BIOS 255

Question 1

Identify the major components of the lymphatic system and explain their functions.

Answer 1

Thymus, The spleen, Lymph Nodes, Lymph vessels, and Tonsils.

Question 2

Thymus

Answer 2

produces T-cells for immune response.

Question 3

The spleen

Answer 3

largest single mass of lymphatic tissue in the body. The spleen destroy blood-borne pathogens and
worn-out red blood cells by phagocytosis.

Question 4

Lymph Nodes

Answer 4

produce lymphocytes that kill pathogens, harmful foreign particles and debris from lymph before it is
returned to the blood stream.

Question 5

Lymph vessels

Answer 5

act as reservoirs for plasma and other substances including cells that have leaked from the vascular
system and transport lymph fluid back from the tissues to the circulatory system.

Question 6

Tonsils

Answer 6

• trap bacteria and viruses that are people breathe. Antibodies produced in the tonsils kill these bacteria and
  viruses to prevent throat and lung infections.

Question 7

List the body’s nonspecific defenses, and explain the function of two of them, also describe the
components and mechanisms.

Answer 7

Mechanical defenses - Epidermis of skin, Mucous membranes, Mucus, Hairs, Lacrimal apparatus, Saliva, Urine, and Defecation and vomiting.
Chemical defenses - Sebum, Lysozyme, Gastric juice, and Vaginal secretions.

Question 8

Vaginal secretions

Answer 8

Slight acidity discourages bacterial growth; flush microbes out of vagina.

Question 9

Gastric juice

Answer 9

Destroys bacteria and most toxins in stomach.

Question 10

Lysozyme

Answer 10

Antimicrobial substance in perspiration, tears, saliva, nasal secretions, and tissue fluids.

Question 11

Sebum

Answer 11

Forms protective acidic film over skin surface that inhibits growth of many microbes.

Question 12

Defecation and vomiting

Answer 12

Expel microbes from body.

Question 13

Urine

Answer 13

Washes microbes from urethra.

Question 14

Saliva

Answer 14

Washes microbes from surfaces of teeth and mucous membranes of mouth.

Question 15

Lacrimal apparatus

Answer 15

Tears dilute and wash away irritating substances and microbes.

Question 16

Hairs

Answer 16

Filter out microbes and dust in nose. Cilia Together with mucus trap and remove microbes and dust
from upper respiratory tract.

Question 17

Mucus

Answer 17

Traps microbes in respiratory and gastrointestinal tracts.

Question 18

Mucous membranes

Answer 18

Inhibit entrance of many microbes, but not as effective as intact skin.

Question 19

Epidermis of skin

Answer 19

Forms physical barrier to entrance of microbes.

Question 20

Discuss the types of T cells and the role played by each in the immune response, and explain the mechanisms of their activation.

Answer 20

Cytotoxic T cell, Helper T cell, and Memory T cell.

Question 21

Memory T cell

Answer 21

Remains in lymphatic tissue and recognizes original invading antigens, even years after
first encounter.

Question 22

Cytotoxic T cell

Answer 22

Kills host target cells by releasing granzymes that induce apoptosis, perforin that forms
channels to cause cytolysis, granulysin that destroys microbes, lymphotoxin that destroys target cell DNA,
gamma-interferon that attracts macrophages and increases their phagocytic activity, and macrophage
migration inhibition factor that prevents macrophage migration from site of infection.

Question 23

Helper T cell

Answer 23

Cooperates with B cells to amplify antibody production by plasma cells and secretes
interleukin-2, which stimulates proliferation of T cells and B cells. May secrete gamma-IFN and tumor
necrosis factor (TNF), which stimulate inflammatory response.