This document provides an overview of transport across the cell membrane. It begins with an introduction to the importance of transport for cellular function and maintenance. It then describes the key components and functions of the cell membrane. The document outlines the different mechanisms of transport, including passive transport mechanisms like diffusion, osmosis, and facilitated diffusion that do not require energy. It also discusses active transport mechanisms like primary active transport, endocytosis, and exocytosis that move molecules against their concentration gradient with the use of cellular energy. The objectives are to describe the cell membrane, explain the different transport processes, and discuss the clinical implications of transport across the cell membrane.

1. TRANSPORT
ACROSS THE
CELL MEMBRANE
BY
RAJAH AMINA SULEIMAN
(RN, RM, RNE, BNSC., MSC)

2. OUTLINE
• INTRODUCTION
• CELL MEMBRANE
• DIFFUSION
• OSMOSIS
• FILTRATION
• FACILITATED DIFFUSION
• ACTIVE TRANSPORT
• ENDOCYTOSIS
• EXOCYTOSIS

3. LEARNING OBJECTIVES
AT THE END OF THIS LESSON, THE STUDENT SHOULD BE ABLE TO:
• DESCRIBE THE CELL MEMBRANE
• ENUMERATE THE FUNCTIONS OF THE CELL MEMBRANE
• EXPLAIN THE PROCESS OF DIFFUSION
• ELABORATE ON OSMOSIS
• LIST AND EXPLAIN THE TYPES OF ACTIVE TRANSPORT
• DISCUSS THE CLINICAL IMPLICATION OF TRANSPORT ACROSS THE CELL
MEMBRANE

4. INTRODUCTION
Transport across the cell membrane is essential
for cellular life.
As cells proceed through their life cycle, a vast
amount of exchange is necessary to maintain
function.
The cells require nutrients and also need to
remove waste products, the cells achieve these by
means of transport mechanisms across the cell
membrane.

5. THE CELL MEMBRANE
The cell membrane is a thin membrane that forms
the outermost layer of a cell, and it is also called
the plasma membrane.
This membrane separates the fluid outside the
cell called extracellular fluid (ECF) and the fluid
inside the cell called intracellular fluid (ICF).
The cell membrane is a semipermeable
membrane.

6. THE CELL MEMBRANE
The cell membrane is made of:
• Double layer phospholipids
• Proteins
• Carbohydrate
The phospholipid layer consists of a polar ‘head’
end, which is hydrophilic (water loving), and fatty
acid ‘tails’, which are hydrophobic (water hating).

9. FUNCTIONS OF THE CELL MEMBRANE
 Protection
 Selective permeability
 Absorption
 Excretion
 Exchange of gases
 Maintenance of shape and size of the cell

10. PASSAGE ACROSS THE MEMBRANE
 There are two major ways that molecules can be
moved across a membrane, and the distinction
has to do with whether or not cell energy is used.
 Passive mechanisms like diffusion use no energy
 While active transport requires energy to get
done.

11. PASSIVE TRANSPORT
 When molecules pass in and out of a cell
membrane without the use of cellular energy it
is called a passive transport system. This
includes:
• Diffusion
• Osmosis
• filtration
• Facilitated diffusion

12. SIMPLE DIFFUSION
 Diffusion is a process of passive transport in
which molecules move from an area of higher
concentration to one of lower concentration.
Example: oxygen, carbondioxide and small fatty
acids.

14. OSMOSIS
 Osmosis is a process where water moves from an
area of high water concentration to low water
concentration through a selective permeable
membrane.

16. FILTRATION
 Filtration is a process where small substances are
forced through a semipermeable membrane. The
cell membrane acts as a filter, controlling the
entrance and exit of small molecules.

17. FACILITATED DIFFUSION
 Facilitated diffusion is a process by which
molecules are transported across the plasma
membrane with the help of membrane proteins.
 This occurs through protein channels (e.g. ions)
or carrier proteins (e.g. glucose, amino acids).

19. ACTIVE TRANSPORT
 Active transport is the movement of molecules across a
cell membrane from a region of lower concentration to a
region of higher concentration against the concentration
gradient.
 This system requires energy to move
substances in and out of a cell. The active
transport systems include:
 Primary active transport
 Endocytosis
 Exocytosis

20. PRIMARY ACTIVE TRANSPORT
 This involves movement of substances against a
concentration gradient from an area of lower to
higher concentration.
 Example: Sodium-potassium pump, which helps
to maintain the cell potential.

22. ENDOCYTOSIS
 Endocytosis is the process by which cells take in
molecules such as proteins from outside the
cell by swallowing them with their cell
membranes.
 Examples: Pinocytosis (cell drinking) and
phagocytosis

24. EXOCYTOSIS
 Exocytosis is a process for moving items from
the cytoplasm of the cell to the outside.

25. CLINICAL IMPLICATION

27. CREDITS: This presentation template was created by
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