The word microscope (word part= micro), for example, is used not only by healthcare professionals but in customary language as well. MISCELLANEOUS WORD PARTS Word Part Meaning Word Association adip/o, lip/o fat adipose, hyperlipidemia amyl/o starch amylase glyc/o sugar hyperglycemia hemat/o blood hematology lact/o milk lactation litho/o stone lithotripsy micro- small microscopy muc/o mucus mucous 15  Medical terminology prote/o, protein/o protein proteolysis, proteinuria pyr/o fire pyromania NUMBERS AND QUANTITIES The medical field, like any other group of professions, makes use of terms related to numbers and quantities. The prefixes used in these medical terms are the same ones we use in everyday language. For example, the prefix bi- is a prefix which means two. Examples of words associated with this prefix include bicycle (a vehicle with two wheels) and biannual (an event occurring twice a year). The prefix bi- has the same meaning when used in medical language. Bicuspid means two cusps or valves, as in the case of heart valves. Study the following table for more examples. PREFIXES: NUMBERS AND QUANTITIES NUMBERS Prefix Meaning Example Word Association mono-, one mononucle Mononuclear refers to a cell mad uni- ar, of one nucleus. unilateral Unilateral means one side. bi-, di- two bicuspid, Bicuspid means having two cusp disaccharide as in the bicuspid valves of the heart. A disaccharide is a type of car- bohydrate that is made up of two simple sugars. tri- three tricuspid Tricuspid means having three cusps, as in the tricuspid valve of the heart. 16  Medical terminology quad-, four quadriplegia The paralysis of all four quadri-, extremities is known as tetra- quadriplegia. centi- one centigrade The centigrade or Celsius scale i hundred, unit of measure- ment for one- temperature, which is divided into hundredt 100 degrees. h (Contin PREFIXES: NUMBERS AND QUANTITIES (continued) NUMBERS Prefix Meaning Example Word Association milli- one- milliunit A milliunit is 1/1000 of a unit. thousandth QUANTITIES diplo- double diplopia Diplopia means double vision or the perception of two images of a single object. hemi-, semi- half, partly hemipare Hemiparesis refers to weak- ness of sis, one entire side of the body. semi- Semi-fowler’s position is a position fowler’s assumed when a cli- ent is supine on bed with the head of the bed elevated about 30–45 degrees. hyper- excessive, hyperglycem Hyperglycemia is excessive blood more than ia sugar. normal hypo- under, less than hypoglycemi Decreased blood sugar in the blood normal a is known as hypoglycemia. 17  Medical terminology multi-, poly- many multigra Multigravid means multiple pregnan vid, Polyuria means excessive pro- ducti or passage of urine. polyuria nulli- none nulliparous A woman who hasn’t given birth is referred to as nulliparous. pan- all pancytopenia Pancytopenia occurs when all blood types are decreased. primi- first primigravida Primigravida refers to a woman bein pregnant for the first time. super-, excessive, superior, Superior vena cava is a large- ultra- above or supraspinatus diameter blood vessel that drains superior , blood from the upper parts of the body. ultraviolet Ultraviolet light is a form of radiatio Body Organs and Organ Systems Tissues are arranged into organs, which serve specific functions, and organs, in turn, are grouped into individual systems. 18  Medical terminology Integumentary system, which includes the skin and its associated structures, such as hair, sweat glands, and oil glands. This system functions in protection and also helps to regulate body temperature. Skeletal system, which includes the bones and joints. Muscular system, which moves the skeleton and makes up the walls of internal organs. Nervous system, consisting of the brain, spinal cord, and nerves, Endocrine system, consisting of individual glands that produce hormones. Cardiovascular system, consisting of the blood, heart, and blood vessels. Lymphatic system, organs, and vessels that aid circulation and help protect the body from foreign materials Respiratory system, which obtains the oxygen needed for metabolism and eliminates carbon dioxide, Digestive system, which takes in, breaks down, and absorbs nutrients and eliminates undigested waste. Urinary system, which eliminates soluble waste and balances the volume and composition of body fluids The male and female reproductive systems concerned with production of offspring ,They work together to maintain the body’s state of internal stability, 19  Medical terminology termed homeostasis (ho-me-o-STA-sis). Pharmacology: ( drug names, administration of drugs, drug classes Microbiology : to learn the medical terms related to the general characteristics of microorganisms; - to understand the basis for classification of microorganisms - Physio1ogy: branch of biology that deals with the normal functions of living organisms and their parts. Biochemistry: he branch of science concerned with the chemical and physico-chemical processes and substances that occur within living organisms. Pathology: the study of the essential nature of diseases and especially of the structural and functional changes produced Diagnosis he identification of the nature of an illness or other problem Investigations a systematic, minute, and thorough attempt to learn the facts about something complex or hidden 20  Medical terminology Ophthalmology the specialized field of medicine that focuses on the health of the eye. I Dermatology : e branch of medicine concerned with the diagnosis and treatment of skin disorders Internal medicine he study, diagnosis, and treatment of conditions that affect the internal organ Surgery: Medical treatment in which someone's body is cut open so that a doctor can repair, remove, or