White Blood Cells Flashcards
Define hematopoiesis. Where does it occur in the fetus and in an adult? What is leucopoesis?
hematopoises - formation of new blood cells
- fetal - flat bones, long bones, vertebrae, liver, spleen
- adult - flat bones, epiphyses of longs bones, vertebrae
leucopoiesis - formation of WBC
- all white blood cells drive from same common cells as RBC - hematocytoblast
Describe formation of the different WBC
all comes from hematocytoblast like RBC
can either become:
- lymphoid - then becomes a lymphocyte
- myeloid - all other WBC: monocytes, granulocytes
Describe the size, nucleus, and presence/lack of granules in a neutrophil. What are its functions?
12-15 microns (2x size RBC)
distinctive multi lobular nucleus
contains granules - fine, light pink
- lysosomal and bactericidal enzymes
70% of total WBC
phagocytosis - non specific defense - lysosomes and proteases
- leave post capillary venues via diapedesis
increases during bacterial infections - pus, lining membrane
Describe the size, nucleus, and presence/lack of granules in an eosinophil. What are its functions?
12-15 microns in diameter
bilobed, horseshoe like nucleus
contains granules - moderately sized, salmon colored
functions:
- phagocytic cells interact with antigen-antibody complexes
- releases enzymes that destroy parasites
- breaks down histamine (released by basophils/mast cells), allergens
- increases in parasitic infection, allergies, diseases of spleen/CNS
2-5% of total WBC
Describe the size, nucleus, and presence/lack of granules in a basophil. What are its functions?
10-12 microns in diameter
irregular surface of nucleus - similar to lymphocytes but granulated
large, dark blue/pink granules that obscure nucleus
functions:
- secrete histamine, heparin - associated with asthma, allergies
- increases in chickenpox, DM, polycythemia, sinusitis
- bind to dock of Y of IgE to release histamine and heparin
LEAST COMMON WBC - nonphagocytic
Describe the size, nucleus, and presence/lack of granules in a lymphocyte. What are its functions?
8-10 microns in diameter
round nucleus surrounded by thin rim of clear cytoplasm - uniform stain of blue/purple
no granules
function: SPECIFIC IMMUNITY
- T cells: granzymes and perforin, non phagocytic
- B lymphocyte: releases antibodies, phagocytic, may function as APC
- natural killer cells - large, nonspecific T cells that release granzymes and perfori
Describe the size, nucleus, and presence/lack of granules in a monocyte. What are its functions?
16-20 microns in diameter - largest
nucleus late, bilobed/kidney shaped, blue stained
function:
- differentiates into macrophages - phagocytic APC’s
- can become dendritic cell
- increase in viral infections and inflammation
- synthesizes tumor necrosis factor and interleukin-1
differentiation occurs in CT outside of bloodstream
- macrophage: alveolar (lung), Kupffer (liver
- dendritic cell
- microglia
What is the order of most common to least common WBC? how do WBC relate to RBC?
RBC - mostly function within blood stream
WBC - use blood stream to get to where they need to go
- interstitial fluid, CT, organs
neutrophils > lymphocyte > monocyte > eosinophil > basophil
Describe lymphatic capillaries. What kind of ET, and what kind of system?
wall of simple squamous ET with restricted basement membrane for cells
- very permeable, loosely joined endothelial cells
- collagen filaments anchored to endothelial cells increase openings s interstitial fluid increases
- can absorb cell debris, pathogen, cancer cells
considered part of an open system
- anything that can cross capillary membrane into extracellular space can enter the lymphatic system
Describe the different pressures between cardiovascular capillaries, lymphatic capillaries, and interstitial fluid. What will have a higher hydrostatic P, the arterial or venous system?
P capillaries > P extracellular > P lymphatic capillaries
arterial system has high P and flows out - increases [albumin]
- increased [albumin] on venous side encourages uptake, but not enough to offset H2O loss on arterial side
- causes increase in extracellular fluid - picked up by lymphatics
Describe the following lymphatic vessels: collecting vessels, trunks, ducts
collecting vessels - have same 3 tunics as veins with less tunica media
- have more valves - prevent back flow
- branch and anastomose more frequently
trunks - paired with lumbar, bronchomediastinal, subclavian, jugular and single intestinal trunk
ducts
- R lymphatic duct: drains R upper extremity, R side of head and thorax
- L lymphatic trunk: originates from cisterna chyli and drains the rest of the body
Where do the R and the thoracic duct empty? What is the cisterna chyli?
where the external jugular vein and subclavian vein meet on both sides
- both enter on respective subclavian vein
cisterna chyli - drains R and L lumbar trunks, intestinal trunk and emptied into the thoracic duct
What are the lymphoid cells?
