Chapter 12 - Defense mechanism of the host

Question 1

The First Line of Defense

Answer 1

Any barrier that blocks invasion at the portal of entry. This nonspecific line of defense limits access to the internal tissues of the body.

Question 2

The Second Line of Defense

Answer 2

Called the Innate Immunity, is a more internal system of protective cells, fluids, and processes that includes inflammation and phagocytosis.

Question 3

Third Line of Defense

Answer 3

Highly Specific and is acquired only as each foreign substance is encountered by white blood cells called lymphocytes. The goal of this response is to make lymphocytes that are specifically adapted to each individual invader.

For that reason, it is called adaptive immunity.

Third line of defense provides long-term immunity.

Question 4

Adaptive Immunity

Answer 4

The reaction with each different foreign microbe produces unique protective substances and cells that can come into play if that microbe is encountered again.

Question 5

Lymphocytes

Answer 5

a form of small leukocyte (white blood cell) with a single round nucleus, occurring especially in the lymphatic system.

Lymphocytes mainly constitute T cells, B cells, and natural killer (NK) cells. Their most salient role is in immune system. Thus we can say: All lymphocytes are leukocytes but all leukocytes are not lymphocytes

Question 6

Leukocytes

Answer 6

a colorless cell that circulates in the blood and body fluids and is involved in counteracting foreign substances and disease; a white (blood) cell. There are several types, all amoeboid cells with a nucleus, including lymphocytes, granulocytes, monocytes, and macrophages.

Question 7

What is a healthy functioning immune system responsible for?

Answer 7

1. ) Surveillance of the body
2. ) Recognition of foreign materials
3. ) Destruction of entities deemed to be foreign.

Question 8

Antigen

Answer 8

All cells (microbial and otherwise) as well as particles such as pollen, display a unique mix of macromolecules on their surfaces that the immune system “senses” to determine if they are foreign or not. These are called Antigen.

a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.

Question 9

Markers

Answer 9

Another word for Antigen

Generally consists of proteins and/or sugars, can be thought of as the cellular equivalent of facial characteristics in humans and allow the cells of the immune system to identify whether or not a newly discovered cell poses a threat.

Question 10

Pathogen-associated molecular patterns (PAMPs)

Answer 10

Markers that many different kinds of microbes have in common.

Molecules on the surfaces of many types of microbes that are not present on host cells that mark the microbes as foreign.

Question 11

Pattern Recognition Receptors (PRRs)

Answer 11

Host cells with important roles in the innate immunity of the second line of defense have PRRs.

Molecules on the surface of host defense cells that recognize pathogen-associated molecular patterns on microbes.

Question 12

Mononuclear phagocyte system

Answer 12

A collection of monocytes and macrophages scattered throughout the extracellular spaces that function to engulf and degrade foreign molecules.

Question 13

Lymphatic System

Answer 13

Compartmentalized network of vessels, cells, and specialized accessory organs. It begins in the farthest reaches as tiny capillaries that transport a special fluid, lymph, through an increasingly larger tributary system of vessels and filters (lymph nodes), and it leads to major vessels that drain back into the regular circulatory system.

Question 14

Major Functions of the Lymphatic System

Answer 14

1. ) To provide a route for the return of extracellular fluid to the circulatory system proper
2. ) To act as a “drain-off” system for the inflammatory response
3. ) To render surveillance, recognition, and protection against foreign materials through a system of lymphocytes, phagocytes, and antibodies.