ANATOMY & PHYSIOLOGY – UNIT I
CHAPTER 2: CELL – STRUCTURE AND FUNCTIONS
(For General Nursing & Midwifery – GNM 1st Year)
INTRODUCTION
After understanding how the human body is organized, the next important step is to understand the cell. The cell is the starting point of life. Every tissue, organ, and system in the human body is made up of cells.
For nursing students, understanding the cell is very important because disease begins at the cellular level. Infection, inflammation, healing, and even cancer are related to changes in cells. If the basics of the cell are clear, many medical conditions become easier to understand later.
DEFINITION OF CELL
A cell is defined as the basic structural and functional unit of life.
This means:
- All living organisms are made up of cells
- Cells perform all vital functions of the body
👉 Without cells, there is no life.
DISCOVERY OF CELL
- The cell was first discovered by Robert Hooke in 1665
- He observed thin slices of cork under a microscope and named the small compartments as “cells”
TYPES OF CELLS
Cells in the human body are of different types depending on their function.
Some common examples are:
- Nerve cells – carry messages
- Muscle cells – help in movement
- Blood cells – transport oxygen and fight infection
- Epithelial cells – protect body surfaces
Each type of cell is specialized to perform a particular function.
STRUCTURE OF A CELL
A typical human cell consists of three main parts:
- Cell membrane
- Cytoplasm
- Nucleus
Each part has a specific structure and function.
1. CELL MEMBRANE
The cell membrane is the thin outer covering of the cell.
Functions of Cell Membrane
- Gives shape to the cell
- Protects the cell
- Controls entry and exit of substances
- Maintains internal environment of the cell
👉 It acts like a gatekeeper of the cell.
2. CYTOPLASM
The cytoplasm is a jelly-like substance present inside the cell membrane.
It contains:
- Cell organelles
- Water, proteins, and enzymes
Functions of Cytoplasm
- Site for many chemical reactions
- Holds cell organelles in position
- Helps in transport within the cell
CELL ORGANELLES AND THEIR FUNCTIONS
Cell organelles are small structures present in the cytoplasm, each performing a specific function.
MITOCHONDRIA
- Known as the powerhouse of the cell
- Produces energy (ATP)
Function:
Provides energy required for all cell activities.
ENDOPLASMIC RETICULUM (ER)
There are two types:
- Rough ER – has ribosomes
- Smooth ER – no ribosomes
Functions:
- Rough ER helps in protein synthesis
- Smooth ER helps in lipid synthesis and detoxification
RIBOSOMES
- Small granular structures
- Present on rough ER or free in cytoplasm
Function:
Protein synthesis
GOLGI APPARATUS
- Also called Golgi body
Functions:
- Modifies and packages proteins
- Helps in secretion
- Forms lysosomes
LYSOSOMES
- Known as the suicide bags of the cell
Functions:
- Destroy waste materials
- Break down damaged organelles
- Help in cell defense
CENTROSOME
- Important during cell division
Function:
Helps in formation of spindle fibers during cell division
3. NUCLEUS
The nucleus is the control center of the cell.
It contains:
- Genetic material (DNA)
- Chromosomes
Functions of Nucleus
- Controls all cell activities
- Stores genetic information
- Helps in cell division
👉 Cells without a nucleus (like RBCs) have limited life span.
CELL DIVISION
Cell division is the process by which new cells are formed.
Types of Cell Division
1. Mitosis
- Occurs in body (somatic) cells
- Helps in growth and repair
2. Meiosis
- Occurs in reproductive cells
- Produces gametes (sperm and ovum)
IMPORTANCE OF CELL IN NURSING
Understanding the cell helps nurses to:
- Understand disease process
- Know how healing occurs
- Understand infection and immunity
- Provide better patient care
Many medical terms like inflammation, degeneration, and regeneration are related to cellular changes.
KEY POINTS FOR EXAM
- Cell is the basic unit of life
- Mitochondria = powerhouse
- Lysosomes = suicide bags
- Ribosomes = protein synthesis
- Nucleus = control center
FINAL NOTE FOR STUDENTS
Do not try to memorize everything at once. First, understand the structure, then learn the functions. Once the cell is clear, tissues and systems will become easy.
👉 Previous Chapter: Anatomical Terms and Organization of the Human Body – GNM
👉 Practice MCQs: MCQs on Cell – Structure and Functions (GNM)
👉 Next Chapter: Tissues – Types and Functions (GNM)