Introduction to Anatomy & Physiology

Anatomy and Physiology (A&P) is the study of the structure and function of the human body. This guide covers foundational concepts, body organization, anatomical terminology, and essential cell biology relevant to introductory college-level A&P.

Levels of Structural Organization

Hierarchy of Organization

• Chemical Level: Atoms and molecules essential for life.

• Cellular Level: The basic structural and functional units of life.

• Tissue Level: Groups of similar cells performing a common function.

• Organ Level: Structures composed of at least two tissue types performing specific functions.

• Organ System Level: Groups of organs working together for a common purpose.

• Organismal Level: The complete living being.

Example: Muscle tissue (tissue level) forms the heart (organ level), which is part of the cardiovascular system (organ system level).

Anatomical Terminology and Body Organization

Directional Terms

• Anterior (ventral): Toward the front of the body.

• Posterior (dorsal): Toward the back of the body.

• Superior (cranial): Toward the head or upper part of a structure.

• Inferior (caudal): Away from the head or toward the lower part.

• Medial: Toward the midline of the body.

• Lateral: Away from the midline.

• Proximal: Closer to the origin of a body part or point of attachment.

• Distal: Farther from the origin or point of attachment.

• Superficial: Toward or at the body surface.

• Deep: Away from the body surface; more internal.

Example: The heart is superior to the diaphragm. The thumb is lateral to the index finger in anatomical position.

Body Regions and Common Names

Body Planes

• Midsagittal (median) plane: Divides the body into equal right and left halves.

• Frontal (coronal) plane: Divides the body into anterior and posterior parts.

• Transverse (horizontal) plane: Divides the body into superior and inferior parts.

Application: The heart would be cut by a midsagittal plane, but the urinary bladder may not be, depending on its position.

Body Cavities

• Dorsal Body Cavity: Contains the cranial cavity (brain) and vertebral cavity (spinal cord).

• Ventral Body Cavity: Contains the thoracic cavity (heart, lungs) and abdominopelvic cavity (digestive organs, etc.).

Example: The lungs are in the ventral body cavity; the spinal cord is in the dorsal body cavity.

Serous Membranes

Microscopy and Histology

Microscopy Techniques

• Light Microscopy: Uses visible light to observe cells and tissues at moderate magnification.

• Electron Microscopy: Uses electron beams for much higher magnification and resolution.

• Scanning Electron Microscopy (SEM): Provides three-dimensional images of surfaces.

• Transmission Electron Microscopy (TEM): Provides detailed images of internal cell structures.

Example: TEM is used to view the ultrastructure of organelles.

Histology

• Definition: The study of tissues at the microscopic level.

• Applications: Used to diagnose diseases and understand tissue organization.

Cell Structure and Function

Plasma Membrane

• Structure: Composed primarily of a phospholipid bilayer with embedded proteins and cholesterol.

• Function: Regulates entry and exit of substances, provides protection and communication.

Cell Organelles

Cell Cycle and Mitosis

• Stages: G1 (growth), S (DNA synthesis), G2 (preparation for mitosis), M (mitosis), G0 (resting phase).

• Mitosis Phases:

  • Prophase: Chromosomes condense, nuclear envelope breaks down.

  • Metaphase: Chromosomes align at the cell's equator.

  • Anaphase: Chromatids separate and move to opposite poles.

  • Telophase: Nuclear membranes reform, chromosomes decondense.

Endocytosis and Exocytosis

• Phagocytosis: "Cell eating"; engulfing large particles.

• Pinocytosis: "Cell drinking"; uptake of fluid and dissolved substances.

• Receptor-mediated endocytosis: Uptake of specific molecules via receptor binding.

• Exocytosis: Release of substances from the cell via vesicles.

Cytoskeletal Elements

Summary Table: Organelle Abundance in Cell Types

Key Definitions

• Histology: The study of tissues.

• Phagocytosis: The process by which a cell engulfs large particles.

• Pinocytosis: The process by which a cell ingests extracellular fluid and its dissolved solutes.

• Exocytosis: The process by which substances are expelled from a cell.

• Receptor-mediated endocytosis: Endocytosis involving specific membrane receptors.

Additional info:

• Some content was inferred and expanded for clarity and completeness, such as the full definitions of organelles and the cell cycle stages.

• Tables were reconstructed and expanded for study purposes.