replace a diseased or damaged part. Vital signs (VS) are also recorded for comparison with normal ranges. Temperature (T). Pulse rate, measured in beats per minute (bpm) (Pulse rate normally corresponds to the heart rate (HR), the number of times the heart beats per minute. Respiration rate (R), measured in breaths per minute. Blood pressure (BP), measured in millimeters of mer-cury (mm Hg) and recorded when the heart is contract-ing (systolic pressure) and relaxing (diastolic pressure) 21  Medical terminology The Digestive Tract The digestive tract, also known as the alimentary canal or gastrointestinal (GI) tract, is essentially a long tube modified into separate organs with special functions (summarizes the activities of the digestive organs Pharynx Organ Digestive Actions mouth Used to bite and chew food. Mixes food with saliva, which contains salivary amylase, an enzyme that begins the digestion of starch. Shapes food into small portions, which the tongue pushes into the pharynx. pharynx Swallows food by reflex action and moves it into the esophagus. esophagus Moves food into the stomach by peristalsis. stomach Stores food; churns to mix food with water and digestive juices. Secretes protein-digesting hydrochloric acid (HCl) and the enzyme pepsin. small Secretes enzymes. Receives secretions from the accessory organs, intestine which digest and neutralize food. Site of most digestion and absorption of nutrients into the circulation. large Forms, stores, and eliminates undigested waste material. intestine THE SMALL INTESTINE Food leaving the stomach enters the duodenum, the first portion of the small intestine. As the food continues through the jejunum and ileum, the small intestine’s remaining sections, digestion is completed. (Ileum sounds like ilium, a large bone of the pelvis. For information on these and other homonyms, 22  Medical terminology THE LARGE INTESTINE Any food that has not been digested, along with water and digestive juices, passes into the large intestine. This part of the digestive tract begins in the lower right region of the abdomen with a small pouch, the cecum, to which the appendix is attached. (The appendix does not aid in digestion, but contains lymphatic tissue and may function in immunity.) The large intestine continues as the colon, The colon travels upward along the right side of the abdomen as the ascending colon, crosses below the stomach as the transverse colon, and then continues down the left side of the abdomen as the descending colon. Clinical Aspects of the Digestive System DIGESTIVE TRACT Infection A variety of organisms can infect the GI tract, from viruses and bacteria to protozoa and worms. Infections of the stomach or intestine may produce short-lived upsets with gastroenteritis, nausea, diarrhea, and emesis (vomiting). Other infectious diseases of the GI tract, such as typhoid, cholera, and dysentery, are more serious, even fatal. Appendicitis results from infection of the appendix. Ulcers: lesions of the skin or a mucous membrane marked by inflammation and tissue damage. Ulcers caused by the damaging action of gastric juices, also called peptic juices, on the lining of the GI tract are termed peptic ulcers. Polyps (growths) in the intestine often become cancerous and should be removed. Polyps can be identified and even removed by endoscopy. 23  Medical terminology The most common sites for GI tract cancer are the colon and rectum. Together, these colorectal cancers One sign of colorectal cancer is bleeding into the intestine, which can be detected by testing the stool for blood. Because this blood may be present in very small amounts, it is described as occult (―hidden‖) blood. A hernia is the protrusion of an organ through an abnormal opening. The most common type is an inguinal hernia. dysphagia (difficulty in swallowing), or reflux (backflow) of stomach contents into the esophagus. In pyloric stenosis, the opening between the stomach and small intestine is too narrow. This usually occurs in infants and in boys more often than in girls. A sign of pyloric stenosis is projectile vomiting. Surgery may be needed to correct it. Other types of obstruction include intussusception, slipping of an intestinal segment into a part below it; volvulus, twisting of the intestine; and ileus, intestinal obstruction often caused by lack of peristalsis. Hemorrhoids are varicose veins in the rectum associated with pain, bleeding, and, in some cases, rectal prolapse. Gastroesophageal reflux disease (GERD) refers to reflux of gastric juices into the esophagus due to weakness at the gastroesophageal junction, specifically the LES. These acidic secretions irritate the lining of the esophagus. A GERD symptom commonly known as heartburn, an upward- radiating burning sensation behind the sternum, GERD symptoms are more likely to occur when there is increased pressure in the stomach, such as after meals when the stomach is full, when one is lying or bending down, and with obesity and pregnancy. Treatment includes weight 24  Medical terminology reduction if needed, elevating the head of the bed 4 to 6 in, avoidance of irritating foods, and drugs to reduce gastric acid secretion. Surgery to repair an incompetent LES might be needed. Persistent reflux esophagitis may cause injury to the esophageal lining leading to Barrett syndrome or Barrett esophagus. In this condition, the esophageal mucosa is gradually replaced with epithelium resembling that of the stomach or intestines. Barrett esophagus frequently has no early symptoms, but possible complications include esophageal spasms, formation of scar tissue, esophageal strictures, and increased risk of cancer. Two similar diseases are included under the heading of inflammatory bowel disease (IBD): Crohn disease Ulcerative colitis ACCESSORY ORGANS Hepatitis hepatitis is most often caused by viral infection. More than five types of hepatitis viruses have now been identified. Vaccines are available for hepatitis A and hepatitis B. Hepatitis A virus (HAV) is the most common hepatitis virus. It is spread by fecal–oral contamination, often by food handlers, and in crowded, unsanitary conditions. It may also be acquired by eating contaminated food. Hepatitis B virus (HBV) is spread by blood and other body fluids. It may be transmitted sexually, by sharing injection needles, and by close interpersonal contact. Infected individuals may become carriers of the disease. Most patients recover, but the disease may be serious, even fatal, and may lead to liver cancer. 