Host ResistanceHost Resistance

Three levels.Three levels.

Mechanical FactorsMechanical Factors EpidermisEpidermis

Keratinized -skinKeratinized -skin Non-keratinized Non-keratinized

mucous mucous membranes, membranes,

Mouth- GI tractMouth- GI tract Trachea- bronchiTrachea- bronchi VaginaVagina

Physical BarrierPhysical Barrier

Lachrymal GlandsLachrymal Glands

TearsTears LysozymeLysozyme

Gram positiveGram positive

Ciliary EscalatorCiliary Escalator Ciliated epitheliumCiliated epithelium

Upper tracheaUpper trachea Moves mucusMoves mucus Dust, microbes Dust, microbes

trapped in sticky trapped in sticky mucusmucus

EscalatorEscalator SwallowedSwallowed Destroyed by Destroyed by

stomach acidstomach acid

Chemical factorsChemical factors

Sebum -oil, pH 5.5Sebum -oil, pH 5.5 PerspirationPerspiration Lysozyme- G +Lysozyme- G + Gastric Juices- pH Gastric Juices- pH

22 Vaginal secretions Vaginal secretions

- pH 5.- pH 5. Antimicrobial Antimicrobial

peptides - NEW !peptides - NEW !

Normal MicrofloraNormal Microflora

LactobacillusLactobacillus inhibits inhibits Candida albicans Candida albicans in in vagina. vagina.

E. coli E. coli inhibitsinhibits Salmonella Salmonella andand Shigella Shigella in large in large intestinesintestines..

Proprioibacteria Proprioibacteria andand S. S. epidermidis (epidermidis (skinskin) ) inhibitinhibit S. aureus.S. aureus.

Blood ActivitiesBlood Activities

Leukocytes = all white blood cells.Leukocytes = all white blood cells.

Phagocytes - WBCs that can engulf particles.Phagocytes - WBCs that can engulf particles.

Granulocytes -basophils, neutrophils, Granulocytes -basophils, neutrophils, eosinophils.eosinophils.

Lymphocytes - make antibodies (specific).Lymphocytes - make antibodies (specific).

Lymphatic SystemLymphatic System

Lymphocytes - make Lymphocytes - make antibodies (specific).antibodies (specific).

Lymphatic system - a Lymphatic system - a system that parallels system that parallels the circulatory the circulatory system. system.

Stimulated by bacteria, Stimulated by bacteria, LPS.LPS.

Controlled by cytokines Controlled by cytokines (chemical (chemical messengers).messengers).

PhagocytosisPhagocytosis

PhagocytosisPhagocytosis

WBC engulfing bacteria. Note pseudopods.

InflammationInflammation

1. Injury

2. Vasodilation and clotting

3. Histamine release.

4. Kinins -increase permeability of BV.

5. Prostaglandins - released by damaged cells.

InflammationInflammation

6. Phagocyte Migration and Phagocytosis

7. Tissue Repair.

FEVERFEVER

Hypothalamus controls body temperature.

Interleukin-1 released from phagocytes.

Hypothalamus releases prostaglandins.

Prostaglandins raise body temperature.

Skin temperature remains cold causing chills.

Once IL-1 removed, fever breaks.

ComplementComplement

2 pathways- makes Membrane Attack Complexes (MACs)

Incites :

• Inflammation

• Cytolysis

• Opsinization

Too much can cause anaphylactic shock.

ComplementComplement

InterferonsInterferons

Interferons -IFNs- anti-viral.

Prevent viral replication.

Chemical factorsChemical factors

Antimicrobial peptidesAntimicrobial peptides-defensins - WBCs-defensins - WBCs

Cathelecidins - skin, lungs, testisCathelecidins - skin, lungs, testis

Forms channels that insert into Forms channels that insert into bacterial membranes.bacterial membranes.

Present in insects and lower life forms. Present in insects and lower life forms. Mammals (include Humans) have Mammals (include Humans) have these too.these too.

Mechanisms of Peptide Action

"carpet mechanism""barrel-stave"mechanism