A&P Chapter 21 Lymphatics and Immune

Question 1

What are the Lymphatic System functions?

Answer 1

1. To provide an alternative pathway for extracellular fluids to return to circulation.
2. Provide pathways for waste materials to be removed from tissues/organs and to be destroyed.
3. Provide a protective lining along internal organs which are exposed to the environment such as the organs of the respiratory, digestive and reproductive systems.
4. To provide places for surveillance, proliferation and maturation of lymphocytes and other immune cells.

Question 2

What are the two interrelated components of the lymphatic system?

Answer 2

1. The network of lymphatic capillaries, ducts and vessels.
2. The lymphatic organs such as the spleen and lymph nodes. Lymphatic tissues such as the tonsils and the Lymphatic cells dispersed through the walls of organs.

Question 3

What are the major cells of the lymphatic system? Where are they found?

Answer 3

Macrophages and Lymphocytes, they are found everywhere except the CNS, the brain and spinal cord.

Question 4

Describe the flow of lymph:

Answer 4

Tissues–>Lymphatic Capillaries –>Lymphatic ducts –> Lymphatic Vessels

Tissue fluid flows into lymphatic capillaries embedded in the capillary beds of the cardiovascular system.

The lymphatic capillaries carry lymph to lymphatic ducts then to lymphatic vessels. Along the way the lymph flows through many lymph nodes.

Question 5

Where are lymph nodes concentrated?

Answer 5

The Inguinal, Axillary and Cervical Regions

Question 6

Describe the ANATOMY of a Lymph Node:

Answer 6

Small and bean shaped. It has as many as 30-40 AFFERENT lymphatic vessels draining into the node. The node is surrounded by a cortex, just inside the cortex are lymphatic nodules where lymphocytes and macrophages are rapidly reproducing. The center of the lymphatic nodule is called the GERMINAL CENTER. The space between nodules is called the CORTICAL SINUS. The center of a lymph node is called the MEDULLA. There is a single EFFERENT lymphatic vessel through which lymph travels after it has passed through the medulla.

Question 7

Where does lymph flow back into the blood supply?

Answer 7

The majority of lymph returns via the Thoracic duct draining into the left subclavian vein. The thoracic duct drains the lower half of the body and the left upper half of the body.

The right lymphatic duct drains the right arm, thorax and head. It flows into the right subclavian vein.

Question 8

What are the lymphatic organs?

Answer 8

The Spleen and Thymus.

Question 9

Describe the Spleen:

Answer 9

It is located in the left upper quadrant of the abdomen, it’s inferior to the diaphragm. It has a large blood supply fed by the splenic artery.

The spleen filters damaged RBC’s.

It is made of two types of tissue: Red Pulp and White pulp. The Red Pulp is a reservoir for erythrocytes not in use by the body. In newborns and infants the red pulp is a site of Erythropoiesis.
The white pulp is comprised of lymphocytes and macrophages. These remove bacteria, viruses, debris from the blood as well as old damaged erythrocytes.

Question 10

Describe the Thymus:

Answer 10

It sits anterior to the aorta, superior to the heart and posterior to the sternum. It is Large in children and shrinks in adults.

The thymus secrets a hormone that causes undifferentiated lymphocytes to mature into T Lymphocytes which stands for Thymic-derived lymphocytes.

Many lymphocytes that leave the bone marrow and goto the thymus are killed by macrophages instead of differentiating into T cells.

Question 11

Describe Lymphoid tissues:

Answer 11

Lymphoid tissues line hollow organs exposed to the external environment, the digestive tract, the respiratory tract and the reproductive organs.

All of the different kinds of leukocytes can be found in lymphoid tissues but the lymphocytes and macrophages make up the majority.

The tissues contain clusters of closely packed, rapidly proliferating lymphocytes and macrophages called LYMPHATIC NODULES. The nodules lie just deep to the epithelia that lines the hollow organ. This allows them easy access to incoming antigens they also secrete antibodies into and across the epithelia into the lumen.

Question 12

Describe the location of Lymphatic Nodules:

Answer 12

They are located in the connective tissue just deep to the basement membrane of the epithelia that lines hollow organs.

Outside World
Epithelia
Basement Membrane
Connective Tissue–> Lymphatic nodules in the connective tissue.

Question 13

What are examples of named Lymphoid tissues?

Answer 13

Tonsils located in the pharynx and Peyer’s patches in the small intestines. The Peyer’s patches are much larger than nodules by 5-9x’s.

Question 14

What are the two forms of body defenses?

Answer 14

Nonspecific Defenses which are a generalized defense, they are the first line of defense and Specific Defenses which are targeted against a specific threat.

Question 15

What are the Nonspecific Body Defenses?

Answer 15

First line:Epithelial Barriers, Phagocytes and Antimicrobial chemicals.