25  Medical terminology Hepatitis C is spread through blood and blood products or by close contact with an infected person. Drug treatment is available to cure hepatitis C. Hepatitis D, the delta virus, is highly pathogenic but infects only those already infected with hepatitis B. Hepatitis E, like HAV, is spread by contaminated food and water. It has caused epidemics in Asia, Africa, and Mexico. Jaundice, or icterus, is a symptom of hepatitis and other diseases of the liver and biliary system. It appears as yellowness of the skin, whites of the eyes, and mucous membranes Cirrhosis is a chronic liver disease characterized by hepatomegaly, edema, ascites (fluid in the abdomen), and jaundice. Gallstones Cholelithiasis refers to the presence of stones in the gallbladder or bile ducts, which is usually associated with cholecystitis, inflammation of the gallbladder. Most gallstones are composed of cholesterol, an ingredient of bile. Drugs may dissolve gallstones, but often the cure is removal of the gallbladder in a cholecystectomy. Originally, this procedure required an extensive incision, but now the gallbladder is almost always removed laparoscopically through a small abdominal slit. Pancreatitis Pancreatitis, or inflammation of the pancreas, may result from alcohol abuse, drug toxicity, bile obstruction, infections, and other causes. Blood tests in acute pancreatitis show increased levels of the enzymes amylase and lipase. Glucose and bilirubin levels may also be elevated. 26  Medical terminology OCardiovascular The heart is located between the lungs, with its point, or apex, The wall of the heart consists of three layers, all named with the root cardi, meaning ―heart.‖ Moving from the innermost to the outermost layer, these are the: 1. Endocardium—a thin membrane that lines the chambers and valves (the prefix endo- means ―within‖). 2. Myocardium—a thick muscle layer that makes up most of the heart wall (the root my/o means ―muscle‖). 3. Epicardium—a thin membrane that covers the heart (the prefix epi- means ―on‖). A fibrous sac, the pericardium, contains the heart and anchors it to surrounding structures, such as the sternum (breastbone) and diaphragm (the prefix peri- means ―around‖). Each of the heart’s upper receiving chambers is an atrium (plural: atria). Each of the lower pumping chambers is a ventricle (plural: ventricles). The chambers of the heart are divided by walls, each of which is called a septum. The interventricular septum separates the two ventricles; the interatrial septum divides the two atria. 27  Medical terminology The heart pumps blood through two circuits. The right side pumps blood to the lungs to be oxygenated through the pulmonary circuit. The left side pumps to the remainder of the body through the systemic circuit. BLOOD FLOW THROUGH THE HEART The pathway of blood through the heart is shown by the arrows in FIGURE 10-2. The sequence is as follows. 1. The right atrium receives blood low in oxygen from all body tissues through the superior vena cava and the inferior vena cava. 2. The blood then enters the right ventricle and is pumped to the lungs through the pulmonary artery. 28  Medical terminology 3. Blood returns from the lungs high in oxygen and enters the left atrium through the pulmonary veins. 4. Blood enters the left ventricle and is forcefully pumped into the aorta to be distributed to all tissues. One-way valves in the heart keep blood moving in a forward direction. The valves between the atrium and ventricle on each side are the atrioventricular (AV) valves. The valve between the right atrium and ventricle is the right AV valve, also known as the tricuspid valve because it has three cusps (flaps). The valve between the left atrium and ventricle is the left AV valve, which is a bicuspid valve with two cusps; it is often called the mitral valve (named for a miter, the pointed, two-sided hat worn by bishops). The valves leading into the pulmonary artery and the aorta have three cusps. Each cusp is shaped like a half-moon, so these valves are described as semilunar valves (lunar refers to the moon). The valve at the entrance to the pulmonary artery is specifically named the pulmonary valve; the valve at the entrance to the aorta is the aortic valve. BLOOD SUPPLY TO THE MYOCARDIUM Only the endocardium comes into contact with the blood that flows through the heart chambers. Therefore, the myocardium must have its own blood vessels to provide oxygen and nourishment and to remove waste products. Together, these blood vessels form the coronary circulation. THE HEARTBEAT 29  Medical terminology Each contraction of the heart, termed systole is followed by a relaxation phase, diastole , during which the chambers fill. The number of times the heart contracts per minute is the heart rate. The wave of increased pressure produced in the vessels each time the ventricles contract is the pulse. Pulse rate is usually counted by palpating a peripheral artery, such as the radial artery at the