micro ch 122

Species Reistance

pathogens of other species rarely are able to infect cross-species

First line of defense

Skin and mucous membranes (innate)

Second line of defense

Innate immunity, protective cells, chemicals in our blood that inhibit invaders (innate)

Innate immunity

Natural, macrophages, Phils, complement system

Adaptive immunity

Acquired — cellular (cytotoxic), humoral (antibodies)

Third line of defense

Adaptive, B and T lymphocytes

Self

Leukocytes are trained not to attack cells of this, but the non- instead

Markers

Basis of cell identity — which are proteins and sugars in the glycocalyx

PAMPs (pathogen associated molecular patterns) 

Molecular patterns associated with pathogens like LPS or flagellin

PRR (pattern recognition receptors)

receptors on our immune cell’s membranes that “recognize” PAMPs

Lymph system

composed of tissues that form nodes and vessels filled with this - clusters near the most likely points of entry for microbes

Lymphatic vessels

one way system that conducts lymph from tissues and returns them into the circulatory system

Lymph

Colorless watery liquid similar to plasma collected from most tissues. This only moves if you do

Lymph nodes

Organs that monitor composition of this

sit near likely entry points for microbes (neck, armpit, groin)

Primary organs

⁃ where immune cells are made

⁃ Red bone marrow, thymus

Spleen

Filters blood, removes bacteria, viruses, toxins

Tonsils

Sample microbes that enter mouth or nose

MALT (mucosa associated lymphoid tissue)

Tissues in the appendix, respiratory tract, vagina, bladder, mammary glands and Peyer’s patches in small intestine

Secondary organs

⁃ Where immunity occurs

⁃ Lymph nodes, spleen, SALT, MALT, tonsils, GALT, blood

Stem cells

Give rise to erythrocytes and leukocytes

Granulocytes

can leave circulation by squeezing through capillaries (diapedesis)

Basophils

⁃ release histamine and other inflammatory chemicals

⁃ Dark purple

Eosinophils

⁃ Phagocytize pathogens

⁃ Attach to worms, secrete toxins

⁃ Don’t usually phagocytize

⁃ Red, two lobed nucleus

Neutrophils

⁃ Phagocytize pathogens, consumed once

⁃ the most common WBC (60–70%)

⁃ Multi lobed nucleus

Agranulocytes

⁃ Cytoplasm appears uniform

Monocytes

⁃ Grow up into macrophages (cell eaters)

⁃ Can phagocytize multiple times

⁃ Big cell with kidney shaped nucleus

Lymphocytes

⁃ Adaptive immunity and killer T cells

⁃ Small cell with large round nucleus

55% of centrifuged blood tube

Plasma

45% of centrifuged blood tube

⁃ Formed elements

⁃ <1% leukocytes

Cytokines

are the chemical “language” cells use to communicate. Examples are interferon, TNF, EPO and interleukins

Cytokine storm

uncontrolled overproduction of cytokines. It leads to hyperinflammation, and in the lungs fluid and dead cells fill the alveoli, so breathing fails.

Mononuclear phagocyte system

connective tissue network between tissues and organs, populated by phagocytes

Brain

Microglia macrophageSki

Skin

Dendritic cells macrophage, intercept pathogens with slender finger like projections

Liver

Kupffer cells macrophage

Lungs

Alveolar macrophageB

Bone

Osteoclasts

Kidneys

Mesangial cells

Epidermis

Tightly packed layer of cells, things can’t penetrate unless burn cut scrape or breech it

⁃ First line of defense

Dermis

Layer that contains hair follicles, glands, nerve tissue, tough collagen fibers to make skin pliant

Lysozyme

enzyme that breaks down the bacterial cell wall (peptidoglycan). It’s found in tears, saliva and sweatSe

Sebum

Fatty acids lower skin pH to 5

Antimicrobial peptides

⁃ Found on skin, mucous membranes, some WBCs

⁃ acts on Grams, against protozoa, enveloped viruses,

Ciliary escalator

⁃ pseudostratified ciliated columnar epithelium (PCCE), which has goblet cells that make mucus

⁃ Mucus traps microbes, and the cilia sweep it up toward the throat to be swallowed or coughed out.

Microbiome/microbial antagonism

⁃ Good microbes use up nutrients and space, change the pH, train the immune system and make their own antimicrobials.

Natural killer lymphocytes

Secrete toxins onto surfaces of virally infected cells tumors

Signs of inflammation

Redness (rubor), heat (calor), swelling(tumor) , pain (dolor), loss of function

Vasodilation

⁃ increase of diameter in blood vessels

⁃ triggered by histamines, prostaglandins

Histamines

released by basophils, platelets, mast cells

Abscess

isolated site of infection containing pussP

Pyogenic

Bacteria that attract neutrophils and results in pus

Pyogens

Reset hypothalamus to a higher temperature

⁃ Bacterial toxins, LPS; TNF

Fever lasts as long as this is present

Pyogens

Interferons

⁃ Released by host cells to inhibit viral infections

⁃ Cause symptoms of viral infections (aching, sleepiness, fatigue)

Type 1 (alpha and beta)

⁃ infected cells release them, and they warn neighboring cells to make antiviral proteins. Viruses then can’t replicate in those cells

Alpha type 1 interferons

Comes from monocytes, macrophages, lymphosites

Beta type 1 interferons

Comes from Connective tissue cells

Type II gamma

activates macrophages, T cells and NK cells

Complement system

⁃ Serum proteins that trigger inflammation and fever

⁃ Activated by antibodies, binding of C3b