TopHat Immune System Questions

Match the cell with its main function in the innate immune system. a. neutrophils b. mast cells c. basophils d. eosinophils 1) phagocytosis 2) histamine release 3) histamine release 4) protection against parasites

a. 1) phagocytosis b. 2) histamine release c. 3) histamine release d. 4) protection against parasites Neutrophils destroy by releasing anti-bacterial substances; Mast cells and basophils both release histamine; Eosinophils protects against parasitic infection.

The largest (by area) component of the innate immune system is the ________.

(the) mucosal membrane The mucosal membrane is the largest component of the innate immune system. It protects against all threats.

Describe the process by which an APC presents an antigen to other cells.

An APC engulfs and digests the foreign protein and then presents peptide fragments on the surface of the MHC complex for other immune cells to detect.

How feasible as a clinical treatment is the removal of mast cells from people suffering from seasonal allergies?

The removal of any part of the immune system carries risk. Mast cells have evolved to play an important role in innate immunity, their removal would compromise that aspect of innate immunity and might affect adaptive immunity also. This is why the best clinical treatment is to treat the symptoms induced by histamine release.

Lymph nodes play a key role in immunity by filtering __________.

lymph Lymph moves slowly through the node, allowing foreign cells to be trapped by macrophages, dendritic cells, and reticular cells.

Trace the path a foreign object would take from the interstitial space to the vein passing through the lymphatic system. lymph vessel veins lymph capillary lymph node

lymph capillary lymph vessel lymph node veins Lymph enters fenestrated lymphatic capillaries. It is then transported through progressively larger vessels, through lymph nodes, and finally drains into the vena cava.

Macrophages phagocytose foreign particles and internally digest them with ________.

lysosomes NK cells are cytotoxic due to the release of their granule contents, which includes powerful proteases and perforin. Perforin released by NK cells forms a water-filled pore within the plasma membrane of infected cells, allowing the infusion of proteases into the cell. NK cells also secrete α-defensins—antibacterial peptides that kill bacteria by disrupting cell walls in a similar way to how perforin destroys cells.

NK cells secrete ____________- and _________ to destroy virally infected cells.

perforin; ɑ-defensins NK cells are cytotoxic due to the release of their granule contents, which includes powerful proteases and perforin. Perforin released by NK cells forms a water-filled pore within the plasma membrane of infected cells, allowing the infusion of proteases into the cell. NK cells also secrete α-defensins—antibacterial peptides that kill bacteria by disrupting cell walls in a similar way to how perforin destroys cells.

Foreign threats are filtered from the lymph in structures known as __________.

secondary lymph organs Lymph nodes are secondary lymph organs that are important for filtration.

Why do some cells have both MHC I and MHC II proteins expressed on their surface?

Antigen-presenting cells, which express MHC II, also need to establish that they are a self-cell, so they need to also express MHC I on their surface.

The immune system ________. Select all that apply. a. is capable of differentiating self from nonself b. possesses memory of prior exposure to foreign threats c. is composed solely of cells d. can only recognize viruses

A, B The general functions of the immune system are to protect against foreign threats (and abnormal cells) by coordinating the actions of a variety of cells, proteins, as well as chemicals to differentiate foreign threats from the self-tissues that make up the body, "remember" prior exposures to foreign threats and to mount a more effective immune response to that threat if exposed again.

What does a plasma B cell do? Select all that apply. a. it carries the memory of prior exposure to a foreign threat b. it produces antibodies c. it is aided by Th cells during maturation d. it can last for the lifetime of a person

A, B, C, D Plasma B cells are long-lived, non-proliferating, antibody-secreting cells arising after naive B cell activation. These cells are also generated after T cell exposure to an antigen. Helper T (TH) cells also secrete cytokines that facilitate the maturation of B cells.

What are cytokines? Select all that apply. a. they are part of the innate immune response b. they are classical hormones c. they can be an autocrine factor d. they are hormones produced by macrophages

A, C Cytokines affect both the innate and adaptive immune systems and act in an autocrine, paracrine, and endocrine manner.

