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54 Cards in this Set

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Innate Immunity
Barriers to primary infection:
Phagocytosis, Inflammation and
Complement System
Adaptive Immunity
Self vs. non-self; Clonal lymphocyte response,
Antigen recognition molecules,
Memory
Immune cells develop in______
bone marrow
______ cells take infections to lymph nodes and stimulate adaptive immunity
dendritic
Antigen recognition induces expression of effector molecules by __ cells which activate __ cells.
T, B
Proliferating B cells differentiate to resting ____ cells and antibody secreting _____ cells.
memory, plasma
Primary Organs
Bone Marrow, Thymus; sites of lymphocyte production and development.
Secondary Organs
Lymph Nodes, Spleen, Mucosal Lymphoid Tissue; sites where lymphocytes encounter and respond to antigens.
T cells
include several functionally distinct subtypes and are responsible for cell-mediated responses. They assist B cells in developing antibody responses
B cells
develop into antibody-secreting plasma cells. Each plasma cell secretes only one class of immunoglobulin that binds only one antigen. The memory cells can react to the same antigen in subsequent encounters.
thymus
no significant filtering function, but supports the proliferation and programming of T lymphocyte precursors.
Where is the thymus?
lies in the mediastinum anterior to the large vessels emerging from the heart. It is divided into two lobes and covered by a thin connective tissue capsule that penetrates the lobes as septa, dividing each lobe into lobules.
Each thymic lobule has an outer, dark-staining _____ and an inner, lighter-staining _____.
cortex, medulla
Part of the maturation process for T-cells is the elimination of self-reactive cells, to limit ______ disease.
autoimmune
What goes down w/in the thymic cortex and medulla?
The densely-packed cortex contains the rapidly proliferating more immature thymocytes. As they mature they move towards the medulla. As many as 95% of the thymocytes fail to develop or display inappropriate self-reactivity, and die by apoptosis.
Describe the blood supply of the Thymus.
Enters through the capsule and connective tissue septa. Branches of arteries and then capillaries go into the cortex. The continuous capillaries are sheathed by processes of epithelial reticular cells.
What makes up the blood-thymus barrier?
The epithelial reticular cells, thick basal lamina, and continuous capillaries
There are no ____ lymphatic vessels coming into the thymus.
afferent; it's job is not to filter lymph, but grow T cells.
What primarily constitutes the thymic cortex?
thymocytes, along with epithelial reticular cells (large pale cells), and macrophages
cortical epithelial reticular cells
program which thymocytes (T cells) will die and which ones will live and progress to the thymic medulla.
The medulla contains ____ epithelial reticular cells and ____ T lymphocytes than the cortex
more, fewer
Does the medulla or cortex have more mature T lymphocytes?
medulla
Hassall's Corpuscles
-concentric layers of flattened epithelial reticular cells that have died and calcified with age. They are found only in the thymic medulla and their function is unknown.
Compared to a young thymus, an aged thymus looks______.
moth eaten
T/F: Babies are born with a fully fnx thymus gland.
true; w/ aging, thymic tissue is replaced with adipose.
Digeorge's Syndrome
congenital thymus abnormality- chromosome 22 defect. Complete Digeorge means there is no thymus present.
Lymphatic System
vast complex network of capillaries, thin vessels, valves, ducts, nodes, and organs. It helps to protect and maintain the fluid environment of the body by producing, filtering, and conveying lymph
Lymph is roughly __% of the tissue fluid that surrounds cells; usually 1-2 quarts makes up___% of the body weight
10%, 1-3%
What do Lymph Node concave and convex surfaces do/contain?
Convex surface = receives afferent lymphatic vessels

Concave surface = contains arterioles and efferent lymphatic vessels
The lymph node stroma contains_____.
reticular fibers
What's in the cortex and paracortex of lymph nodes?
cortex= . Lymphoid follicles (B cells with some T cells & other cell types)
paracortex= mostly T cells
germinal centers
light staining regions containing activated B cells undergoing transformations that yield memory cells and plasma cells
the paracortex is ____ staining because it's full of T cells.
dark
lymph node medulla
contains cords with reticular cells and plasma cells present; stains lighter than cortex
Lymphadenopathy
When antigen-specific T and B cells are stimulated, they rapidly proliferate in the follicles (B-cells) and paracortex (T-cells) to produce effector clones and memory cells. This cellular expansion can result in the lymph node enlarging
high endothelial venule-HEV
paracortex of lymph node; lymphocyte point of entry from blood
largest lymphoid organ
spleen; filters blood
in the spleen, connective tissue _____ pass from capsule to interior.
trabeculae; trabecular artery→ central artery (w/ sheath full of T-cells)→ penicillar arterioles→ sheathed capillaries
white pulp
spleen; a thick accumulation of lymphocytes surrounding the central arterioles; thickens to form splenic nodules
red pulp
occurs in irregular masses - splenic cords, and splenic sinuses
What separates red and white pulp?
marginal zone
What makes up PALS in white pulp?
T cells
Where are the B cells in white pulp?
splenic nodules
cords of billroth
red pulp; The regions between sinusoids are occupied by pulp cords, rich in macrophages, reticular cells, and plasma cells
Does the spleen have afferent lymphatics? Lymph sinuses?
no, no.
Where is most of the spleen's lymphoid tissue located?
white pulp (i.e. B cell nodules and PALS)
MALT
mucosa-associated lymphatic tissue, found on mucus membranes lining the respiratory, gastrointestinal, and urogenital systems; secondary lymphoid tissue
non-encapsulated lymphoid nodules
inactive= primary, active=secondary; B cells in the germinal center's center surrounded by marginal zone of memory cells
peyer's patches
Large aggregates of lymphoid follicles/nodules in the *ileum.* Nodules originate in the lamina propria and extend into the submucosa.
microfold (M) cells
specialized epithelial cells over follicles that endocytose microorganisms from the lumen, and pass them intact to the antigen-presenting cells in the Peyer’s patches.
Pharyngeal Tonsils (Adenoids)
nasopharynx posterior wall; covered with ciliated pseudostratified columnar epithelium- some portions may be stratified squamous epithelium (especially in older individuals).
Tonsillectomy
surgical excision of the palatine tonsils
Waldeyer’s ring
composed of the tonsils and form a ring of lymphoid tissue around the entrance to the GI and respiratory tracts.
Lingual Tonsils
diffuse infiltration of lymphocytes or multiple small nodules below epithelium of the posterior third of the tongue.