Physiology Ex 1 - Immune System Flashcards
Where are all leukocytes (immune system cells) formed?
Bone marrow
Where do T-Lymphocytes mature?
Thymus
Where do B-Lymphocytes mature?
Bone Marrow and Liver
What do T-Lymphocytes mature into?
Cytotoxic T-Cells (mostly CD8)
for cellular immunity
What do B-Lymphocytes mature into?
Plasma cells ->
igG
igA
igM
igE
igD
for humoral immunity
What are the functions of the lymphatic system and vessels?
Fluid Balance
Fat Absorption
Defense
What system removes fluid gained by tissues?
Lymphatic system
Where does the lymphatic system return excess fluid to the cardiovascular system?
The large subclavian veins of the thorax
What is an imbalance where more capillary filtration than lymph drainage called?
Edema
Do lymphatic vessels have valves?
Yes
What do lymph nodes do?
Filter lymph
Name the 5 lymphatic trunks
Jugular
Subclavian
Bronchomediastinal
Intestinal
Lumbar
Name the 2 lymphatic ducts
Right
Thoracic
They empty into the large veins in the thorax
What happens to the 20L of fluid that filters out of the capillaries to the tissues every day?
17 L is reabsorbed by the capillaries
3 L is returned to the blood via the lymphatic vessels
What type of an imbalance causes edema?
Imbalace of fluid homeostasis:
- increased secretion of fluid into interstitium
- impared removal of interstitial fluid
Which factors can cause edema?
1 - Increased hydrostatic pressure
2 - Reduced oncotic pressure (pressure by albumin pulling water into circulatory system - low serum protein)
3 - Lymphatic obstruction
4 - Impaired circulation
5 - Sodium retention
6 - Inflammation
What two parts do lymph nodes consist of?
Cortex
Medulla
Post surgery damage due to removal of lymph nodes can cause?
Edema
Where are lymphatic nodules found?
Loose connective tissue of the following systems:
Digestive (Peyer’s patches)
Respiratory
Reproductive
Urinary
Lymphatic tissue consists mainly of?
Lymphocytes
What is lymphoid tissue?
Collection of lymphoid cells:
B-lymphocytes
T-lymphocytes
Macrophages & Dentritic cells
Other immune & connective tissue cells
What are tonsils?
Lymphatic nodules located in nasopharynx and oral cavity
Name the 3 tonsil groups
Palatine
Pharyngeal (adenoids)
Lingual
What are the functions of the spleen?
Filters blood and removes defective RBC’s
Lymphoid tissue detects and responds to foreign substances
Limited reservoir for blood
List the steps in T-Cell Maturation
Stem cells -> (in bone marrow) Immature Thymocytes (TCR-,CD4-,CD8-) -> (in thymus) Thymocytes (TCR+, CD4+, CD8+) -> (in thymus: positive and negative selection) MHC II: Helper T Cells (TCR+, CD4+), MHC I: Cytotoxic T cells (TCR+,CD8+)
What is positive selection of T-Lymphocytes
lymphocytes that bind to MHC complex will be stimulated to survive and mature to CD4 or CD8 cells
What is negative seelction of T-Lymphocytes?
T-Lymphocytes that react to self-antigens on the MHC complex will undergo apoptosis
What is the TCR?
The T cell receptor, a heterodimeric transmembrane protein on the surface of T lymphocytes (T cells)
What does the TCR do?
Recognizes antigens bound to MHC molecules. Lymphocytes with TCRs that can bind to MHC are stimulated to survive (positive selection)
What is CD8?
A transmembrane glycoprotein on the surface of cytotoxic T cells and NK cells. Important for cell mediated immmunity
Which MHC complex does CD8 bind to?
I
and produces memory T-cells
What do cytotoxic T cells do?
lyse virus-infected cells, tumor cells, and tissue transplants
They also produce cytokines, which promote phagocytosis and inflammation
What is CD4?
