Elements of Host Protective Response 8/18

blood content in humans

composes 1/12 of body weight and is 5-6 liters

blood composititon

55% plasma and 45% cells

three major types/formed elements of blood cells

red blood cells (RBCs)/erythrocytes, white blood cells/leukocytes (WBCs), platelets/thrombocytes

5 types of white blood cells

1. monocyte (larger)

2. lymphocyte (smaller)

3. eosinophil (granulocyte)

4. basophil (granulocyte)

5. neutrophil (granulocyte)

function of red blood cells

carry O2 from the lungs to the body's tissues and carry CO2 from the tissues to the lungs

function of white blood cells

fight infections and diseases

function of platelets

form blood clots and control bleeding

immunity

usually refers to protection against infectious pathogens; reactions to some non-infectious substances

types of non-infectious substances that can cause immune reactions

allergy - harmless environmental molecules

tumor immunity - tumors

autoimmunity - one's own molecules

components of immune system

cells, tissues, molecules

immune response

the reaction of immune cells and molecules to infectious pathogens and other substances

5 major roles of the immune system

1. defense against infections

2. defense against tumors

3. control of tissue regeneration and scarring

4. cell injury and pathologic inflammation

5. recognition of and injury to tissue grafts and newly introduced proteins

implications of immune system in defense against infections

deficient immunity results in increased susceptibility to infections (ex. AIDS)

vaccination boosts immune defenses and protects against infections

implications of immune system in defense against tumors

potential for immunotherapy of cancer

implications of immune system in control of tissue regeneration and scarring

repair of damaged tissues

implications of immune system in cell injury and pathologic inflammation

immune responses are the cause of allergic, autoimmune, and other inflammatory diseases, and for some of the harmful consequences of infections

implications of immune system in recognition of and injury to tissue grafts and newly introduced proteins

immune responses are barriers to transplantation and gene therapy

types of immunity

Innate immunity and adaptive immunity

innate immunity

also called "natural immunity" or "native immunity" (present at birth)

purpose of innate immunity

block the entry of microbes and rapidly eliminate microbes

characteristics of innate immunity

rapid (immediate), limited, nonspecific, does not have memory (cannot recognize all types of bacteria/fungi/viruses)

cells involved in innate immunity

epithelial barriers, mast cells, phagocytes, dendritic cells, complement, NK cells, and ILCs

adaptive immunity

also called "specific immunity" or "acquired immunity"

types of adaptive immunity

humoral and cell-based

components of humoral immunity

B lymphocytes, antibodies (effectors), and plasma cells (differentiate from B cells and release antibodies to recognize specific microbes)

components of cell-based immunity

T lymphocytes and effector T cells

location of adaptive immune system in body

mucous membranes, tonsils, lymphatic vessels, thymus, lymph nodes, skin, spleen, bone marrow, lymphatic vessels

origin of B cells

bone marrow

origin of T cells

thymus

role of B cells (humoral immunity)

use antibodies to neutralize/eliminate microbes (recognize specific microbes)

role of T cells (cell-based immunity)

regulate immune responses (CD4+ helper T cells) and kill target cells such as virus-infected cells (CD8+ cytotoxic T cells) (T cells can only recognize PEPTIDES from microbes, not the microbes themselves)

characteristics of adaptive immunity

slow, diverse, specific, have memory which results in a stronger response when encountering the same microbes

role of immunity

provide resistance to disease and prevent or eradicate infections and other diseases