Which of the following are characteristics of a lymph node? Select all that apply. a. it is a secondary lymphatic organ b. there are a relatively low number of lymph nodes within the body c. it is filled with both T cells and B cells d. it is important for neutralizing foreign threats

A, C, D Lymph nodes are encapsulated lymphatic tissue that is distributed throughout the body. They are organized into follicles that consist of lymphatic and non-lymphatic cells surrounded by a network of lymphatic capillaries. The outermost cortex contains mostly B cells, macrophages, and dendritic cells. The paracortex is filled with T cells and dendritic cells arranged in a network. The medulla is sparsely populated with B cells and epithelial reticular cells. Lymph nodes are found clustered at the junctions of lymphatic vessels and are a second or third line of defense against foreign threats found within lymph.

A lymphocyte _________. Select all that apply. a. is produced by the same process that produces erythrocytes b. has a very small nucleus c. has a small amount of cytoplasm d. is part of the adaptive immune response

A, C, D Lymphocytes are a type of leukocyte produced in the red bone marrow and the thymus from progenitor cells that give rise to all blood cells. Lymphocytes contain a single, large nucleus, a small amount of cytoplasm, and a wide range of proteins expressed on their surface. Lymphocytes play a role in adaptive immunity.

Which antibody type activates complement? Select all that apply. a. IgM b. IgA c. IgD d. IgE e. IgG

A, E IgG activates complement, binds to macrophages, and mediates increased macrophage-mediated phagocytosis of foreign antigens that are complexed to antibodies (via opsonization). Also IgM antibodies are effective in activating complement.

Which of the following statements correctly describe complement proteins? Select all that apply. a. they are a family of proteins produced by eosinophils that attack cancer cells in the body b. they act as an opsonin to increase phagocytosis of foreign threats by macrophages c. they act to inhibit inflammation at sites of damage or infection d. they can lyse cells through the formation of the membrane-attack complex

B, D Complement refers to a family of over 30 soluble and cell-bound proteins that make up 5% of the globulin part of serum. Most of the complement proteins are produced by the liver in inactive forms. When activated, they can be converted into the membrane attack complex (MAC) or they can attach to the surface of bacterial cells (primarily C3b and C4b) and stimulate macrophages to phagocytose them by attracting other proteins that stimulate phagocytosis in a process known as opsonization.

Why does IgA make up only 15% of serum antibodies even though it is produced at a higher rate each day than any other antibody?

IgA are found in surface secretions on mucosal membranes, protecting against foreign threats without triggering inflammation.

Why are proteins the most effective antigens?

Remember the role of APCs. Foreign proteins are ingested and then peptide fragments are presented on the surface of MHC I and II. There is no equivalent mechanism for the processing of carbohydrates, lipids, or nucleotides by APCs.

How might a splenectomy (spleen removal as a result of physical damage) affect the adaptive immune response?

Splenectomies are common in patients suffering abdominal injuries as a result of a car accident. Losing the spleen means that there is no direct filtering of blood by the adaptive immune system. The system is redundant in that there is a physical link between lymph vessels and blood vessels, allowing for blood components to be filtered by the lymph nodes.

Match the T cell with its function. a. Th cells b. Tc cells c. Tm cells d. Tr cells 1) memory of prior exposure to antigen 2) aid in maturation of B cells 3) termination of adaptive immune response 4) destruction of virus-infected cells

a. 2) aid in maturation of B cells b. 4) destruction of virus-infected cells c. 1) memory of prior exposure to antigen d. 3) termination of the adaptive immune response The helper T (TH) cells secrete cytokines that facilitate the maturation of B cells to plasma cells and participate in the activation of cytotoxic T (TC) cells and macrophages. T cytotoxic cells (TC) are designed to destroy virus-infected and tumor cells. T memory cells (TM) carry the memory of exposure to an antigen after the antigen is removed from the body. T regulatory (TR) or suppressor cells are crucial to limit the immune response to foreign antigens only.

Recognition and memory is part of ________ immunity. a. innate b. adaptive

b. adaptive Innate immunity does not target specific pathogens or have "memory" and acquired immunity precisely acts against a specific pathogen and does have "memory".

