Chapter 21 Lymphatics

Question 1

What does the lymphatic system do and house?

Answer 1

Returns interstitial fluid, leaked plasma proteins, and electrolytes back to the blood.

Houses phagocytes (Macrophages) and lymphocytes (B/T cells) essential for body defense.

Question 2

The lymphatic vessel is a one-way system. Lymph flows toward the heart and include, from small to large:

Answer 2

Lymphatic collecting vessels with valves. ->Lymph nodes ->lymph trunks (9)->lymph ducts (2)

Question 3

Speaking of lymphatic capillaries, mini valves function as one way gates that:

During inflammation, lymph Capillaries develop larger openings to absorb what three items?

Answer 3

Allow interstitial fluid to enter lymph capillaries, do not allow lymph to escape.

Cell debris
pathogens
cancer cells

Question 4

What are lacteals?

Answer 4

Specialized lymph capillaries present an intestinal mucosa.

Absorb digested fat and deliver this Chyle (juice)to the blood

Question 5

Discuss the anatomy of lymphatic vessel walls.

Answer 5

Same three tunics as veins.

Dinner walls, more internal valves then veins.

More frequent anastomoses

Can travel with superficial veins, and deep arteries

Question 6

What are lymphatic trunks formed by? What are the major trunks?

Answer 6

By the union of the largest collecting vessels.

Paired lumbar, bronchomediastinal, subclavian, and jugular trunks.
A single intestinal trunk.

Question 7

What are the two large ducts? What is drained there?

Answer 7

Right lymphatic duct: drains right upper arm and right side of head/thorax.

Thoracic duct: arises from cisterna Chyli and intestinal trunk that drains the rest of the body.

   Cisterna Chyli-collects lymph from the two lumbar trunks that drain the lower limbs.
   Intestinal trunk – collect lymph from digestive organs.

Question 8

What is lymphedema? And three major known medical causes?

Answer 8

Localized swelling distal to the blockage/damage.

Mastectomy – upper limb Edema

Inguinal-lower limb Edema

elephantiasis – parasitic roundworms

Question 9

Since the lymphatic system lacks a pumping organ, how are these low pressure vessels in motion?

How much enters bloodstream each 24 hours?

Answer 9

Milking of skeletal muscles.
Pressure changes in thorax.
Pulsation of nearby arteries.
Contractions of smooth muscles in walls of lymphatics.

3L of lymph

Question 10

Compare T and B cells.

What are antigens?

Answer 10

Both protect body against antigens.

T cells – (inside cell) mature in thymus. Manage immune response, attack and destroy foreign cells.
B cells – (tissue) mature in bone marrow. Produce plasma cells that secrete antibodies which immobilize antigens until they can be destroyed.

Antigen – anything perceived as foreign on cell surface.(bacteria, viruses, mismatch RBCs, cancer cells).

Question 11

Define the other lymphoid cells:

Macrophages

Dendrite cells

Reticular cells

Answer 11

Macro-phagocytes foreign substances and activate T cells.

Den-spiny looking cells with function similar to macrophages except embedded in the skin.

Ret-fibroblast like cells that produce a stroma to capture foreign material and wait for macro phages.

Question 12

What is the definition of lymph?

Answer 12

Interstitial fluid once it has entered lymphatic vessels. Very similar to blood plasma.

Question 13

What are lymphatic follicles made of, and where they found?

Answer 13

Spherical bodies with packed reticular elements and cells. Has germinal center composed of dendritic and B cells.

Found in isolation and as part of lymph node.

Question 14

Where are The major lymphatic organs, lymph nodes found?

Answer 14

Embedded in connective tissue and clustered along lymphatic vessels.

Nodes occur near body surface and inguinal, axillary, and cervical regions.

Question 15

What are the two functions of the lymph node?

Answer 15

Filtration – lymph filtered, Macrophages destroy any micro organisms and debris.

Immune system activation – lymphocytes in the nodes monitor for antigens, and mount an attack against them.

Question 16

Explain the structural anatomy of a lymph node, including types of cells.

