Anatomy & Physiology Exam 1 Study Guide: Directional Terminology, Cells, Development, and Tissues

Directional Terminology

Regions of the Head & Associated Structures

Understanding the anatomical regions of the head and their associated structures is fundamental for describing locations and relationships in the human body.

• Regions of the Head: Include the frontal (forehead), orbital (eye), nasal (nose), oral (mouth), mental (chin), and others.

• Associated Structures: Bones, muscles, nerves, and blood vessels specific to each region.

• Example: The orbital region contains the eye and associated structures such as the lacrimal gland.

Directional Terminology

Directional terms are used to describe the locations of structures relative to other structures or locations in the body.

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

• Inferior (Caudal): Away from the head or toward the lower part of a structure.

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

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

• Medial: Toward the midline of the body.

• Lateral: Away from the midline of the body.

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

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

• Example: The heart is medial to the lungs.

Anatomical Position

The standard reference position for the body in the study of anatomy.

• Definition: The body stands upright, facing forward, arms at the sides with palms facing forward, and feet parallel.

• Importance: Provides a consistent frame of reference for anatomical terminology.

Planes/Sections

Body planes are imaginary lines that divide the body into sections.

• Sagittal Plane: Divides the body into right and left parts.

• 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.

• Example: A CT scan is often taken in the transverse plane.

Body Cavities

Body cavities are spaces within the body that contain internal organs.

• Dorsal Cavity: Includes the cranial and vertebral cavities.

• Ventral Cavity: Includes the thoracic and abdominopelvic cavities.

• Membranes: Serous membranes line body cavities and cover organs (e.g., pleura, pericardium, peritoneum).

Abdominal Regions & Organs

The abdomen is divided into regions to help locate organs more precisely.

• Nine Regions: Right/left hypochondriac, epigastric, right/left lumbar, umbilical, right/left iliac, hypogastric.

• Organs: Each region contains specific organs (e.g., liver in right hypochondriac, bladder in hypogastric).

Cells

Plasma Membrane & Passive Processes

The plasma membrane controls the movement of substances into and out of the cell.

• Structure: Phospholipid bilayer with embedded proteins.

• Passive Processes: Do not require energy. Include diffusion, osmosis, and facilitated diffusion.

• Example: Oxygen moves into cells by simple diffusion.

Organelle Identification

Organelles are specialized structures within cells that perform specific functions.

• Nucleus: Contains genetic material (DNA).

• Mitochondria: Site of ATP production.

• Endoplasmic Reticulum (ER): Rough ER synthesizes proteins; smooth ER synthesizes lipids.

• Golgi Apparatus: Modifies, sorts, and packages proteins.

• Lysosomes: Contain digestive enzymes.

Organelle Processes (Definitions)

• Endocytosis: Process by which cells take in substances by engulfing them in a vesicle.

• Exocytosis: Process by which cells expel materials in vesicles that fuse with the plasma membrane.

• Osmosis: Diffusion of water across a selectively permeable membrane.

Unique Cell Types

• Examples: Neurons (nerve cells), erythrocytes (red blood cells), myocytes (muscle cells).

Transportation Processes

• Active Transport: Movement of substances against a concentration gradient, requiring energy (ATP).

• Passive Transport: Movement of substances down a concentration gradient, not requiring energy.

• Example: Sodium-potassium pump is an example of active transport.

Mechanisms of Endocytosis/Exocytosis

• Phagocytosis: "Cell eating"; engulfment of large particles.

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

• Receptor-mediated Endocytosis: Specific molecules are taken in after binding to receptors.

Mitosis

Mitosis is the process of cell division that results in two genetically identical daughter cells.

• Phases: Prophase, Metaphase, Anaphase, Telophase.

• Purpose: Growth, repair, and maintenance of tissues.

Interphase - Chromosome Position

• Interphase: The cell grows, replicates its DNA, and prepares for mitosis.

• Chromosomes: Not visible as distinct structures; DNA is in the form of chromatin.

Development

Fertilization

Fertilization is the union of a sperm and an egg cell to form a zygote.

• Location: Usually occurs in the fallopian tube.

• Result: Formation of a diploid zygote.

Morula & Blastocyst

• Morula: Solid ball of cells resulting from early cell divisions of the zygote.

• Blastocyst: Hollow ball of cells with an inner cell mass that will become the embryo.

Embryonic Period

• Time Frame: Weeks 3-8 of development.

• Key Events: Formation of major organs and structures.

Germ Layers: Endoderm, Ectoderm, Mesoderm

• Endoderm: Forms the lining of the digestive and respiratory tracts.

• Ectoderm: Forms the skin and nervous system.

• Mesoderm: Forms muscles, bones, and the circulatory system.

Teratogens

• Definition: Substances that can cause birth defects during embryonic development.

• Examples: Alcohol, certain medications, infections.

Identical Twins

• Formation: Result from the splitting of a single fertilized egg (zygote).

• Genetics: Genetically identical.

Sequence of Embryonic Development

• Order: Fertilization → Zygote → Morula → Blastocyst → Gastrula → Embryo.

Tissues

Classification of Epithelial Tissues

Epithelial tissues are classified based on the number of cell layers and the shape of the cells.

• Simple Epithelium: Single layer of cells.

• Stratified Epithelium: Multiple layers of cells.

• Cell Shapes: Squamous (flat), cuboidal (cube-shaped), columnar (tall).

Types of Cell Junctions

• Tight Junctions: Prevent leakage between cells.

• Desmosomes: Provide mechanical strength by anchoring cells together.

• Gap Junctions: Allow communication between cells via channels.

Processes that make up Cell Junctions

• Protein Interactions: Cell adhesion molecules (CAMs) and proteins like claudins, cadherins, and connexins form junctions.

Four Main Types of Body Tissues

• Epithelial Tissue: Covers surfaces and lines cavities.

• Connective Tissue: Supports and binds other tissues.

• Muscle Tissue: Responsible for movement.

• Nervous Tissue: Conducts electrical impulses.

Regions of Epithelial Tissues

• Apical Surface: Exposed to the body surface or cavity.

• Basal Surface: Attached to the underlying connective tissue.

Epithelial Nomenclature

• Naming: Based on number of layers (simple, stratified) and cell shape (squamous, cuboidal, columnar).

• Example: Simple squamous epithelium is a single layer of flat cells.

Types of Glands

• Exocrine Glands: Secrete products into ducts (e.g., sweat glands).

• Endocrine Glands: Secrete hormones directly into the bloodstream (e.g., thyroid gland).

Aging in Tissues

• Effects: Decreased cell division, reduced tissue repair, and changes in tissue structure and function.