Deck 14: An Introduction to Host Defenses and Innate Immunities

Question 1

Explain the functions of the three lines of defense and indicate which are the most essential to survival.

Answer 1

Human body is equipped with intricate network of defense mechanisms that provide protection from foreign materials and harmful microorganisms. These defense mechanisms act on several levels and involve physical barriers, cells, chemicals etc. The defenses in human body range from non-specific to specific and are innate or acquired.
Human body defenses are be classified in different categories - first line, second line and third line of defense. The first line of defense comprises of physical barriers and blocks that prevent entry of foreign substance or microorganisms. This line of defense is mostly nonspecific as it is general in action and not specific for any particular foreign substance. The barriers in first line of defense are physical (skin, coughing and sneezing mechanism, tears etc.), chemical (different enzymes in the body, pH of body fluids etc.), and genetic (resistance to any particular pathogen because of certain genetic makeup) barriers.
The second line of defense is formed by the internal systems and it comprises of protective cells and fluids. This line of defense includes phagocytosis and inflammation. The onset of this defense is rapid once the first line of defense fails and this line of defense involves systemic level. The second line of defense is also nonspecific.
The first line and second line of defenses are innate. The third line of defense is highly specific and is adaptive and acquired. The foreign substances or microorganisms are encountered by the white blood cells. Responses unique to the microorganism or foreign substances are generated by the lymphocytes (white blood cells). Also, the memory cells remember the invading substance and recognize if the substance or microbe is encountered again.
Thus, the three line of defenses of the human body form overlapping network, sometimes redundant, and ensure protection of the body from foreign substances and microbes.

Question 2

Summarize the characteristics of basic host defenses.

Answer 2

The immune system depends on an overlapping network of host defenses for working on various levels to provide protection to the body against pathogens. These include two main types of defenses namely the innate and the adaptive resistance. The innate defense is a natural immunity that is present from the birth and provides nonspecific resistance and the adaptive immunity is acquired in the middle and provides specific resistance.
The levels of protection exhibited by the body are further categorized into three main types namely the following:
• First line of defense
• Second line of defense
• Third line of defense
First line of defense - It includes the barriers that prevent the entry of pathogens at the portal of entry. This is a nonspecific line of defense that limits access to the internal body tissues. The first line of defense is not a true immune response as it has very general actions and does not possess the ability to detect a specific foreign substance.
Example of the first line of defense include the skin, sneezing, coughing, tears that act as physical barriers; digestive enzymes, lysozyme, low pH (potential of Hydrogen) that act as chemical barriers; and resistance inherited through genetic makeup of the host that acts as a genetic barrier.
Second line of defense - It is a more internalized system involving protective fluids and cells. This is also a nonspecific resistance that acts very quickly at both the systemic and local levels when the first line of defense has been breached. Examples include fever, interferon, inflammation, and phagocytosis.
Third line of defense - It is an adaptive and acquired immunity that serves on an individual basis where the lymphocytes (white blood cells) act against invading foreign substances. The response of the immune system to microbes vary depending on the type of organism that has invaded the body.
The immune response towards each different microbe shall result in the production of unique protective substances and memory cells that shall be ready to act when the same microbe attacks the cell again for the second time. Examples include antibodies, T lymphocytes, and B lymphocytes.
The various defenses are a normal part of the anatomy and physiology of the body. These are the innate (inborn), nonspecific defenses that are divided into three barriers namely the physical barrier, chemical barriers, and genetic barriers that fight against the entry of living or nonliving foreign substances.
Physical or anatomical barriers - These are usually located on the surface of the body like the skin and mucous membrane of the digestive and respiratory tract. The outermost layer of the skin is made of compact, intact epithelial cells that are infused with an insoluble protein called keratin.
There are some pathogens that have the capability to penetrate through the unbroken barrier mainly in the regions like the palms of hands and soles of feet where the stratum corneum is thicker compared to other parts of the body. The other cutaneous barriers include skin glands and the hair follicles.
The mucocutaneous membranes of the respiratory, urinary, and digestive tracts and the eye are permeable and moist. The mucous coat present on the free surface of some membranes prevents the entry and attachment of the bacteria. The production of tears and the blinking of eyes help in getting rid of irritants by flushing the eyes with tears.
Chemical barriers - The skin and mucous membrane offers different chemical defenses. The sebaceous secretions are mainly involved in providing an antimicrobial effect and the specialized glands like Meibomian glands present in the eyelids secrete antimicrobial substances that help in lubricating the conjunctiva.
There are other defenses exerted by the defensins and the lysozymes present in the saliva and tears. Defensins are the peptides that damage the membrane of the cell and lyse the fungi and bacteria. Lysozymes are the enzymes that hydrolyze the peptidoglycan present in the bacterial cell wall.
A defensin called dermcidin produced by the skin cells help in eliminating the bacteria. The acidic pH (potential of Hydrogen) of the skin and the high electrolyte and lactic acid concentration of the sweat helps in preventing the growth of bacteria. The hydrochloric acid present in the stomach provides protection against pathogens that are ingested.
The digestive juices present in the intestine and the bile juices produced by the liver also effectively destroy the invading microbes. The acidic pH of the vagina maintained by the lactobacilli and the antimicrobial chemicals present in the semen prevent the growth of bacteria and provide protection.
Genetic barriers - The genetic makeup varies between different individuals providing protection from infection by some pathogens. There are some pathogens that have high specificity for one species of host and shall be able to attack only that host and cannot infect other species.
The differences in the genetic makeup for susceptibility to certain infections also occur within the members of one species. For example, humans carrying genes for sickle-cell anemia are known to be resistant to malaria. The genetic differences also exist in susceptibility to leprosy, tuberculosis, and some systemic fungal infections.

