assignment 2.1 word structure of medical terminology

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1. Basic Word Structure

CHAPTER 1 Basic Word Structure CHAPTER SECTIONS Word Analysis, 2 Combining Forms, Suffixes, and Prefixes, 5 In Person, 21 Exercises and Answers, 23 Pronunciation of Terms, 33 Practical Applications, 37 Picture Show, 39 Review, 43 Terminology CheckUp, 46 CHAPTER OBJECTIVES •  To divide medical terms into component parts •  To analyze, pronounce, and spell medical terms using common combining forms, suffixes, and prefixes Word Analysis If you work in a medical setting, you use medical words every day. In addition, you hear medical terms spoken in your doctor’s office, read about health issues, and make daily decisions about your own health care and the health care of your family. Terms such as arthritis, electrocardiogram, hepatitis, and anemia describe conditions and tests that are familiar. Other medical words are more complicated, but as you work in this book, you will begin to understand them even if you have never studied biology or science. Medical words are like individual jigsaw puzzles. Once you divide the terms into their component parts and learn the meaning of the individual parts, you can use that knowledge to understand many other new terms. For example, the term HEMATOLOGY is divided into three parts: When you analyze a medical term, begin at the end of the word. The ending is called a suffix. All medical terms contain suffixes. The suffix in HEMATOLOGY is -LOGY, which means study of. Next, look at the beginning of the term. HEMAT is the word root. The root gives the essential meaning of the term. The root HEMAT means blood. The third part of this term, which is the letter O, has no meaning of its own but is an important connector between the root (HEMAT) and the suffix (-LOGY). It is called a combining vowel. The letter O is the combining vowel usually found in medical terms. Now put together the meanings of the suffix and the root: HEMATOLOGY means study of blood. Another familiar medical term is ELECTROCARDIOGRAM. You probably know this term, often abbreviated as ECG (or sometimes EKG). This is how you divide it into its parts: Start with the suffix at the end of the term. The suffix -GRAM means a record. Now look at the beginning of the term. ELECTR is a word root, and it means electricity. This medical term has two roots. The second root is CARDI, meaning heart. Whenever you see CARDI in other medical terms, you will know that it means heart. Read the meaning of medical terms from the suffix, back to the beginning of the term, and then across. Broken down this way, ELECTROCARDIOGRAM means record of the electricity in the heart. It is the electrical current flowing within the heart that causes the heart muscle to contract, pumping blood throughout the body. The sound made by contraction and relaxation of the heart muscle is called the heartbeat. Notice the two combining vowels in ELECTROCARDIOGRAM. Looking for the O in medical terms will help you divide the term into its parts. One combining vowel (O) lies between two roots (ELECTR and CARDI), and another between the root (CARDI) and the suffix (-GRAM). The combining vowel plus the root is called a combining form. For example, there are two combining forms in the word ELECTROCARDIOGRAM. These combining forms are ELECTR/O, meaning electricity, and CARDI/O, meaning heart. Notice how the following medical term is analyzed. Can you locate the two combining forms in this term? The two combining forms are GASTR/O and ENTER/O. The entire word (reading from the suffix, back to the beginning of the term, and across) means study of the stomach and the intestines. Here are other words that are divided into component parts: means instrument to visually examine the stomach. means pertaining to the stomach. Notice that the combining vowel is dropped when the suffix (-IC) begins with a vowel. -IC means pertaining to. Words ending with -IC are adjectives that modify a noun (e.g., gastric pain, gastric cancer). means pertaining to the heart. Again, the combining vowel (0) is dropped when the suffix (-AC) begins with a vowel. Words ending in -AC are adjectives (e.g., cardiac care, cardiac arrest). means inflammation of the intestines. Notice again that the combining vowel (0) is dropped because the suffix (-ITIS) begins with a vowel. means inflammation of the stomach and intestines. Notice that the combining vowel (0) remains between the two roots here, even though the second root (ENTER) begins with a vowel. In addition to roots, suffixes, combining forms, and combining vowels, many medical terms have a word part attached to the beginning of the term. This is called a prefix, and it can change the meaning of a term in important ways. For example, watch what happens to the meaning of the following medical terms when the prefix changes: means pertaining to below the stomach. means pertaining to across the stomach. means pertaining to behind the stomach. Let’s review the important word parts: 1.  Root —gives the essential meaning of the term. 2.  Suffix —is the word ending. 3.  