lymphoid and immune system

all organims of same species have a _____

unique molecular organization

all organisms have a?

immune system or lymphoid system

what does the immune system and the lymphoid system do

it will protect from macromolecules other that their own

what does the immune system consist of?

• lymphoid tissues

• organs

the main components of the immune system (constituents) are?

lymphocytes and their aggregations which are connected through lymphatic and cardiovascular system

cells are enmeshed in a supportive framework called?

stroma (contains reticular cells and fibers)

the lymphoid organs include?

• thymus

• lymph nodes

• spleen

• tonsils

the thymus in birds (fabricius) and in mammals (fetal liver) are what?

training centers for developing lymphocytes

peripheral lymphoid tissues are

battle fields

how do lymphoid tissues "dispose off invaders”

by directly attacking them or by producing antibodies against them

what does immune response involve?

• antigens

• antibodies (immunglobulins)

what are the immune system components (overview)

• lymphocytes

• lymphoid tissues

• lymphoid organs

who are the main warriors of the immune system

lymphocytes

where do lymphocytes arise?

blood marrow

what do lymphocytes mature into?

T and B lymphocytes and protect against antigens

b cells transform into?

plasma cells

b cells will later change into plasma cells and will produce

immunoglobulins (antibodies)

t cells do what?

phagocytize (eat) foreign substances

reticular cells do what?

dominate and make CT for support

lymphoid tissues is what kind of site? and for what?

a proliferation site for lymphocytes

lymphoid tissue is a

surveillance point for lymphocytes and macrophages

lymphoid comes in different packages what are they?

• diffuse lymphoid tissue

• lymphatic follicles (nodules)

diffuse lymphoid tissue

has a scattered reticular tissue element that is found in every organ (hold things together)

what is the scattered reticular tissue element that is found in every organ called?

lack capsule

lymphatic follicles (nodules)

also a lack capsule but are SOLID spherical bodies

lymphatic follicles (nodules) often contain what kind of center?

germinal centers (light staining)

what are isolated aggregations of lymphoid follicles called?

peyers patches

what are some lymphoid organs

• lymph nodes

• thymus

• spleen

• tonsils

what kind of organs are lymph nodes

small organs

where do lymph nodes occur

in series along lymphatic vessels

what do lymph nodes recognize?

antigenic material and are rich and microphages

what do lymph nodes look like

• flattened

• ovoid

• reniform (kidney shaped)

• slight indention aka HILUS

afferent lymphatic vessels

ex: cars go in (carwash)

these vessels will bring in lymph to lymph node through a “capsule” that contains a one-way valve (to keep that flow going)

efferent lymphatic vessels

ex: cars are clean to go out

vessel exit lymph node through the hilus

in the hilus is where want can enter and exit?

blood vessels & nerves (arteries and veins) along with the efferent lymphatic vessels

a lymph node has a

• cortex

• medulla

a lymph nodes cortex has?

three areas of parenchymal cells

what are three areas of the cortex of a lymph node

• primary

• secondary

• diffused

primary lymph nodules

are in the outer cortex that contains tightly packed b cells

secondary lymph nodules

are in the outer cortex but are those that are formed after a antigenic stimulation

diffused lymph nodules

are the lymph nodules that are in the inner cortex

the medulla contains

aggregations of lymphoid tissues that form medullary cords and sinuses

lymph nodes are ______ of parenchymal lymphoid tissue

masses

sinuses (lymphatic vessels)

where the lymph is able to travel through

the lymph node is covered by/with a

collagenous capsule that flows into the organ as trabeculae

in the cortex of the lymph nodes there are how many sinuses?

two

one sinus in the cortex is what?

marginal/subcapsular that is found under the capsule

another sinus in the cortex is?

located in the medulla aka the medulla sinus

the lymph node has a ______ inner and outer cortex and medulla and a prominent _______

distinct, germinal center

what are the cells found in lymph nodes?

