Chapter 17 study guide Flashcards
can be characterized as a multifaceted system of defenses that targets invading
pathogens in a nonspecific manner
Nonspecific innate immunity
One of the body’s most important physical barriers is the skin barrier, which is composed of three layers of closely
packed cells.
epidermis - thin upper layer
dermis - hair follicles, sweat glands, nerves and blood vessels
hypodermis- fatty layer contains blood and lymph
- How does our skin act as a physical barrier against infection?
The skin’s surface is made of keratin-filled, dead cells, forming a tough, dense barrier.
Fatty acids on the skin create a dry, salty, and acidic environment that inhibits microbial growth.
Dead skin cells are shed regularly, removing attached microbes.
New cells replace shed skin, maintaining an ongoing protective barrier.
How does mucus act as a physical barrier against infection?
Mucus traps debris, particulate matter, and microbes, protecting fragile cell layers beneath it. It also contains antimicrobial peptides.
What kinds of cells produce mucus?
epithelial and goblet cells
Where are mucous membranes found?
nose, mouth, lungs, urinary tract, and digestive tract.
What is the mucociliary escalator and how does it protect against infection?
mucociliary escalator
The _____ is the movement of cilia in the respiratory tract that propels mucus (with trapped debris and microbes) out of the lungs, either by coughing, sneezing, or swallowing.
mucociliary escalator
What common activity damages cilia, increasing the risk of respiratory infections?
smoking
- List some common mechanical defenses against infection.
Shedding of skin cells
Expulsion of mucus via the mucociliary escalator
Excretion of feces through intestinal peristalsis
Flushing action of urine
Flushing action of tears
Blinking to wash debris away from the eyes
Eyelashes and eyelids preventing dust and microorganisms from reaching the eye
Our _____ protects against infection by occupying cellular binding sites and competing for nutrients with pathogens
microbiome
is an endogenous mediator, providing an additional layer of defense by helping seal off the pore of the hair follicle,
preventing bacteria on the skin’s surface from invading sweat glands and surrounding tissue
sebum
In the oral cavity, saliva contains mediators such as lactoperoxidase enzymes, and mucus secreted by the esophagus contains
the antibacterial enzyme ____.
lysozyme
In the stomach, highly acidic ____kills most microbes. In the lower
digestive tract, the intestines have pancreatic and intestinal enzymes, antibacterial peptides (cryptins), bile
produced from the liver, and specialized Paneth cells that produce lysozyme.
gastric fluids
In the urinary tract, urine flushes microbes out of the body during ______. Furthermore, the slight acidity of urine
(the average pH is about 6) inhibits the growth of many microbes and potential pathogens in the urinary tract.
urination
The female reproductive system employs ____, an exogenously produced chemical mediator, to inhibit microbial
growth.
lactate
Lactobacilli in the area ferment glycogen to produce ______, lowering the pH in the vagina and inhibiting
transient microbiota, opportunistic pathogens like Candida (a yeast associated with vaginal infections), and other
pathogens responsible for sexually transmitted diseases.
lactate
In the ears, _____ exhibits antimicrobial properties due to the presence of fatty acids, which lower the
pH to between 3 and 5.
ear wax
______ cleaves the bond between NAG and NAM in
peptidoglycan, a component of the cell wall in bacteria. It is more effective against gram-positive bacteria, which
lack the protective outer membrane associated with gram-negative bacteria. _____ inhibits microbial growth by
chemically binding and sequestering iron.
lysozyme
lactoferrin
are produced by the body, with some being produced routinely and others in greater quantities in response to the presence of an invading pathogen. They can be produced by epithelial cells, macrophages, neutrophils, and certain members of the resident microbiota.
AMPs
How do AMPs protect against infection?
damaging microbial membranes, destroying DNA and RNA, or interfering with cell-wall synthesis.
The ______ is a group of more than 30 plasma proteins that play a role in innate nonspecific immunity and also link innate and adaptive immunity. These proteins circulate in an inactive form and become activated in response to microorganisms, helping to target and destroy pathogens.
complement system
is the process by which the precursor complement proteins become functional. This is a cascade reaction that can be triggered by three different pathways: the alternative, classical, and lectin pathways
complement activation
A _____ is formed when activated complement proteins, such as C5b, C6, C7, C8, and C9, assemble on the surface of a target cell. This complex creates pores in the cell membrane, leading to cell lysis (destruction) by allowing the influx of water and ions, causing the cell to burst.
membrane attack complex MAC
The process of coating pathogens with _____, making it easier for phagocytes to recognize, engulf, and destroy them.
Complement proteins: C1q, C3b, C4b
opsonin
creates pores in the membranes of gram-negative bacteria, causing cell lysis by allowing ions and water to flow in and out of the cell.
does not affect gram-positive bacteria
C6, C7, C8, and C9
MAC
What are the 3 major groups of cytokines?
