anatomy ch21

Lymphatic system consist of what two semi independent parts:

returns interstitual body fluid and leaked plasma proteins back to the blood, absorbs fat in small intestines, filters/destroys foriegn antigens

interstitual fluid once it has entered lymphatic vessels; contains many protiens, microbes, cancer cells, about 3 L lymph return/day; relies on skeletal and respiratory pumps to move

§Similar to blood
capillaries, yet more permeable with endothelial minivalves that remain open and withstand pressure

Allow interstitial fluid to enter, but not to
escape from lymph capillaries

Keeps lymph flowing in a one-way direction

can absorb cell debris, pathogens, and cancer cells durign inflammation

§Have thinner walls, with more internal valves than veins and more anastomoses

travel with arteries/veins

nutrients are supplied from branching_______________

are formed by the union
of the largest collecting vessels

Major trunks include:

Lymph is ultimately
drained into one of two large ducts:

drains the right upper
arm and the right side of the head and thorax

arises from the cisterna chyli and drains the rest of the body

Parasitic worms clog up lymph vessels,
leading to enormous swelling (edema).

scattered reticular tissue elements in every body organ with
many macrophages and lymphocytes

diffuse lymphatic tissue includes:

solid, spherical bodies consisting of tightly packed reticular elements
and cells

Have a germinal center composed of maturing B cells

Peyer’s Patches, Tonsils is an example of:

isolated clusters of lymphoid tissue, similar to
tonsils, found in small intestine (esp. ileum)

Destroy bacteria and preventing them from breaching the intestinal wall

Located in oro/nasopharynx, filters aiire and removes foreign materials

three types of tonsils:

in nasopharynx (near auditory tube)

located on either side
of oral cavity

located at root of tongue

the principal lymphoid
organs of the body

occur near the body
surface in thoracic, abdominal, intestinal/mesenteric, popliteal, inguinal, axillary, and cervical regions of the body

swell with infection or cancer

The cortex contains follicles with germinal centers, heavy with maturing B cells, The deep cortex houses T cells in transit

largest lymph node organ

Site of B lymphocyte production, Cleanses the
blood, Stores products of RBC breakdown for later reuse, macrophages salvage and store iron for later use by bone marrow, Site of fetal erythrocyte production (normally ceases after birth), Stores blood platelets

Surrounded by a fibrous capsule, it has trabeculae that extend inward and contains lymphocytes, macrophages, and
huge numbers of erythrocytes

two distinct areas of the spleen are:

area containing mostly
lymphocytes suspended on reticular fibers and involved in immune functions
(lymphocyte maturation

remaining splenic tissue concerned with disposing
of worn-out RBCs and bloodborne pathogens

A bilobed organ that secrets hormones (thymosin) that cause maturation of T lymphocytes, size varies with age, stops growing during adolescense then eventually atropies, important in development of the entire immune system

red bone marrow forms in children in:

red bone marrow forms in adults :

site of lymphocyte and macrophage development

Contains sinusoids with macrophages that destroy
malformed blood cells

responds quickly; results in same response with each exposure
to pathogen; consists of first line of defense and second line of defense

physical barrier: intact skin and mucosa to prevent entry of microorganisms
Includes: skin and mucous membrane’s defenses (sebum, acidity, lysozyme/defensins, mucus)

internal defenses: antimicrobial chemicals, phagocytes, and other cells, Inhibits spread of invaders throughout the body, Inflammation is its hallmark and most
important mechanism

adaptive (specific) immunity includes:

mounts attack against particular foreign substances, Takes longer to react than the innate system, Works in
conjunction with the innate system, Results from exposure to a pathogen (acquired), Memory Cells
are produced that reduce response time upon 2nd exposure to pathogen
Two Types:
Humoral (aka Antibody Mediated) and Cellular (aka Cell-Mediated)
Immunity

anti body mediated

cell mediated

§Antibodies bind to extracellular pathogens (antigens on bacteria, bacterial
toxins, venoms, allergens, and free viruses) and present them to phagocytes and
complement

Employs
B-Lymphocytes (made/mature in bone marrow)
which become either memory cells or plasma cells (that secrete antibodies

examples of anitbodies

four ways to acquire humoral immunity:

antibodies
produced in response to natural exposure to pathogen

antibodies
produced in response to vaccination;
may require “booster.”

person
produces own antibodies; long lasting

antibodies
come from outside source; temporary

antibodies passed from mother to fetus
across placenta or in breast milk.

antibodies injected from serum (e.g. gamma globulin, antivenom, antitoxins for tetanus,rabies).

Lymphocytes attack intracellular pathogens (viral-infected cells and
parasite-infected cells) or diseased host cells (cancer cells and foreign
tissue graft cells).
Employs T Lymphocytes
(made in bone marrow; mature in thymus)
which either become memory cells or become Helper T cells,
Cytotoxic T cells, Memory T cells, and
Suppressor T Cells (among others).
Attack and Lyse “Foreign” Cells.