The Body’s DefensesThe lymphatic System

Functions of Lymphatic System

• Help protect body from infection by disease causing agents

• Must detect a wide variety of agents, known as pathogens, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue.

• Antigen: proteins that body recognizes as foreign (pathogens, foreign cells, or cancer cells)

The boy in a bubble

• David Vetter• https://www.youtube.com/watch?v=-G_SW8LmidA

How does the body combat disease?

Specific immunity

Specific Immunity aka: acquired immunity• Direct contact with antigens and intimate a response that

marks and destroys antigens

Non-specific Immunity

NON-specific immunity (innate immunity)• cells of the innate system recognize and respond to

pathogens in a generic way, but, unlike the adaptive immune system (which is found only in vertebrates), it does not confer long-lasting or protective immunity to the host

Body’s Defenses: concept map

• Specific • Cell Mediated immunity• T cells

• Humoral immunity• B cells which stimulate

Ab production from plasma cells

• Antibodies: proteins capable of interactive with antigens

• Non-specific• Mechanical Barriers• Mucous membranes, GI, eyes,

Respiratory system, and skin

• WBC• Neutrophils Natural killer cell• monocytes• Lymphocytes• Eosinophils• basophils

• Inflammatory responses• Histamine reactions• chemical factors released by injured

cells and serves to establish a physical barrier against the spread of infection, and to promote healing of any damaged tissue following the clearance of pathogens

Blood Cells: Leukocytes

• White Blood Cells• Approximately 5,000 to

9,000 per cubic mm of blood

• Defends body from pathogens

• Divided into two types• Granular Leukocytes• Nongranular Leukocytes

Granular Leukocytes

• Neutrophils• Phagocyte; 1st to arrive at injury

site• Releases chemicals to degrade

pathogen and attract other phagocytes

• Hallmark of ACUTE infections

• 50-70% of WBC’s• Nucleus is segmented into 4-5

lobes

Granular Leukocytes

• Eosinophils• Phagocytes of antibody

marked pathogens• Mediate for allergies• Reduces inflammation• Defend against large parasites• Strong chemotaxis• Attraction to injury and infection

• 2-4% of WBC’s• Nucleus is segmented into 2

lobes• Red Granules

Granular Leukocytes

• Basophils• Functions in allergic

response by releasing histamine

• Secretes heparin• Anticoagulant

• Rare, less than 1%

• Deep blue granules• Difficult to see nucleus

Nongranular Leukocytes

Lymphocytes• Part of acquired immune

response… specific defense against bacteria and viruses

• Forms different types of cells:• T-Cells: destroys foreign cells

• B-Cells: differentiate into plasma cells which secrete specific antibodies

• NK Cells: prevent cancer

• 20-30% of WBC’s • Large round nucleus

Nongranular Leukocytes

• Monocytes• Phagocytes• Scavengers • Fixed vs. Free• Releases chemicals to

attract other WBCs and fibroblasts (scar tissue)

• 2-8% of WBC• Large, kidney bean shaped

nucleus

White Blood Cell Disorders

• Leukopenia• Low WBC (> 5,000 mm3)• May accompany:• Typhoid fever, Flu, Chicken Pox, AIDS

• Leukocytosis• High WBC• Indicates acute infection

• Leukemia• Extremely high WBC• Malignant

Practice Identifying Leukocytes

• View following cells for practice

WBC: Matching

• Match the cell types with the descriptions and microscope images

 Neutrophils

  

40-70%Phagocytizes

primarily bacteria

 Eosinophils

 1-4%

Phaocytizes and destroys antigen-

antibody complexes

  

Basophils 

0-1% Releases histamine

when stimulated

Lymphocytes 

20-45%B type produces

antibodies in blood and lymp; T types

kills virus containing cells

 Monocyte

 4-8%

Becomes macrophage-phagocytizes bacteria and

viruses

Exit Slip: turn in as you leave

1. Pretend your friend was absent from class today. She/he asks you to explain the lesson.• On your own paper, tell him/her about your lesson today.

Be sure to relate to the learning target.

2. Include one new thing you learned.

3. Share something that you would like me to go over in class tomorrow to help you learn material/concept better.