CHAPTER 4 Body Structure

Levels of Human Organization

  • Conceptual Framework: The human body is organized into various levels of complexity, from basic structures to the complete organism.

  • Hierarchical Order:

    • Cell: The fundamental unit of life. Components include the cell membrane and cytoplasm.

    • Nucleus: The central structure within the cell that contains genetic material.

    • Tissue: A collection of similar cells performing a specific function.

    • Organ: A structure composed of different tissues working together (e.g., the stomach).

    • System: A group of organs that coordinate to perform complex functions (e.g., the digestive system).

    • Organism: The highest level of organization, representing the complete human being.

Body Planes

  • Body planes are imaginary lines used to section the body into various dimensions for anatomical reference:

    • Midsagittal (Median) Plane: Vertically divides the body into equal right and left halves.

    • Coronal (Frontal) Plane: Vertically divides the body into anterior (front) and posterior (back) portions.

    • Transverse (Horizontal) Plane: Horizontally divides the body into superior (upper) and inferior (lower) portions.

Body Cavities and Divisions

  • The body is divided into two main cavities, which are further subdivided into specific sections:

    • Dorsal (Posterior) Cavity: Located at the back of the body, includes:

      • Cranial Cavity: Houses the brain.

      • Spinal Cavity: Houses the spinal cord.

    • Ventral (Anterior) Cavity: Located at the front of the body, includes:

      • Thoracic Cavity: The chest area.

      • Abdominal Cavity: Contains digestive organs.

      • Pelvic Cavity: Contains reproductive and urinary organs.

Abdominopelvic Cavity: Quadrants and Regions

  • Quadrants: The abdominopelvic cavity is divided into four quadrants by two imaginary lines (one horizontal, one vertical) that intersect at the umbilicus (navel):

    • Right Upper Quadrant (RUQ)

    • Left Upper Quadrant (LUQ)

    • Right Lower Quadrant (RLQ)

    • Left Lower Quadrant (LLQ)

    • Clinical Applications: Used to describe the location of organs, clinical examinations, reporting/charting, abdominal pain, surgical incision sites, tumor locations, and physical/operative examinations.

  • Abdominopelvic Regions: Divided into nine distinct zones to provide precise reference points:

    • Right and Left Hypochondriac: Upper lateral regions beneath the ribs.

    • Epigastric: Upper middle region above the stomach.

    • Right and Left Lumbar: Middle lateral regions near the waist/loins.

    • Umbilical: Centrally located region around the navel.

    • Right and Left Inguinal (Iliac): Lower lateral regions near the groin.

    • Hypogastric: Lower middle region beneath the umbilical area.

    • Clinical Applications: Essential for describing organ location, abdominal pain, surgical procedures, incision sites, and tumor location in operative reports.

Medical Terminology: Combining Forms (CFs)

  • Anatomical Structures:

    • Cell: cyt/o

    • Nucleus: kary/o, nucle/o

    • Tissue: hist/o

    • Internal organs: viscer/o

  • Position and Direction:

    • Anterior, front: anter/o

    • Middle: medi/o

    • Lower, below: infer/o

    • Side, to one side: later/o

    • Back (of body), behind, posterior: dors/o, poster/o

  • Body Regions:

    • Stomach: gastr/o

    • Chest: thorac/o

    • Cranium (skull): crani/o

    • Pelvis: pelv/i, pelv/o

    • Abdomen: abdomin/o

    • Loins (lower back): lumb/o

  • Colors:

    • Red: erythr/o

    • White: leuk/o

    • Black: melan/o

    • Blue: cyan/o

    • Yellow: xanth/o

  • Other Descriptors:

    • Dry: xer/o

    • Extremity: acr/o

    • Disease: path/o

    • Unknown, peculiar: idi/o

Diseases and Conditions

  • Disease Defined: A pathological or morbid condition characterized by a group of signs, symptoms, and clinical findings. It disrupts homeostasis, which is the state of equilibrium within the internal environment of the body.

  • Homeostasis Factors: Disruptions include changes in temperature, hydration (fluid volume), and acidity/salts (electrolytes).

  • Indicators of Disease:

    • Sign: An objective indicator detectable by an observer (e.g., rash, swelling, lump).

    • Symptom: A subjective indicator reported by the patient (e.g., dizziness, nausea, pain).

  • Etiology (Causes):

    • Metabolic: e.g., diabetes.

    • Infectious: e.g., influenza.

    • Congenital: e.g., cleft palate.