Answer 16

Cortex – has follicles (encapsulated by dendritic cells) with germinal centers, many B cells.(stays in node and makes antibody when in attack mode, sends it back to heart for circulation into bloodstream body wide.)

Deep cortex houses T cells (are everywhere) in transit.

Medullary cords (no follicle) – extend from cortex and contain B cells, T cells, plasma cells.

Lymph sinuses crisscrossed by reticular fibers throughout.
Macro phages reside on fibers and Phagocytize foreign matter.
Lymph-bourne antigens leak into surrounding lymph tissue and activate lymphocytes.

Question 17

What happens when lymph nodes are overwhelmed by bacteria that they are trying to destroy? What are those called?

Answer 17

When large amounts of bacteria are trapped in notes, they become inflamed, swollen and painful.

Called buboes.

• Black death

Question 18

Explain the route of lymph through the node.

Answer 18

Enters via afferent lymphatic vessel.

Enters subscapular sinus and travels into smaller sinuses.

Exits node at hilus via the efferent vessels.

*** since you there are fewer efferent vessels, lymph stagnates in node allowing lymphocytes and macrophages time to work.

Question 19

All lymphoid organs are composed of ______________ __________________ ________.

Only lymph ___________ filter lymph.

Answer 19

Reticular connective tissue.

Nodes

Question 20

What are the other lymphoid organs in the body other than lymph vessels/nodes?

Answer 20

Spleen, thymus gland, tonsils.

Peyers patches in the intestines

Question 21

What are the functions of the largest lymphoid organ, the spleen?

Answer 21

Site of lymphocyte rapid reproduction.
Immune surveillance and response.
Cleanses the blood.
Stores broken down old RBCs for later use.
Site of fetal erythrocyte production.
Stores blood platelets.

Question 22

What is the general description of the anatomy of the spleen?

And the two distinct areas: white pulp and red pulp?

Answer 22

Has a fibrous capsule. Trabeculae that extend inward, containing lymphocytes, macrophages, and huge numbers of erythrocytes.
WP-lymphocytes (WBC) suspended on reticular fibers. Involved with infection removal.

RP-disposing of worn-out RBCs and blood-borne pathogen’s

Question 23

What is the important and yet different functions of the thymus?

Answer 23

Secretes hormones that cause T cells to become immunocompetent.

Does not directly fight antigens (infections).

Stroma consists of star shaped epithelial cells, called thymocytes, that secrete hormones to stimulate lymphocyte to be immunocompetent.

(immunocompetent – ability to bind to foreign antigen and mount an immune response.)

Question 24

What are the four tonsils? Where are those located?

Answer 24

Palatine tonsils – either side of posterior end of oral cavity.
lingual tonsils – base of the tongue
Pharyngeal tonsils – posterior wall of the nasopharynx
Two will consuls – surround openings of auditory tubes into pharnyx

Question 25

What are tonsil crypts?

Answer 25

Epithelial tissue overlying tonsil masses invaginate, forming blind ended crypts.

Trap and destroy bacteria and particulate matter.

Question 26

What are Peyers patches? Where are they found, and they work with what other organ, doing what?

Answer 26

Isolated clusters of lymphoid tissue. (similar to tonsils).
Found in the wall of the distal small intestine.
Appendix (has similar structures)
Destroy bacteria preventing intestinal breach. Generate memory lymphocytes for long term immunity.

Question 27

What is malt? What does its major function serve?

Answer 27

Mucosa associated lymphatic tissue.

Protect the digestive and respiratory systems from foreign matter.

(Peyers patches, tonsils, appendix, lymphoid nodules and bronchi walls)

Question 28

Where do each lymphoid organs and vessels originate?

Answer 28

Vessels and lymph node clusters arise from budding lymph sacs from developing veins.

Lymphatic organs, except THYMUS, arise from mesoderm.

THYMUS forms as an outgrowth of the pharnyx.

Question 29

What is elephantiasis?

Answer 29

Clogged lymphatics with parasitic roundworms. Swelling from edema.