wrist or the carotid artery in the neck The Vascular System The vascular system consists of: 1. Arteries that carry blood away from the heart 2. Arterioles, vessels smaller than arteries that lead into the capillaries 3. Capillaries, the smallest vessels, through which exchanges take place between the blood and the tissues 4. Venules, small vessels that receive blood from the capillaries and drain into the veins 5. Veins that carry blood back to the heart BLOOD PRESSURE Blood pressure (BP) is the force exerted by blood against the wall of a blood vessel. It falls as the blood travels away from the heart and is influenced by a variety of factors, Atherosclerosis is the most common form of a more general condition known as arteriosclerosis in which vessel walls harden from any cause. In addition to plaque, calcium salts and scar tissue may contribute to arterial wall thickening, with a narrowing of the lumen and loss of elasticity. THROMBOSIS AND EMBOLISM 30  Medical terminology Atherosclerosis predisposes a person to thrombosis, the formation of a blood clot within a vessel. Blockage of a vessel by a thrombus or other mass carried in the bloodstream is embolism. The use of anticoagulant drugs (―blood thinners‖) when appropriate has greatly reduced the incidence of these conditions. ANEURYSM An arterial wall weakened by atherosclerosis, malformation, injury, or other changes may balloon out, forming an aneurysm. If an aneurysm ruptures, hemorrhage results. HYPERTENSION : High blood pressure, HEART DISEASE Coronary Artery Disease Coronary artery disease (CAD) results from atherosclerosis in the vessels that supply blood to the heart muscle. It is a leading cause of death in industrialized countries. An early sign of CAD is the type of chest pain known as angina pectoris. This is a feeling of constriction around the heart or pain that may radiate to the left arm or shoulder, usually brought on by exertion. Often there is anxiety. Degenerative changes in the arteries predispose a person to thrombosis and sudden coronary artery occlusion (obstruction). The resultant area of myocardial necrosis is termed an infarct, and the process is known as myocardial infarction (MI), the ―heart attack‖ that may cause sudden death. Arrhythmia is any irregularity of heart rhythm, such as an altered heart rate, extra beats, or a change in the pattern of the beat. 31  Medical terminology Bradycardia is a slower-than-average rate, and tachycardia is a higher-than- average rate. Heart Failure The general term heart failure refers to any condition in which the heart fails to empty effectively. Heart failure is one cause of shock, a severe disturbance in the circulatory system resulting in inadequate blood delivery to the tissues. Shock is classified according to cause as: Cardiogenic shock, caused by heart failure Hypovolemic shock, caused by loss of blood volume Septic shock, caused by bacterial infection Anaphylactic shock, caused by severe allergic reaction Congenital Heart Disease A congenital defect is any defect that is present at birth. The most common type of congenital heart defect is a septal defect, a hole in the septum (wall) that separates the atria or Rheumatic Heart Disease In rheumatic heart disease, infection with a specific type of Streptococcus sets up an immune reaction that ultimately damages the heart valves. The infection usually begins as a ―strep throat,‖ and most often the mitral valve is involved. Scar tissue fuses the valve’s leaflets, causing a narrowing or stenosis that interferes with proper function. DISORDERS OF THE VEINS 32  Medical terminology A breakdown in the valves of the veins in combination with a chronic dilatation of these vessels results in varicose veins. These appear twisted and swollen under the skin, Blood and Immunity Introduction Blood is the fluid that circulates through the vessels, bringing oxygen and nourishment to all cells and carrying away carbon dioxide and other waste products. The blood also distributes body heat and carries special substances, such as antibodies and hormones. Certain blood cells are a major component of the immune system, which protects against disease. The total adult blood volume is about 5 L. Whole blood can be divided into two main components: the liquid portion, or plasma (55%), and formed elements, more commonly known as blood cells (45%) Blood Plasma Plasma is about 90% water. The remaining 10% contains nutrients, electrolytes (dissolved salts), gases, albumin (a protein), clotting factors, antibodies, wastes, enzymes, and hormones. Blood Cells The blood cells include erythrocytes, or red blood cells (RBCs); leukocytes, or white blood cells (WBCs); and platelets, also called thrombocytes. All blood cells are produced in red bone marrow. Some WBCs multiply in lymphoid tissue as well. Erythrocytes 33  Medical terminology The major function of erythrocytes is to carry oxygen to cells. This oxygen is bound to an iron-containing pigment in the cells called hemoglobin. Erythrocytes are small, disk-shaped cells with no nuclei. Leukocytes All WBCs show prominent nuclei when stained. They total about 5,000 to 10,000/μL, but their number may increase during infection. There are five types of leukocytes that vary in their relative percentages and their functions. Platelets The blood platelets (thrombocytes) are not complete cells, but fragments of large cells named megakaryocytes, which form in bone marrow. Platelets are important in hemostasis, the prevention of blood loss, which includes the process of blood clotting, or coagulation. Respiratory system The main function of the respiratory system is to provide oxygen to body cells for energy metabolism and to eliminate carbon dioxide, a byproduct of metabolism. Because these gases must be carried to and from the cells in the blood, the respiratory system works closely with the cardiovascular system to accomplish gas exchange. This activity has two phases: External gas exchange occurs between the outside atmosphere and the blood. Internal gas exchange occurs between the blood and the tissues. 