    • Hereditary: e.g., hemophilia.

    • Neoplastic: e.g., cancer.

    • Environmental: e.g., trauma, burns.

  • Key Vocabulary:

    • Adhesion: An abnormal fibrous band that binds tissues together that are normally separated.

    • Inflammation: A defense mechanism against injury characterized by redness, heat, swelling, and pain.

    • Febrile: Pertaining to a fever; feverish.

    • Morbid: Diseased or unhealthy.

    • Sepsis: The presence of pathogens in the blood or other tissues.

    • Suppurative: Pertaining to the generation of or producing pus.

Diagnostic Procedures and Clinical Terms

  • Physical Examination Techniques:

    • Auscultation: Listening to heart, lungs, and bowel sounds (often with a stethoscope) to assess quality.

    • Inspection: General observation of the patient as a whole followed by specific body areas.

    • Palpation: Using the hands to feel structures to determine size, consistency, texture, and tenderness.

    • Percussion: Tapping the body to assess consistency and the presence of fluids.

  • Medical Procedures:

    • Electrocardiography (ECG): Recording the heart's electrical impulses. A Holter monitor may track impulses for 24 hours24\,\text{hours}.

    • Spirometry: A pulmonary function test measuring air volume and flow. Used postoperatively to improve lung function and prevent fluid buildup.

    • Anastomosis: Surgical joining of two ducts, vessels, or bowel segments. Types include end-to-end, end-to-side, and side-to-side.

    • Biopsy: Removal of a representative sample (tissue, blood, or fluid) for evaluation (e.g., bone marrow aspiration).

    • Endoscopy: Visual examination of a cavity/organ using an endoscope. Named after the area examined (e.g., gastroscopy).

    • Radiography (X-ray): Electromagnetic beams produce images; radiopaque dye may be used for soft tissues.

    • Ultrasound (US): High-frequency sound waves emitted by a transducer (often using gel for transmission) produce images from echoes.

    • Positron Emission Tomography (PET): Uses a radioactive tracer to identify metabolic activity. Increased activity may indicate a tumor; decreased activity may indicate Alzheimer disease, Parkinson disease, or epilepsy.

    • Magnetic Resonance Imaging (MRI): Multiplanar, cross-sectional images produced via radio waves and strong magnets, providing exceptional soft tissue detail.

    • Computed Tomography (CT): A rotating beam of x-rays acquired from multiple views and interpreted by a computer.

Questions & Discussion

  • Body Cavities Exercise:

    • What is another term for dorsal? Posterior.

    • What is another term for ventral? Anterior.

    • Name the two dorsal cavities: Cranial and Spinal.

    • Name the ventral cavities: Thoracic, Abdominal, and Pelvic.

  • Medical Word Building Exercises:

    • Destruction of white cells: Leukocytolysis (leuk/o/cyt/o/lysis).

    • Pertaining to the coccyx: Coccygeal.

    • Resembling red: Erythroid.

    • Tumor of black cells: Melanoma.

    • Pertaining to the neck: Cervical.

    • Abnormal condition of yellowness: Xanthosis.

    • Abnormal condition of blueness: Cyanosis.

    • Pertaining to the loins: Lumbar.

    • Pertaining to a disease of unknown origin: Idiopathic.

    • Pertaining to the body: Somatic.

    • Specialist in the study of diseases: Pathologist.

    • Pertaining to internal organs: Visceral.

    • Pain in the stomach: Gastralgia.

    • Instrument to measure the cranium: Craniometer.

    • Enlargement of internal organs: Visceromegaly.

    • Incision of the chest: Thoracotomy.

    • Study of tissues: Histology.

    • Record of an x-ray: Radiogram.

    • Pertaining to a deficient color: Hypochromic.

    • Record of sound: Sonogram.

    • Process of recording images beyond sound: Ultrasonography.

    • Instrument to cut skin: Dermatome.

    • Instrument for examining bronchi: Bronchoscope.

    • Visual examination within: Endoscopy.

    • Pertaining to through the abdomen: Transabdominal.

    • Study of blood: Hematology.

    • Instrument for measuring heat: Thermometer.

    • Specialist in the study of x-rays: Radiologist.

  • Clinical Scenarios:

    • Scenario: Mr. L.’s saphenous vein is used to bypass an occlusion. This surgery is an anastomosis.

    • Scenario: Mrs. W. uses an incentive spirometer postoperatively. This helps prevent fluid buildup in the lungs.