Prefix —is a small part added to the beginning of a term. 4.  Combining vowel — connects roots to suffixes and roots to other roots. 5.  Combining form —is the combination of the root and the combining vowel. Some important rules to remember are: 1.  Read the meaning of medical words from the suffix to the beginning of the word and then across. 2.  Drop the combining vowel before a suffix that starts with a vowel. 3.  Keep the combining vowel between word roots, even if the second root begins with a vowel. COMBINING FORMS, SUFFIXES, AND PREFIXES Presented in this section are lists of combining forms, suffixes, and prefixes that are commonly found in medical terms. Write the meaning of the medical term on the line that is provided. Some terms will be more difficult to understand even after you know the meanings of individual word parts. For these, more extensive explanations are given in italics. To check your work, see the Mini-Dictionary: Glossary of Medical Terms on page 341 , which contains meanings of all terms used in this book. In your study of medical terminology, you will find it helpful to practice writing terms and their meanings many times. You’ll succeed when you follow these simple steps: 1.  Complete Exercises beginning on page 23 for this chapter and faithfully check your answers on pages 31 to 32 . 2.  Fill in the meanings in the Pronunciation of Terms list on pages 33 to 36 . 3.  Apply your knowledge in the Practical Applications and Picture Show features beginning on page 37 . 4.  Complete the Review of word parts beginning on page 43 and check your answers. 5.  Make sure you understand the key medical terminology concepts in the Terminology Checkup on page 46 . COMBINING FORMS Notice that the combining form is in bold type, while the root in the medical term is underlined . COMBINING FORM MEANING MEDICAL TERM MEANING aden/o gland aden oma ____________________     -OMA means tumor or mass.     aden itis ____________________     -ITIS means inflammation. arthr/o joint arthr itis ____________________ bi/o life bi olopy ____________________     -LOGY means study of.     bi onpsy ____________________     -OPSY means (process of) viewing. Living tissue is removed and viewed under a microscope. carcin/o cancer, cancerous carcin oma ____________________ cardi/o heart carrl inlnpy ____________________ cephal/o head cep halic ____________________     -IC means pertaining to. If an infant is born with the head delivered first, it is a cephalic presentation. cerebr/o cerebrum, largest part of the brain cerebral ____________________     -AL means pertaining to. Figure 1-1 shows the cerebrum and its functions.     cerebro vascular accident (CVA) ____________________     -VASCULAR means pertaining to blood vessels; a CVA is commonly known as a stroke . What happens in a stroke? Blood is prevented from reaching areas of the cerebrum. Depending on the location and extent of reduced blood flow, signs and symptoms may include loss of movement (paralysis), loss of speech (aphasia), weakness, and changes in sensation. cyst/o urinary bladder cyst oscope _________________________________     -SCOPE means instrument to visually examine. Figure 1-2 shows the urinary bladder and urinary tract in a male. A cystoscope is placed through the urethra into the urinary bladder. See Figure 1-3 . cyt/o cell cyt nlnpy ____________________ derm/o skin derm al ____________________ dermat/o skin derma titis ____________________ electr/o electricity elect rocardiogram (ECG) ____________________     -GRAM means record. EKG is an older abbreviation for this test. Figure 1-1 Functions of the cerebrum. Figure 1-2 The male urinary tract. Note that the prostate gland lies below the urinary bladder. It secretes fluid that combines with sperm to form semen. Semen leaves the body through the urethra during ejaculation. ( Modified from Chabner D-E : The Language of Medicine, ed 9, Philadelphia, 2011, Saunders .) Figure 1-3 A cystoscope is placed into the urinary bladder through the urethra within the penis. (Modified from Chabner D-E: T he Language of Medicine, ed 9, Philadelphia, 2011, Saunders.) encephal/o brain electro encephal ogram (EEG) ____________________     This record is helpful in determining whether a patient has a seizure disorder, such as epilepsy. enter/o intestines (often the small intestine) enter itis ____________________     Figure 1-4 shows the small and large intestines. ENTER/O describes the small intestine and sometimes intestines in general. COL/O and COLON/O are combining forms for the large i ntestine (colon). erythr/o red erythr ocyte ____________________     -CYTE means cell. Figure 1-5 shows the three major types of blood cells. Figure 1-4 Location of the small and large intestines in the abdominal cavity . Note that the lungs, bronchial tubes, trachea, and esophagus are in the chest cavity, which is above the diaphragm. (Modified from Chabner D-E: The Language of Medicine, ed 9, Philadelphia, 2011, Saunders.) Figure 1-5 Blood cells: erythrocytes (carry oxygen), leukocytes (five different types help fight disease), and thrombocytes or platelets (help blood to clot). (Modified from Chabner D-E: The Language of Medicine, ed 9, Philadelphia, 2011, Saunders.) gastr/o stomach gastr nscnpy ____________________     -SCOPY means process of visual examination using an instrument, or “scope.” gnos/o knowledge dia gnosis ____________________     -SIS means state of; DIA- means complete. A diagnosis is the complete knowledge gained after testing and examining the patient. The plural of diagnosis is diagnoses. Table 1-1 shows other plural formations.     