Lymphatic System

Question 1

Lymph

Answer 1

Tissue fluid formed at the post-capillary venule, percolates through cells taking up wastes, and is collected by the lymphatic system

Question 2

Functions of the lymphatic system

Answer 2

Fluid recovery
Lipid absorption
Immunity

Question 3

What are lymphatic capillaries?

Answer 3

Begin closed-ended in tissue spaces between cells
Unique one-way structure permits interstitial flow into but not out of the vessels
- Lymph vessels have valves like veins to prevent backflow

Question 4

What are lacteals?

Answer 4

Blind-ended lymphatic capillaries found in the center of the villi of the small intestine

• specialized for the absorption of chylomicrons (lipids) that are eventually dumped into venous system with the rest of the lymph
• openings allows for the diffusion of fluid and lipids into the lacteal

Question 5

What are the function of lymph nodes?

Answer 5

Help to recover fluid

Question 6

Flow of lymph back to the heart: 1-6

Answer 6

1. Interstitial spaces - lymphatic capillaries
2. Lymphatic vessels
3. Lymph nodes
4. Lymph trunks
5. Collecting ducts
6. Subclavian vein

Question 7

What is a thoracic duct?

Answer 7

Main duct that begins as cisterna chyli dilation in abdomen

- also receives lymph from left head, neck, and chest

Question 8

What is the right lymphatic duct?

Answer 8

Receives lymph from the right head, neck, and chest

Question 9

The thoracic and right lymphatic ducts drain into the junction of the …

Answer 9

internal jugular vein and subclavian veins

Question 10

Elephantiasis - Lymphatic Filariasis

Answer 10

Mosquito-born round worm called filariae

• swelling upstream of the blockage
• skin becomes thickened and cracked

Question 11

Immunity

Answer 11

The defense capability of the body against pathogens

Question 12

Pseudopods

Answer 12

Extensions that grab foreign materials and pull them in

Question 13

Antigen

Answer 13

A molecule that provokes and immune response

Question 14

Non-specific immunity

Answer 14

Mechanical barriers
phagocytosis
inflammation/fever

Question 15

Specific immunity

Answer 15

Built over time
Humoral (antibody mediated)
Cell-mediated (t-cells)

Question 16

Natural Killer cells

Answer 16

Immunological surveillance

Question 17

T lymphocytes (T-cells) - 3 types

Answer 17

3 types:
Cytotoxic - directly attach and kill other cells
Helper - activate defense mechanisms
Memory - provide long lasting memory of an antigen

Question 18

B lymphocytes

Answer 18

Differentiate into plasma cells (secrete antibodies)
- Some become memory B cells (long-lasting immunity)
Antigen presenting cell

Question 19

What would be the effect of a virus that selectively destroyed memory T and B cells?

Answer 19

Prevents from keeping memory of that virus

Question 20

Macrophages

Answer 20

Develop from monocytes
- phagocyte cells - get rid of tissue and debris
- display foreign fragments to cytotoxic and helper T cells
Antigen presenting cells

Question 21

Dendritic cells

Answer 21

Branched macrophages

Question 22

Reticular cels

Answer 22

Found in the thymus
Contribute to stroma of lymphatic organs
Antigen presenting cells

Question 23

Primary lymphatic organs and tissues

Answer 23

Site of stem cell division and development of immunocompetent B and T lymphocytes
- Includes red bone marrow and the thymus

Question 24

Secondary lymphatic organs and tissues

Answer 24

Site of most immune responses

- Includes lymph nodes, spleen, and lymphatic follicles

Question 25

Lymphatic nodule

Answer 25

Structural and functional unit of lymphatic tissue - not enclosed in a CT capsule - 1st line of immunological defense

Question 26

Function of lymphatic nodule

Answer 26

Identify sites where B-lymphocytes in loose areolar CT have encountered antigens - germinal center is surrounded by corona, where activated B-cells enlarge and divide into plasma cells

Question 27

Location of lymphatic nodules

Answer 27

Tonsils Peyer's patches Appendix

Question 28

Lingual Tonsils

Answer 28

Posterior aspect of tongue

Question 29

Palatine tonsils

Answer 29

Between anterior and posterior pillars

Question 30

Pharyngeal tonsils (Adenoids)

Answer 30

Posterior wall of nasopharynx

Question 31

Waldeyer's Ring

Answer 31

Aggregations of lymphatic tissue in the oro- and nasopharynx that form a ring around the opening of the digestive and respiratory tracts

Question 32

Red Bone Marrow

Answer 32

In flat bones and epididymis of long bones in adults - stem cells produce both B and T lymphocytes - Where B cells mature

Question 33

Thymus function

Answer 33

Where immature T cells migrate and multiply to mature - Thymosin is produced here by the reticuloendothelial cells - Found in the anterior mediastinum next to the heart

Question 34

Thymus structure

Answer 34

Made of 2 lobes, each has a different cortex and medulla - Has efferent ductules but no afferent ductules - Replaced by fat after puberty

Question 35

Lymph node 2 main regions and their functions

Answer 35

Cortex - Outer area composed of lymphoid nodules (B-cells) | Medulla - Inner area composed of lymphoid sinusoids

Question 36

How do lymph nodes work?

Answer 36

They filter foreign substances - Reticular fibers trap and lymph flows through - Macrophages destroy through phagocytosis - Lymphocytes destroy through immune responses

Question 37

How does lymph travel through the lymph node?

Answer 37

Lymph enters in through the afferent vessels into the subcapsular sinuses - its then contacted by B-cells in the cortex and T-cells in the T-cell dependent zone (between the cortex and medulla) - Then it exits through the efferent vessels

Question 38

Histology of the lymph node

Answer 38

Reticular connective tissue

Question 39

Why are superficial lymph nodes important?

Answer 39

They are scattered throughout the body and are easily palpable - swelling of these can indicate infection - Important ones: cervical, axillary, inguinal

Question 40

Significance of the umbilicus and lymph nodes

Answer 40

The umbilicus is a watershed area for the lymph collected by the superficial nodes

Question 41

Spleen Characteristics

Answer 41

Largest mass of lymphatic tissues | Contains Red and white pulp

Question 42

Lymphatic follicles

Answer 42

Concentrations of lymphatic tissue without capsule - mucosa-associated lymphatic tissue scattered throughout - also has large aggregations (appendix and tonsils)

Question 43

Spleen location

Answer 43

Located in the abdomen, posterior-lateral to stomach

Question 44

White pulp in the spleen

Answer 44

Made of white blood cells - produces antibodies - lymphatic tissue - B-cells differentiate into plasma cells

Question 45

Red Pulp in the spleen

Answer 45

Made of red blood cells - destroys old RBC and platelets - contains macrophages