Immune System and Lymphatic Organs Flashcards
Two general function of the lymphoid system(NONE)
General: facilitate immunity by:
Production of lymphocytes
Activation of lymphocytes
‘Self’ (NONE)
an organism’s own mecums (literally itself)
Non-self (NONE)
foreign molecules
Network and function of lymphatic vessels
➔ Lymphatic tubules travel alongside the blood vessels and collect extra fluid at the capillaries
➔ This fluid carries proteins, WBC’s, some RBC’s
➔ Connects chains of lymph nodes
➔ Tubules converge to form lymphatic ducts that carry the fluid to the lymph nodes for filtration & phagocytosis
➔ Eventually dumps the filtered fluid back into the venous system at the subclavian veins
➔ Right upper body drains to lymphatic trunkà right subclavian vein
➔ Rest of body drains to thoracic ductà left subclavian vein
Major network of lymph nodes
◆ Neck (cervical, occipital) ◆ Clavicular ◆ Axillary ◆ Bronchial ◆ Mediastinal ◆ Mesentery ◆ Iliac ◆ Inguinal
Immunocompetent cell
A cell that is able to recognize antigens and act against them
Immune response
How your body recognizes and defends itself against bacteria viruses, and substances that appear to be foreign and harmful
Humoral immunity
B cells differentiate into plasma cells which end up secreting antibodies that bind to specific antigens
Cellular immunity
Mediated by T cells that either:
- Secrete cytokines that act on B lymphocytes, on other T cells, and on inflammatory cells (macrophages & neutrophils
- Attack foreign cells
Memory cells
cell derived from B or T cells that can quickly recognize a foreign antigen to which the body has been previously exposed
Antigen-presenting cell (APC)
Immunocompetent cels that mediate the cellular immune response by processing and presenting antigens to T cells. Examples: macrophages, dendritic cells, B lymphocytes
Central lymphoid organs
Primary, sites of antigen independent lymphocyte generation. The bone marrow for B cells and thymus for T cells
Peripheral lymphoid organs
Secondary, where adaptive immune responses are initiated and include MALT, GALT, BALT, CALT
Waldeyer’s ring
composed of pharyngeal, palatine, and lingual tonsils which form a circle at the entrance of the gut and airway and monitors what comes into mouth and nose before it gets into the gut and lungs. The tonsils are an aggregate of partially encapsulated, confluent lymphoid follicles
Peyers patches
a group of lymphoid nodules in the mucosa of the ileum that response to foreign antigens in the GI tract
Immunoglobulin (Ig) antibody
a protein produced by B cells in response to one unique antigen. Combines with that specific antigen to destroy it
Antigen
any substance that causes your immune system to produce antibodies against it
Innate immunity (natural)
Most primitive immune response, fast. Specificity to pathogens is very broad and is programmed in germline DNA. Key players of this system who are directly involved in killing pathogens include macrophages, neutrophils, eosinophils, and NK cells. Dysfunctional activatio can lead to autoimmune diseases.
Adaptive immunity
Antigen specific immune response that is more complex than the innate response. When an antigen is recognized, the adaptive immune system creates immune cells that will specifically attack that antigen. Also involves the creation of memory cells which will make subsequent responses to that antigen faster and more efficient. Two types of adaptive responses=humoral and cell-mediated.
Immunodeficiency
decreased or compromised ability to respond to antigenic stimuli with an appropriate immune response, as the result of one or more disorders in B-cell mediated immunity, T cell mediated immunity, compliment, or phagocytic cells. Some causes include genetics, aquired infections, drug abuse, immunosuppressive therapy (chemo), or malnutrition. Treated based on underlying cause with transplants, antibiotics, infusions of immune globulin.
Development and maturation sites for B lymphocytes and T lymphocytes
B: develop and mature in bone marrow
T: develop in bone marrow, mature in thymus
Plasma cells
Some B cells will differentiate into plasma cells. Their primary function is to create and secrete antibodies. However, each plasma cell can only create one type of antibody in the five classes (IgG, IgA, etc.). Most live for 2-5 days.
Types of peripheral lymph tissue (NONE)
Diffuse: scattered T and B cells
Confluent: aggregates of many lymph nodules
Tonsils, lymph nodes, spleen, peyer patches
Tonsils
confluent - called Waldeyer’s ring, composed of pharyngeal, palatine, and lingual tonsils.
Lymph nodes
filters fluid before entering blood stream. Remove foreign substances, etc. This is where antigens and antigen-specific lymphocytes cross paths and do battle.
B cells located in the cortex, T cells in the parafollicular (deep) cortex, macrophages and plasma cells in the medullary cords.
Spleen
filters blood but activates immune responses to substances found in the blood. Red pulp filters blood cells, white pulp is lymphatic tissue.
Peyer patches
confluent areas of the small intestine
Three sets of tonsils and function
Palatine: principally composed of lymph tissue, they are organized as follicles and crypts covered by mucous membranes
Pharyngeal (adenoids) and lingual: provide defensive responses to inhaled and intranasal antigens
Afferent lymphatic vessels
carry fluid/lymph/stuff into lymph nodes
Efferent lymphatic vessels
E for Exit! Carry exiting fluid/lymph/stuff
Follicular cortex
Outer cortex, B cell zone
Parafollicular cortex
deep cortex, T cell zone
Medulla
macrophages and plasma cells chill here
Cortical sinuses
lymph sinuses in the cortex (lymph flows through these)
Medullary sinuses
Collect lymph that has filtered through the cortex
Medullary cords
Cords of lymphatic tissue where the macrophages and plasma cells chill
T and B cell rich zones
T: parafollicular cortex
B: outer cortex
Spleen
- Largest secondary lymphoid organ
- Filters blood to get rid of damaged and old cells
- Activates immune responses and microbes in blood
- Blood flow: Splenic artery–>trabecular arteries—>central arteries and arterioles in white pulp–>red pulp–>marginal zone sinuses or arterioles and macrophage sheathed capilaries and sinusoids
Red pulp
Main filtration function of spleen. Contains sinusoids and cords
White pulp
Lymphoid tissue
Pariarterial lymphatic sheath (PALS)-T cells around central artery
Follicles that are B-cell rich, interspersed in PALS
Marginal zone and sinus, has a lot of antigen-presenting cells
Lymphocytes leave via lymphatics that originate in white pulp
Splenic cords
Rich in macrophages that eat old cells and foreign particles. Contain plasma cells and all blood cells
Splenic sinusoids
Barrel-like, lined by endothelial cells, reticular fibers circle sinusoids like bands around a barrel. Has a discontinuous wall that allows blood to fill cords as well as sinusoids
Two function of the thymus
The thymus is the central lymphoid organ for development of T lymphocytes.
It produces the lymphocytes and also regulates immune function by secretion of hormones that promote T-lymphocyte differentiation.
Blood thymus barrier
Impermeable epithelium vessel walls-complete tight junctions and thickened basement membrane
Macrophage in perivascular space
Epithelial reticular cells
Basically keeps foreign materials out
Cortex of thymus
Immature T-cells (thymocytes)
No B cells, no follicles
Macrophages that act as phagocytes to T cells that aren’t up to par
CFU-L cells leave bone marrow, migrate to cortex where they undergo DNA rearrangements to generate antigen recognition diversity
Medulla of thymus
T cells
Epithelial reticular cell stroma
Hassall’s corpuscles
Hassal’s corpuscle
Concentric, flattened epithelial reticular cells
Can calficy
May secrete factors (interleukins 4 & 7) needed for thymic function
