Immunology: Non-Specific and Specific Defenses

This set covers the first and second lines of defense, including mechanical barriers, chemical barriers, phagocytosis, white blood cell types, fever, and the steps/signs of inflammation.

First Line of Defense

The body's initial defense system consisting of mechanical (physical) barriers and chemical barriers.

Keratin

A waxy protein found in the epidermis that acts as a sealant for protection.

Mucous Membranes

Multilayered tissues for protection that produce mucus to keep tissues moist; locations include the conjunctiva, urinary tract, nasal cavity, and digestive tract.

Lacrimal Sack

Part of the lacrimal apparatus that contains lysozymes for protection against bacteria.

Cilia

The lining of the respiratory tract that acts as an "Up escalator" to move substances.

Epiglottis

A flap of elastic cartilage that temporarily closes off the airway during swallowing.

Sebum

Secretions from sebaceous glands with a $pH$ of $3$–$5$.

Gastric Juices

Substances that produce hydrochloric acid ($HCl$) to kill microbes.

Hemglobin ($Hb$), Transferrin, and Transferritin

Chemicals that bind iron; pathogens require iron to replicate, thus these chemicals combat them.

Competitive Exclusion

Also known as microbial antagonism; involving the normal flora, microbiota, or microbiomal environment.

Phagosome

A vesicle formed when a microbe is ingested during the process of phagocytosis.

Phagolysosome

The structure formed when a phagosome fuses with a lysosome to "digest" a microbe.

Neutrophils

Phagocytes that leave circulation but do not re-enter; their numbers increase during acute infections.

Eosinophils

White blood cells that are weakly phagocytic and associated with parasitic infections.

Monocytes

Cells that leave circulation to become macrophages; their numbers increase during chronic infections.

Wandering Macrophage

A type of macrophage that migrates through tissues "looking for trouble."

Fixed Macrophage

Macrophages that stay in specific tissues, such as those lining the liver sinusoids or the alveolar ducts.

Hypothalamus

The body's thermostat, which maintains a normal body temperature of $98.6^{\circ}F$ ($37\,^{\circ}C$).

Pyrogens

Chemicals released by injured cells due to infection that target the hypothalamus to increase body temperature.

Cardinal Signs of Inflammation

The five indicators of inflammation: 1. redness, 2. heat, 3. pain, 4. edema, and 5. loss of function.

Margination

A step in inflammation where white blood cells line up along the lining of the blood vessels.

Diapedesis

The process where white blood cells go through the capillary and out into the tissue spaces.

Stroma

The support tissue, such as collagen, involved in tissue repair.

Parenchyma

The functioning component of an organ involved in tissue repair.