pro gnos is ____________________     PRO- means before. A prognosis is a prediction (before knowledge) that is made after the diagnosis. It forecasts the outcome of treatment. Table 1-1 FORMATION OF PLURALS Consult the Mini-Dictionary: Glossary of Medical Terms on page 341 for pronunciations of all terms. 1. Words ending in a retain the a and add e: Singular Plural Meaning vertebr a vertebra e backbones burs a bursa e Sacs of fluid near a joint 2. Words ending in is drop the is and add es: Singular Plural Meaning diagnos is diagnos es determinations of the nature and cause of diseases psychos is psychos es Abnormal conditions of the mind 3. Words ending in ex or ix drop the ex or ix and add ices: Singular Plural Meaning ap ex ap ices Pointed ends of organs cort ex cort ices outer parts of organs var ix var ices Enlarged, swollen veins Singular Plural Meaning gangli on gangli a Groups of nerve cells; benign cysts near a joint (such as the wrist) 5. Words ending in um drop the um and add a: Singular Plural Meaning bacteri um ov um bacteri a ov a Types of one-celled organisms Egg cells 6. Words ending in us drop the us and add i * : Singular Plural Meaning bronch us bronch i Tubes leading from the windpipe to the lungs calcul us calcul i Stones * Exceptions to this rule are viruses and sinuses. gynec/o woman, female gyneco lopy ____________________ hem/o, blood   hem oglobin ____________________ hemat/o     -GLOBIN means protein. Hemoglobin is the protein in red blood cells (erythrocytes) that helps carry oxygen in the blood.       hemat om ____________________       -OMA means mass or tumor. In this term, -oma indicates a mass or swelling containing blood. hepat/o liver   hepat itis ____________________ Be careful about spelling this term! The combining form is gynec /o. A gynecologist specializes in diseases of the female reproductive organs. Gynecology involves both surgical and internal medicine expertise and is often practiced with obstetrics (care of pregnant women and delivery of a fetus). Hematoma A hematoma is a mass of blood trapped in tissues of the skin or in an organ. It often results from trauma and is commonly called a bruise or “black-and-blue” mark. Figure 1-6, A and B shows hematomas. Figure 1-6 A, Subungual hematoma. This collection of blood under (SUB-) a nail (UNGU/O = nail) resulted from trauma to the toe. B, Hematoma from broken ribs. ( A, From Habif TP: Clinical Dermatology, ed 4, St Louis, 2004, Mosby.) lapar/o abdomen (area between the chest and hip) lapar otomy ____________________     -TOMY means cutting into. In an exploratory laparotomy the surgeon makes a large incision in the abdominal wall to inspect organs for evidence of disease. See Figure 1-7 . Another combining form for abdomen is ABDOMIN/O, as in abdominal. leuk/o white leuk ocyte ____________________     Figure 1-5 on page 9 shows fve different types of leukocytes. nephr/o kidney nephr ectomy ____________________     -ECTOMY means cutting out—an excision or resection of an organ or other part of the body. neur/o nerve neur ology____________________ onc/o tumor onc ologist ____________________     -IST means a specialist. Figure 1-7 Laparotomy. This incision was closed with surgical staples. ophthalm/o eye ophthalmoscope____________________     Figure 1-8 shows an ophthalmologist, a medical doctor, examining a patient’s eyes with an ophthalm oscope. oste/o bone oste oarthritis ____________________     Figure 1-9 shows a normal knee joint and a knee joint with osteoarthritis. Degenerative changes and thinning and loss of cartilage occur. Inflammation of the joint membrane occurs late in the disease. Figure 1-8 Ophthalmoscope. This instrument allows the ophthalmologist to view the outer and inner areas of the eye. ( From Jarvis C : Physical Examination and Health Assessment, ed 3, Philadelphia, 2000, Saunders .) Figure 1-9 Normal knee joint and knee joint with osteoarthritis. path/o disease path ologist ____________________     A pathologist is a medical doctor who views biopsy samples to make a diagnosis and examines dead bodies (in an autopsy) to determine the cause of death. AUT- means self, and -OPSY means (process of) viewing. Thus, an autopsy is an opportunity to see for oneself what caused a patient’s death. psych/o mind psych osis ____________________     -OSIS means abnormal condition. In this serious mental condition, the patient loses touch with reality. Psychotic symptoms include hallucinations (unreal sensory perceptions, such as hearing voices when none are present) and delusions (fixed, false beliefs that can’t be changed by logical reasoning). ren/o kidney ren al ____________________     Sometimes there are two combining