Chapter 23 Flashcards
____________ is the community of microbes inhabiting a body site
Microbiota
____________ encompasses the community of microbes and their genes.
Microbiome
Our bodies carry about ___________ bacterial cells.
1−10 ×
1012)
__________ identify our resident microbes
Metagenomic strategies
In 2016, the U.S. government announced __________
The National Microbiome
Initiative
An immunocompromised host is at risk due to ________________.
opportunistic pathogens
When and how does a person develop a microbiome?
The baby breaking out of the embryonic membrane and Eeposed to microbes residing in the birth canal and the
outside world
By _________ years, diversity assumes adult composition.
3
The skin is populated by ___________ microorganisms
10^12–10^13
Which type of bacteria populate the skln?
aerobes, anaerobes, and facultative bacteria
Why is the skin difficult to colonize?
― Acidic pH (pH 4-6)
― High in salt
― Low in water activity
________ is present on the skin and degrades bacterial peptidoglycan
lysozymes
_________ are more resistant to salt and dryness, so they mostly inhabit the skin
Gram-positive bacteria
Which areas of the skin do most bacteria colonize?
scalp, ears, armpits, genital, and anal areas
The ____________ and ______________ species benefit us by prompting the expression of epithelial cell tight-junction proteins, modulating functions of the immune system, and secreting antibacterial peptides
Corynebacterium species and Staphylococcus epidermidis
__________ or ___________ are sued to treat bacteria that cause acne
tetracycline or clindamycin
Pathogenic (diseasegenerating) agents include:
bacteria, viruses, and fungi
In addition to neutralizing pathogens, the immune system is also responsible for:
disposing of unneeded components of the body (aging cells and
cellular debris), wound healing, recognizing and eliminating mutant cells that may develop into cancer, and rejecting tissues and cells that are not identical to “self”
The immune system is divided into 2 parts, _______________ and _________________.
nonspecific (innate) immunity and specific (adaptive) immunity
__________________ provides the first defenses against pathogens
regardless of the type
nonspecific (innate) immunity
____________________represents a stronger defense against a specific
pathogen that takes longer to develop
The immune system
specific (adaptive) immunity
The immune system consists of 3 components, _________________, _______________, and __________________.
Physical barriers, Leukocytes, and Lymphoid tissues
Physical barriers include _______ and _______.
Epithelium and Chemicals
Leukocytes are
White blood cells that produce a wide range of immune responses
Lymphoid tissues are
Bone marrow, thymus, spleen, lymph nodes, and tonsils where leukocytes develop, reside, and come into contact with foreign materials
_______and ______ provide nonspecific protection against foreign matter
Skin and Mucous
Skin is made up of the __________ and ___________
epidermis and dermis
______________ consists of tightly packed epithelial cells and lacks blood vessel. The outermost layer is composed of dead epithelial cells and keratin
Epidermis
______________ contains sebaceous glands that secret an acidic oily, bacteriostatic substance called sebum
Dermis
__________ are in saliva
lysozymes
________ are in sebum
Fatty acids
_____________ have cytoplasmic granules that contain secretory products
Granulocytes
__________ do not have granules
Agranulocytes
What are the three granulocytes?
Neutrophils, Eosinophils, and Basophils
What are the two agranulocytes?
Monocytes and Lymphocytes
In addition to the leukocytes, three types of tissue cells are derived from the hematopoietic stem cells:
- Macrophages
- Mast cells
- Dendritic cells
What are all the phagocytic cells?
Neutrophils (most abundant), Eosinophils, Monocytes, Macrophages, and Dendritic cells
What are phagocytes?
Neutrophils that increase in number during infections (fight bacterial infection). Secrete cytokines involved in inflammation.
How do Eosinophils work?
They defend against parasites by releasing toxic substances
What are monocytes?
phagocytes in the blood that differentiate into macrophages in the tissue to phagocytose foreign matter
What are macrophages?
(five to ten times larger than monocytes) have greater activity in both phagocytosis and secretory activity that are found in almost all tissues of the body
_________________ provide the immune system with diversity, specificity, memory, and the ability to distinguish between self and nonself
lymphocytes
Lymphocytes account for ______________ of leukocytes.