Which of the following is an example of passive artificial adaptive immunity? a. injection of blood factors collected from patients who successfully fought off a hepatitis infection into a nurse who accidentally stuck with a needle b. injection with a vaccine against chickenpox c. your response to your roommate's cold d. your protection against chickenpox if you had chickenpox as a young child

a. injection of blood factors collected from patients who successfully fought off a hepatitis infection into a nurse who accidentally stuck with a needle Passive means that a patient is given the cells or proteins developed in a different person through an active response, and it does not include memory. Artificial immunity refers to a deliberate exposure to a foreign threat or antigen through the injection of a vaccine.

What are the characteristics of the thymus? a. it helps to mature lymphocytes b. it grows in size with age c. it is the only site capable of filtering blood d. it is a secondary lymphatic organ

a. it helps to mature lymphocytes The thymus is a primary lymph organ and therefore, provides an environment for the growth and maturation of lymphocytes. It enlarges during childhood and then atrophies.

Neutrophils are drawn toward sites of infection by the _________. a. presence of basophils b. chemotactic cues released by infected cells and other leukocytes c. presence of B cells and T cells d. presence of macrophages

b. chemotactic cues released by infected cells and other leukocytes Neutrophils are attracted by chemotactic cues released by other leukocytes.

Which of the following statements best explains the concept of memory within the adaptive immune system? a. clonal growth of Th cells b. increased growth of specific B cells or T cells after antigen exposure c. clonal growth of Tc cells d. the ability of antibodies to bind to two antigens

b. increased growth of specific B cells or T cells after antigen exposure Memory cells do not produce antibodies, but instead they increase the number of B cells that express a receptor for a specific antigen. The growth of memory cells increases the total number of cells that recognize that specific antigen, from that first few upon first exposure to many thousands in subsequent exposures, resulting in a much larger immune response.

What does the spleen do? a. it filters lymph b. it filters blood c. it stores fat and lymphocytes d. it is the main site of T cell development in adults

b. it filters blood The spleen's primary function is to filter the blood, not the lymph . It stores erythrocytes, removes defective erythrocytes and platelets from circulation, and recycles iron for use elsewhere.

Predict what would happen if MHC II was removed from the surface of macrophages. a. the adaptive immune system would no longer be able to differentiate between self and non-self antigens b. the macrophage could no longer present antigens to Th cells c. complement could no longer be activated d. Th cells would disappear

b. the macrophage could no longer present antigens to Th cells The MHC II proteins can be recognized by CD4 co-receptors and the T cell receptor. MHC proteins also carry peptide fragments from within the cell to the cell surface, 'presenting' them to the cells of the immune system.

Which of the following is the best definition of a cluster-of-differentiation (CD)? a. the CD system is a means by which all human cells can be differentiated from each other b. a CD is simply any protein expressed on the surface of leukocytes c. a CD is a protein expressed on the surface of some but not all lymphocytes d. a CD is a unique type of lipid expressed on the surface of all blood cells

c. a CD is a protein expressed on the surface of some but not all lymphocytes CD refers to a numerical system for classifying proteins expressed on the surface of leukocytes.

How does acute inflammation differ from chronic inflammation? a. histamine stimulates acute but not chronic inflammation b. chronic inflammation starts in several tissues but then continues only in one c. acute inflammation lasts for a short period of time, and chronic inflammation lasts for a long time

c. acute inflammation lasts for a short period of time, and chronic inflammation lasts for a long time Acute inflammation has a rapid onset and lasts a short time and chronic inflammation has a slow onset and lasts for a long time.

What is the first step in B cell activation? a. digestion of proteins within the proteasome b. presentation of peptide fragments in MHC II c. binding of antigen to the BcR d. secretion of cytokines by Th cells

c. binding of antigen to the BcR Binding of an antigen to the BcR results in the antigen being engulfed into an endosome in the B cell. Within the proteasome, the antigen is then digested into peptide fragments and presented at the surface with MHC II. Interaction between TH cells and presenting B cells leads to the secretion of cytokines, inducing B cell clonal growth and differentiation into plasma and memory cells.