34  Medical terminology External exchange takes place in the lungs, located in the thoracic cavity. The remainder of the respiratory tract consists of a series of passageways that conduct air to and from the lungs. No gas exchange occurs in these regions. Upper Respiratory Passageways The upper respiratory passageways consist of the nose and pharynx (throat). Air can also be exchanged through the mouth, but there are fewer mechanisms for cleansing the air taken in by this route. THE NOSE Air enters through the nose, where it is warmed, filtered, and moistened as it passes over the hair-covered mucous membranes of the nasal cavity. Cilia— microscopic hair-like projections from the cells that line the nasal passageways— sweep dirt and foreign material toward the throat for elimination. Material that is eliminated from the respiratory tract by coughing or clearing the throat is called sputum. Receptors for the sense of smell are located within bony side projections of the nasal cavity called turbinate bones or conchae. THE PHARYNX Inhaled air passes into the throat, or pharynx, where it mixes with air that enters through the mouth and also with food destined for the digestive tract. The pharynx is divided into three regions, which are shown in The nasopharynx is the superior portion located behind the nasal cavity. The oropharynx is the middle portion located behind the mouth. The laryngopharynx is the inferior portion located behind the larynx. The tonsils, lymphoid tissue are in the region of the pharynx. Inspiration 35  Medical terminology The breathing cycle begins when the phrenic nerve stimulates the diaphragm to contract and flatten, enlarging the chest cavity. Expiration Expiration occurs as the breathing muscles relax and the elastic lungs spring back to their original size. Pneumonia is caused by many different microorganisms, usually bacteria or viruses. Bacterial agents are most commonly Streptococcus pneumoniae and Klebsiella pneumoniae. Viral pneumonia is more diffuse and is commonly caused by influenza virus and adenovirus. Acute rhinitis, which is inflammation of the nasal passageways with copious secretion of watery mucus; tearing of the eyes; and congestion. The infection may spread from the nose and throat to the sinuses, middle ear, and lower respiratory tract. Cold viruses are mostly spread by airborne virus-filled droplets released by an infected person’s coughs and sneezes. Frequent hand washing and not touching one’s hands to any part of the face are good preventive measures. EMPHYSEMA Emphysema is a chronic disease associated with overexpansion and destruction of the alveoli. Common causes are exposure to cigarette smoke and other forms of pollution as well as chronic infection. In pleural effusion, other materials accumulate in the pleural space. Depending on the substance involved, these are described as empyema (pus), also termed pyothorax; hemothorax (blood); or hydrothorax (fluid). Causes of these conditions include injury, infection, heart failure, and pulmonary embolism. Thoracentesis, needle puncture of the chest to remove fluids , 36  Medical terminology DIAGNOSIS OF RESPIRATORY DISORDERS In addition to chest radiographs, CT scans, and magnetic resonance imaging (MRI) scans, methods for diagnosing respiratory disorders include lung scans, bronchoscopy The Bronchial System At its lower end, the trachea divides into a right and a left primary bronchus, which enter the lungs. The right bronchus is shorter and wider; it divides into three secondary bronchi in the right lung. The left bronchus divides into two branches that supply the left lung. Further divisions produce an increasing 37  Medical terminology number of smaller tubes that supply air to smaller subdivisions of lung tissue. As the air passageways progress through the lungs, the cartilage in the walls gradually disappears and is replaced by smooth (involuntary) muscle. The smallest of the conducting tubes, the bronchioles, carry air into the microscopic air sacs, the alveoli, through which gases are exchanged between the lungs and the blood. It is through the ultrathin walls of the alveoli and their surrounding capillaries that oxygen (O2) diffuses into the blood and carbon dioxide diffuses out of the blood for elimination. THE LUNGS The cone-shaped lungs occupy the major portion of the thoracic cavity. The right lung is larger and divided into mthree lobes. The left lung, which is smaller to accommodate the heart, is divided into two lobes. The lobes are further subdivided to correspond to divisions of the bronchial network. A double membrane, the pleura, covers the lungs and lines the thoracic cavity. There are two pleural layers: The parietal pleura, the outer layer, is attached to the wall of the thoracic cavity. The visceral pleura, the inner layer, is attached to the surface of the lungs. Breathing Air is moved into and out of the lungs by the process of breathing, technically called pulmonary ventilation. This consists of a steady cycle of inspiration (inhalation) and expiration (exhalation). Urinary System Introduction 38  Medical terminology The urinary system excretes metabolic waste. While forming and eliminating urine, it also regulates the composition, volume, and acid–base balance (pH) of body fluids. In several ways, kidney activity affects the circulation and blood pressure. The urinary system is thus of critical importance in maintaining