20%-40%
What are the three types of lymphocytes?
T cells, B cells, and Null cells
____________ upon contact with antigen, develop into plasma cells
B cells
Plasma cell secretes ____________
antibodies (immunoglobulins)
True or False: Antibodies mark invaders but do not damage bacteria BY THEMSELVES
True
What do T cells do?
Directly damage foreign/abnormal cells
Develop into ____________ that destroy target cells (infected or abnormal) which takes several days
cytotoxic T cells
Secretory products from T cells:
Form pores in the target’s cell membrane (called perforins) and cause lysis
____________ lack cell membrane components (present in B cells and T cells), are mostly natural killer cells (large, granular), serve as an important defense against viral infections, attack virus-infected cells and cause lysis, are fast acting, and are part of the early immune response (well before B cells and T cells). These also recognize and kill mutant cells that may develop into cancer
Null cells
________________ are formed in bone marrow from hematopoietic stem cells and circulate for a brief time before entering the tissues where they mature
Tissue Cells of Hematopoietic Origin
____________ are found in skin and mucosal membrane that secrete histamine and other substances
Mast cells
___________ are able to phagocytose or endocytose pathogens. They also activate certain types of T cells.
Dendritic cells
What are the two types of lymphatic tissue?
central lymphoid tissue and peripheral lymphoid tissue
______________ is the site of lymphocyte production and maturation. It includes bone marrow and the thymus,
central lymphoid tissue
___________ is the site where lymphocytes contact pathogens/foreign matter and become activated as part of the immune response
peripheral lymphoid tissue
_____________ is the site where all leukocytes develop from hematopoietic stem cells
Bone marrow
T lymphocytes migrate from bone marrow to _________ where they reach maturity
Thymus
________ and _________ filter blood and lymph respectively. They are part of the peripheral lymphoid tissue.
Spleen and lymph nodes
________ and ________ trap inhaled particles and microorganisms. They are part of the peripheral lymphoid tissue.
tonsils and adenoids
________________, __________________, and _______________ trap substances
that enter the body in ingested food or water. They are part of the peripheral lymphoid tissue.
Appendix, lymph nodes, and peyer patches.
Nonspecific (innate) defenses include:
Physical barriers, inflammation, interferons, and the complement system
__________ are a family of related proteins that can induce virus resistance to other cells.
Interferons
___________ is a group of plasma proteins that act to lyse foreign cells, especially bacteria..
the complement system
What are the five main events that occur during inflammation?
-Phagocytosis by nearby macrophages
-Capillaries dilate and become more permeable
-Foreign matter is contained
-More leukocytes migrate to area
-Continued activity of recruited leukocytes
During phagocytosis in inflammation:
nearby macrophages quickly adhere to bacteria introduced, initiate phagocytosis, cytokines are secreted that induce the synthesis of adhesion molecules (blood vessels) and release of more neutrophils (bone marrow)
During dilation and increased permeability:
mast cells secrete histamine which causes the blood vessels to dilate resulting in increased blood flow and increased movement of proteins and cells to injured tissue
What are the four symptoms of inflammation induced by effects of histamine?
Redness, swelling, heat, and pain
When foreign matter is contained:
mast cells and basophils release the anticoagulant, heparin which initially prevents the formation of a clot. This lets blood enter the area; however, a clot is eventually formed and prevents the foreign material from spreading further
Clots form ________ on the skin.
scabs
During leukocyte proliferation and migration:
There is an increase 4 to 5 times in circulating
numbers of leukocytes
What happens after 1 hour of tissue injury?
neutrophil migration
What happens after 10 hours after tissue injury?
monocyte migration and
development into macrophages
__________________ is the weak interaction of leukocytes with endothelial cells
lining the blood vessel near the site of injury
Margination
______________ is movement between endothelial cells
Diapedesis
___________ is movement in tissue to injury
Chemotaxis
In the continued activity of recruited leukocytes 2 important functions are served:
Phagocytosis and the secretion of cytokines
What are the four steps of phagocytosis?
attachment
internalization
degradation
exocytosis
Phagocytosis is greatly enhanced by _____________
opsonins
What are opsonins?