forms for the same part of the body. Often, one comes from Latin, and the other from Greek. ( REN- is the Latin root meaning “kidney,” and NEPHR- is the Greek root meaning “kidney.”) The Greek root describes abnormal conditions and procedures, whereas the Latin root is used with -AL, meaning “pertaining to.” rhin/o nose rhin itis ____________________ sarc/o flesh sarc oma ____________________     Sarcomas and carcinomas are cancerous tumors. Sarcomas grow from the fleshy tissues of the body, such as muscle, flat, bone, and cartilage, whereas carcinomas arise from skin tissue and the linings of internal organs. thromb/o clotting thromb ooyte ____________________     A thrombocyte (platelet) is a small cell that helps blood to clot. Platelets are shown in Figure 1-5 ( see page 9 ).     thromb osis ____________________     Formation of a thrombus (blood clot) occurs when thrombocytes and other clotting factors combine. Thrombosis describes the condition of forming a clot (thrombus). Pathologist/Medical examiner/Coroner A medical examiner (M.E.) is a pathologist who specializes in forensic (legal) medicine related to criminal issues. A coroner , however, is an elected official (administrator) who investigates any suspicious death. This official may or may not be a medical examiner. SUFFIXES Each suffix is in bold type in the Suffix column and underlined in the Medical Term column. SUFFIX MEANING MEDICAL TERM MEANING -al pertaining to neur al ____________________     Other suffixes meaning pertaining to are listed on page 375 in the Mini-Dictionary: Glossary of Word Parts. -algia pain arthr algia ____________________ -cyte cell leuko cyte ____________________ -ectomy cutting out; removal, excision gastr ectomy ____________________     In a partial or subtotal gastrectomy, only a portion of the stomach is removed. -emia blood condition leuk emia ____________________     Large numbers of immature, cancerous cells are found in the bloodstream and bone marrow (inner part of bone that makes blood cells). -globin protein hemo globin ____________________ -gram record arthro gram     This is an x-ray record of a joint. -ia condition neuralg ia ____________________ -ic pertaining to gastr ic ____________________ -ism condition, process hyperthyroid ism     HYPER- means excessive. The thyroid gland is in the neck. It secretes the hormone thyroxine, which helps cells burn food to release energy. See Figure 1-10 . -itis inflammation gastroenter itis ____________________ -logist specialist in the study of neuro logist ____________________ -logy study of nephro logy ____________________     See Table 1-2 on page 16 for a list of other terms using -LOGY. -oma tumor, mass hepat oma ____________________     This is a cancerous (malignant) tumor, also called hepatocellular carcinoma. Figure 1-10 Hyperthyroidism (Graves disease). The thyroid gland produces too much hormone, which causes signs and symptoms such as rapid pulse, nervousness, excessive sweating, and swelling of tissue behind the eyeball (resulting in exophthalmos, or “bulging” of the eyes). ( Modified from Seidel H, et al : Mosby’s Guide to Physical Examination, ed 4, St Louis , 1998, Mosby.) Table 1-2 TERMS USING -LOGY (STUDY OF) cardiology Study of the heart dermatology Study of the skin endocrinology Study of the endocrine glands gastroenterology Study of the stomach and intestines gynecology Study of women and women’s diseases hematology Study of the blood neurology Study of the nerves and the brain and spinal cord oncology Study of tumors (cancerous or malignant diseases) ophthalmology Study of the eye pathology Study of disease psychology Study of the mind and mental disorders rheumatology Study of joint diseases (RHEUMAT/O = flow or watery discharge, which was once thought to cause aches and pains, especially in joints) -opsy to view bi opsy __________ -osis abnormal nfiphr osis __________   condition lfiiikocyt osis __________     This is an increase in numbers of normal white blood cells as a response to infection. -scope instrument to visually examine gastro scope ____________________     laparnsfopfi ____________________ -scopy process of visual examination laparo scope ____________________     Small incisions are made near the navel, and instruments are inserted into the abdomen for viewing organs and performing procedures such as tying off the fallopian or uterine tubes. See Figure 1-11 .     arthro scopy ____________________     See Figure 1-12 ( page 18 ). -sis state of propno sis ____________________ -tomy process of cutting into; incision neuro tomy ____________________ PREFIXES Each prefix is in bold type in the Prefix column and underlined in the Medical Term column. Figure 1-11 Laparoscopy for tubal ligation (interruption of the continuity of the fallopian tubes) as a means of preventing future pregnancy. The vaginal speculum keeps the vaginal cavity open. The uterine cannula is a tube placed into the uterus to manipulate the uterus during the procedure. Forceps and tenaculum are used for grasping or manipulating tissue. (Modified from Chabner D-E: The Language of Medicine, ed 9, Philadelphia, 2011, Saunders.)

