Unit 1: Introduction to the Human Body – Anatomy & Physiology Study Notes

Introduction to the Human Body

Learning Objectives

• Describe and understand the major characteristics and needs of life

• Describe the components of positive and negative feedback loops, and give examples

• Describe each of the levels of organization within the human body

• Describe the location of the major body cavities

• Properly use the terms that describe relative positions, body sections, and regions

Anatomy and Physiology

Definitions

• Anatomy: The study of the physical form and structure of living systems.

• Physiology: The study of the function of living systems.

Subdivisions of Anatomy

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

• Systemic Anatomy: Study of the structure of organ systems. This is the primary approach in this course.

• Relational Anatomy: Study of how organs relate to one another spatially (e.g., the superior vena cava is above the heart).

• Other Subdivisions: Includes cardiac anatomy, microscopic anatomy, etc.

Subdivisions of Physiology

• Pathophysiology: Study of how diseases or pathogens cause changes to a healthy system.

• Immunology: Study of the function of the immune system.

• Cardiovascular Physiology: Study of the function of the heart and blood vessels.

• Other Subdivisions: Includes renal physiology, musculoskeletal physiology, etc.

Levels of Organization in the Human Body

Overview

The human body is organized into hierarchical levels, each with increasing complexity. Understanding these levels is fundamental to anatomy and physiology.

Chemical Level

• Includes atoms, the smallest units of matter (mainly C, H, O, N, P, S).

• Atoms combine to form molecules (e.g., DNA).

• Molecule: A group of two or more atoms joined together by chemical bonds.

Cellular Level

• Cells are the basic structural and functional units of the human body.

• Cells are made up of many different molecules.

• There are many different cell types, such as smooth muscle cells.

Tissue Level

• Tissues are groups of specialized cells and the materials that surround them, working together for a common purpose.

• Four main tissue types in the body:

  • Epithelial tissue

  • Connective tissue

  • Nervous tissue

  • Muscular tissue

Organ Level

• An organ is a collection of two or more tissue types working together to perform specific functions.

• Examples: Stomach (contains epithelial, connective, and muscle tissue layers).

System Level

• Organ systems consist of related organs that share a common function.

• There are 11 major organ systems in the human body (e.g., digestive system, cardiovascular system).

• Example: The digestive system includes the esophagus, liver, stomach, pancreas, gallbladder, small intestine, and large intestine.

Organismal Level

• The organism level represents a single living individual.

• All organ systems work together to maintain life and health.

Summary Table: Levels of Organization

Level	Main Components	Example
Chemical	Atoms, molecules	DNA, water
Cellular	Cells	Smooth muscle cell
Tissue	Groups of cells	Muscle tissue
Organ	Two or more tissue types	Stomach
System	Related organs	Digestive system
Organismal	All organ systems	Human being

Key Terms

• Atom: The smallest unit of matter that retains the properties of an element.

• Molecule: Two or more atoms bonded together.

• Cell: The basic unit of structure and function in living organisms.

• Tissue: A group of similar cells performing a specific function.

• Organ: A structure composed of two or more tissue types that performs a specific function.

• Organ System: A group of organs that work together to perform complex functions.

• Organism: An individual living being.

Example: DNA Molecule

• DNA (Deoxyribonucleic Acid) is a molecule that carries genetic information in cells.

• Composed of atoms: C, H, O, N, P.

• DNA is essential for cell function and heredity.

Additional info: Later sections of the unit (not shown in these slides) typically cover body cavities, anatomical terminology, and feedback mechanisms in homeostasis.