the immune system 1.bone marrow a. review of structure and function a.located in marrow cavities of...
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The Immune System
1. Bone marrow
A. Review of structure and function
a. Located in marrow cavities of bones
b. Yellow vs. red marrow
c. Hematopoiesis
thymus gland
spleen
lymph nodes
lymphatic vessels
bone marrow
The Immune System
2. Thymus gland
a. Location
b. Consists of thymocytes, lymphocytes, and macrophages
c. Confers immunocompetence to T cells via thymosins
A. Review of structure and function
The Immune System
3. Spleen
a. Location
b. Red vs. white pulp
c. Functions
A. Review of structure and function
The Immune System
4. Lymph nodes
A. Review of structure and function
a. Locations
b. Structure
c. Functions
LYMPH IN
LYMPH IN
LYMPH IN
LYMPH OUT
capsule
trabeculum
afferent lymphatics
lymphatic nodule with germinal center
medullary cordssubcapsular
sinus
The Immune System
5. Tonsils
a. Locations
b. Functions
A. Review of structure and function
soft palate
palatine tonsils
lingual tonsils
pharyngeal tonsil
palatine tonsil
The Immune System
6. Lymphocytes and plasma cells
a. What is immunity?
b. Origin and immunocompetence
c. T cells = cell-mediated immunity
i. Cytotoxic T, helper T, suppressor T, memory T cells
ii. Fight cancer cells, transplants, bacteria, virus-laden cells
A. Review of structure and function
d. B cells = antibody-mediated immunity
i. Plasma cells, memory B cells
ii. Fight viruses and bacteria
e. Primary response vs. secondary (anamnestic) response
The Immune System
1. All lymphoid tissues decrease in mass and efficiency with age
2. Bone marrow decreases blood cell formation
3. Thymus gland
B. Age-related changes
a. Puberty to 50, lose 90% of mass, involutes with fat
b. Loss of size = loss of thymosins
c. New T cell immunocompetence decreases
The Immune System
4. B cells
B. Age-related changes
a. No decline in numbers with age
b. Decreased responsiveness to antigens
c. By 70, 85% reduction in antibody production
d. B cell changes may be the result of decreased helper T cell numbers
5. Spleen
6. Lymph nodes
7. Tonsils
The Circulatory System
1. General decrease in immune responses
C. Age-related dysfunctions
a. Decreased immune sensitivity to antigens
b. Increased autoimmunity
c. Causes
i. Decrease in precursor cells (bone marrow ?)
ii. Decreased differentiation into T- and B-cells
iii. Increased ratio of suppressor T cells
iv. Increased factors that inhibit immunity (?)
The Circulatory System
2. Age-associated T-cell defects
C. Age-related dysfunctions
a. T cell numbers decrease with age
b. Diseases normally held in check by T cells are allowed to appear
c. Immunosuppressive treatment has the same effect
3. Lymphomas
The Circulatory System
a. Human immunodifficiency virus (HIV) infects helper T cells (CD4) cells, ultimately killing them
b. This alters the ratio between helper T cells and suppressor T cells
c. Normal ratio is 2:1
d. At ratio 1:1, AIDS symptoms begin to appear
e. At ration 0.5:1, full-blown disease in progress
3. Acquired immune deficiency syndrome (AIDS)
C. Age-related dysfunctions
end
The Immune System
D. Take home messages
1. Decreased lymphoid tissue body wide
2. General decline in immunity
3. Decreased T cell numbers
4. Decreased B cell activity
5. Increased incidences of autoimmune responses