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1.4 Anatomical Terminology

Learning objectives.

By the end of this section, you will be able to:

• Use appropriate anatomical terminology to identify key body structures, body regions, and directions in the body
• Demonstrate the anatomical position
• Describe the human body using directional and regional terms
• Identify three planes most commonly used in the study of anatomy
• Distinguish between major body cavities

Anatomists and health care providers use terminology that can be bewildering to the uninitiated; however, the purpose of this language is not to confuse, but rather to increase precision and reduce medical errors. For example, is a scar “above the wrist” located on the forearm two or three inches away from the hand? Or is it at the base of the hand? Is it on the palm-side or back-side? By using precise anatomical terminology, we eliminate ambiguity. For example, you might say a scar “on the anterior antebrachium 3 inches proximal to the carpus”. Anatomical terms are derived from ancient Greek and Latin words. Because these languages are no longer used in everyday conversation, the meaning of their words do not change.

Anatomical terms are made up of roots, prefixes, and suffixes. The root of a term often refers to an organ, tissue, or condition, whereas the prefix or suffix often describes the root. For example, in the disorder hypertension, the prefix “hyper-” means “high” or “over,” and the root word “tension” refers to pressure, so the word “hypertension” refers to abnormally high blood pressure.

Anatomical Position

To further increase precision, anatomists standardize the way in which they view the body. Just as maps are normally oriented with north at the top, the standard body “map,” or anatomical position , is that of the body standing upright, with the feet at shoulder width and parallel, toes forward. The upper limbs are held out to each side, and the palms of the hands face forward as illustrated in Figure 1.4.1 . Using this standard position reduces confusion. It does not matter how the body being described is oriented, the terms are used as if it is in anatomical position. For example, a scar in the “anterior (front) carpal (wrist) region” would be present on the palm side of the wrist. The term “anterior” would be used even if the hand were palm down on a table.

A body that is lying down is described as either prone or supine. Prone describes a face-down orientation, and supine describes a face up orientation. These terms are sometimes used in describing the position of the body during specific physical examinations or surgical procedures.

Regional Terms

The human body’s numerous regions have specific terms to help increase precision (see Figure 1.4.1 ). Notice that the term “brachium” or “arm” is reserved for the “upper arm” and “antebrachium” or “forearm” is used rather than “lower arm.” Similarly, “femur” or “thigh” is correct, and “leg” or “crus” is reserved for the portion of the lower limb between the knee and the ankle. You will be able to describe the body’s regions using the terms from the figure.

Directional Terms

Certain directional anatomical terms appear throughout this and any other anatomy textbook ( Figure 1.4.2 ). These terms are essential for describing the relative locations of different body structures. For instance, an anatomist might describe one band of tissue as “inferior to” another or a physician might describe a tumor as “superficial to” a deeper body structure. Commit these terms to memory to avoid confusion when you are studying or describing the locations of particular body parts.

• Anterior (or ventral ) describes the front or direction toward the front of the body. The toes are anterior to the foot.
• Posterior (or dorsal ) describes the back or direction toward the back of the body. The popliteus is posterior to the patella.
• Superior (or cranial ) describes a position above or higher than another part of the body proper. The orbits are superior to the oris.
• Inferior (or caudal ) describes a position below or lower than another part of the body proper; near or toward the tail (in humans, the coccyx, or lowest part of the spinal column). The pelvis is inferior to the abdomen.
• Lateral describes the side or direction toward the side of the body. The thumb (pollex) is lateral to the digits.
• Medial describes the middle or direction toward the middle of the body. The hallux is the medial toe.
• Proximal describes a position in a limb that is nearer to the point of attachment or the trunk of the body. The brachium is proximal to the antebrachium.
• Distal describes a position in a limb that is farther from the point of attachment or the trunk of the body. The crus is distal to the femur.
• Superficial describes a position closer to the surface of the body. The skin is superficial to the bones.
• Deep describes a position farther from the surface of the body. The brain is deep to the skull.

Body Planes

A section is a two-dimensional surface of a three-dimensional structure that has been cut. Modern medical imaging devices enable clinicians to obtain “virtual sections” of living bodies. We call these scans. Body sections and scans can be correctly interpreted, only if the viewer understands the plane along which the section was made. A plane is an imaginary, two-dimensional surface that passes through the body. There are three planes commonly referred to in anatomy and medicine, as illustrated in Figure 1.4.3 .