Interleukins
Chemokines
Interferons
Modulate nearly every function of the immune system.
Produced by and stimulate a variety of cells, not just immune cells.
interleukins
Act as chemotactic factors that specifically recruit leukocytes to sites of infection, tissue damage, and inflammation.
Chemokines:
Type I (α, β): Produced by virus-infected cells to inhibit viral replication, stop mRNA production, and stimulate immune cells to attack infected cells.
Type II (γ): Activates immune cells to enhance the immune response, especially in viral infections.
interferons
Released by mast cells and basophils in response to cytokines.
Mediates proinflammatory events like bronchoconstriction (tightening of airways) and smooth muscle contraction.
histamine
Produced from the metabolism of arachidonic acid in leukocytes and tissue cells.
More potent and longer-lasting than histamine, contributing to proinflammatory effects, including coughing, vomiting, and diarrhea, which help expel pathogens from the body.
Leukotrienes:
Contributes to edema by causing fluid and leukocytes to leak from blood vessels into tissues.
Binds to receptors on capillary walls, causing dilation and increased permeability of capillaries.
Bradykinin:
inflammation eliciting mediators
histamine
leukotriens
bradykinin
prostaglandins
is the process of blood cell formation, where pluripotent hematopoietic stem cells (HSCs) in the bone marrow differentiate into various types of blood cells.
also, forms in the bone marrow.
Hematopoiesis
The 3 major types of granulocytes:
Neutrophils
Eosinophils
Basophils
What is another name for a neutrophil?
Polymorphonuclear neutrophils (PMNs)
List 2 ways that neutrophils protect against infection
Phagocytosis:
Neutrophil extracellular traps (NETs)
Neutrophils engulf and destroy infectious bacteria using their granules containing defensins and hydrolytic enzymes.
phagocytosis
Neutrophils release chromatin-based structures with antimicrobial proteins that trap and kill pathogens.
Neutrophil extracellular traps (NETs):
protect against protozoa and helminths (parasitic infections)
Eosinophils
contribute to allergic reactions.
Eosinophils
Basophils release _______, which is involved in inflammatory responses.
histamine
What other type of cell is closely related to basophils?
mast cells
Nucleus: Multi-lobed (3-5 lobes).
Granules: Small, numerous, lilac-colored.
Each lobe is connected by a thin strand of nuclear material.
neutrophils
Nucleus: Typically 2-3 lobes.
Granules: Larger, stain reddish-orange.
eosinophils
Nucleus: Two-lobed.
Granules: Large, stain dark blue or purple.
Basophils:
They are often associated with blood vessels and nerves or found close to
surfaces that interface with the external environment, such as the skin and mucous membranes in various regions of
the body.
leave the circulating blood and are most
frequently found residing in tissues.
very similar to basophils, containing
many of the same components in their granules (e.g., histamine) and playing a similar role in allergic responses and
other inflammatory reactions
mast cells
are a type of white blood cell that lack visible granules in their cytoplasm. Unlike granulocytes, they do not have numerous granules, and they are involved in various immune responses, primarily in adaptive immunity.
Agranulocytes
recognize infected or cancerous cells through a process of identifying molecular markers on the cell’s surface. They look for the presence of inhibitory signals, such as the major histocompatibility complex (MHC) markers, which healthy cells express. Cancerous and virus-infected cells often have reduced MHC markers and increased activating molecules on their surfaces. This reduction in MHC markers and presence of activating signals alerts NK cells to the abnormality.
NK cells
What two types of compounds do NK cells release to destroy a target cell?
perforin and granzymes
______ creates pores in the target cell’s membrane, allowing _____, which are proteases, to enter the cell and trigger apoptosis, or programmed cell death.
perforin and granzymes
all protect against infection through phagocytosis, engulfing pathogens and apoptotic cells. They also promote immune responses by producing and releasing cytokines.
Monocytes, macrophages, and dendritic cells
Found circulating in the bloodstream. When they enter body tissues, they differentiate into macrophages or dendritic cells.
Monocytes:
Reside in specific body tissues for extended periods, adapting to the characteristics of those tissues. They are important in lymphoid and nonlymphoid tissues and help support neighboring cells.
macrophages
Primarily found in skin and mucous membranes, which are key entry points for pathogens. They act as sentinels, monitoring these areas for invaders.
Dendritic Cells:
are a diverse group of immune signaling molecules and are especially important in our defense against
viruses. (interferon-α and interferon-β) are produced and released by cells infected with virus. stimulate nearby cells to stop production of mRNA, destroy RNA already produced, and reduce
protein synthesis.
interferons
Stimulate and modulate most functions of immune
system
Interleukins
