Question 1

_____ cells persist long after an individual has been vaccinated.

Accepted Answer

Memory cells are a type of immune cell that "remembers" an encounter with a specific pathogen, such as a virus or bacteria, and can quickly respond if the pathogen is encountered again. They persist long after an individual has been vaccinated or has recovered from an infection, providing long-lasting immunity.

Question 2

Which of the following pairs is mismatched?

Accepted Answer

Innate immunity does not involve highly specialized defenses. It is the non-specific immune response that is present at birth and provides immediate defense against pathogens. Specialized defenses are part of the adaptive immune system.

Question 3

A. Name the parts of the body where epithelia act as barriers to infection.
B. Describe the three main ways in which epithelia carry out this barrier function, giving details of the mechanisms employed.

Accepted Answer

A.Skin; mucosal epithelium of the gastrointestinal tract; mucosal epithelium of the respiratory tract; mucosal epithelium of the urinogenital tract. B. (i)Mechanical (physical)barriers.Tight junctions between the epithelial cells prevent the penetration of pathogens between the cells to underlying tissues.In addition,there is a flow of air and fluid over epithelial surfaces,which oxygenates and flushes the surface,preventing anaerobic bacterial growth and transient adhesion.On ciliated epithelial surfaces,such as those of the respiratory tract,the formation of a layer of mucus that is kept in continual movement by the beating cilia inhibits colonization and invasion by microorganisms. (ii)Chemical barriers.The epithelium produces a variety of chemical substances that interfere with the adherence of microorganisms to epithelium and with their replication.The skin produces fatty acids in sebaceous glands,which helps to create an acid environment inhibitory to the growth of many bacteria.Lysozyme,an enzyme that inhibits cell-wall formation in bacteria,is secreted in tears,saliva,and sweat.The stomach produces strong hydrochloric acid,creating a highly acidic and formidable environment,which when combined with the stomach enzyme pepsin (an acid protease)poses one of the most inhospitable environments for microbial growth in our bodies.Defensins are antimicrobial peptides secreted by all the protective epithelia. (iii)Microbiological barriers.A microbiota of non-pathogenic commensal microorganisms colonizes many epithelial surfaces and provides an additional barrier to infection.They compete with pathogenic microbes for space and nutrients,and sometimes produce antibacterial proteins that further inhibit attachment to epithelium.For example,Escherichia coli in the large intestine produce colicins,which prevent colonization by other bacteria.

Question 4

The first line of defense against microorganisms that infect the body is referred to as _____.

Accepted Answer

Innate immunity is the first line of defense against microorganisms that infect the body. It includes physical and chemical barriers such as skin, mucous membranes, and stomach acid, as well as cellular defenses such as phagocytic cells and natural killer cells. Opportunistic immunity, adaptive immunity, primary immunity, and central immunity are not terms commonly used to refer to the first line of defense against infection.

Question 5

A bacterium that causes a common disease in a population that has been previously exposed to it is called _____.

Accepted Answer

A bacterium that causes a common disease in a population that has been previously exposed to it is called endemic. Endemic diseases are those that are regularly found in a particular geographic region or population. They can be caused by a variety of factors, including environmental conditions, genetic predisposition, and exposure to infectious agents. However, because the population has been previously exposed, it may have developed some level of immunity or resistance to the disease.

Question 6

_____ act as cellular messengers by delivering degraded pathogens to lymphoid organs.

Accepted Answer

Dendritic cells are professional antigen-presenting cells that capture, process, and present antigens to adaptive immune cells. They also act as cellular messengers by migrating from peripheral tissues to lymphoid organs, where they deliver degraded pathogens to activate adaptive immune responses. Plasma cells produce antibodies, large granular lymphocytes are involved in innate immune responses, and mast cells and basophils are involved in allergic reactions and inflammation.

Question 7

How can antibiotics upset the barrier function of intestinal epithelia? Give a specific example.

Accepted Answer

The answer of How can antibiotics upset the barrier function...

Question 8

In most cases,adaptive immune responses rely on the initial activation of _____ in secondary lymphoid tissue:

Accepted Answer

The answer of In most cases,adaptive immune responses rely on...