Question 3

Each numbered figure 1-4 represents a cell that provides an immune defense. Each lettered figure A-D shows a pathogenic microbe. Name the type of defense and match it with its primary target microbe and effects.
(1) Figure 14.19
(2) Page 435
(3) Page 435
(4) Page 435
A Figure 18.8
B Figure 23.21 inset
C Table 25.1
D Opener, Chapter 14

Answer 3

No Answer

Question 4

What is the difference between nonspecific host defenses and immune responses?

Question 5

Differentiate between the three lines of defense, describing examples of each.

Question 6

Differentiate innate and acquired immunity. What are the general characteristics of each? Discuss the advantages of having multiple defenses (innate and acquired) against the same microbe.

Question 7

Explain the nature of the different types of innate, nonspecific defenses.

Question 8

Give four innate immune responses present in the body, and explain how each type functions to combat infection.

Question 9

Describe the primary functions and organs of the immune system.

Question 10

Describe the main elements of the process through which the immune system distinguishes self from foreign cells and particles.

Question 11

Describe several features of the recognition system of host defenses.

Question 12

How is surveillance of the tissues carried out and what is responsible for it?

Question 13

Characterize pattern recognition receptors and pathogen-associated molecular patterns.

Question 14

What does the term nonself mean in reference to the immune system?

Question 15

Describe the microscopic anatomy of body compartments and how they interconnect.

Question 16

What are the main components of the reticuloendothelial system, and why is it also called the mononuclear phagocyte system?

Question 17

Outline the anatomy and functions of the reticuloendothelial system.

Question 18

How does the RES communicate with tissues and the vascular system?

Question 19

Outline the origin and composition of the blood, and characterize the types of blood cells and their functions.

Question 20

Explain the functions of stem cells and summarize the stages of hematopoiesis.

Question 21

Explain the behavior of white blood cells with regard to the blood circulation and tissues.

Question 22

Differentiate between granulocytes and agranulocytes.

Question 23

Describe the characteristics and functions of the lymphatic system.

Question 24

Describe the main types of granulocytes and agranulocytes, their functions, and their incidence in the circulation.

Question 25

Describe the main events in the inflammatory reaction, and explain what is occurring in each.

Question 26

Give the principal function of lymphocytes, and differentiate between the two lymphocyte types and between humoral and cellmediated immunity.

Question 27

Summarize the functions of cytokines, chemokines, and other inflammatory mediators.

Question 28

What is lymph, and how is it formed?

