Organisation of the Human Body

Introduction to Anatomy and Physiology

Anatomy and physiology are foundational sciences in understanding the structure and function of the human body. Anatomy focuses on the identification and description of body structures, while physiology explains how these structures function individually and collectively.

• Anatomy: The study of body structures, their composition, location, and associated features.

• Physiology: The study of the functions and mechanisms of anatomical structures.

Example: Studying the heart's chambers (anatomy) and how they pump blood (physiology).

Branches of Anatomy

• Gross (Macroscopic) Anatomy: Examines large, visible structures.

• Surface Anatomy: Study of external features.

• Regional Anatomy: Focuses on specific body areas.

• Sectional Anatomy: Analysis of cross-sections.

• Systemic Anatomy: Study of organ systems.

• Clinical Anatomy: Application to medical specialties.

• Developmental Anatomy: Study from conception to adulthood, including embryology.

• Microscopic Anatomy: Examines cells (cytology) and tissues (histology).

Branches of Physiology

• Cell Physiology: Functions of cells.

• Organ Physiology: Functions of specific organs.

• Systemic Physiology: Functions of organ systems.

• Pathological Physiology: Effects of diseases on organs or systems.

Levels of Organisation in the Human Body

The human body is organized into hierarchical levels, each building upon the previous to form a complete organism.

• Chemical Level: Atoms and molecules, the smallest units of matter.

• Cellular Level: Cells, the basic living units of the body.

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

• Organ Level: Structures composed of two or more tissue types working together.

• Organ System Level: Groups of organs that perform related functions. Humans have 11 organ systems.

• Organism Level: The complete living individual.

Organ Systems of the Human Body

The human body contains 11 major organ systems, each with specific functions essential for survival and homeostasis.

• Integumentary System

• Skeletal System

• Muscular System

• Nervous System

• Endocrine System

• Cardiovascular System

• Lymphatic System

• Respiratory System

• Digestive System

• Urinary System

• Reproductive System

Example: The muscular system enables movement, while the skeletal system provides structural support.

Anatomical Terminology

Anatomical Position and Landmarks

The anatomical position is the standard reference for describing body locations and directions: the body stands upright, facing forward, arms at the sides with palms facing forward, and feet together.

• Supine: Lying face up.

• Prone: Lying face down.

Anatomical landmarks are structures that can be felt or palpated, aiding in the identification of body regions.

Anatomical Regions

To describe locations, two main methods are used:

• Quadrants: The abdominopelvic area is divided into four quadrants (RUQ, LUQ, RLQ, LLQ) using imaginary lines intersecting at the umbilicus.

• Regions: The abdominopelvic area can also be divided into nine regions for more precise localization.

Example: Tenderness in the RLQ may indicate appendicitis; RUQ pain may suggest gallbladder or liver issues.

Anatomical Directions

Directional terms provide clarity in describing the location of structures:

• Superior (cranial): Toward the head.

• Inferior (caudal): Toward the feet.

• Anterior (ventral): Toward the front.

• Posterior (dorsal): Toward the back.

• Medial: Toward the midline.

• Lateral: Away from the midline.

• Proximal: Closer to the point of attachment.

• Distal: Farther from the point of attachment.

• Superficial: Toward the surface.

• Deep: Away from the surface.

Sectional (Anatomy) Planes

Sectional planes are used to describe internal views of the body:

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

• Sagittal plane: Divides the body into left and right portions. The midsagittal plane is at the midline; the parasagittal plane is offset from the midline.

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

Body Cavities of the Trunk

Body cavities are closed, fluid-filled spaces lined by serous membranes, housing and protecting internal organs (viscera).

• Functions: Protect organs from shocks, allow changes in size/shape, reduce friction via serous fluid.

• Serous Membrane: Has two layers: visceral (covers organs) and parietal (lines cavity walls).

Major Body Cavities

• Ventral Body Cavity (Coelom): Subdivided by the diaphragm into:

  • Thoracic Cavity: Contains right and left pleural cavities (lungs) and the pericardial cavity (heart).

  • Abdominopelvic Cavity: Contains the peritoneal cavity (abdominal organs), abdominal cavity (digestive organs), and pelvic cavity (reproductive organs, rectum, bladder).

Homeostasis in the Human Body

Homeostasis is the maintenance of a stable internal environment, essential for survival. It involves dynamic equilibrium, where physiological processes limit fluctuations to keep variables near a set point.

• Failure to maintain homeostasis leads to illness or death.

• Systems integration: Organ systems work together to maintain homeostasis.

Mechanisms of Homeostatic Regulation

• Autoregulation: Automatic response at the cell, tissue, or organ level.

• Extrinsic Regulation: Responses controlled by the nervous and endocrine systems.

Components of a Homeostatic Regulatory Mechanism

• Receptor: Detects changes (stimulus).

• Control Center: Processes information and sends instructions.

• Effector: Carries out the response.

Feedback Loops

• Negative Feedback: The effector's response negates the stimulus, restoring homeostasis. Example: Regulation of body temperature.

• Positive Feedback: The effector's response amplifies the stimulus, moving the body away from homeostasis to complete a process quickly. Example: Blood clotting after injury.

Table: Comparison of Negative and Positive Feedback

Summary of Intended Learning Outcomes

• Describe the organisation of human body systems.

• Identify and label major structures of each organ system.

• List major functions of each organ system.

• Demonstrate and explain joint movements using anatomical terminology.

• Identify muscles involved in sport/exercise movements.

• Provide examples of muscle contractions in sport/exercise.

• Articulate the role of each organ system in human performance, health, and fitness.

Additional info: For further study, refer to Martini, F.H., Nath, J.L., & Bartholomew, E.F. (2018). Fundamentals of Anatomy & Physiology (11th ed.). Global Edition. Pearson.