Ch 14 Flashcards
Immune system
Collection of defenses (natural and adaptive) that protects the body from infection
Essence of immunology
Discrimination through recognition of self from non-self - keeps us from attacking ourselves
Genetic barriers
Allow us as a human race to be resistant to most plant and animal pathogens - the correct receptors for these pathogens are not present on human cells
Species resistance
Physiological processes of humans are not going compatible with those of the specific pathogen - conditions are incompatible with those needed for pathogen survival
First line of defense
Innate, nonspecific, blocks invasion, through portal of entry
- limits access to internal tissues
- physical barrier: skin, tears, coughing, sneezing
- Chemical barriers: low pH, lysozyme, digestive enzymes
- Genetic barriers: resistance inherent in genetic make up of host (pathogen can’t invade)
- skin (1.5-2 meters squared) lungs (70-140 meters squared) , gastrointestinal tract (40 meters squared)
* not a true immune response
Skin
- Composed of two major layers: epidermidis and dermis
- Contains chemicals that defend against pathogens: sweat and sebaceous glands
Epidermidis
- Multiple layers of tightly packed cells
- Few pathogens can penetrate these layers
- Shedding of dead skin cells removes microorganisms
Dermis
Collagen fibers helps skin resist, abrasions that could introduce microorganism’s
Perspiration secreted by sweat glands
- Salt, inhibits growth of pathogens
- antimicrobial peptides act against microorganisms
- Lysozyme destroy cell walls of bacteria
- Uses the flushing, the fact that helps remove micros
Sebaceous (oil) glands
- helps keep skin pliable, and less likely to break or tear
- Lower skin pH to a level inhibitory to many bacteria
Innate, natural defenses
Present at birth, and provide nonspecific resistance to infection
Adaptive immunities
Specific resistance, and must be acquired
Second line of defense
Innate - mostly nonspecific - consists of protective cells and fluids
- phagocytosis, inflammation, interferon, fever, and complement
* acts rapidly at both local and system levels
Phagocytosis
- cell uses its plasma membrane to engulf a large particle
Inflammation
Read, hot, swollen
Interferon
Interfere with viral replication
Complement
Uses antibodies to kill bacteria (compliments, antibacterial activity)
Third line of defense
Acquired, specific, occurs as a development of immuno logic memory
- Uses T lymphocytes, B lymphocytes, and antibodies
* provides long-term immunity 
Outer most layer of the skin
Stratum corneum
- Composed of epithelial cells that has become compacted, cemented together, and embedded with keratin (an insoluble protein) - this creates a thick, tough waterproof layer that is thickest in the soles of feet and palms of hand
- Physical barrier for first line of defense
Mucutaneous membranes
Found in digestive, urinary, respiratory tract’s, and of the eye
- moist and permeable
- Damaged cells are rapidly replaced
- Mucus coat impede the entry and attachment of some bacteria
- Rhinitis: inflammation of the nasal mucosa creates a copious flow of mucus and fluids that helps flush out nasal passages
Other physical barriers for the first line of defense are
- blinking and tear production: flushes the eye surface to get rid of irritants
- Flow of saliva: carries microbes in the harsh conditions of the stomach
- Vomiting and defecation: evacuate noxious substances, or microorganisms
- nasal hair: traps, larger particles found within the respiratory track
- Ciliary escalator: ciliated epithelium that is primarily in the trachea and bronchi that propels foreign particles trapped in mucus towards the pharynx to be removed
- Sneezing: expels a large volume of air at high velocity
- Coughing: the sensitivity of bronchi, trachea, and asked to foreign material triggers, this, which ejects irritants
- Genitourinary tract colon through the continuous trickle of urine, the bladder empties periodically and flushes the urethra
- Microbiota: presents can block the access of pathogens to epithelial services, and can compete with pathogens for limited resources, or alter the environment of the body, both of which can make it less welcoming for pathogens (some bacteria in the large intestine can secrete antibodies which can inhibit or kill other bacteria)
Chemical barriers first line of defense
Sebaceous, secretions, lysozyme, defensins, sweat, skin, stomach, intestines, semen, and vagina
Lysozyme: chemical first line
Enzyme that hydrolyzes the Pepto glycan in the cell wall of bacteria
Defenses: chemical first line
Peptides that are produced by various cells and tissues, that damage, cell membranes and lyse bacteria and fungi
- Skin cells: produce germicide in which eliminate bacteria
-Paneth cells: located in intestine and secrete defenses that can destroy or inhibit some types of infectious agents