• The sagittal plane divides the body or an organ vertically into right and left sides. If this vertical plane runs directly down the middle of the body, it is called the midsagittal or median plane. If it divides the body into unequal right and left sides, it is called a parasagittal plane or less commonly a longitudinal section.
• The frontal plane divides the body or an organ into an anterior (front) portion and a posterior (rear) portion. The frontal plane is often referred to as a coronal plane. (“Corona” is Latin for “crown.”)
• The transverse (or horizontal) plane divides the body or organ horizontally into upper and lower portions. Transverse planes produce images referred to as cross sections.

Body Cavities

The body maintains its internal organization by means of membranes, sheaths, and other structures that separate compartments. The main cavities of the body include the cranial, thoracic and abdominopelvic (also known as the peritoneal) cavities. The cranial bones create the cranial cavity where the brain sits. The thoracic cavity is enclosed by the rib cage and contains the lungs and the heart, which is located in the mediastinum. The diaphragm forms the floor of the thoracic cavity and separates it from the more inferior abdominopelvic/peritoneal cavity. The abdominopelvic/peritoneal cavity is the largest cavity in the body. Although no membrane physically divides the abdominopelvic cavity, it can be useful to distinguish between the abdominal cavity, (the division that houses the digestive organs), and the pelvic cavity, (the division that houses the organs of reproduction).

Abdominal Regions and Quadrants

To promote clear communication, for instance, about the location of a patient’s abdominal pain or a suspicious mass, health care providers typically divide up the cavity into either nine regions or four quadrants ( Figure 1.4.4 ).

The more detailed regional approach subdivides the cavity with one horizontal line immediately inferior to the ribs and one immediately superior to the pelvis, and two vertical lines drawn as if dropped from the midpoint of each clavicle (collarbone). There are nine resulting regions. The simpler quadrants approach, which is more commonly used in medicine, subdivides the cavity with one horizontal and one vertical line that intersect at the patient’s umbilicus (navel).

Chapter Review

Ancient Greek and Latin words are used to build anatomical terms. A standard reference position for mapping the body’s structures is the normal anatomical position. Regions of the body are identified using terms such as “occipital” that are more precise than common words and phrases such as “the back of the head.” Directional terms such as anterior and posterior are essential for accurately describing the relative locations of body structures. Images of the body’s interior commonly align along one of three planes: the sagittal, frontal, or transverse.

Review Questions

Critical thinking questions.

In which direction would an MRI scanner move to produce sequential images of the body in the frontal plane, and in which direction would an MRI scanner move to produce sequential images of the body in the sagittal plane?

If the body were supine or prone, the MRI scanner would move from top to bottom to produce frontal sections, which would divide the body into anterior and posterior portions, as in “cutting” a deck of cards. Again, if the body were supine or prone, to produce sagittal sections, the scanner would move from left to right or from right to left to divide the body lengthwise into left and right portions.

This work, Anatomy & Physiology, is adapted from Anatomy & Physiology by OpenStax , licensed under CC BY . This edition, with revised content and artwork, is licensed under CC BY-SA except where otherwise noted.

Images, from Anatomy & Physiology by OpenStax , are licensed under CC BY except where otherwise noted.

Access the original for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction .

Anatomy & Physiology Copyright © 2019 by Lindsay M. Biga, Staci Bronson, Sierra Dawson, Amy Harwell, Robin Hopkins, Joel Kaufmann, Mike LeMaster, Philip Matern, Katie Morrison-Graham, Kristen Oja, Devon Quick, Jon Runyeon, OSU OERU, and OpenStax is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License , except where otherwise noted.

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17.4 Anatomy of the Endocrine System

The endocrine system includes the pineal, pituitary, thyroid, parathyroid, and adrenal glands, as well as the pancreas, ovaries, and testes. See Figure 17.1 [1] for an illustration of the endocrine system. [2]

Endocrine glands secrete hormones (HŌR-mōnz) as chemical messengers. Hormones are transported via the bloodstream throughout the body, where they bind to receptors on target cells, triggering a characteristic response. This long-distance communication is the fundamental function of the endocrine system. [3]

Pineal Gland

The pineal gland (PĪ-nē-ăl gland) is a small cone-shaped structure that extends from a ventricle of the brain. The pineal gland produces the hormone melatonin (MĔL-ă-tō-nĭn). Melatonin affects reproductive development and daily physiological cycles. [4]

Pituitary Gland

The pituitary gland (pĭ-TŪ-ĭ-tĕr-ē gland) is about the size of a pea. It is a protrusion off the bottom of the hypothalamus at the base of the brain. There are two parts of the pituitary gland called the anterior and the posterior pituitary.

