L0 - Body Organization and Organ Systems

Introduction to Anatomy and Physiology

Overview

Anatomy and physiology are foundational sciences for understanding the structure and function of the human body. Mastery of these subjects is essential for careers in health professions and for making informed decisions about personal health.

• Anatomy: The study of body structure.

• Physiology: The study of body function.

• Knowledge of anatomy and physiology aids in understanding medical news, making healthful choices, and responding to illness.

Basic Definitions and Divisions of Anatomy

Types of Anatomy

• Gross Anatomy: Study of structures visible to the naked eye.

• Systemic Anatomy: Study of the body by systems (e.g., skeletal, muscular).

• Regional Anatomy: Study of specific areas of the body (e.g., head, arm).

• Surface Anatomy: Study of external features and their relation to deeper structures.

Anatomic Position and Descriptive Terminology

Anatomic Position

The standard reference position for the body is standing erect, arms at the sides, and palms facing forward. This position is used to describe locations and directions in the body.

Directional Terms

• Cranial (Cephalic, Superior): Toward the head

• Caudal (Inferior): Away from the head

• Ventral (Anterior): Front (belly) side

• Dorsal (Posterior): Back side

• Proximal: Nearer to a point of reference

• Distal: Farther from a point of reference

• Medial: Toward the midline

• Lateral: Away from the midline

• Afferent: Toward a structure

• Efferent: Away from a structure

• Internal (Deep): Away from the surface

• External (Superficial): Toward the surface

• Visceral: Related to internal organs

• Parietal: Related to the body wall

• Prone: Lying face down

• Supine: Lying face up

• Ipsilateral: Same side of the body

• Contralateral: Opposite side of the body

Body Planes

Major Body Planes

Body planes are imaginary lines used to divide the body for anatomical study.

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

• Coronal (Frontal) Plane: Divides the body into anterior (front) and posterior (back) parts

• Transverse (Horizontal) Plane: Divides the body into superior (upper) and inferior (lower) parts

• Oblique Plane: Divides the body at an angle

Body Cavities

Major Body Cavities and Subdivisions

• Dorsal Cavity: Houses the brain and spinal cord

  • Cranial Cavity: Contains the brain

  • Vertebral (Spinal) Cavity: Contains the spinal cord

• Ventral (Coelom) Cavity: Houses the viscera (internal organs)

  • Thoracic Cavity: Contains heart, lungs, trachea, bronchi, esophagus, thymus, thyroid

    • Pericardial Cavity: Surrounds the heart

    • Pleural Cavities: Surround the lungs

    • Mediastinum: Central compartment between pleural cavities

  • Abdominopelvic (Peritoneal) Cavity: Separated from thoracic by the diaphragm

    • Abdominal Cavity: Contains liver, stomach, spleen, pancreas, intestines

    • Pelvic Cavity: Contains bladder, rectum, reproductive organs

Membranes of Body Cavities

• Visceral Membrane: Covers organs

• Parietal Membrane: Lines body cavity

• Serous Fluid: Secreted between membranes for lubrication

Body Regions and Surface Anatomy

Major Body Regions

• Head

• Neck

• Trunk: Thorax (chest), Abdomen

• Upper Extremities: Arms

• Lower Extremities: Legs

Abdominal/Pelvic Regions and Quadrants

• Regions (9): Epigastric, Umbilical, Hypogastric, R/L Hypochondriac, R/L Lumbar, R/L Inguinal

• Quadrants (4): Right Upper (RUQ), Left Upper (LUQ), Right Lower (RLQ), Left Lower (LLQ)

Surface Anatomy Landmarks

Specific anatomical terms are used to describe surface regions of the body. For example, 'cranial' refers to the skull, 'coxal' to the hip, and 'patellar' to the kneecap.

Organ Systems of the Human Body

Classification and Functions

System Name	Major Organs	Functions
Integumentary	Skin, hair, nails, sweat and sebaceous glands	Protection, temperature regulation, vitamin D synthesis
Skeletal	Bones, tendons, ligaments, cartilage	Support, protection, movement, calcium storage, blood cell formation
Muscular	Skeletal muscles	Movement, heat production
Nervous	Brain, spinal cord, nerves	Coordination, information processing
Endocrine	Endocrine glands (e.g., thyroid, pancreas, adrenal)	Hormone secretion, homeostasis
Cardiovascular	Heart, blood vessels	Transport of nutrients, wastes, gases; electrolyte balance
Lymphatic	Bone marrow, lymph nodes, thymus, spleen	Immune response, fluid return
Respiratory	Nose, pharynx, larynx, trachea, bronchi, lungs	Gas exchange, pH balance, voice production
Urinary	Kidneys, ureters, bladder, urethra	Waste removal, blood pH and pressure regulation
Digestive	Mouth, esophagus, stomach, intestines, liver, pancreas, gall bladder	Breakdown and absorption of food
Reproductive	Testes, ovaries, associated ducts and glands	Production and transport of gametes, hormone production, fetal development (female)

Practice and Review

Sample Questions

• Which organ system controls cell function with hormones? Endocrine

• The membrane on the surface of the lung is called the: Visceral pleura

• The trachea is anterior to the esophagus.

• The organ system that returns fluid to the bloodstream and provides protection against pathogens is the lymphatic/immune system.

• The anatomical term meaning "on the other side of the body" is contralateral.

• A plane dividing the body into anterior and posterior portions is called a frontal (coronal) plane.

• The organ system including skin, hair, and nails is the integumentary system.

• The "shoulder" is the acromial region.

• The "armpit" region is the axillary region.

• The "fingers or toes" are digits.

• A transverse section is the same as a horizontal section.

• The heart lies in the thoracic cavity.

• Femoral refers to the thigh.

• The fingers are proximal to the wrist: False.

• Bones are deep to the skin: True.

• The sternum is anterior to the vertebral column: True.

• The organ system containing the liver is the digestive system.

• The urinary bladder is located in the pelvic cavity.

• The testis and ovaries are part of both the endocrine and reproductive systems: True.

• The spleen is part of the lymphatic/immune system.

Additional info:

• Understanding anatomical terminology and body organization is essential for communication in health sciences.

• Practice labeling diagrams and identifying organs in each body cavity and region for mastery.