Immune System
The Immune System
CHAPTER 4
Learning objectives
• By the end of this chapter, students should be able to : i) Differentiate the three line of defense system in the human body ii) Describe the agglutination process in the case of the ABO blood group iii) Differentiate between active and passive immunization iv) Discuss the homeostatic imbalances in the immune system
Introduction
• Barriers help an animal to defend itself from the many dangerous pathogens it may encounter
• The immune system recognizes foreign bodies and responds with the production of immune cells and proteins • Two major kinds of defense have evolved: a) innate immunity b) acquired immunity
Innate immunity
• Also known as external defenses • It involves nonspecific responses to pathogens • Nonspecific defense mechanism can be divided into two lines. • The first lines of defenses are barriers at body surfaces. They help fight undistinguishable pathogens that enter our body.
Barriers at body surface
1) Skin
Oil and sweat gland secretions acidify the skin. pH at about 3.5-5 (discourage bacterial growth) The skin itself is a tough and intact barrier of dead skin cells that most bacteria and viruses cannot penetrate.
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2) Protective fluids - The body secretes protective fluid tha trap foreign agents - Lysozyme - enzyme that attacks the cell wall of many bacteria - The body also excretes several body fluids such as saliva, tears and perspiration containing protective substance
3) Defenses of the respiratory system - The hair in our nostrils filters the incoming air. - Mucous membrane - traps most microbes and dirt that get past the nasal filter. - Cillia on cells lining the tubes sweep the mucous upward and downward out of the system.
4) Defenses of the digestive system • Stomach acids kill many bacteria that enter the stomach with food, • Lysozyme in saliva
5) Defenses of the urogenital tract • Low pH - kills bacteria from the urinary tract. This is
CHAPTER 4
Learning objectives
• By the end of this chapter, students should be able to : i) Differentiate the three line of defense system in the human body ii) Describe the agglutination process in the case of the ABO blood group iii) Differentiate between active and passive immunization iv) Discuss the homeostatic imbalances in the immune system
Introduction
• Barriers help an animal to defend itself from the many dangerous pathogens it may encounter
• The immune system recognizes foreign bodies and responds with the production of immune cells and proteins • Two major kinds of defense have evolved: a) innate immunity b) acquired immunity
Innate immunity
• Also known as external defenses • It involves nonspecific responses to pathogens • Nonspecific defense mechanism can be divided into two lines. • The first lines of defenses are barriers at body surfaces. They help fight undistinguishable pathogens that enter our body.
Barriers at body surface
1) Skin
Oil and sweat gland secretions acidify the skin. pH at about 3.5-5 (discourage bacterial growth) The skin itself is a tough and intact barrier of dead skin cells that most bacteria and viruses cannot penetrate.
-
-
2) Protective fluids - The body secretes protective fluid tha trap foreign agents - Lysozyme - enzyme that attacks the cell wall of many bacteria - The body also excretes several body fluids such as saliva, tears and perspiration containing protective substance
3) Defenses of the respiratory system - The hair in our nostrils filters the incoming air. - Mucous membrane - traps most microbes and dirt that get past the nasal filter. - Cillia on cells lining the tubes sweep the mucous upward and downward out of the system.
4) Defenses of the digestive system • Stomach acids kill many bacteria that enter the stomach with food, • Lysozyme in saliva
5) Defenses of the urogenital tract • Low pH - kills bacteria from the urinary tract. This is