Interferons do not carry out which of the following in innate immunity? a. inhibition of viral infection of cells b. activation of NK cells c. direct attacks on virally infected cells

c. direct attacks on virally infected cells Interferons do not protect infected cells, nor do they directly attack viral particles. They bind to the surface of neighboring cells and induce them to produce antiviral proteins. Some of these proteins block viral replication by blocking protein synthesis. Interferons also activate NK cells and increase the ability of the innate and adaptive immune system to recognize infected cells.

Which of the following is not a normal physiological function of the lymphatic vessels? a. filtering foreign particles from lymph and plasma b. returning excess interstitial fluid back to the venous supply c. growth and development of connective tissue cells d. blood cell maturation e. transport of absorbed fats

c. growth and development of connective tissue cells The lymphatic system plays a key role in the growth, maturation, transportation, and activation of leukocytes. It returns excess interstitial fluid to the venous system. It absorbs fats from the digestive tract and returns them to the venous system for processing in the liver. It produces and brings to maturity many immune cells.

What is an antigen? a. it is recognized by innate immunity b. it is a large collection of proteins expressed on the surface of macrophages c. it is recognized by the adaptive immune system d. it is recognized by macrophages

c. it is recognized by the adaptive immune system An antigen is anything that can trigger an adaptive immune response.

How does T cell activation differ from B cell activation? a. B cells are responsible for cell-mediated adaptive immunity, while T cells are responsible for humoral immunity b. both B cells and T cells secrete antibodies, but of very different classes c. only B cells interact with antigen-presenting cells d. T cells interact with antigen-presenting cells

d. T cells interact with antigen-presenting cells TH cells recognize antigen fragments presented by MHC II on the surface of APCs.

​A mother comes into a pediatrician's office with her one-year-old son. During the visit, the pediatrician informs the mother that it is time to vaccinate her son against diphtheria, tetanus, pertussis, Hib (Haemophilus influenza type B), hepatitis B, polio, and pneumococcal disease. The mother is concerned about the side effects of these vaccinations. The doctor tries to reassure her of the efficacy of vaccinations. What type of immunity is her son gaining by these vaccinations? a. natural active immunity b. adaptive natural immunity c. humoral immunity d. adaptive artificial immunity

d. adaptive artificial immunity Vaccines are comprised of attenuated (weakened or non-infectious) versions of pathogenic microorganisms. Vaccines challenge the adaptive immune system to develop memory B- and T-cells against these pathogens to give life-long protection against some of them. Since the vaccine is an artificial means by which people are exposed to these pathogens this is an example of adaptive artificial immunity.

Inflammation is triggered by __________. a. cell damage b. histamine release c. viral infection d. all of the above

d. all of the above Inflammation has the same symptoms regardless of the causative factor—such as tissue injury, infections, or foreign threats. Tissue injury, regardless of the cells involved, can elicit inflammation. Damage leads to the release of chemicals (histamine, prostaglandins, leukotrienes, complement, kinins, and cellular contents) that are not normally found in the extracellular space.

A 32-year-old women presents to her Gyn/Ob for a normal pregnancy visit and complains of nausea, changes in diet, and the onset of blurry and double-vision. She also complains of her feet and hands becoming numb and tingling, incontinence (inability to control her bladder), and tremors in her hands. Which of the following may be causing her unusual symptoms? a. preeclampsia b. hormonal imbalances caused by pregnancy c. over-production of complement d. an autoimmune disorder attacking her nervous system (both sensory and motor control) e. a cytokine storm

d. an autoimmune disorder attacking her nervous system (both sensory and motor control) The standard next step in the development of a differential diagnosis is to take an MRI. The most likely problem the patient has is MS (multiple sclerosis) - the autoimmune destruction of myelin within axons of the nervous system, which would explain all of the symptoms we see. In this case, no MRI would be taken of a pregnant woman for fear of harming the developing baby. If she has MS, the MRI would show scarring where axons had been damaged. Other tests can be given to look for elevated blood levels of IgG's against myelin.

Which process physically removes a B cell or T cell that is recognizing a self-antigen from the body? a. receptor editing b. anergy c. ignorance d. apoptosis

d. apoptosis Failure to effectively express TcR, CD8, or CD4 results in the apoptosis of that T cell during positive selection.