The Body’s
Defenses
The 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.
Functions of Lymphatic System
• Antigen: proteins that body recognizes as foreign
(pathogens, foreign cells, or cancer cells)
• David Vetter
• https://www.youtube.com/watch?v=-G_SW8LmidA
The boy in a bubble
How does the body combat disease?
Specific Immunity aka: acquired immunity
• Direct contact with antigens and intimate a response that
marks and destroys antigens
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
Non-specific Immunity
• Non-specific
• Mechanical Barriers
• Specific
• Cell Mediated immunity
• T cells
• Humoral immunity
• B cells which stimulate Ab
production from plasma cells
• Antibodies: proteins capable of
interactive with antigens
• 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
Body’s Defenses: concept map
• 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
Blood Cells: 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
Granular 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
Nongranular Leukocytes
• 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
White Blood Cell Disorders
• View following cells for practice
Practice Identifying
Leukocytes
• Match the cell types with the descriptions and microscope
images
WBC: Matching
Neutrophils
40-70%
Phagocytizes
primarily bacteria
Eosinophils
1-4%
Phaocytizes and
destroys antigenantibody
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
macrophagephagocytizes
bacteria and
viruses
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.
Exit Slip: turn in as you leave