Chapter 20 - The Lymphatic System

Question 1

The Lymphatic System

Answer 1

a system that picks up fluids that have leaked from the vascular system and returns it to the blood. It also plays a role in immunity and removes wastes.

Question 2

Distribution of Lymph

Answer 2

Lymph is picked up by blind-ended capillaries, and only flows one way, towards the heart.

Question 3

Endothelial Cells

Answer 3

In the walls of the lymphatic capillaries that have edges that overlap with minivalves to prevent backflow of fluid.

Question 4

Bundles of Filaments

Answer 4

They anchor endothelial cells to surrounding structures

Question 5

Lacteals

Answer 5

Highly specialized lymphatic capillaries found on the villi of the intestines. They transport absorbed fat.

Question 6

Interstitial Space

Answer 6

Lymphatic system helps maintain a fluid balance in the interstitial space

Question 7

2 Large Ducts

Answer 7

• right lymphatic duct: drains from the right upper arm, right side of the head and thorax.
• thoracic duct: drains from the rest of the body

Question 8

Lymph Transport

Answer 8

The same mechanism as with the veins. A “milking” due to muscular mechanisms and pressure changes.

Question 9

Lymph Nodes

Answer 9

Small organs associated with the lymphatic vessels. They’re formed in large clusters. Found in the inguinal, cervical, and axillary regions.

Question 10

Function of Lymph Nodes

Answer 10

To filter lymph. They have macrophages that remove debris and pathogens, and lymphocytes which form the “early warning” system

Question 11

Structure of Lymph Nodes

Answer 11

1. Cortex - follicles of lymphocytes. Full of transitory T-cells with a germinal center full of B-cells.
2. Medulla - Inner area with a large concentration of macrophages

Question 12

Circulation of Lymph Nodes

Answer 12

Lymph enters the node through the afferent lymph vessels, it moves from the cortex to the medullary sinus, and exits through the efferent vessels towards the heart.

Question 13

Other Lymphoid Organs

Answer 13

All of them have reticular connective tissue. Their main function is protection of the body.

Question 14

Spleen Location

Answer 14

On the left side of the abdominal cavity, beneath the diaphragm. It is the largest lymphatic organ.

Question 15

2 Histological Areas

Answer 15

White pulp - has mostly lymphocytes (WBCs) and macrophages

Red pulp - has mostly erythrocytes (RBCs) and macrophages.

Question 16

Function of the Spleen

Answer 16

• It removes old and defective blood cells
• It filters blood, removed bacteria and wastes
• In embryo it is a site of erythropoiesis
• It stores platelets and iron
• Site of lymphocyte proliferation and immune surveillance

Question 17

Thymus Gland

Answer 17

Works by secreting hormones. T-lymphocyte production happens here, and here they become immunocompetent. Size of the thymus increases around puberty to adolescence and then growth stops, after age 20, it starts decreasing in size.

Question 18

Thymus Cortex

Answer 18

It maintains the blood-thymus barrier. Because T-cells mature in the thymus, it is important to keep them from being contaminated by the external environment.

Question 19

Tonsils

Answer 19

Rings of lymphatic tissue.

• Palatine: Paired, located on either side of the posterior end of the oral cavity.
• Lingual: Located on the base of the tongue
• Pharyngeal: Located on the posterior superior wall of the nasopharynx

Question 20

Peyer’s Patches

Answer 20

Clusters of lymph nodules found in the walls of the distal portion of the small intestine. Have macrophages that destroy bacteria. Along with the tonsils, they protect the upper respiratory and digestive tract.

Question 21

MALT or GALT

Answer 21

GALT - Gut Associated Lymphatic Tissue

MALT - Mucus Associated Lymphatic Tissue

Question 22

Elephantiasis

Answer 22

The lymphatics become clogged with parasitic worms

Question 23

Hodgkins Disease

Answer 23

Lymph node malignancy or cancer