Chapter 21 the Lymphatic and immune system, condensed definitions

Microbiome

Microorganisms that are on and in the body; can be beneficial or harmful. Protection is provided by the immune system.

Immune system

not an organ system; a population of cells found throughout the body. It defends the body from agents of disease.

Lymphatic system

responsible for immune processes in the body.

Lymphatic system functions

organs and vein-like vessels that recover fluid, inspect it for disease agents, activate an immune response, and return fluid to the bloodstream.

Lymphatic tissue

a form of reticular connective tissue that contains many lymphocytes.

Lymphatic system components

lymph, lymphatic vessels, lymphoid tissue, lymphoid organs

Lymph

recovered fluid

Lymphatic vessels

transport the lymph, then merge to form lymph trunks

Lymphoid tissue

lymphocytes and macrophages that populate many organs

Lymphoid organs

organs where lymphoid cells are concentrated and are surrounded by connective tissue capsules

Fluid recovery

filters from the blood capillaries into the tissue. Blood capillaries reabsorb 85%, and the rest enters the lymphatic vessels.

lymphedema

swelling due to interference in lymphatic drainage

Interstitial fluid

Originates from blood plasma that passes through capillary walls. The excess fluid drains into lymphatic vessels.

Lymphatic capillaries

smallest lymphatic vessels that join to form lymphatic vessels.

Lumbar trunks

drain lymph from the lower limbs and pelvis

intestinal trunk

drains lymph from the stomach, intestines, pancreas, spleen, and liver

Intercostal trunks

drain the posterolateral chest

bronchomediastinal trunks

drain lymph from the lungs, heart, and thoracic wall

subclavian trunks

drain the upper limbs

jugular trunks

drain the head and neck

lymphatic ducts

A large vessel that empties lymph into the veins between the internal jugular and subclavian veins

thoracic (left lymphatic) duct

receives lymph from the intestinal trunk, both lumbar trunks, and left intercostal, left bronchomediastinal, left subclavian, and left jugular trunks.

Right lymphatic duct

receives lymph from the right intercostal, right bronchomediastinal, right subclavian, and right jugular trunks.

Lymphoid cells include:

neutrophils, Natural killer cells, T cells, B cells, macrophages, and dendritic cells

Neutrophils

antibacterial, kills bacteria in connective tissue because of the neutrophil extracellular trap (NET), and it phagocytizes and digests microbes

Natural Killer cells

lymphocytes that attack infected host cells and cancerous cells, contain granules filled with toxic substances, which are the perforins and granzymes

T Cells

mature in thymus

B cells

activation causes proliferation and differentiation into plasma cells that produce antibodies.

macrophages

large phagocytic cells and antigen-presenting cells

antigen-presenting cells

display antigens on the surface to alert other immune cells

dendritic cells

APCs found in the skin, mucous membranes, and lymhoid organs.

Lymphatic organs and tissues

It contains many lymphocytes. There are primary and secondary lymphatic organs and tissues.

Primary lymphatic organs

generate immunocompetent cells

What organs are primary lymphatic organs?

thymus and red bone marrow

Immunocompetent cells

cells that are capable of mounting an immune response

Secondary lymphatic organs

The place where most immune responses occur

What organs are the secondary lymphatic organs?

spleen, lymph nodes, tonsils, and lymphatic nodules

Thymus

responsible for training T cells, which play a key role in cell-mediated immunity

Spleen

works to remove worn-out blood cells from the blood and serves as a platelet storage area.

Tonsils

lymphoid tissue that is located at the entrance to the pharynx, they guard against ingested or inhaled pathogens, and there are 3 sets.

3 tonsil sets include:

Pharyngeal, Palatine, Lingual

Mucosa-associated lymphatic tissue (MALT, lymphatic nodules, Peyer’s patches)

masses of lymphatic tissue that contain both T and B cells, they can be found by themselves or in large groups.

The Lymph Node

filters the lymph before it returns to the veins, 2 parts

Where do B and T cells enter the lymph through?

