Microbial Entry, Spread, and Host Defense Mechanisms in Human Body Systems

What is the portal of entry for microorganisms into the human host?

exit enables microorganisms to enter, spread, and escape the host.

What are the characteristics of pathogenic microbes that enhance their ability to invade a host?

possess virulence factors that help them invade, survive, and cause disease.

What are innate defenses of the host?

include nonspecific responses such as physical barriers and immune responses at each body site.

What are adaptive defenses of the host?

involve specific immune responses that recognize and remember pathogens.

How do microbes enter the integumentary system?

openings in the skin and mucous membranes.

How do microbes enter the respiratory system?

inhaled and can bind to epithelial cell receptors; nasal hairs filter air and mucous traps particles.

What is the role of adhesins in microbial infection?

molecules that help pathogens stick to host cells, preventing them from being washed away.

What are invasins?

enable pathogens to enter host cells or tissues, often through mechanisms like zipper phagocytosis.

How can microbes spread through the cardiovascular system?

enter the circulatory system through skin, mucous membranes, needle picks, insect bites, or invasive procedures.

What is the significance of the blood-brain barrier for pathogens?

pathogens can cross the blood-brain barrier, often using leukocytes as a means of entry.

How do microbes enter the gastrointestinal system?

through food or water, with adhesins promoting colonization and invasion.

What is systemic spread in the context of microbial infection?

occurs when organisms gain access to the blood, putting the entire system at risk of infection.

What are virulence factors?

traits that pathogens use to invade, survive, and cause disease in a host.

What are exotoxins?

chemicals secreted by organisms that help microbes spread, invade, and resist host defenses.

What are endotoxins?

toxic components of the outer membrane of Gram-negative bacteria, such as Lipopolysaccharides (LPS).

What is the role of immune evasion factors?

help pathogens hide from or disable the immune system.

What is biofilm formation?

involves communities of microbes encased in a protective matrix, increasing resistance to antibiotics.

What is quorum sensing?

is a chemical communication process that coordinates group behaviors in microbial communities.

How do antibodies function in agglutination?

cause antigens to clump together and fall out, aiding in their removal from the body.

What is opsonization?

the process where antibodies coat an antigen to enhance its digestion by phagocytic cells.

What is the role of antigen-presenting cells (APCs)?

capture, process, and present antigens to T cells, activating the adaptive immune response.

What are dendritic cells?

powerful APCs found in tissues that contact the environment, activating naïve T cells.

What is the function of macrophages in the immune response?

pathogens through phagocytosis and present antigens to helper T cells.

What is the significance of B cells in the immune response?

bind specific antigens and present them to helper T cells, which help them become plasma cells.

What is the function of the capsule in bacteria?

protects binding sites from antibodies and aids in resisting phagocytosis.

What are endospores and their significance?

are formed by Bacillus and Clostridium in response to stress, making them more difficult to kill.

What is the difference between Gram-positive and Gram-negative cell walls?

have a thick peptidoglycan wall, while Gram-negative bacteria have an outer membrane with endotoxins.