Introduction to Human Anatomy and Physiology: Organisation of the Human Body

Course Overview

This course, Human Anatomy and Physiology (SS1020 & SS5601), introduces the foundational concepts of the structure and function of the human body. The initial weeks focus on the organisation of the human body, anatomical terminology, and the principles of homeostasis.

Intended Learning Outcomes

• Describe the organisation of human body systems.

• Identify and label major structures of each human organ system.

• List the major functions of each human organ system.

• Demonstrate and explain joint movements using anatomical terminology.

• Identify muscles involved in sport/exercise movements.

• Provide examples of sport/exercise movements, explaining types of muscle contraction.

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

Organisation of the Human Body

Levels of Organisation

The human body is organised into hierarchical levels, each with increasing complexity:

• Chemical Level: Atoms (smallest stable units of matter) combine to form molecules.

• Cellular Level: Cells are the smallest living units in the body, composed of molecules.

• Tissue Level: Tissues are groups of similar cells working together to perform specific functions.

• Organ Level: Organs consist of two or more types of tissues working together to perform complex functions.

• Organ System Level: Organ systems are groups of organs that interact to perform major body functions. Humans have 11 organ systems.

• Organism Level: The individual living being, composed of all organ systems working together.

Human Anatomy

Anatomy is the study of body structures, their composition, location, and associated structures. It is divided into:

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

• Surface Anatomy: Study of external features.

• Regional Anatomy: Study of specific body areas.

• Sectional Anatomy: Study 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: Study of structures not visible to the naked eye, including:

  • Cytology: Study of cells.

  • Histology: Study of tissues.

Human Physiology

Physiology is the study of the functions of anatomical structures, both individually and in cooperation. Subfields include:

• 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.

Organ Systems of the Human Body

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

• Integumentary System (skin, hair, nails)

• Skeletal System (bones, joints)

• Muscular System (skeletal muscles)

• Nervous System (brain, spinal cord, nerves)

• Endocrine System (glands, hormones)

• Cardiovascular System (heart, blood vessels)

• Lymphatic System (lymph nodes, lymphatic vessels)

• Respiratory System (lungs, airways)

• Digestive System (stomach, intestines)

• Urinary System (kidneys, bladder)

• Reproductive System (ovaries, testes)

Anatomical Terminology

Anatomical Position and Landmarks

• Anatomical Position: Standard reference position: body standing upright, hands at sides, palms facing forward, feet together.

• Supine: Lying face up.

• Prone: Lying face down.

• Anatomical Landmarks: Structures that can be felt or palpated, used for orientation and description.

Anatomical Regions

• Quadrants: The abdominopelvic area is divided into four quadrants (RUQ, LUQ, RLQ, LLQ) for clinical reference.

• Regions: Anatomists use nine abdominopelvic regions for more precise description.

Anatomical Directions

• Superior/Inferior: Above/below.

• Anterior (Ventral)/Posterior (Dorsal): Front/back.

• Medial/Lateral: Toward the midline/away from the midline.

• Proximal/Distal: Closer to/farther from the point of attachment.

• Superficial/Deep: Toward/away from the body surface.

Sectional (Anatomy) Planes

• Frontal (Coronal) Plane: Divides body into anterior and posterior portions.

• Sagittal Plane: Divides body into left and right portions. Midsagittal is exactly at the midline; parasagittal is offset.

• Transverse (Horizontal) Plane: Divides body into superior and inferior portions.

Body Cavities of the Trunk

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

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

• Serous Membrane: Double-layered; visceral layer covers organs, parietal layer 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 pericardial cavity (heart).

  • Abdominopelvic Cavity: Contains 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 systems respond to internal and external changes to keep variables within normal ranges.

• Autoregulation: Automatic local response in a cell, tissue, or organ.

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

Homeostatic Regulatory Mechanism

• Receptor: Detects changes (stimulus).

• Control Center: Processes information and sends instructions.

• Effector: Carries out instructions to restore balance.

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.

Example: Negative Feedback Equation

General form for negative feedback regulation:

$\text{Set Point} - \text{Current Value} = \text{Error Signal}$

The control center acts to minimize the error signal.

Summary Table: Levels of Organisation

Level	Description	Example
Chemical	Atoms and molecules	Water (H2O), proteins
Cellular	Smallest living units	Muscle cell, neuron
Tissue	Group of similar cells	Muscle tissue
Organ	Two or more tissue types	Heart, liver
Organ System	Group of organs	Cardiovascular system
Organism	All organ systems	Human being

Key Takeaways

• The human body is organised into hierarchical levels, from atoms to the whole organism.

• Understanding anatomical terminology and body organisation is essential for studying anatomy and physiology.

• Homeostasis is vital for health, maintained by feedback mechanisms involving multiple organ systems.

Additional info: This guide is based on the course outline and introductory materials for Human Anatomy and Physiology, focusing on foundational concepts for further study.