Question 29

Describe the mechanism behind fever, and explain its beneficial and harmful effects.

Question 30

Differentiate between primary and secondary lymphoid organs.

Question 31

Define phagocytosis and identify which cells serve this function.

Question 32

Outline the functions of the lymphatic system and describe the actions of associated lymphatic tissues such as MALT and GALT.

Question 33

Indicate the major stages of phagocytosis, and describe what is happening at each stage.

Question 34

Describe the major events in the inflammatory response, including the stimuli, physiological reactions, and signs and symptoms.

Question 35

Explain how phagocytes kill pathogens.

Question 36

Of rubor, calor, dolor, and tumor, which are signs and which are symptoms?

Question 37

Describe the origin of interferon, and explain its role in controlling viruses and other immune functions.

Question 38

What actions of the inflammatory and immune defenses account for swollen lymph nodes and leukocytosis?

Question 39

Characterize the complement system, its origins, and basic functions.

Question 40

What is pus, and what does it indicate?

Question 41

In what ways can edema be beneficial and in what ways is it harmful?

Question 42

Describe the physiological events leading to fever and review the ways that fever is naturally beneficial.

Question 43

Explain the processes of diapedesis and chemotaxis, and show how they interrelate.

Question 44

Briefly account for the origins and actions of the major types of inflammatory mediators and cytokines.

Question 45

Describe the events that give rise to macrophages.

Question 46

What types of macrophages are there, and what are their principal functions?

Question 47

Outline the major phases of phagocytosis.

Question 48

Briefly describe the three major types of interferon, their sources, and their biological effects.

Question 49

Describe the mechanism by which interferon acts as an antiviral compound.

Question 50

Describe the general complement reaction in terms of a feedback system or cascade.

Question 51

What are some factors that trigger the complement cascade?

Question 52

Using figure 14.21 as a guide, give examples for each category shaded brown, purple, and gold.

Question 53

An Introduction to Concept Mapping found at http:\\www.mhhe.com\talaro9 provides guidance for working with concept maps.
Construct your own concept map using the following words as the concepts. Supply the linking words between each pair of concepts.

Question 54

What are signs of chronic granulomatous disease?
a. unresolved inflammation
b. opportunistic fungal infections
c. low levels of white blood cells
d. recurrent infections
e. a, b, and c
f. a, b, and d

Question 55

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles, and in most cases, they do not have a single correct answer.
Suggest some reasons that there is so much redundancy of action and there are so many interacting aspects of immune responses.

Question 56

Select the correct answer from the answers provided. For questions with blanks, choose the combination of answers that most accurately completes the statement. An example\examples of a nonspecific chemical barrier to infection is\are

A) unbroken skin
B) lysozyme in saliva
C) cilia in respiratory tract
D) all of these

Question 57

Compose a one- or two-paragraph answer that includes the factual information needed to completely address the question. Check Your Progress questions can also be used for writing-challenge exercises.
a. Use the lines on the figure to describe the major components of the first line of defense.
b. What effects do these defenses have on microbes?

Question 58

What feature of CGD phagocytes is defective?
a. the ability to engulf pathogens
b. production of toxic forms of oxygen
c. mechanisms to eliminate viruses
d. chemotaxis

Question 59

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles, and in most cases, they do not have a single correct answer.
a. What are some possible elements missing in children born without a functioning lymphocyte system?
b. What is the most important component extracted in bone marrow transplants?

Question 60

Select the correct answer from the answers provided. For questions with blanks, choose the combination of answers that most accurately completes the statement. Which nonspecific host defense is associated with the trachea?

A) lacrimation
B) ciliary lining
C) desquamation
D) lactic acid

Question 61

Compose a one- or two-paragraph answer that includes the factual information needed to completely address the question. Check Your Progress questions can also be used for writing-challenge exercises.
a. Describe the initial response system that is found in the primary responders to foreign matter.

Question 62

Explain why children with CGD would be more prone to infections from fungi and bacteria than from viruses.

Question 63

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles, and in most cases, they do not have a single correct answer.
A patient's chart shows an increase in eosinophil levels.
a. What does this cause you to suspect?
b. What does it mean if the basophil levels are very high?
c. What if the neutrophil levels are very high?

