Introduction to human anatomy

• The anatomical position is a specific orientation used for descriptions of body structures
• In the anatomical position:

  • The subject is facing forward
  • The head is level
  • Eyes are facing forward
  • Feet are flat on the ground
  • Arms are down the sides
  • Palms are turned forward
• When laying down:

  • Prone position: body facing down
  • Supine position: body facing up
• Anterior or ventral refers to the front of the body
• Posterior or dorsal refers to the back of the body
• Superior means toward the top, while inferior means toward the bottom

  • Example: Thigh is inferior to the abdomen, Neck is superior to the abdomen
• Distal means away from or farther from the origin, while proximal means near or closer to the origin
• Lateral means away from the midline of the body, while medial means toward the midline of the body
• Contralateral means on the opposite side, while ipsilateral means on the same side
• Superficial refers to towards the surface, while deep refers to towards the center
• Anatomical planes are imaginary flat surfaces used to divide the body or organs into specific areas

  • Coronal plane separates the body into front and back halves
  • Sagittal plane divides the body into left and right halves
  • Transverse plane divides the body into superior and inferior halves
• The abdominopelvic cavity can be divided into nine regions for describing the location of organs

  • The nine regions are: epigastric, right hypochondriac, left hypochondriac, umbilical, right lumbar, left lumbar, hypogastric (pubic), right iliac (inguinal), and left iliac (inguinal)
• The abdominopelvic cavity can also be divided into four quadrants by passing imaginary horizontal and vertical lines through the umbilicus

  • The four quadrants are: right upper quadrant (RUQ), left upper quadrant (LUQ), right lower quadrant (RLQ), and left lower quadrant (LLQ)
• The body has two major cavities: Dorsal and Ventral Cavity

  • Dorsal cavity contains the brain and spine, subdivided into cranial and vertebral/spinal cavities
  • Ventral cavity is anterior to the vertebral column and posterior to the sternum and abdominal muscle wall, further divided into thoracic cavity and abdominopelvic cavity
• Body cavity membranes line the cavities and provide a smooth surface for internal organs

  • Abdominal cavity membrane: peritoneum
  • Dorsal cavity membrane: Dura mater
  • Thoracic cavity membrane: pleura
  • Membranes are double-layered with lubricant fluid between them
  • Visceral layer covers organs in a cavity, while parietal layer lines the cavity walls
• Levels of Structural Organization:

  • Chemical
  • Cellular
  • Tissue
  • Organ
  • System
  • Organismic levels
• Tissue Overview:

  • Epithelial
  • Muscle
  • Neural
  • Connective
• Epithelial Tissue:

  • Cells close together
  • Apical surface free to environment
  • Attachment to basement membrane
  • Avascular
• Functions of Epithelia:

  • Physical protection
  • Controls permeability
  • Provides sensation
  • Produce specialized secretions (glands)
  • Exocrine
  • Endocrine
• Classifying Epithelia:

  • Simple vs. Stratified
  • Cell shapes: Squamous, Cuboidal, Columnar, Transitional
• Glandular Epithelia:

  • Endocrine vs. exocrine
  • Exocrine structure: Unicellular (Goblet cells), Multicellular
  • Further classified on branching pattern of duct
  • Mode of secretion: Merocrine, Apocrine, Holocrine
• Connective Tissue:

  • Composed of cells, extracellular matrix (ground substance, fibers)
  • Never exposed to outside environment
  • Ranges from highly vascularized to avascular
• Classification of Connective Tissue:

  • Connective Tissue Proper
  • Loose: Areolar, Adipose
  • Dense
  • Fluid Connective Tissues: Blood, Lymph
  • Supporting Connective Tissues: Cartilage (Hyaline, Elastic, Fibrocartilage), Bone
• Areolar Tissue:

  • Most widely distributed connective tissue in the body
  • Functions include connecting skin with muscles, attaching blood vessels and nerves, and forming dermis of the skin and submucosa
• Fluid Connective Tissues:

  • Blood: RBCs, WBCs, Platelets
  • Matrix: Plasma, Interstitial fluid, Lymph
  • Respond to injury and infection
• Supporting Connective Tissue - Cartilage:

  • Matrix: Firm gel
  • Cells: Chondrocytes found in lacunae
  • Avascular
  • Types: Hyaline, Elastic, Fibrocartilage
• Mucous Membranes:

  • Epithelial membranes with mucous-forming epithelium attached to areolar connective tissue
  • Line body cavities that open to the outside
• Serous Membranes:

  • Line body cavities that do not open directly to the outside
  • Covered by a single layer of squamous cells and serous fluid
  • Reduce friction and abrasion when organs move