The immune system defends the body against infectious diseases and foreign substances. It is made up of several organs and cell types that work together, including the white blood cells, lymph nodes, spleen, bone marrow, thymus, and tonsils. The main functions of the immune system are to recognize foreign substances in the body, destroy and remove them, and develop immunological memory so the body can recognize and fight them off quickly if exposed again in the future.

1. Immune system -
Immunity

2. Keywords • Pathogen
• Microorganism
• Pus
• Suspected specif cause
• Culture/cultured specimen
• Host
• Postulates
• Vaccination
• Pasteurization
• Memory cells
• Antibodies
• Recovery
• Immune response
• Immune system
• Epidemic
• Pandemic

3. Objectives
State the parts of the immune
system
State the function of each part
Differentiate the 3 types of
immunity( compare)
What evidence established the
cause of infectious diseases?
How do vaccines work?
Explain with evidence stating
the name of the scientist.

5. What is the main function of
immune system?
What is immune system?
Learning objectives: an introduction to the immune system.​
What parts of the body that make
up the immune system
?

6. What is the immune
system?
• The function of the body’s immune
system is to ‘fight’ diseases that might
enter the body. It does this by
producing antibodies which fight
infections and help the body to stay
healthy.
The immune system is the body's
defense against infections. The immune
(pronounced: ih-MYOON) system
attacks germs and helps keep us
healthy.

7. Parts of the immune system
• The white blood cells
• The lymph nodes
• The appendix
• Bone marrow
• The tonsils and adenoids
• The thymus
• The spleen
• Payer’s patch (in the intestines)

8. Lymph nodes
• Small, bean-shaped glands.
• They produce and store cells that fight
infection and disease.
• When the body is fighting infection,
lymph nodes can become bigger and
feel sore.
• Part of the lymphatic system.

9. Spleen
• Contains white blood cells that fight
infection or disease.
• Helps control the amount of blood in the
body and disposes of old or damaged blood
cells.

10. Types of
immunity
• Humans have three types of immunity — innate,
adaptive, and passive:
• Innate immunity: Everyone is born with innate (or
natural) immunity, a type of general protection. For
example, the skin acts as a barrier to block germs from
entering the body. And the immune system recognizes
when some invaders are foreign and could be dangerous.
• Adaptive immunity: Adaptive (or active) immunity
develops throughout our lives. We develop adaptive
immunity when we're exposed to diseases or when we're
immunized against them with vaccines.
• Passive immunity: Passive immunity is "borrowed" from
another source and it lasts for a short time. For example,
antibodies in a mother's breast milk give a baby
temporary immunity to diseases the mother has been
exposed to.

11. Bone marrow and thymus
Bone marrow:
• Soft tissue in the centre of the bones.
• White blood cells are made here.
Thymus:
• A small organ is where the T-cells
develop.

12. What are white blood cells?
+ Cells of the immune system that protect the
body against infectious diseases and foreign
bodies.
+ There are two main types of white blood cells:
+ Phagocytes
+ Lymphocytes

13. These cells destroy any disease-causing
organisms that enter the body. They do this by
surrounding and ingesting or engulfing the
bacterial cells
Phagocytes Lymphocytes
+ These white blood cells start in the bone marrow.
There are two types:
• B-lymphocytes (B-cells) which make antibodies to
fight an infection.
• T-lymphocytes (T-cells) which attack the virus,
infection or foreign cells.

14. Immune
Cells
(Types)
Many cells and organs work together to protect the body. White blood cells, also
called leukocytes (pronounced: LOO-kuh-sytes), play an important role in the immune system.
Some types of white blood cells, called phagocytes (pronounced: FAH-guh-sytes), chew up invading
organisms. Others, called lymphocytes (pronounced: LIM-fuh-sytes), help the body remember the
invaders and destroy them.
One type of phagocyte is the neutrophil (pronounced: NOO-truh-fil), which fights bacteria. When
someone might have bacterial infection, doctors can order a blood test to see if it caused the body to
have lots of neutrophils. Other types of phagocytes do their own jobs to make sure that the body
responds to invaders.
The two kinds of lymphocytes are B lymphocytes and T lymphocytes. Lymphocytes start out in the
bone marrow and either stay there and mature into B cells, or go to the thymus gland to mature into
T cells. B lymphocytes are like the body's military intelligence system — they find their targets and
send defenses to lock onto them. T cells are like the soldiers — they destroy the invaders that the
intelligence system finds they find their targets and send defenses to lock onto them. T cells are like
the soldiers — they destroy the invaders that the intelligence system finds.

16. Exit ticket
Look at the list of these organs and
decide if they’re part of the immune
system:
Lymph nodes
Cardiac Muscles
Spleen
Bone Marrow
Joints
Tonsils