Through the Lymph nodes

2 parts of the lymph node:

stroma, parenchyma

Stroma

supporting connective tissue framework of the lymph node

Parenchyma

functional component of the lymph node

Afferent lymphatic vessels

lymph enters the lymph node, and then passes through the subcapsular, cortical, and medullary sinuses

Efferent lymphatic vessels

lymph exits the lymph node, there are only one or two efferent lymphatic vessels attached to a lymph node, and the slow outflow of the lymph allows for extensive filtering

Innate immunity

non-specific bodily defenses against foreign substances

Outer components of innate immunity include:

skin, mucus, and other secreted fluids

Skin

provides a physical barrier to foreign substances and microbes

mucus and other secreted fluids

help to protect epithelial surfaces, like the digestive, respiratory, urinary, and reproductive tracts

Phagocytes

cells that engulf foreign matter, follow behind natural killer cells

Leukocytes contain:

neutrophils, eosinophils, basophils, monocytes, lymphocytes

Eosinophils

found in mucous membranes, guard against large parasites like tapeworms, play a role in inflammation, react to allergens, and participate in allergic reactions

Basophils

secrete chemicals that aid leukocytes, the chemicals include leukotriene, histamine, heparin, and mast cells

Leukotriene

activate and attract neutrophils and eosinophils

Histamine

a vasodilator; increases blood flow and speeds delviery of leukocytes to the area

Heparin

inhibits clot formation that would impede leukocyte mobility; anticoagulant

Mast cells

secrete the same substances (Leukotriene, histamine, heparin) and are found in connective tissues

Lymphocytes include:

T cells, B cells, Natural Killer cells

T cells and B cells both participate in what?

participate in adaptive immunity

Natural Killer cells are a part of what?

Innate immunity

Monocytes

turn into macrophages

macrophage system

all the body’s avidly phagocytic cells, except leukocytes. They have both wandering cells and stationary cells, and specialized forms in specific locations.

Macrophage system cells include:

monocytes, macrophages, dendritic cells, and others

Specific locations of specialized forms in macrophage system:

microglia, alveolar macrophages, and stellate macrophages

Internal component of innate immunity include:

anti-microbial substances, Natural killer (NK) cells, phagocytes, inflammation, fever

Antimicrobial substances include:

interferons, iron-binding proteins, and antimicrobial proteins

Interferons

proteins that interfere with viral replication

Interferons are produced by:

lymphocytes, macrophages, and fibroblasts that are infected with viruses

Iron-binding proteins

inhibit bacterial growth by limiting available iron in the body

anti-microbial proteins

directly attack microbes and attract dendritic cells and mast cells to stimulate immune responses

The complement system

a group of proteins activated to enhance immune responses.

The complement system contributes to what?

innate and adaptive immunity

How does the complement system destroy microbes?

by inducing phagocytosis, cytolysis, and inflammation

The complement system has what?

C proteins, that are designated 1-9

C proteins, designated 1-9

most common, and are normally inactive, and require enzyme activation into two fragments

Perforins

create holes in plasma membranes

granzymes

cause a cell to undergo apoptosis

Inflammation

defensive response to tissue injury, including trauma and infection

How is inflammation characterized?

redness, pain, heat, and swelling. Also, possible loss of function in the affected area.

Inflammation response

vasodilation, emigration, removal

Vasodilation

arterioles and increased capillary permeability

emigration

phagocytes from the blood into the interstitial fluid

removal

foreign material and tissue repair

arterioles

vasodilation allows more blood to flow into the affected area

capillary permeability

allows large proteins to enter the affected area from the blood

vasodilation and increased capillary permeability contribute to what?

redness, heat, swelling, pain

pain

caused by microbial toxins or pressure due to swelling during inflammation

acute inflammation

intense but short-lived inflammation response

chronic inflammation

less intense, longer lasting than acute inflammation

Margination

the adhesion of phagocytes to the inner lining of blood vessels, and is triggered by the presence of cytokines

diapedesis

the migration of phagocytes from the blood vessel into the damaged tissue area

Fever

an abnormally high body temperature, caused by pyrogens

Fever results from what?

trauma, infections, drug reactions, brain tumors, and other causes

pyrogens

chemicals that induce the hypothalamus to increase body temperature, 2 types

exogenous pyrogens

derived from microbes

Endogenous pyrogens

produced by the body