A glycoprotein on the surface of helper T cells, regulatory T cells, monocytes, macrophages, and dendritic cells
Its intracellular portion activates tyrosine kinase- lck, which is involved in the signaling cascade of an activated T cell and plays a role in activating humoral immunity
What is immunity?
The ability to resist damage from foreign substances:
- Microorganisms
- Parasites
- Viruses
- Harmful chemicals
- Tumor cells
What are the 3 types of innate or nonspecific resistance?
- Mechanical mechanisms, which prevent entry or remove microbes (epidermis and mucous membranes)
- Chemical mediators which promote cell lyses, phagocytocis and inflammation
- Cells: involved in phagocytosis and production of chemicals
Where are the mechanical mechanisms of innate immune mechanisms found?
skin
tears
saliva
mucous membranes
mucus
Which are the chemical mediators of innate immune mechanisms?
Acid
Lysozymes
Complement
Inteferons (prevent viral replication)
Prostaglandins & leukotrienes
Pyrogens
Others
Which are the cells involved in innate immune?
- White blood cells via chemotaxis and phagocytosis
- Neutrophils - phagocytic and first cells to enter infected tissue
- Macrophages
- Basophils and mast cells (promote inflammation)
- Eosinophils (Modify inflammation response, attack parasitic worms)
- NK cells (lyse tumor and virus infected cells)
What is the complement?
A group of 20 proteins that circulate in the blood. They become activeated in cascade form by antibodies or an alternate pathway. They insert into the plasma membrane of the attacked cell causing lysis.
What is meant by specificity in an adaptive or specific immunity?
The ability of immune ceslls to recognize and generate a response agains a particular substance (pathogen or antigen)
What is meant by Memory in adaptive or specific immunity?
The ability to remember previous encounters with a particular substance and response rapidly during later exposure to the substance
Which are the 2 types of adaptive or specific immunity?
Cell-Mediated Immunity
and
Humoral Immunity
What stimulates adaptive immunity?
Antigens: Foreign (not produced by the body) and Self-Antigens (normal body components)
Haptens: small molecules that combine with other molecules to produce an immune response
Which cells are responsible for humoral or antibody mediated adaptive immunity?
B cells
Which cellls mediate cell-mediated adaptive immunity?
Cytotoxic T cells (TCR+, CD8+)
What are primary lymphatic organs?
Where lymphocytes mature into functional cells (red bone marrow, thymus)
What are secondary lymphatic organs?
Where lymphocytes produce an immune response
What is the B-Cell maturation flowchart?
Stem cells -> (in bone marrow) Pro-B cells (lg-) -> (gene rearrangement) Pre-B cells (lg-) -> Immature B cells (igM+ igD-) -> (light chain rearrangement) Mature B cells (igM+ igD+) -> (selection & migration to lymphoid tissue) Mature B cells (igM+ igD+)
Why do immunoglobin genes in B-lymphocytes undergo mutation and rearrangements as the cell matures?
It allows production of antibodies with higher affinity for the antigen
What is an antigen?
A molecule that binds to the antigen binding site of an antibody, B cell, or T cell
What are mature antibody producing cells called?
Plasma cells
What protein is produced by B lymphocytes?
Immunoglobulin
What do B lymphocytes become?
B lymphocyte -> Plasma cell -> Antibody
What is the Fab or Fab2 fragment of the lg molecule used for?
To avoid the activities of the Fc region (compliment activation, etc)
What is produced when the lg gene is fused with the gene of another protein?
A unique fusion protein
Which are the actions of antibodies?
- Antigen inactivation
- Antigen aggregation
- Complement activation
- Inflammatory cell activation
- Opsonization - enhances phagocytosis
Where are Class I MHC molecules found?
On the surface of all nucleated cells
What are cells that display foreign antigens on their Class I MHC destroyed by?
Cytotoxic T cells (CD8)
What are cells without Class I MHC destroyed by?
NK cells
Name the parts of the lymphatic system
- Lymphatic capillaries (become lymphatic vessels)
- Lymphatic nodes
- Lymphatic trunks
- Lymphatic ducts
