Human Digestive System Defense Mechanisms

Study Notes

Strong hydrochloric acid in stomach juices often kills pathogens that reach this organ.
In intestines, bile emulsifies fats and kills microbes, acting as a secondary defense.

Injury prompts W cells to release histamine, causing blood vessel dilation.
Dilation results in redness and warmth around the injury site.
Increased permeability of blood vessels allows more phagocytes to enter and attack pathogens.

Body temperature increases to 101°F or higher, hindering the growth of most invading microorganisms.

Specialized lymphocytes, either B cells or T cells, serve as the third line of defense.
Lymphocytes are located in lymph tissues such as the spleen, thymus, lymph nodes, and tonsils.

Infectious Agents:
- Capable of causing disease includes bacteria, viruses, fungi, and protozoa.
Reservoirs:
- Locations where organisms grow, including humans, animals, insects, and environmental surfaces.
Portal of Exit:
- The route through which an organism leaves its reservoir.

Sources:
- Exogenous: From the hospital environment or personnel.
- Endogenous: Originates from the patients themselves.
Types:
- Urinary tract infections: 30-40% of cases, often due to urinary catheters.
- Lower respiratory and surgical wound infections: Each around 15%.
- Bacteraemia: 5%, along with various other infections.

Aimed at preventing the spread of infection, often referred to as clean technique.
Reduces pathogen numbers and prevents transmission between individuals.

Hand Washing:
- Most effective method for preventing infection transmission.
- Wash hands for 10-15 seconds with soap or water or use antibacterial gel.
- Surgical scrub lasts 2-5 minutes using antimicrobial solutions.
Hand Hygiene Moments:
- Before and after invasive procedures, patient contact, and handling body fluids.
Masks and Protective Eyewear:
- Required during procedures with a risk of splashing body fluids.
Gowns/Aprons:
- Worn during procedures where exposure to fluids is possible.
- Gowns should be removed carefully to prevent contamination.
Needles and Sharps:
- Never recap used needles; use safety needles and place in puncture-resistant containers.
Respiratory Hygiene/Cough Etiquette:
- Cover mouth and nose when sneezing or coughing; wash hands afterward.
Environmental Control:
- Facilities must meet infection control standards through cleanliness and disinfection protocols.

Mercurochrome:
- Alters microbial cellular proteins.
Glutaraldehyde (Cidex):
- Sterilizes equipment by inactivating proteins of bacteria, viruses, and spores.

Use gloves and gowns when entering patient rooms or in cases of high drainage or infection risk.
Disinfect surfaces and wash hands post-contact to prevent pathogen spread.