Anterior Pituitary Gland

The anterior pituitary gland secretes several hormones that stimulate the other endocrine glands. These hormones include human growth hormone (HYOO-măn GRŌTH HŌR-mōn) (HGH) , thyroid-stimulating hormone (THĪ-rŏid-STĬM-yū-lāt-ing HŌR-mōn) (TSH) , adrenocorticotropic hormone (ă-drē-nō-kôr-tĭ-kō-TRŌP-ik HŌR-mōn) (ACTH) , follicle-stimulating hormone (FŎL-ĭ-kŭl STĬM-yū-lāt-ing HŌR-mōn) (FSH) , luteinizing hormone (LŪ-tē-ĭ-nīz-ing HŌR-mōn) (LH) , beta endorphin (BĀ-tă ĕn-DŌR-fĭn), and prolactin (prō-LĂK-tĭn). [5]

Hypopituitarism (hī-pō-pĭ-TŪ-ĭt-ă-rizm) refers to deficient pituitary gland activity. Human growth hormone (HGH) deficiency, also known as dwarfism (DWÔR-fĭz-əm), is a condition caused by insufficient amounts of human growth hormone in the body. In contrast, gigantism (jī-GĂN-tĭz-əm) is caused by excessive human growth hormone in childhood that causes excessive growth and height.

Posterior Pituitary Gland

The posterior pituitary secretes antidiuretic hormone (ăn-tī-dī-yū-RĔT-ik HŌR-mōn) (ADH) that acts on the kidneys. Its effect is to regulate water reabsorption and control fluid balance. For example, if a person becomes dehydrated, the posterior pituitary releases ADH to stimulate additional water reabsorption by the kidneys and return more water to the bloodstream. In contrast, if a person becomes overhydrated from drinking too much water without other substances, the posterior pituitary decreases ADH release. In response, the kidneys decrease water reabsorption, and the excessive water is eliminated in urine output. The posterior pituitary gland also secretes the hormone oxytocin. Oxytocin (ŏk-sē-TŌ-sĭn) is a hormone that stimulates labor contractions and lactation after delivery. [6]

Thyroid Gland

The thyroid gland (THĪ-rŏid gland) is a butterfly-shaped endocrine gland located in the neck, just below the larynx. It helps to regulate metabolic processes in the body by producing and releasing thyroid hormones called thyroxine (thī-RŌK-sĭn) (T4) and triiodothyronine (trī-ī-ō-dō-THĪ-rō-nēn) (T3) . These hormones are critical for regulating the basal metabolic rate (BĀ-săl MĔT-ă-bŏl-ĭk RĀT) (BMR) , the rate at which the body burns energy while at rest. T3 and T4 control how the body uses energy and oxygen, impacting processes such as digestion, heart rate, and temperature regulation. The thyroid also secretes calcitonin (kăl-sĭ-TŌ-nĭn), a hormone that lowers blood calcium levels. [7]

Euthyroid (yū-THĪ-rŏid) refers to normal thyroid gland functioning with the production of the correct amount of thyroid hormones. Hypothyroidism (hī-pō-THĪ-rŏid-ĭzm) refers to deficient thyroid gland activity. Hyperthyroidism (hī-pĕr-THĪ-rŏid-ĭzm) refers to excessive thyroid gland activity. Goiter (GOI-tĕr) is the abnormal enlargement of the thyroid gland that is a symptom of either hypothyroidism or hyperthyroidism. Read more information about hypothyroidism and hyperthyroidism in the “ Diseases and Disorders of the Endocrine System ” section.

Parathyroid Glands

Four small masses of tissue are embedded on the surface of the thyroid gland called parathyroid glands (PĂR-ă-THĪ-rŏid glandz). Parathyroid glands secrete parathyroid hormone (PĂR-ă-THĪ-rŏid HŌR-mōn) (PTH) that increases blood calcium levels when necessary to maintain homeostatic balance. [8]

Adrenal Glands

The adrenal glands (ă-DRĒ-nal glandz) are small glands located on top of each kidney. There are two parts to each adrenal gland called the adrenal cortex and the adrenal medulla.

The adrenal cortex (ă-DRĒ-nal KŌR-tĕks), the outer part of the adrenal gland, consists of three different regions, with each region producing different types of hormones called mineralocorticoids, glucocorticoids, and androgens. The principal mineralocorticoid is aldosterone (ăl-DŌS-tĕ-rōn), which acts on the kidneys to reabsorb sodium and water and return these substances to the bloodstream. The principal glucocorticoid is cortisol (KŌR-tĭ-sŏl). Cortisol helps control blood glucose, blood pressure, and metabolism. Androgens (ĂN-drō-jĕnz) contribute to the development and maintenance of male characteristics. Androgens are secreted in minimal amounts in both sexes by the adrenal cortex, but their effects in females are typically masked by hormones secreted by the ovaries. [9]