Question 9

Another name for a large granular lymphocyte is a _____.

Accepted Answer

Natural killer cells are large granular lymphocytes that play a crucial role in innate immunity by recognizing and eliminating infected or cancerous cells without prior sensitization. Plasma cells are not lymphocytes, but rather a type of differentiated B cell that secretes antibodies. Helper T cells are also not large granular lymphocytes, but rather a type of T cell that assists in the activation and differentiation of other immune cells. Monocytes are a type of white blood cell that differentiate into macrophages and dendritic cells. Eosinophils are a type of granulocyte involved in allergic reactions and parasitic infections.

Question 10

Identify the incorrect statement regarding hematopoiesis.

Accepted Answer

Erythrocytes also go through hematopoiesis to develop.

Question 11

The thin layer of cells that makes up the interior lining of the blood vessels is called the _____.

Accepted Answer

The thin layer of cells that makes up the interior lining of the blood vessels is called the endothelium. A is incorrect because mucosa refers to the lining of organs like the respiratory or digestive tract. B is incorrect because epithelium can refer to several types of tissues in the body and is not specific to blood vessels. D is incorrect because connective tissue is a different type of tissue that supports and connects different types of tissue in the body. E is incorrect because lymphoid tissue is a type of tissue that contains specialized cells that help fight infection and is not specific to blood vessels.

Question 12

All of the following statements are characteristic of secondary immune responses except _____.

Accepted Answer

Secondary immune responses are initiated upon re-exposure to an antigen, not because primary immune responses fail to eradicate an infection. They are characterized by a more rapid and robust response due to the presence of memory cells from the initial exposure.

Question 13

The _____ is (are)the lymphoid organ(s)that filter(s)the blood.

Accepted Answer

The spleen is the lymphoid organ that filters the blood.

Question 14

An example of an antimicrobial peptide that protects epithelial surfaces from pathogens is _____.

Accepted Answer

Defensin is an example of an antimicrobial peptide that protects epithelial surfaces from pathogens, by disrupting the cell membrane of the pathogen by forming pores, leading to the death of the pathogen.

Question 15

Spherical regions in lymph nodes containing areas that are packed densely with proliferating B cells are called _____.

Accepted Answer

Germinal centers are spherical regions in lymph nodes where B cells proliferate and differentiate into plasma cells or memory B cells, producing antibodies against antigens. Efferent vessels are lymphatic vessels that carry lymph away from the lymph node. Red pulp zones are areas in the spleen where old red blood cells are removed. Periarterial lymphoid sheaths are areas surrounding arteries in lymph nodes where T cells are found. Medullary sinuses are spaces in the medulla of lymph nodes where lymph flows.

Question 16

During an infection,_____ are mobilized in large numbers from the bone marrow.

Accepted Answer

Neutrophils are the first line of defense in the immune response and are quickly recruited to the site of infection. They are the most abundant type of white blood cell and are mobilized in large numbers from the bone marrow during an infection.

Question 17

When effector lymphocytes secrete _____,an inflammatory response ensues.

Accepted Answer

Effector lymphocytes secrete cytokines, which are signaling molecules that can stimulate an inflammatory response.

Question 18

The last cases of smallpox were reported in the _____.

Accepted Answer

The World Health Organization declared smallpox eradicated in 1980, meaning that there were no more cases reported after that year. Therefore, the last cases of smallpox were reported in the 1970s.

Question 19

Identify the four classes of pathogens that provoke immune responses in our bodies and give an example of each.

Accepted Answer

The answer of Identify the four classes of pathogens that...

Question 20

All of the following are examples of chemical barriers of innate immunity except _____.

Accepted Answer

Normal microbiota are not chemical barriers of innate immunity, but rather a physical barrier that occupies sites on the body surface and prevents pathogens from colonizing. Lactic acid, lysozyme, fatty acids, and proteases are all examples of chemical barriers that have antimicrobial properties.

Quiz 1: Elements of the Immune System and Their Roles in Defense