Chapter 01 Notes: The Human Organism – Organization, Terminology and Imaging

Anatomy and Physiology

• Anatomy: scientific discipline that investigates the body’s structure.

• Physiology: scientific investigation of the processes or functions of living things.

Topics of Anatomy

• Gross anatomy: structures examined without a microscope.

  • Regional: studied area by area.

  • Systemic: studied system by system.

  • Surface: external form and relation to deeper structures (e.g., imaging like X-rays).

• Cytology: cellular anatomy.

• Histology: study of tissues.

Structural and Functional Organization of the Human Body

• Chemical level: interaction of atoms.

• Cell level: structural and functional unit of living organisms.

• Tissue level: group of similar cells and the surrounding materials.

• Organ level: one or more tissues functioning together.

• Organ System level: group of organs functioning together.

• Organism level: any living thing.

Anatomical Imaging (Overview)

• X-ray: shortwave electromagnetic radiation forms radiographs; bones and radiopaque dyes appear white; provides 2-D images.

• Ultrasound: high-frequency sound waves create real-time images (sonogram); includes real-time movement.

• Computed Tomography (CT): computer-analyzed x-ray images; slices or 3-D reconstructions.

• Digital Subtraction Angiography (DSA): 3-D radiographic image with dye subtraction to highlight vessels; used in angioplasty.

• Magnetic Resonance Imaging (MRI): radio waves in a strong magnetic field; detailed sections; good for certain cancers.

• Positron Emission Tomography (PET): detects metabolic activity via radiolabeled glucose; highlights active tissues (e.g., brain).

Major Organs and Organ Systems

• Integumentary: skin, hair, nails, sweat glands; protection, temperature regulation, vitamin D synthesis.

• Skeletal: bones, cartilage, ligaments, joints; protection, support, movement, blood cell production, mineral storage.

• Muscular: produces movement, maintains posture, generates heat.

• Nervous: detects sensations, regulates body processes, cognitive functions; brain, spinal cord, nerves.

• Endocrine: glands that secrete hormones; regulates metabolism, growth, reproduction.

• Cardiovascular: transports nutrients, wastes, gases, hormones; temperature regulation; heart, vessels, blood.

• Lymphatic: removes foreign substances, fights disease, maintains tissue fluid balance, fat absorption; vessels, nodes.

• Respiratory: gas exchange and pH regulation; lungs and passages.

• Digestive: digestion, nutrient absorption, waste elimination; GI tract and accessory organs.

• Urinary: waste removal, pH and ion/water balance.

• Male Reproductive: produces/transfers sperm; hormones; testes and associated structures.

• Female Reproductive: oocytes, fertilization, fetal development, lactation; ovaries, uterus, mammary glands.

1.4 Characteristics of Life

• Organization: relational structure and function.

• Metabolism: all chemical reactions of the body.

• Responsiveness: sensing and reacting to changes.

• Growth: increase in size or cell number.

• Development: progressive changes over time.

• Differentiation: generic-to-specific changes.

• Morphogenesis: changes in tissue/organ shape.

• Reproduction: production of new cells or new organisms.

1.5 Homeostasis

• Homeostasis: maintenance of a relatively constant internal environment; variables fluctuate around a set point.

• Set point: ideal normal value of a variable.

• Negative feedback: primary mechanism restoring set points; counteracts deviation.

• Positive feedback: exaggerates deviation; rare in normal homeostasis; can be beneficial (e.g., childbirth) or harmful (e.g., hemorrhage effects).

Negative-Feedback Mechanism: Body Temperature Example

• Receptors monitor body temperature.

• Control center (e.g., brain) compares value to the set point.

• If needed, an effector responds to restore normal temperature (e.g., sweat glands vs. shivering).

• Once at set point, response is shut off.

1.6 Terminology and the Body Plan

• Anatomical Position: body erect, face forward, feet together, palms forward.

• Supine: lying face upward. Prone: lying face downward.

• Directional Terms:

  • Superior (cranial) vs. Inferior (caudal): toward/away from the head.

  • Medial vs. Lateral: relative to the midline.

  • Proximal vs. Distal: closer to vs. farther from the trunk.

  • Superficial vs. Deep: closer to vs. farther from the surface.

  • Anterior (Ventral) vs. Posterior (Dorsal): front vs. back.

• Midline: a line down the center of the body.

• Proximal/Distal and Medial/Lateral examples illustrate spatial relationships.

Planes Through the Body

• Sagittal: divides left and right portions; Median (mid-sagittal) is down the body’s midline.

• Frontal (Coronal): divides anterior and posterior sections.

• Transverse (Horizontal): divides superior and inferior sections.

• Oblique: any plane not at a right angle.

Planes Through an Organ

• Longitudinal: along the length of an organ.

• Transverse (Cross): at right angles to the length.

• Oblique: at an angle other than right angle.

Medical Errors

• Most errors arise from breakdowns in communication.

• Examples: wrong kidney removed, wrong limb operated on, wrong organ implanted.

• Emphasizes the need for precise communication.

Body Cavities and Serous Membranes

• Dorsal body cavity: cranial cavity (brain) and vertebral canal (spinal cord).

• Ventral body cavity: thoracic cavity (pleural cavities for lungs and mediastinum for heart, vessels, thymus, trachea, esophagus) and abdominopelvic cavity (abdominal and pelvic).

• Abdominal cavity contains digestive organs and spleen; pelvic cavity contains urinary and reproductive organs.

• Serous membranes: visceral and parietal layers with serous fluid in the cavity to reduce friction.

• Specific membranes:

  • Pericardium around the heart.

  • Pleura around the lungs.

  • Peritoneum around many abdominal organs.

Location of Serous Membranes (Illustrative)

• Parietal vs. Visceral layers delineate cavities such as pericardial and pleural spaces.

• Examples: parietal pericardium with pericardial cavity; pleural cavities with visceral pleura around lungs; peritoneum around abdominal organs.

Subdivisions of the Abdomen

• Four abdominopelvic quadrants: $RUQ, LUQ, RLQ, LLQ$.

• Nine abdominopelvic regions: right/left hypochondriac, epigastric, right/left lumbar, umbilical, right/left iliac, hypogastric.

Planes of the Brain and Body (Additional Geometry Notes)

• Sagittal, Midsagittal, Parasagittal sections; Frontal (coronal); Transverse planes; Brain features align with these planes.

• Planes are used to create cross-sectional images for anatomy imaging.