Module Two
,Knowledge Acquisition Figures 2-1 and 2-2 illustrate a human body cell with its typical structures.
Most cells have many of the structures shown in this diagram.
Cells and Homeostasis
Cells carry out lots of functions that help each system contribute to the homeostasis of the A human cell is divided into three main parts:
entire body. At the same time, all cells share key structures and functions that support their • Plasma membrane
intense activity. • Cytoplasm
• Nucleus
Atoms and molecules are combined into about 200 different types of cells. All cells arise
from existing cells in which one cell divides into two identical cells. Different types of cells
Cytoplasm Nucleus Plasm
fulfill unique roles that support homeostasis and contribute to the many functional
capabilities of the human organism. mem
Cell structure and function are closely linked. Cells carry out a dazzling array of chemical
reactions to create and maintain life processes – in part, by isolating specific types of
chemical reactions within specialized cellular structures. Although isolated, the chemical
reactions are coordinated to maintain life in a cell, tissue, organ, system, and organism.
Source: Principles of Anatomy and Physiology by Brian H. Derrickson and Gerard J. Tortora
Section 2-1: Parts of a Human Cell
What is expected of you from this section?
At the end of this section, you are expected to:
1. Describe the three main parts of a human cell.
Where do you acquire knowledge to meet expectations?
1. .
2. Course Notes 2-1
Course Notes 2-1
The average adult human body consists of more than 100 trillion cells.
Cells are the basic, living, structural, and functional units of the body.
Figure 2-1. A typical human cell. Source: Principles of Anatomy and Physiology
The scientific study of cells is called cell biology or cytology. Derrickson and Gerard J. Tortora
,Figure 2-2. Typical structures found in human body cells. The cell is the basic living, structural, and functional unit of the body. Source: Principles of Anatomy and
Physiology by Brian H. Derrickson and Gerard J. Tortora
, Plasma Membrane Self-Assessment 2-1
• The plasma membrane forms the cell’s flexible outer surface, separating the cell’s 1. List the three main parts of a human cell and explain their functions.
internal environment (everything inside the cell) from the external environment
(everything outside the cell).
• It is also known as the cell membrane or plasmalemma.
• It is a selective barrier that regulates the flow of materials into and out of a cell.
• Due to this selectivity, it helps establish and maintain the appropriate environment for
normal cellular activities.
• It also plays a key role in communication among cells and between cells and their
external environment.
Cytoplasm
• The cytoplasm (-plasm = formed or molded) consists of all the cellular contents between
the plasma membrane and the nucleus.
• It has two components: cytosol and organelles.
• Cytosol
o Fluid portion of cytoplasm
o Also called intracellular fluid
o It contains water, dissolved solutes, and suspended particles.
• Organelles
o Within the cytosol are several different types of organelles (or-gan-ELZ = little
organs).
o Each type of organelle has a characteristic shape and specific functions.
o Examples include the cytoskeleton, ribosomes, endoplasmic reticulum, Golgi
complex, lysosomes, peroxisomes, and mitochondria.
Nucleus
• The nucleus (nut kernel) is a large organelle that houses most of a cell’s DNA.
• Found within the nucleus are the 46 human chromosomes.
• A chromosome (chromo- = colored) is a single molecule of DNA associated with several
proteins.
• Each chromosome contains thousands of hereditary units called genes that control most
aspects of cellular structure and function.
,Knowledge Acquisition Figures 2-1 and 2-2 illustrate a human body cell with its typical structures.
Most cells have many of the structures shown in this diagram.
Cells and Homeostasis
Cells carry out lots of functions that help each system contribute to the homeostasis of the A human cell is divided into three main parts:
entire body. At the same time, all cells share key structures and functions that support their • Plasma membrane
intense activity. • Cytoplasm
• Nucleus
Atoms and molecules are combined into about 200 different types of cells. All cells arise
from existing cells in which one cell divides into two identical cells. Different types of cells
Cytoplasm Nucleus Plasm
fulfill unique roles that support homeostasis and contribute to the many functional
capabilities of the human organism. mem
Cell structure and function are closely linked. Cells carry out a dazzling array of chemical
reactions to create and maintain life processes – in part, by isolating specific types of
chemical reactions within specialized cellular structures. Although isolated, the chemical
reactions are coordinated to maintain life in a cell, tissue, organ, system, and organism.
Source: Principles of Anatomy and Physiology by Brian H. Derrickson and Gerard J. Tortora
Section 2-1: Parts of a Human Cell
What is expected of you from this section?
At the end of this section, you are expected to:
1. Describe the three main parts of a human cell.
Where do you acquire knowledge to meet expectations?
1. .
2. Course Notes 2-1
Course Notes 2-1
The average adult human body consists of more than 100 trillion cells.
Cells are the basic, living, structural, and functional units of the body.
Figure 2-1. A typical human cell. Source: Principles of Anatomy and Physiology
The scientific study of cells is called cell biology or cytology. Derrickson and Gerard J. Tortora
,Figure 2-2. Typical structures found in human body cells. The cell is the basic living, structural, and functional unit of the body. Source: Principles of Anatomy and
Physiology by Brian H. Derrickson and Gerard J. Tortora
, Plasma Membrane Self-Assessment 2-1
• The plasma membrane forms the cell’s flexible outer surface, separating the cell’s 1. List the three main parts of a human cell and explain their functions.
internal environment (everything inside the cell) from the external environment
(everything outside the cell).
• It is also known as the cell membrane or plasmalemma.
• It is a selective barrier that regulates the flow of materials into and out of a cell.
• Due to this selectivity, it helps establish and maintain the appropriate environment for
normal cellular activities.
• It also plays a key role in communication among cells and between cells and their
external environment.
Cytoplasm
• The cytoplasm (-plasm = formed or molded) consists of all the cellular contents between
the plasma membrane and the nucleus.
• It has two components: cytosol and organelles.
• Cytosol
o Fluid portion of cytoplasm
o Also called intracellular fluid
o It contains water, dissolved solutes, and suspended particles.
• Organelles
o Within the cytosol are several different types of organelles (or-gan-ELZ = little
organs).
o Each type of organelle has a characteristic shape and specific functions.
o Examples include the cytoskeleton, ribosomes, endoplasmic reticulum, Golgi
complex, lysosomes, peroxisomes, and mitochondria.
Nucleus
• The nucleus (nut kernel) is a large organelle that houses most of a cell’s DNA.
• Found within the nucleus are the 46 human chromosomes.
• A chromosome (chromo- = colored) is a single molecule of DNA associated with several
proteins.
• Each chromosome contains thousands of hereditary units called genes that control most
aspects of cellular structure and function.