homeostasis, the state of internal balance, the urinary system consists of: Two kidneys, the organs that form urine Two ureters, which transport urine from the kidneys to the bladder The urinary bladder, which stores and eliminates urine The urethra, which carries urine out of the body The Kidneys The kidneys are the organs that form urine from substances filtered out of the blood. In addition to metabolic wastes, urine contains water and ions, so its formation is important in regulating the blood’s volume and composition. In addition. KIDNEY LOCATION AND STRUCTURE The kidneys are located behind the peritoneum in the lumbar region. On the top of each kidney rests an adrenal gland. The kidney is encased in a capsule of fibrous connective tissue overlaid with fat. An outermost layer of connective tissue supports the kidney and anchors it to the body wall. 39  Medical terminology Clinical Aspects of the Urinary System INFECTIONS Organisms that infect the urinary tract generally enter through the urethra and ascend toward the bladder, producing cystitis. Untreated, the infection can ascend even further into the urinary tract. The infecting organisms are usually colon bacteria carried in feces, particularly Escherichia coli. Although urinary tract infections (UTIs) do occur in men, they appear more commonly in women because the female urethra is shorter than the male urethra and its opening is closer to the anus. Poor toilet habits and urinary stasis are contributing factors. In hospitals, UTIs may result from procedures involving the urinary system, especially catheterization, in which a tube is inserted into the bladder to withdraw An infection that involves the kidney and renal pelvis is termed pyelonephritis. Urethritis is inflammation of the urethra. GLOMERULONEPHRITIS Although the name simply means inflammation of the glomeruli and kidney, glomerulonephritis is a specific disorder that follows an immunologic 40  Medical terminology reaction. It is usually a response to infection in another system, The symptoms are hypertension, edema, and oliguria, the passage of small amounts of urine. This urine is highly concentrated. Because of damage to kidney tissue, blood and proteins escape into the nephrons, causing hematuria, blood in the urine, and proteinuria, protein in the urine. Blood cells may also form into small molds of the kidney tubule, called casts, which can be found in the Uterus Urinary bladder Catheter but in some cases, especially among the elderly, the disorder may lead to chronic renal failure (CRF) or end-stage renal disease (ESRD). RENAL FAILURE Chronic renal failure results from a gradual loss of nephrons. As more and more nephrons are destroyed, the kidneys slowly lose the ability to perform their normal functions. In many cases, there is a lesser decrease in renal function, known as renal insufficiency, that produces fewer symptoms. Injury, shock, exposure to toxins, infections, and other renal disorders may cause sudden damage to the nephrons, resulting in a rapid loss of kidney function, or acute renal failure (ARF). When destruction (necrosis) of kidney tubules is involved, the condition may be referred to as acute tubular necrosis (ATN). A few of the characteristic signs and symptoms of renal failure are the following: Dehydration (de-hi-DRA-shun). Excessive loss of body fluid may occur early in renal failure. URINARY STONES Urinary lithiasis (presence of stones) may be related to infection, irritation, diet, or hormone imbalances that lead to increased calcium in the blood. Most urinary calculi (stones) are made up of calcium salts, but they may be 41  Medical terminology composed of other materials as well. Causes of stone formation include dehydration, infection, abnormal pH of urine, urinary stasis, and metabolic imbalances. The stones generally form in the kidney and may move to the bladder). This results in great pain, termed renal colic, and obstruction that can promote infection and cause hydronephrosis, collection of urine in the renal pelvis. CANCER Carcinoma of the bladder has been linked to occupational exposure to chemicals, parasitic infections, and cigarette smoking. A key symptom is sudden, painless hematuria. Often, the cancer can be seen by viewing the bladder lining with a cystoscope If treatment is not effective in permanently removing the tumor, a cystectomy (removal of the bladder) may be necessary. URINALYSIS Urinalysis (UA) is a simple and widely used method for diagnosing urinary tract disorders. It may also reveal disturbances in other systems when abnormal byproducts are eliminated in the urine. 42  Medical terminology TRANSPORT AND REMOVAL OF URINE urine is drained from the renal pelvis and carried by the left and right ureters to the urinary bladder where it is stored. The bladder is located posterior to the pubic bone and below the peritoneum. As the bladder fills, it expands upward from a stable triangle at its base. This triangle, the Internal trigone, is marked by the ureteral openings and the urethral opening below. Fullness stimulates a reflex contraction of the bladder muscle and expulsion of urine through the urethra. The female urethra is short (4 cm) and carries only urine. The male urethra is longer (20 cm) and carries both urine and semen. The voiding (release) of urine, called urination or more technically, micturition, 43  Medical terminology Nervous System Organization of the Nervous System For study purposes, the nervous system may be divided structurally into two parts: The central nervous system (CNS), consisting of the brain and spinal cord The peripheral nervous system (PNS), consisting of all nervous tissue outside the brain and spinal cord Functionally, the nervous system can be divided into the: Somatic nervous system, which controls skeletal muscles Autonomic nervous system (ANS), or visceral nervous system, which controls smooth muscle, cardiac muscle, and glands; regulates responses to stress; and helps to maintain homeostasis Two types of cells are found in the nervous system. Neurons, or nerve cells, make up the conducting tissue of the nervous system. Neuroglia are the cells that support and protect nervous tissue. 