The adrenal medulla, the inner part of the adrenal gland, secretes two hormones, epinephrine (ĕp-ĭ-NĔF-rĭn) and norepinephrine (nôr-ĕp-ĭ-NĔF-rĭn), also referred to as catecholamines (kăt-ĕ-KŌL-ă-mēns). These hormones are secreted by the nervous system in response to stress. [10]

The pancreas (PĂN-krē-ăs) is a long, flat gland that lies behind the stomach. The pancreas serves two functions called exocrine and endocrine roles. The exocrine (ĔK-sō-krīn) role refers to the release of digestive enzymes, including amylase and lipase that help to digest food. The endocrine (ĔN-dō-krīn) role refers to the production of hormones called glucagon and insulin that regulate blood glucose levels. [11]

Glucose (GLŪ-kōs) is the preferred fuel for all body cells. The digestive system breaks down carbohydrate-containing foods and fluids into glucose, where it is absorbed into the bloodstream. Glucose is taken up by cells from the bloodstream for fuel. [12]

Blood glucose levels are maintained by healthy individuals’ bodies between 70 mg/dL and 110 mg/dL. Hyperglycemia (hī-pĕr-glī-SĒ-mē-ă) refers to excessively high blood glucose. Hypoglycemia (hī-pō-glī-SĒ-mē-ă) refers to abnormally low blood glucose. Receptors located in the pancreas sense blood glucose levels. Specialized cells called islet cells secrete glucagon or insulin to maintain normal blood glucose levels. For example, if blood glucose levels rise above normal range, insulin (ĬN-sū-lĭn) is released, which facilitates the uptake of glucose into cells. However, if blood glucose levels drop below normal range, glucagon (GLŪ-kă-gŏn) is released, which stimulates the liver cells to release more glucose into the bloodstream. [13]

Ovaries and Testes

The ovaries and testes are responsible for producing ova and sperm and also secrete hormones.

In females, ovaries secrete estrogen  (ĕs-trō-jĕn) and progesterone (prō-JĔS-tĕ-rōn). At the onset of puberty, estrogen promotes the development of breasts and the maturation of the uterus. Progesterone causes the uterine lining to thicken in preparation for pregnancy. Together, progesterone and estrogen are responsible for the changes that occur in the uterus during the menstrual cycle. [14]

In males, testes secrete testosterone (tĕs-TŌS-tĕ-rōn). At the onset of puberty, testosterone is responsible for the following actions [15] :

• Growth and development of the male reproductive structures
• Increased skeletal and muscular growth
• Enlargement of the larynx accompanied by a deepening voice
• Growth and distribution of body hair
• “e73bab44e2c1a6d18058e8ac13c76807add6c209.jpg” by Betts et al., is licensed under CC BY 4.0 . Access for free at https://openstax.org/books/anatomy-and-physiology/pages/17-1-an-overview-of-the-endocrine-system ↵
• This work is a derivative of Anatomy and Physiology by OpenStax licensed under CC BY 4.0 . Access for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction ↵
• National Cancer Institute. (n.d.). Endocrine glands & their function. National Institutes of Health. https://training.seer.cancer.gov/anatomy/endocrine/glands/ ↵
• National Cancer Institute. (n.d.). Gonads . National Institutes of Health. https://training.seer.cancer.gov/anatomy/endocrine/glands/gonads.html ↵

Medical Terminology - 2e Copyright © 2024 by Open Resources for Nursing (Open RN) is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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6.1 Introduction to Body Systems

Learning objectives.

By the end of this chapter, you will be able to

• Differentiate the body systems
• Define the common functions of each of the body systems
• Describe the key components of each of the body systems
• List the combining forms common to each body system
• Describe the common pathologies that affect each of the body systems

Chapter Overview

An understanding of body systems is fundamental to any career in a health profession. Much of the content covered in this chapter is required knowledge about topics that are frequently discussed in any clinic or hospital. Familiarity with the human body can even help you make healthful choices for yourself and prompt you to take appropriate action when signs of illness arise. This chapter will discuss the functions, components, and common pathologies found in all body systems. There will be an ample number of practice questions and activities throughout the chapter, as well as a final review.

Attribution

Unless otherwise indicated, material on this page has been adapted from the following resource:

Betts, J. G., Young, K. A., Wise, J. A., Johnson, E., Poe, B., Kruse, D. H., Korol, O., Johnson, J. E., Womble, M., & DeSaix, P. (2013). Anatomy and physiology. OpenStax. https://openstax.org/details/books/anatomy-and-physiology licensed under CC BY 4.0

The Language of Medical Terminology Copyright © 2022 by Lisa Sturdy and Susanne Erickson is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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