Question 64

Select the correct answer from the answers provided. For questions with blanks, choose the combination of answers that most accurately completes the statement. Which of the following blood cells function primarily as phagocytes?

A) eosinophils
B) basophils
C) lymphocytes
D) neutrophils

Question 65

Compose a one- or two-paragraph answer that includes the factual information needed to completely address the question. Check Your Progress questions can also be used for writing-challenge exercises.
Explain what PRRs and TLRs are and the nature of their interaction with PAMPs.

Question 66

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles, and in most cases, they do not have a single correct answer.
How can adults continue to function relatively normally after surgery to remove the thymus, tonsils, spleen, or lymph nodes?

Question 67

Select the correct answer from the answers provided. For questions with blanks, choose the combination of answers that most accurately completes the statement. Which of the following is not a lymphoid tissue?

A) spleen
B) thyroid gland
C) lymph node
D) GALT

Question 68

Compose a one- or two-paragraph answer that includes the factual information needed to completely address the question. Check Your Progress questions can also be used for writing-challenge exercises.
Make a simple drawing of the functions of toll-like receptors.

Question 69

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles, and in most cases, they do not have a single correct answer.
Explain why the X-linked form of CGD is more common in boys and more severe than autosomal forms of the disease.

Question 70

Select the correct answer from the answers provided. For questions with blanks, choose the combination of answers that most accurately completes the statement. What is included in GALT?

A) thymus
B) Peyer's patches
C) tonsils
D) breast lymph nodes

Question 71

Compose a one- or two-paragraph answer that includes the factual information needed to completely address the question. Check Your Progress questions can also be used for writing-challenge exercises.
Describe the mechanisms by which leukocytes migrate from the bloodstream into an area of infection. What chemical factors are they reacting to?

Question 72

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles, and in most cases, they do not have a single correct answer.
An obsolete treatment for syphilis involved inducing fever by deliberately infecting patients with the agent of relapsing fever. An experimental AIDS treatment involved infecting patients with malaria to induce high fevers. Can you provide some possible explanations behind these peculiar forms of treatment?

Question 73

Select the correct answer from the answers provided. For questions with blanks, choose the combination of answers that most accurately completes the statement. A signaling molecule from microbes recognized by phagocytes is

A) pyrogen
B) PAMP
C) complement
D) lectin

Question 74

Compose a one- or two-paragraph answer that includes the factual information needed to completely address the question. Check Your Progress questions can also be used for writing-challenge exercises.
Prepare a simplified outline of the cell lines of hematopoiesis.

Question 75

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles, and in most cases, they do not have a single correct answer.
Patients with a history of tuberculosis often show scars and other lesions in the lungs and experience recurrent infection. Account for these effects on the basis of the inflammatory response.

Question 76

Select the correct answer from the answers provided. For questions with blanks, choose the combination of answers that most accurately completes the statement. Monocytes are leukocytes that develop into ______.

A) granular, phagocytes
B) agranular, mast cells
C) agranular, macrophages
D) granular, T cells

Question 77

Compose a one- or two-paragraph answer that includes the factual information needed to completely address the question. Check Your Progress questions can also be used for writing-challenge exercises.
Discuss the multiple, overlapping functions of the immune system. Which tissues and organs are involved in the immune response, and how does each function?

Question 78

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles, and in most cases, they do not have a single correct answer.
Shigella, Mycobacterium, and numerous other pathogens have developed mechanisms that prevent them from being killed by phagocytes.
a. Suggest two or three factors that help them avoid destruction by the powerful antiseptics in macrophages.
b. Suggest the potential implications that these infected macrophages can have on the development of disease.

Question 79

Select the correct answer from the answers provided. For questions with blanks, choose the combination of answers that most accurately completes the statement. Which of the following inflammatory signs specifies pain?

A) tumor
B) dolor
C) calor
D) rubor

Question 80

Compose a one- or two-paragraph answer that includes the factual information needed to completely address the question. Check Your Progress questions can also be used for writing-challenge exercises.
In what ways is a phagocyte a tiny container of disinfectants?