44  Medical terminology THE NEURON The neuron is the nervous system’s basic functional unit. Each neuron has two types of fibers extending from the cell body: A dendrite carries impulses toward the cell body. An axon carries impulses away from the cell body. NERVES Individual neuron fibers are held together in bundles like wires in a cable. If this bundle is part of the PNS, it is called a nerve. A collection of cell bodies along the pathway of a nerve is a ganglion. The Brain The brain is nervous tissue contained within the cranium. It consists of the cerebrum, diencephalon, brainstem, and cerebellum. The cerebrum is the largest part of the brain; it is composed largely of white matter with a thin outer layer of gray matter, the cerebral cortex. It is within the cortex that the higher brain functions of memory, reasoning, and abstract thought occur. The cerebrum’s distinct surface is formed by grooves, or sulci (singular: sulcus), and raised areas, or gyri (singular: gyrus). The cerebrum is divided into two hemispheres by a deep groove, the longitudinal fissure. Each hemisphere is further divided into lobes with specialized functions The diencephalon contains the thalamus, the hypothalamus, and the pituitary gland. The thalamus receives sensory information and directs it to the proper portion of the cortex. The hypothalamus controls the pituitary and forms a link between the endocrine and nervous systems. The brainstem consists of the: Midbrain, which contains reflex centers for improved vision and hearing. 45  Medical terminology Pons, which forms a bulge on the anterior surface of the brainstem. It contains fibers that connect the brain’s different regions. PROTECTING THE BRAIN Within the brain are four ventricles (cavities) in which cerebrospinal fluid (CSF) is formed. This fluid circulates around the brain and spinal cord, acting as a protective cushion for these tissues. Covering the brain and the spinal cord are three protective layers, together called the meninges (FIG. 7-5). All are named with the Latin word mater, meaning ―mother,‖ to indicate their protective function. They are the: Dura mater, the outermost and toughest of the three. Dura means ―hard.‖ Arachnoid mater, the thin, web-like middle layer. It is named for the Latin word for spider, because it resembles a spider web. Pia mater, the thin, vascular inner layer, attached directly to the tissue of the brain and spinal cord. Pia means ―tender.‖ Twelve pairs of cranial nerves connect with the brain. These nerves are identified by Roman numerals and also by name. The Spinal Cord The spinal cord begins at the medulla oblongata and tapers to an end between the first and second lumbar vertebrae. It has enlargements in the cervical and lumbar regions, where nerves for the arms and legs join the cord. Seen in cross-section, THE SPINAL NERVES Thirty-one pairs of spinal nerves connect with the spinal cord. These nerves are grouped in the segments of the cord as follows: Cervical: 8 46  Medical terminology Thoracic: 12 Lumbar: 5 Sacral: 5 Coccygeal: 1 Each nerve joins the cord by two roots. The dorsal, or posterior, root carries sensory impulses into the cord; the ventral, or anterior, root carries motor impulses away from the cord and out toward a muscle or gland. An enlargement on the dorsal root, the dorsal root ganglion, has the cell bodies of sensory neurons carrying impulses toward the CNS. REFLEXES A simple response that requires few neurons is a reflex. In a spinal reflex, impulses travel through the spinal cord only and do not reach the brain. VASCULAR DISORDERS The term cerebrovascular accident (CVA), or stroke, applies to any occurrence that deprives brain tissue of oxygen. These events include blockage in a vessel that supplies the brain, a ruptured blood vessel, or some other damage that leads to hemorrhage within the brain. Stroke is the fourth leading cause of death in developed countries and is a leading cause of paralysis and other neurologic disabilities. Thrombosis is the formation of a blood clot in a vessel. Often, in cases of CVA, thrombosis occurs in the carotid artery, the large vessel in the neck that supplies the brain. Sudden blockage by an obstruction traveling from another part of the body is described as an embolism. In cases of stroke, the embolus usually originates in the heart. Aneurysm is a localized dilation of a vessel that may rupture and cause hemorrhage. An aneurysm may be congenital or may arise from other causes, 47  Medical terminology especially atherosclerosis, which weakens the vessel wall. Hypertension then contributes to its rupture. HEAD INJURY A cerebral contusion is a bruise to the brain’s surface, usually caused by a blow to the head. Blood escapes from local vessels, but the injury is not deep. Cerebral concussion, also known as a mild traumatic brain injury (MTBI), refers to a transient alteration in brain function resulting from head trauma or from acceleration–deceleration events where a head in motion suddenly comes to a stop. The effects include amnesia, headache, dizziness, vomiting, disorientation, and sometimes loss of consciousness. Postconcussion syndrome describes symptoms that persist or develop a month or more after the injury, such as headache, fatigue, mood changes, and cognitive deficits. Individuals who have suffered one concussion are more susceptible to future concussions, and subsequent concussions can cause more severe and long-lasting symptoms. Confusion is a state of reduced comprehension, coherence, and reasoning ability resulting in inappropriate responses to environmental stimuli. Confusion may worsen to include loss of language ability, memory loss, reduced alertness, and emotional changes. This condition may accompany a head injury, drug toxicity, extensive surgery, organ failure, infection, or degenerative disease. Coma is a state of unconsciousness from which one cannot be aroused. Causes of coma include brain injury, epilepsy, toxins, metabolic imbalance , and respiratory, hepatic, or renal failure. 