3 (20) The Lymphatic System

Question 1

What are the three functions of the lymphatic system?

Answer 1

draining interstitial fluid, transporting dietary lipids, protection

Question 2

Describe the structure of a lymphatic capillary. How does it work?

Answer 2

• made of a single layer of squamous epithelial cells
• slightly larger than blood vessels
• cells overlap and act as one-way valves
• opened by pressure of interstitial fluid
• anchoring filaments attach cells to surrounding tissue

Question 3

Where would we find lymphatic capillaries and where are they absent in the body?

Answer 3

• found in tissue spaces between cells

- absent from the central nervous system, bone marrow, teeth, avascular tissues, splenic pulp

Question 4

What is lymph? Is it a circulating fluid?

Answer 4

• interstitial fluid and leaked plasma proteins drain into lymphatic capillaries
• NOT a circulating fluid

Question 5

Trace the flow of lymph from the lymphatic capillaries to the collecting ducts.

Answer 5

lymphatic capillary, lymphatic vessel, lymph node, lymphatic vessel, lymphatic trunk, collecting duct

Question 6

What are the two major lymphatic ducts, and what areas of the body do they drain?

Answer 6

THORACIC DUCT - 3/4 of the body

RIGHT LYMPHATIC DUCT - drains right arm, and right side of head, neck and upper torso

Question 7

Where do the two major lymphatic ducts empty into the circulatory system?

Answer 7

both empty into subclavian veins at junction with internal jugular vein

Question 8

Where would you find the cisterna chyli?

Answer 8

lower end of the thoracic duct (in most mammals) into which lymph from the intestinal trunk and two lumbar lymphatic trunks flow

Question 9

What are the organs of the lymphatic system?

Answer 9

PRIMARY ORGANS - red bone marrow, thymus gland

SECONDARY ORGANS - lymph nodes, lymph nodules, spleen

Question 10

Describe the structure and function of a lymph node.

Answer 10

STRUCTURE #
- vary in shape and size but most bean shaped
- external fibrous CAPSULE
- TRABECULAE extend inward and divide node into compartments
- two histologically distinct regions: Cortex, Medulla
# FUNCTION #
- provide biological filtration
- immune system activation—lymphocytes activated and mount attack against antigens
- site of cancer growth and metastasis

Question 11

What is the medical name for a swollen lymph node?

Answer 11

buboes (singular: bubo)

Question 12

What does albumin do for the blood?

Answer 12

regulates osmotic pressure

Question 13

What happens when the flow of lymph is blocked?

Answer 13

lymphedema, which means swelling due to a blockage of the lymph passages

Question 14

What are lacteals and what do they do?

Answer 14

• specialized lymphatic capillaries in vili of small intestine
• transport lipids

Question 15

What are lymph nodules?

Answer 15

small, localized collection of lymphoid tissue, usually located in the loose connective tissue beneath wet epithelial (covering or lining) membranes, as in the digestive system, respiratory system, and urinary bladder

Question 16

What is MALT?

Answer 16

mucosa associated lymphoid tissue

Question 17

What are Peyer’s patches?

Answer 17

• small masses of lymphatic tissue found throughout the ileum region of the small intestine
• form an important part of the immune system by monitoring intestinal bacteria populations and preventing the growth of pathogenic bacteria in the intestines

Question 18

What are tonsils?

Answer 18

lymphoid tissue under the mucous membranes of the throat

Question 19

Name the three major tonsils.

Answer 19

• (1) the pharyngeal tonsils, commonly known as adenoids
• (2) the palatine tonsils and (3) the lingual tonsils, which are lymphatic tissue on the surface tissue of the base of the tongue

Question 20

What does the thymus do?

Answer 20

• does not directly fight antigens

- functions strictly in T lymphocyte maturation (keeps isolated via blood thymus barrier)

Question 21

Where is the thymus?

Answer 21

inferior neck; extends into mediastinum; partially overlies heart

Question 22

When is the thymus largest? Then what happens to it?

Answer 22

grows in size and most active during childhood, then stops growing during adolescence and then gradually atrophes

Question 23

Locate the spleen. What is white pulp? Red pulp?

Answer 23

• upper left quadrant of abdomen
• WHITE PULP: little islands, mostly B cells
• RED PULP: connective tissue (the cords of Billroth) and many splenic sinusoids that are engorged with blood (red color) primary function - is to filter the blood of antigens, microorganisms, and defective or worn-out red blood cells

Question 24

What are the three functions of the spleen?

Answer 24

• site of lymphocyte proliferation and immune surveillance and response
• cleanses blood of aged cells and platelets, macrophages remove debris
• stores breakdown products of RBCs for later use and stores blood platelets and monocytes