Second line: Fever and Inflammation

Question 16

Describe the Epithelia barriers of Nonspecific Body Defenses

Answer 16

The epithelial barriers are the skin, cornea, mucous membranes, etc. They do 90% of the work of the defense system and they are indiscriminant. They try to prevent stuff from getting into the body.

Question 17

What are the Phagocytes of the Nonspecific Body Defenses?

Answer 17

The Macrophages, Neutrophils, and Eosinophils.

Question 18

Describe the Antimicrobial chemicals of the Nonspecific Body Defenses

Answer 18

Acids: found in the stomach, vagina and urethra.

Lyozyme: A polysaccharide that binds to and destroys cell walls.

Compliment: proteins that bind to bacteria and parasites. These directly lyse them, they also mark them for phagocytes. They attach together and become more effective punching a hold in an individual cell wall.

Inferons: Proteins that are active against viruses. They prevent viruses from entering a cell, they tag viruses and mark them (like a red flashing light saying come eat me).

Question 19

Describe a Fever and how it is a defense against invaders.

Answer 19

Normal body temp is 37degrees C. Bacteria/viruses/parasites have adapted to thrive in this temp. The body runs a fever and goes up a couple degrees C to slow down/inactivate foreign invaders. It also slows down the bodies ability to do what it’s supposed to do as well.

Temperatures of 41+degrees C can do permanent damage to the body.

Question 20

Describe Inflammation:

Answer 20

Inflammatory chemicals are released from damaged tissues. They cause several things to happen: Vasodilation, Pain, Increased capillary permeability, Swelling, Increased O2 and the attraction of Leukocytes.

A foreign material enters tissues causing inflammatory chemicals to be released which causes Basophils diapedese out into tissues becoming MAST cells and release Heparin (a blood thinner) and Histamine (helps makes the vessel dilate and leaky) resulting in vasodilation and increased capillary permeability which allows more Leukocytes to diapedese out of the blood vessels into the tissue.

You CAN HAVE INFLAMMATION WITHOUT INFECTION. Such as Rheumatoid Arthritis (autoimmune disease)

Question 21

What are the characteristics of a SPECIFIC Immune Defense?

Answer 21

Specific: Provides a defense against a SPECIFIC antigen recognized as NON-SELF.

Adaptive: Defenses can be targeted against NEW antigens.

Systematic: Defenses are distributed throughout the entire body.

Memory: The body mounts a stronger/faster defense against PREVIOUSLY encountered antigens.

Question 22

What is Self-Tolerance? Why do we need this?

Answer 22

It is the body’s ability to recognize itself and distinguish it from foreign invaders. The body must have self-tolerance so that the immune defense won’t attack ones own body.

Question 23

Define a Pathogen:

Answer 23

Any LIVING organism (bacteria, virus, parasite) against which the immune system RESPONDS.

Question 24

Define an Antigen:

Answer 24

Any molecule against which the immune system responds, it may be an isolated molecule floating around or it maybe part of a larger structure such as a protein molecule on the surface of a cell membrane.

Question 25

Define Antibody:

Answer 25

A specific protein, AKA an IMMUNOGLOBIN, which binds to an antigen. ALL ANTIBODIES ARE PRODUCED BY LYMPHOCYTES.

Question 26

Define Antigenic Determinant:

Answer 26

The SPECIFIC PART of an antigen which an antibody recognizes and binds to.

Question 27

How many binding sites does an antibody have?

Answer 27

2

Question 28

What does having 2 binding sites allow an antibody to do?

Answer 28

1. It allows it to clump antigens together. By attaching to an Antigenic determinant on one antigen and an Antigenic Determinant on another the antibody can clump antigens together. AGGLUTINATION.
2. It allows it to bind to an Antigenic determinant with one binding site and to signal attacker cells with the other.

Question 29

What are the interrelated components of Specific Immune Defenses?

Answer 29

Cell Mediated Immunity and Humoral Immunity

Question 30

Describe Cell Mediated Immunity

Answer 30

Where Macrophages and T-Lymphocytes DIRECTLY ATTACK invading or damaged cells.

The lymphocytes will have antibodies on their cell membranes.

Question 31

Describe Humoral Immunity

Answer 31

Antibodies produced by PLASMA CELLS (B-Lymphocytes) float free in the extracellular matrix and attach to invading cells or isolated antigens.

Question 32

Outline the Development of Immunity

Answer 32

It can be EITHER Naturally Acquired or Artificially Acquired.

Within each it can be actively or passively acquired.

Question 33

Describe the ACTIVE Naturally Acquired Immunity

Answer 33

Where you get an infection, come in direct contact with a pathogen and actually have a disease, survive and gain an immunity to it afterwards.

Question 34

Describe PASSIVE Naturally Acquired Immunity

Answer 34

Where antibodies pass from mother to fetus via the placenta or to infant via mothers milk.