48  Medical terminology Healthcare professionals use various responses to evaluate coma, for example, reflex behavior and responses to touch, pressure, and mild pain, as from a light pin prick INFECTION Inflammation of the meninges, or meningitis, is usually caused by bacteria that enter through the ear, nose, or throat or are carried by the blood. One of these organisms, the meningococcus (Neisseria meningitidis), is. A stiff neck is a common symptom. The presence of pus or lymphocytes in spinal fluid is also characteristic. Physicians can withdraw fluid for diagnosis by a lumbar puncture, using a needle to remove CSF from the meninges in the lumbar region of the spine. A laboratory can examine this fluid for white blood cells and bacteria in the case of meningitis. NEOPLASMS Almost all tumors that originate in the nervous system are tumors of nonconducting support cells, the neuroglia. These growths are termed gliomas and may be named for the specific cell type involved, such as astrocytoma, a tumor of astrocytes, or neurilemmoma (schwannoma), a tumor of the cells that make the myelin sheath. Because they tend not to metastasize, these tumors may be described as benign. However, they do harm by compressing brain tissue. The symptoms they cause depend on their size and location. There may be seizures, headache, vomiting, muscle weakness, or interference with a special sense, such as vision or hearing. If present, edema and hydrocephalus, accumulation of excess CSF in the ventricles. 49  Medical terminology A meningioma is a tumor of the meninges. Because a meningioma does not spread and is localized at the surface, a surgeon can usually remove it completely. Tumors of nervous tissue generally occur in childhood and may even originate before birth, when this tissue is actively multiplying. Also, cancer may metastasize to the brain from elsewhere in the body. For unknown reasons, certain forms of cancer, especially melanoma, breast cancer, and lung cancer, tend to spread to the brain. DEGENERATIVE DISEASES Multiple sclerosis (MS) is an autoimmune disease resulting in the demyelination (loss of the myelin sheath) of CNS axons and eventually neuronal death. In this disease, Parkinsonism occurs when, for unknown reasons, certain 7 prime characteristic of epilepsy is recurrent seizures brought on by abnormal electric activity of the brain. These attacks may vary from brief and mild episodes known as absence (petit mal) seizures to major tonic–clonic (grand mal) seizures with loss of consciousness, convulsion (intervals of violent involuntary muscle contractions), and sensory disturbances. In other cases (psychomotor seizures), there is a 1- to 2-minute period of disorientation. Epilepsy may be the result of a tumor, injury, or neurologic disease, but in most cases, the cause is unknown. SLEEP DISTURBANCES The general term dyssomnia includes a variety of possible disorders that result in excessive sleepiness or difficulty in beginning or maintaining sleep. Simple causes for such disorders include schedule changes or travel to different time zones (jet lag). Insomnia refers to insufficient or nonrestorative sleep despite ample opportunity to sleep. There may be physical causes for insomnia, but 50  Medical terminology often it is related to emotional upset caused by stressful events. Narcolepsy is characterized by brief, uncontrollable attacks of sleep during the day. The disorder is treated with stimulants, regulation of sleep habits, and short daytime naps. Sleep apnea refers to failure to breathe for brief periods during sleep. It usually results from upper airway obstruction, often associated with obesity, alcohol consumption, or weakened throat muscles. ANXIETY DISORDERS Anxiety is a feeling of fear, worry, uneasiness, or dread. It may be associated with physical problems or drugs and is often prompted by feelings of helplessness or loss of self-esteem. Generaliz Panic disorder is a form of anxiety disorder marked by episodes of intense fear. A person with panic disorder may isolate himself or herself or avoid social situations for fear of having a panic attack or in response to attacks. A phobia is an extreme, persistent fear of a specific object or situation. PSYCHOSIS Psychosis is a mental state in which there is gross misperception of reality. This loss of touch with reality may be evidenced by delusions (false beliefs), including paranoia, delusions of persecution or threat, or hallucinations, imagined sensory experiences. Although the patient’s condition makes it impossible for him or her to cope with the ordinary demands of life, there is lack of awareness that this behavior is inappropriate. Schizophrenia is a form of chronic psychosis that may include bizarre behavior, paranoia, anxiety, delusions, withdrawal, and suicidal tendencies. The diagnosis of schizophrenia encompasses a broad category of disorders 51  Medical terminology with many subtypes. The causes of schizophrenia are unknown, but there is evidence of hereditary factors and imbalance in brain chemistry. 52