• reticular cells

• plasma cells

• lymphocytes

• macrophages

lymph nodes are very effect how?

they are lymph filters

lymphocytes undergo?

intense mitotic activity

what kind of mutations are common in lymphocytes

neoplastic mutations

what are lymphomas

solid tumors affecting nodes that spread from node to node

what is the major type of lymphoma

Hodgkins Disease

how can we know that hodgkins disease is occuring?

there is a presence of Reed-Sternberg cells with bilobed nuclei and prominent nucleoli (resemble owls eyes)

thymus

located in the superior mediastinum anterior to the blood vessels

thymus attains?

greatest relative weight & can grow up to 30-40 grams

in adults what is the thymus replaced by?

adipose tissue

it is the only primary lymphoid organ identified in mammals

thymus

the first organ to become lymphoid during embryonic life?

thymus

seeded by blood borne stem cells that are able to differentiate into lymphpcytes

thymus

thymus has

• 2 lobes

• also enclosed in a capsule

• NO SINUSES below capsule

• each lobe has a cortex and medulla

lobules of the thymus are separated by?

septa and communicate by parenchymal bridges

thymus has 3 kinds of cells

• lymphocytes

• reticular (epithelial cells, supporting cells )

• macrophages (6 types)

main function of thymus?

to mature T lymphocytes

immature cells of the thymus that are growing to mature are called

thymocytes

the thymic cortex will be what kind of stain

dark staining

thymic cortex will have an abundance of & fewer of ?

lymphocytes & reticular acidophilic cells with large nuclei

thymic cortex also has what present?

nurse cells (epithelial reticular cells)

since we do only have one thymus it has to be taken care of and this is achieved how?

through the formation of a blood thymus barrier in the cortex

blood thymus barrier

prevents toxins from coming into thymus

thymic medulla stains?

lightly

in the thymic medulla there are abundant of and fewer of?

reticular cells & lympocytes

in the thymic medulla what is present?

Hassall’s corpuscles

hassalls corpuscles

unique histological feature of thymus with unclear function

• concentric rings that have a type 6 squamous epithelial cel

• ONLY IN THE THYMUS IN THE THYMIC MEDULLAAAAAAAAAAA

what does thymic involution mean?

the function of the thymus is gone

so the thymic involution can be?

• normal

• experimental

• accidental

so with age what occurs to the thymus?

it involutes (gets thinner, curls up), with time and age , there is an decrease in lymphocyte productions

thymic involution can be replaced by

adipose tissue

age related involution

occurs at the same time as puberty, meaning its still there but it does not function.

accidental thymic involution can be due to

• diseases

• stress

• diet

• radiation

• infection

the thymus is required for what?

immune response to foreign bodies like microorganisms, fungi, viruses

what kind of secretions do thymus secrete

• thymosin

• thymopoietin

• thymic humoral factor

• thymic serum factor

the spleen is what kind of organ?

abdominal organ

where is the spleen located?

beneath the diaphragm

how is or what is the spleen connected or attached?

connected to the stomach by a peritoneal membrane, diaphragm and the left kidney

the spleen is also enclosed in a ?

capsule that from trabeculae in the organ

the spleen has two major regions

• white pulp

• red bulp

SEEN WITHOUT STAINING!!!!!!!!!!!!!!!!!!!!!

white pulp

• has lymphocytes very similar to lymph nodules

• here the lymphocytes form a periarterial lymphoid sheath (PALS) around the arteries

red pulp

nothing but containing a lot of blood in them

• a network of venous sinuses with collagen fibers, macrophages and blood vessels

splenic cords of billroth

in the red pulp

** the tissues that are btwn the venous sinuses **

the blood supply of spleen is placed in sheathed capillaries called? (hisotological fetaure)

scheiger siedal sheaths

spleen is a reservoir of?

blood

what is the spleens fucntion?

• to clean and filter blood

• degrade hemoglobin

• produce lymphocytes

what DOESNT spleen filter?

lymph bc it has no afferent lymphatic vessels

tonsils is the?

simplest lymphoid organ

tonsils form what?

waldeyer ring (6) around the throat area (made of lymphatic tissue)

the tissue of tonsils contain….

follicles with obvious germinal centers

like the other organs tonsils are not…

fully encapsulated rather have crypts (trap bacteria)