Question 35

Describe ACTIVE Artificially Acquired Immunity

Answer 35

This is a vaccination with a dead or damaged pathogen resulting in an immune response which prepares the body for future encounters.

Question 36

Describe PASSIVE Artificially Acquired Immunity

Answer 36

The injection of antibodies or immune serum into a person. This is seen mainly in the elderly who lack the ability to make antibodies. The antibodies from one person are isolated and put directly into someone else.

Question 37

What are the cells of the immune system?

Answer 37

Macrophages

T Lymphocytes: Cytotoxic T Cells (Killer T Cells), Helper T-Cells, Suppressor T-Cells, Memory Cells

B Lymphocytes: Plasma Cells, Memory Cells

Question 38

Describe the Role Macrophages play in the immune system.

Answer 38

Macrophages: Engulf and destroy pathogens, damaged cells, etc. They PRESENT antigens to lymphocytes. They SECRETE ACTIVATION FACTORS which tells other leukocytes that the macrophage ate something.

Question 39

Describe the process a Macrophage goes through to PRESENT AN ANTIGEN FRAGMENT

Answer 39

1. The Antigen is Phagocytosed.
2. Lysosomes fuse with the Phagocytosed Antigen
3. The Antigen and Enzymes Mix.
4. The Antigen is degraded
5. ANTIGEN FRAGMENTS ARE DISPLAYED ON THE CELL MEMBRANE on a protein called the MAJOR HISTOCOMPATIBILITY COMPLEX.
6. The degraded antigen residue is voided (exocytosis) by the macrophage.

Question 40

What is the MAJOR HISTOCOMPATIBILITY COMPLEX? What does it do/help with?

Answer 40

It is a protein that allows a Macrophage to display a degraded antigen fragment to lymphocytes. This will SPEED UP an immune response, this presentation activated lymphocytes.

Question 41

Where do T-Lymphocytes become Immunocompetent?

Answer 41

In the THYMUS

Question 42

Explain Humoral Immune Response and how B Lymphocytes Cap and Endocytose antigens.

Answer 42

Humoral immunity is effective against both isolated antigens AND cells.

It begins when an immunocompetent B-Lymphocyte recognizes and binds to an antigen becoming activated. Multiple receptors on the plasma membrane of the B Cell bind to the antigen, they cluster around it and take it into the cell by endocytosis.

If the B Cell cannot bind to the antigen AND take it inside it will NEVER make needed antibodies.

Question 43

Explain the steps required for producing antibodies by plasma cells:

Answer 43

1. The B-Lymphocyte uses its receptors to bind to a specific antigen.
2. The B-Lymphocyte DISPLAYS processed (brokendown) antigen fragments. Helper T-Cells bind to the B Cell and secretes the helper factor.
3. The helper factor stimulates the B Cell to DIVIDE rapidly and form clones.
4. Some of the Clones become PLASMA CELLS and some become MEMORY B CELLS.
5. The PLASMA CELLS synthesize and secrete lots of antibodies.

Question 44

Explain Cell-Mediated Immune Response

Answer 44

It is effective against INVADING CELLS or damaged cells.

It begins when a macrophage or INFECTED cells (of the body) PRESENT antigen fragments to immunocompetent T-Lymphocytes, this ACTIVATES THE T-CELLS.

When a HELPER T-Cell is activated (by a MACROPHAGE PRESENTING THE DEGRADED ANTIGEN FRAGMENT) it secrets chemicals which activates other macrophages and stimulates the reproduction of both B Cells and Cytotoxic T-Cells.

When Cytotoxic (Killer) T-Cells are activated they bind to a target cell and release molecules which directly damage the cell. They can be perforin, lymphtoxins, tumor necrosis factors or oxygen free radicals.

Question 45

What do Suppressor T-Lymphocytes do?

Answer 45

They secrete chemicals which suppress the activites of both T and B Cells. It also tells plasma cells to STOP producing antibodies.

They are nessecary to wind down the immune response after antigens or invading cells are destroyed.

Minimizes the risk of CROSS REACTIVITY and damaging “Self” cells. (Autoimmune diseases).

They help convert activated T and B cells to MEMORY CELLS.

Question 46

What happens during a Primary Humoral Immune Response? How does a Secondary Response differ?

Answer 46

During a primary response you are creating all the plasma cells, memory cells and antibodies for the first time. It takes longer to activate the immune response and fewer antibodies are produced but it’s this PRIMARY response that prepares the body for the secondary response.

In the secondary response the body reacts MUCH faster and stronger, the memory cells already exist and can help make plasma cells much faster resulting in more antibodies being produced faster. The antibodies also stick around in the system for a lot longer the second time around, this is the reason we get BOOSTER shots for vaccines.