Anatomy: Branches and Anatomical Position

• Anatomy is the study of the structure of living organisms.

Branches of Anatomy

• Gross Anatomy (Macroscopic): The study of structures visible to the naked eye.
• Microscopic Anatomy (Histology): The study of structures at the microscopic level.
• Developmental Anatomy (Embryology): The study of the development of an organism from fertilization to birth.
• Systemic Anatomy: Study of the body by systems (e.g., skeletal, muscular, nervous).
• Regional Anatomy: Study of the body by regions (e.g., head, neck, thorax).
• Surface Anatomy: Study of internal structures as they relate to the overlying skin.
• Comparative Anatomy: The study of anatomical similarities and differences between different species.
• Clinical Anatomy: Application of anatomical knowledge to the diagnosis and treatment of disease.

Anatomical Position

• The standard reference point for anatomical descriptions.
• Body is erect, feet slightly apart, palms facing forward, thumbs point away from body.

Anatomical Planes

• Sagittal Plane: Divides the body into right and left parts.
• Midsagittal (Median) Plane: Sagittal plane that lies exactly in the midline.
• Frontal (Coronal) Plane: Divides the body into anterior and posterior parts.
• Transverse (Horizontal) Plane: Divides the body into superior and inferior parts.
• Oblique Section: Cuts made diagonally between the horizontal and vertical planes.

Directional Terms

• Superior (cranial): Toward the head end or upper part of a structure or the body; above.
• Inferior (caudal): Away from the head end or toward the lower part of a structure or the body; below.
• Anterior (ventral): Toward or at the front of the body; in front of.
• Posterior (dorsal): Toward or at the back of the body; behind.
• Medial: Toward or at the midline of the body; on the inner side of.
• Lateral: Away from the midline of the body; on the outer side of.
• Intermediate: Between a more medial and a more lateral structure.
• Proximal: Closer to the origin of the body part or the point of attachment of a limb to the body trunk.
• Distal: Farther from the origin of a body part or the point of attachment of a limb to the body trunk.
• Superficial (external): Toward or at the body surface.
• Deep (internal): Away from the body surface; more internal.
• Ipsilateral: On the same side.
• Contralateral: On opposite sides.

Body Cavities

• Dorsal Body Cavity: Protects the fragile nervous system.
• Cranial Cavity: Encases the brain.
• Vertebral Cavity: Encases the spinal cord.
• Ventral Body Cavity: Houses the internal organs (viscera).
• Thoracic Cavity: Surrounded by the ribs and muscles of the chest.
  • Pleural Cavities: Each enveloping a lung.
  • Mediastinum: Contains the pericardial cavity and surrounds the remaining thoracic organs.
  • Pericardial Cavity: Encloses the heart.
• Abdominopelvic Cavity: Inferior to the thoracic cavity.
  • Abdominal Cavity: Contains the stomach, intestines, spleen, liver, and other organs.
  • Pelvic Cavity: Contains the urinary bladder, reproductive organs, and rectum.

Membranes of the Ventral Body Cavity

• Serosa (Serous Membrane): Thin, double-layered membrane that covers the walls and the organs of the ventral body cavity.
• Parietal Serosa: Lines the cavity walls.
• Visceral Serosa: Covers the organs in the cavity.
• Serous Fluid: Separates the serous membranes.
• Specific serous membranes:
  • Pleura: Lungs
  • Pericardium: Heart
  • Peritoneum: Abdominopelvic cavity

The Integumentary System

• Components: Skin, hair, nails, and cutaneous glands
• Functions: Protection, body temperature regulation, cutaneous sensation, metabolic functions, blood reservoir, excretion of wastes.

The Skeletal System

• Components: Bones, cartilage, ligaments
• Functions: Protection, support, movement, blood cell formation (hematopoiesis), mineral storage.

The Muscular System

• Components: Skeletal muscles
• Functions: Movement, posture, heat production.

The Nervous System

• Components: Brain, spinal cord, nerves
• Functions: Control system of the body, responds to stimuli by activating muscles and glands.

The Endocrine System

• Components: Glands that secrete hormones
• Functions: Regulates processes such as growth, reproduction, and nutrient use (metabolism).

The Cardiovascular System

• Components: Heart, blood vessels
• Functions: Transports blood, which carries oxygen, carbon dioxide, nutrients, and wastes.

The Lymphatic System

• Components: Lymphatic vessels, lymph nodes, lymphoid organs
• Functions: Returns leaked fluid from blood vessels to blood, disposes of debris, involved in immunity.

The Respiratory System

• Components: Lungs and air passageways
• Functions: Supplies oxygen, removes carbon dioxide.

The Digestive System

• Components: Oral cavity, esophagus, stomach, intestines, accessory digestive organs.
• Functions: Breaks down food, absorbs nutrients.

The Urinary System

• Components: Kidneys, ureters, urinary bladder, urethra
• Functions: Eliminates nitrogenous wastes, regulates water, electrolyte, and acid-base balance.

The Reproductive System

• Components: Male and female reproductive organs
• Functions: Production of offspring.

Tissues

• Four basic tissue types: epithelial, connective, muscle, and nervous.

Epithelial Tissue

• Covers body surfaces and lines body cavities and ducts to form glands.
• Functions: protection, absorption, filtration, excretion, secretion, and sensory reception.
• Characteristics: cellularity, specialized contacts, polarity, support by connective tissue, avascularity, regeneration.
• Classification:
  • Covering and lining epithelium: Forms the outer layer of the skin; dips into and lines the open cavities
  • Glandular epithelium: fashions the glands of the body
• Types:
  • Simple Epithelia: single layer of cells; absorption, secretion, and filtration
    • Simple squamous epithelium: single layer of flattened cells
    • Simple cuboidal epithelium: single layer of cube-like cells
    • Simple columnar epithelium: single layer of column-shaped cells
    • Pseudostratified columnar epithelium: single layer of cells of differing heights; may contain mucus-secreting cells and bear cilia
  • Stratified Epithelia: two or more cell layers; protection
    • Stratified squamous epithelium: thick membrane composed of several cell layers
    • Stratified cuboidal epithelium: typically two layers of cuboidal cells
    • Stratified columnar epithelium: several cell layers; basal cells usually cuboidal; superficial cells elongated and columnar
    • Transitional epithelium: resembles both stratified squamous and stratified cuboida

Connective Tissue

• Supports, protects, and binds other tissues together.
• Characteristics: Common origin, varying degrees of vascularity, extracellular matrix (ground substance and fibers).
• Types:
  • Connective Tissue Proper:
    • Loose connective tissues: areolar, adipose, reticular
    • Dense connective tissues: dense regular, dense irregular, elastic
  • Cartilage: hyaline, elastic, fibrocartilage
  • Bone
  • Blood

Muscle Tissue

• Highly vascularized tissues that are responsible for movement.
• Types:
  • Skeletal muscle: attached to bones; voluntary movement
  • Cardiac muscle: walls of the heart; involuntary movement
  • Smooth muscle: walls of hollow organs; involuntary movement

Nervous Tissue

• Main component of the nervous system.
• Types:
  • Neurons: Generate and conduct nerve impulses
  • Supporting cells (neuroglia)

Overview of anatomy, including gross, microscopic, and developmental branches. Covers systemic, regional, surface, comparative, and clinical anatomy. Explains the anatomical position as the standard reference for anatomical descriptions.