Proteins (ex. antibodies) that bind tightly to the foreign material that make engulfment and destruction 4000x faster
True or False: In less than 0.01 second, the phagocyte’s
plasma membrane extends outward and surrounds the material
True
A _______________ is a large irregular vesicle that fuses with a lysosome
phagosome
Lysosome enzymes degrade phagocytosed product in ________________________.
secondary lysosome (large organelle)
The phagocyte uses some bacterial
amino acid and eliminates other
degraded products by _________________.
Exocytosis
When a foreign material attaches to a phagocyte _____________ are secreted,
Cytokines
What are the secretory products of macrophages?
IL-1
IL-6
TNFα
__________ stimulates proliferation and differentiation of B and T lymphocytes
IL-1
_____________ lead to cell-mediated immunity
T cells
________________ act as endogenous pyrogens that stimulate fever via hypothalamus
IL1, TNFα
Hypothalamus increases body temperature via _____________ .
prostaglandins
_____________, ________________, and _________________ stimulate liver to produce acute-phase proteins that have antibacterial and inflammatory effects, marking the bacteria for phagocytosis (acts as an opsonin), and activates the complement system
IL-1
IL-6
TNFα
______________ and ____________ are secreted from virus-infected cells and induce virus resistance in
neighboring uninfected cells
Interferonα and interferonβ
______________ is secreted from active T cells and NK cells that inhibits viral replication, enhances phagocytosis by macrophages, boosts antibody production in B cells, helps to activate NK cells and cytotoxic T cells, and inhibits cell division—defense against cancer, suppressing the growth of tumors
Interferonγ
________________ are an early defensive mechanism from invasion and tumor progression that cause lysis by secreting perforins. Are part of the specific immune response.
Natural killer cells (NK)
Actions of NK cells are enhanced by ________ and ____________.
interleukin-2 produced by T cells and antibodies produced by plasma cells (B cells)
How many proteins are part of the complement system?
30
In what ways are the complement system activated?
Classical pathway
Lectin pathway
Alternative pathway
___________ is the pathway that involves binding to antibodies that are already
attached to bacterial cells
Classical pathway
____________ is the pathway that involves binding of a serum protein, mannose-
binding lectin, to mannose-containing carbohydrates on bacteria or viruses.
Lectin pathway
_____________ is the pathway that involves binding directly to carbohydrates present
on the surface of bacterial cells
Alternative pathway
What are the 4 different ways in which the complement system provides defensive capabilities?
functioning as an opsonin, recruiting more phagocytes, triggering histamine, and the development of membrane attack complex (MAC)
Formation of the MAC complex leads to
A collection of pore-forming proteins that pierce the bacterial membrane which causes the bacterial cell to lose its integrity, swells, and then lyse
Provide a detailed description of the classical pathway.
C1 attaches to the antibodies on the surface of the bacteria, then C1 cleaves C2 which leads to the complete protein cascade resulting in MAC formation. This is part of the specific response.
Provide a detailed description of the lectin pathway.
Mannose binding lectin binds to glycoproteins on the bacteria. This leads to the formation of MBL-MASP complexes that activate C4 and C2. MAC formation occurs after complete cascade. This is part of the nonspecific response.
Provide a detailed description of the alternative pathway.
Proteins attach to carbohydrates on the bacterial surface. Then C3 is activated which in turn activates C5. This leads to complete protein cascade resulting in MAC formation.
MAC consists of _____.
C5-C9
What happens during the solubilization of C3b?
C3b binds to cells with attached antibodies which prevents too many antibodies from accumulating. Also keeps antibodies soluble so the capillaries are not blocked.
True or False: C3b also functions as an opsonin
True
__________________ causes chemotaxis, vasodilation, increased vascular permeability, and activates neutrophils which enhances inflammation.
C5a
_________, ___________, and _________ trigger release of vasoactive amines
(histamine) and activate mast cells.
C3a, C4a, and C5a
