Introduction to Human Anatomy and Physiology
Anatomy is the study of the structure of living organisms, while Physiology is the study of the functions those structures perform. In pharmacy, understanding the human body at this level is essential — it explains how drugs are absorbed, distributed, and why certain conditions arise in specific tissues or organs.
The Cell: Basic Unit of Life
All living organisms are made of cells. The human body contains trillions of cells, each performing specialized functions. Understanding cell structure is the foundation of Anatomy and Physiology.
Key Cell Organelles and Their Functions
| Organelle | Function |
|---|---|
| Cell Membrane | Controls entry and exit of substances; site of receptor proteins |
| Nucleus | Contains DNA; controls cellular activities and protein synthesis |
| Mitochondria | Produces ATP (energy) through cellular respiration |
| Endoplasmic Reticulum (ER) | Rough ER: protein synthesis; Smooth ER: lipid synthesis and detox |
| Golgi Apparatus | Modifies, packages, and secretes proteins |
| Lysosomes | Contain digestive enzymes; break down waste materials |
| Ribosomes | Site of protein synthesis |
Levels of Structural Organization
The human body is organized into increasingly complex levels:
- Chemical level — Atoms and molecules (e.g., water, proteins, lipids)
- Cellular level — The smallest unit of living matter
- Tissue level — Groups of similar cells performing a common function
- Organ level — Two or more tissue types working together (e.g., heart, liver)
- Organ System level — Related organs working toward a common goal
- Organism level — All systems working together as a whole human being
The Four Primary Tissue Types
1. Epithelial Tissue
Covers body surfaces and lines hollow organs. Classified by shape (squamous, cuboidal, columnar) and layers (simple or stratified). Functions include protection, secretion, and absorption.
2. Connective Tissue
The most abundant and widely distributed tissue. Includes bone, cartilage, blood, and adipose tissue. Main function is to support, bind, and protect other tissues.
3. Muscle Tissue
Responsible for movement. Three types:
- Skeletal muscle — Voluntary, striated, attached to bones
- Cardiac muscle — Involuntary, striated, found only in the heart
- Smooth muscle — Involuntary, non-striated, found in walls of hollow organs
4. Nervous Tissue
Found in the brain, spinal cord, and nerves. Composed of neurons (which transmit signals) and neuroglia (supporting cells). This tissue is key to understanding how drugs affecting the CNS work.
Homeostasis: The Body's Balancing Act
Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes. Examples include regulation of body temperature (37°C), blood pH (7.35–7.45), and blood glucose levels. Most diseases represent a failure of homeostatic mechanisms — and many drugs work by restoring homeostasis.
Exam Tips for Unit 1
- Draw and label a detailed cell diagram — this is a common long-answer question.
- Know the differences between the four tissue types with examples.
- Understand homeostasis with a feedback loop diagram (negative vs. positive feedback).
- Learn the levels of structural organization in order — often asked as a short note.