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3 Host Microbe Interaction

Mark Kerwin Sayas・38 minutes read

Microorganisms interact with human hosts through various means, influencing infection and immunity processes, which are crucial for maintaining overall health. The immune system, including antibodies and different cells like B and T lymphocytes, plays a vital role in defending against pathogens and maintaining homeostasis within the body.

Insights

  • Lactobacillus acidophilus in the vaginal canal helps maintain an acidic pH to prevent infections by inhibiting the growth of harmful bacteria, showcasing the importance of beneficial microorganisms in protecting against pathogens.
  • The immune system employs various components like phagocytes, complement system, and cytokines, alongside non-specific responses like inflammation, to combat infections and protect the body from microbial invasion, emphasizing the intricate defense mechanisms involved in maintaining health.

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Recent questions

  • How do humans acquire microbial infections?

    Through direct contact, inhalation, and vectors.

  • What are the primary microbial reservoirs for infections?

    Humans, animals, water, air, and soil.

  • How do vectors contribute to the spread of bacterial infections?

    By transmitting pathogens to humans.

  • What are the natural defense mechanisms against microbial invasion?

    Skin, mucous membranes, and normal flora.

  • What role do antibodies play in the immune response?

    Antibodies are specific proteins that target foreign molecules.

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Summary

00:00

Microbial Interactions and Human Health

  • Microorganisms require a host for multiplication, while humans need bacteria for metabolic processes and as natural flora.
  • Lactobacillus acidophilus in the vaginal canal maintains an acidic pH to prevent opportunistic bacteria from multiplying and causing infection.
  • Human activities play a crucial role in reducing car-associated infectious diseases.
  • Microbial reservoirs include humans, animals, water, air, and soil, with transmission depending on how an individual acquires the infection.
  • Vectors, such as insects, can transmit bacterial infections, while fomites, like contaminated hospital equipment, can also spread bacteria.
  • Direct contact, inhalation, and vectors can introduce microbial agents to humans, such as during childbirth.
  • Arthropods can transmit viral, parasitic, and bacterial infections to humans.
  • Fungal infections can result from physical activities like farming or skin contact.
  • The skin, mucous membranes, and normal flora act as the body's first line of defense against microbial invasion.
  • Normal flora, like Cutibacterium acnes on the skin and Streptococcus mutans in the mouth, help maintain homeostasis but can cause infections in immunocompromised individuals.

27:52

"Bacterial Invasion and Immune Responses in Infection"

  • Clostridium defile is a bacteria that can cause necrotizing enterocolitis, a life-threatening illness affecting neonates with a 50% mortality rate.
  • Necrotizing enterocolitis is characterized by inflammation of the intestine, leading to bacterial invasion and cellular damage or death, potentially resulting in necrosis of the colon and intestine.
  • Bacteroides, anaerobic strepto, enterococcus, and enterobacter are natural flora in the gastrointestinal tract, surviving due to factors like neutral pH, low oxygen, and indigestible polysaccharides.
  • The urogenital tract is colonized by skin organisms, with lactobacillus, anaerobic gram-negative rods, and gram-positive cocci in the vagina, making females more prone to genitourinary infections due to urethra proximity to the vaginal canal.
  • Factors like trauma, burns, surgical wounds, implantation of medical devices, diseases like diabetes, childbirth, and overuse of antibiotics can disrupt host barriers, allowing bacterial invasion.
  • Non-specific responses like phagocytes, including neutrophils and macrophages, engulf bacteria, leading to bacterial destruction and inflammation characterized by swelling, redness, heat, and pain.
  • The complement system, coagulation system, and cytokines work alongside phagocytes to enhance immune responses, with inflammation attracting cells and mediators to eliminate infectious agents and prevent further invasion.
  • Inflammation occurs due to capillary widening, increasing blood flow and causing heat in the injured area, aiding in the removal of pathogens and limiting the spread of infection.

54:00

Understanding Inflammation and Immune Responses in Infection

  • Heat is generated by an increase in temperature in affected tissues due to increased blood flow.
  • Redness occurs as a result of vasodilation of blood vessels at the site of infection, leading to increased blood flow and fluid release into the tissue.
  • Swelling is caused by an increased flow of fluid and cells to the affected body part.
  • Tenderness is due to the attraction of leucocytes and extravasation of lyte in the injury site.
  • Pain results from tissue damage and pressure from increased blood flow and fluid, along with the influx of leucocytes and fever.
  • Antibodies, also known as immunoglobulins, are specific proteins produced in response to foreign molecules called antigens.
  • B lymphocytes produce antibodies against antigens, with subtypes including plasma cells and B memory cells.
  • T lymphocytes, including helper T cells, cytotoxic T cells, and suppressor T cells, interact with antigen-presenting cells to facilitate immune responses.
  • The immune system has two arms: antibody-mediated (humoral immunity) and cell-mediated immunity, involving B cells, T cells, and natural killer cells.
  • Microorganisms can cause infection through virulence factors, such as endotoxins and exotoxins, which affect the body's metabolism and immune response.

01:21:49

Role of antibodies in immune response

  • Antibodies play a crucial role in the body's immune response.
  • The discussion covers host-microbe interactions and the immune system's response mechanisms.
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