T lymphocytes, B lymphocytes, macrophages and reticular cells
What are the functions of T lymphocytes? Where do they arise and where do they mature?
function: manage the immune response
- directly attacks on foreign cells
- T killer cells (cytotoxic T cells) attach directly to tumor cells
arrive in the red bone marrow
mature in the thymus
What are the functions of the B lymphocytes? Where do they arise and where do they mature?
function: protect against antigens by producing antibodies
- APC
- attack from afar
- becomes plasma cell in spleen, lymph, or extracellular fluid
arise in the red bone marrow
mature in the bone marrow and lymph nodes
What are the functions of macrophages? What are they derived from?
function: phagocytose foreign material
- helps activate B lymphocyte
- helps activate T helper cells
- APC
- contains many nuclei, pseudopodia, and lysosomes
differentiates from macrophages
What are the function of reticular cells? Describe their structure
function: secrete reticular fibers (collagen)
- fibers support structure of lymphoid tissue
- support cells only
basket like structure that support placement of plasma cells and macrophages
- help slow fluid to increase time for T/B lymphocytes
What is MALT and what kind of tissue does it contain?
mucosa-associated lymphatic tissue
includes:
diffuse lymphatic tissue
lymphatic follicles (nodules
What are some examples of MALT structures?
Peyer’s patches in the ileum (lymphatic follicles)
tonsils of the pharynx and oral cavity - partially encapsulated
appendix of the colon
lymphoid follicles of trachea and bronchi
Describe diffuse lymphatic tissue
loose accumulation of lymphocytes among reticular fibers in the loose irregular CT present in almost every organ
- lacks capsule around the collection of lymphocytes
- access to lymphatic capillaries
Describe lymphatic follicles (nodules)
unencapsulated clusters of tightly packed spheres of reticular fibers and cells of loose/dense irregular CT found underlying mucous/serous membranes
- consist mostly of lymphocytes and macrophages
- access to lymphatic capillaries
- high concentration of lymphatic follicles
germinal center - dendritic (APC) and B lymphocytes (plasma cells)
peripheral border - T lymphocytes
found in the Payer’s patches in the ileum and the appendix
Describe the flow of lymph through a lymph node
enters via afferent lymphatic vessels, then two options:
- passes through sub capsular sinus
- accesses the cortex and the lymphatic follicles - forms medullary cords and reaches medullary sinus - travel down trabecular sinus to reach medullary sinus
once at medullary sinus, it can flow out efferent lymphatic vessels
sinuses spanned with reticular fibers
What is the function of lymph nodes?
filters lymphatic fluid
activates B and T lymphocytes
lymph flows through many lymph nodes - allows macrophages and lymphocytes to be exposed to the antigen/virus
What structures does the lymph node have that no other structure has?
medullary cords, sinuses, afferent lymphatics
What are the three tonsils? what are their structures like? what is its function?
superficial surface - invaginating epithelium forms deep crypts and crevices
- traps bacteria
deep surface - dense irregular CT capsule
partially encapsulated, no afferent lymphatics
function - 2nd line of defense if foreign cells penetrate epithelium
which tonsil is removed in children? which tonsils have pairs? what is the epithelium for the tonsils?
nasopharyngeal - 1 - pseodostratified with cilia
palatine - 2 - non cornified stratified squamous ET
- most common to be removed as child
lingual - 2 - non cornified stratified squamous ET
describe the spleen. where is it located. what is its vasculature like?
fist sized
intraperitoneal - visceral peritoneum
under the ribbon L side of abdominal cavity
splenic artery - arterioles - open ended capillaries - allow RBCs to leave
what is the function of the spleen? what is the red pulp and white pulp?
complete capsule - contains smooth muscle
functions:
- RBC/platelet storage - ONLY organ that filters blood
- lymphatic filtration
- fetal site of hematopoiesis
red pulp - storage site for RBC, breaks down old RBCs via macrophages
- venous sinuses: large capillaries that RBCs can exit to form splice cords
- splenic cords - network of reticular fibers filled w RBC for storage
white pulp - PALS - periarteriolar lymphatic sheath
- surrounds central arterioles
- areas of sheath demonstrate lymphatic arterioles
describe the thymus’s structure and function
structure - 2 lobes further divided into lobules
- lobules formed by a cortex surrounding inner medulla
- capsule present
- presence of epitheliorecticular cells (Hassal’s corpuscles)
- reticular cells form blood-thymic barrier in cortex
largest in 2 year old - small remnants in adult, replaced by adipose
function - T cell maturation (stem cells - thymocytes)
- MHC restriction: development of receptors that bind only to MHC I or II
- produce the hormone thymosin - stimulated T cell maturation
describe the medulla and the cortex of the thymus
blood supply brings T cells into area btw medulla and cortex
- lymphocytes leave medulla and enter cortex
in cortex, T cell will be tested if they can recognize APC
- if they cant, they die
- if they can, they move into medulla
in the medulla - presented with antigens that are found all over the body
- react too strongly: cell death
describe T lymphocyte maturation. what role do epithelial cells play?
epithelial cells secrete thymosins (hormones), present self-antigens and guide selection, differentiation and division of T cells
Positive selection - cortex - does the T cell react to the antigen?
yes - lives
no - apoptosis
Negative selection - medulla - does the T cell react too strongly to self?
yes - apoptosis
no - lives
