CH 1: Cells of the Immune System Flashcards
Hematopoiesis
Generation of RBCs, WBCs, and platelets
Pluripotent hematopoietic stem cells
Can self renew, or give rise to these different, more mature, hematopoietic cells
differentiated cells don’t self generate
Hematopoietic cells
- Erythrocytes
- Leukocytes
- Megakaryocytes
Erythrocytes
RBCs
- movement of oxygen
Leukocytes
WBCs
- help eliminate infections
Megakaryocytes
Source of platelets
- wound repair
- “cell with giant nucleus”
- platelets aren’t truly cells, but come from cells
- platelets contribute to blood clotting & secreting cytokines & growth factors
Types of Leukocytes
- small lymphocytes
- dendritic cell
- plasma cell
- mast cell
- NK cell
- monocyte
- neutrophil
- macrophage
- eosinophil
- basophil
Granulocytes: Myeloid Linage
Group of myeloid cells with cytoplasmic granules that kill organisms and enhance inflammation
- have irregularly shaped nuclei
- Neutrophils
- Eosinophils
- Basophils
Neutrophils
Phagocytes; die at site of infection to form pus
- recruited to site of infection
Eosinophils
Defend against parasites
Basophils
Defend against parasites, but at very low abundance
Large reserves of neutrophils are stored in?
The BONE MARROW and are released when needed to fight infection. Neutrophils travel to & enter the infected tissue, where they engulf & kill bacteria. The neutrophils die in the tissue & are engulfed & degraded by macrophages.
Monocytes: Myeloid Linage
Circulate in blood; have indented nucleus, gives rise to:
- macrophages
- dendritic cells
Macrophages
Sedentary, scavenger cells of tissue…wait for infection
- eliminates dead/damaged cells
“Large phagocyte”
Dendritic cells
Mobile, star-shaped cellular messengers that can activate an adaptive immune response
Mast cells: Myeloid Linage
Found in connective tissues; have granules
- involved in allergy response
Bacteria and macrophage interaction:
- Binding of bacteria to phagocytic receptors on macrophages induces their engulfment & degradation.
- Binding of bacterial components to signaling receptors on macrophages induces the synthesis of inflammatory cytokines.
Large granular lymphocytes: Lymphoid Lineage
Effector cells of innate immunity; granular cytoplasm
- Natual Killer (NK) cells
Natual Killer (NK) cells
Enter viral-infected tissue to kill infected cells and secrete cytokines
- binds specifically, to prevent killing healthy cells
Small lymphocytes: Lymphoid Lineage
Almost no cytoplasm; adaptive immune response
- circulate in quiescent & immature form
- B & T lymphocytes
- no granules, mostly made of nucleus
- very small
*imp for adaptive response
B lymphocytes/cells
Have cell-surface receptors called immunoglobulins
- plasma cells
Plasma cells
Effector B cells that secrete antibodies - soluble forms of immunoglobulins
T lymphocytes/cells
Have T-cell receptors (never secreted)
Diversity of immunoglobulins & T-cell receptors
We have millions of different immunoglobulins & T-cell receptors
Immunoglobulins
Proteins
- diff shape = diff function
Antigen
Foreign part from a certain pathogen
Diff pathogens have?
Diff antigens
Effector functions of B cells:
- B cells differentiate into antibody-producing plasma cells
- Humoral immunity
- Opsonization
Humoral immunity
Immunity due to antibodies & their actions
- B & T cells
- relating to body fluids
Opsonization
Coating a bacterium with antibodies to enhance phagocytosis
- coating w something
- can activate complement sys
ex: antibodies
Effector functions of T cells
- Two types of effector T cells:
- cytotoxic T cells
- helper T cells
Cytotoxic T cells
Kill cells infected with certain viruses or bacteria
- CD8
Helper T cells
Secrete cytokines to help other cells become effector cells (help active macrophages)
- CD4
- don’t do the killing themselves
- Regulatory T cells
Regulatory T cells
Subset of helper T cells that controls activity of other T cells to prevent tissue damage and stope immune response
- shut it down
- don’t want immune response to continue & damage tissue
- inactivating cells
Where are lymphocytes found?
Most lymphocytes are found in lymphoid tissues or organs
- Bone marrow, thymus, spleen, adenoids, tonsils, appendix, lymph nodes, and Peyer’s patches
*important for keeping us healthy
Peyer’s patches
Areas of lymph tissue in small intestine
Primary/central lymphoid tissues
Where lymphocytes develop & mature
- Bone marrow
- Thymus
Bone marrow
Origination site of B & T cells
- maturation site of B cells
Thymus
Maturation site of T cells
Peripheral/secondary lymphoid tissues
Where mature lymphocytes are stimulated
- activation
Lymph nodes lie at junctions of the LYMPHATICS
Networks of lymphatic vessels, that originate in connective tissues and collect plasma that leaks out of blood vessels
- forms lymph
Lymph
Extracellular fluid, which is eventually returned to the blood
B & T cells move through the body through what?
Through blood and lymph
If a lymphocyte is activated by a pathogen…
It stays in lymph node
- Otherwise, eventually leaves in efferent lymph & return to blood
Lymphocyte recirculation
Movement between blood & lymph
- allows lymphocyte population to continually survey secondary organs for infection
Following infections
- Connective tissue commonly infected
- Intact pathogens, pathogen fragments, & pathogen-infected DCs carried from here to nearest lymph node by the lymphatics
—–draining lymph node - Pathogen-specific B cells proliferate at the germinal center, causing “swollen glands”
Draining lymph node
lymph node receiving fluid collected at infected site
- Closes node to certain pathogen
Spleen
Lymphoid organ that serves as a filter for the blood
- not connected directly, enters thru blood vessels
- 2 functions:
— removes damaged or senescent red cells
—defends against blood-borne pathogens
- Made up of two tissues:
— red pulp
— white pulp
Red pulp
rbcs monitored and removed
- short half life
White pulp
wbcs gather to provide adaptive immunity
Can humans survive without a spleen?
Yes
Most microorganisms in humans found?
Respiratory and GI tract
- vulnerable to infection
— GALT
— BALT
— MALT
Gut-associated lymphoid tissues (GALT)
Tonsils, adenoids, appendix, and Peyer’s patches
Bronchial-associated lymphoid tissue (BALT)
Lines respiratory epithelium
Mucosa-associated lymphoid tissue (MALT)
More diffuse mucosal lymphoid tissues
M cells
Specialized cells of mucosal epithelium
- how pathogens arrive at resp. & GI tact sites
Lymphocytes enter mucosal lymphoid tissue from?
The blood & leave via lymphatics
- activated lymphocytes stay & perform effector funtcions
