Lymphatic System

Question 1

Lymphatic organs

• What are they formed by?
• What do they include?

Answer 1

Formed by lymphatic tissue (makes lymphocytes via lymphocytopoiesis)

Include: lymph nodes, spleen, thymus, tonsils

Question 2

GALT

Answer 2

Gut associated lymphatic tissue

Lymphatic tissue in the gut

Question 3

Lymphocytes made of 2 elements

Answer 3

1. Connective tissue framework

2. Free cells

Question 4

Connective tissue framework

Free cells

Answer 4

Fixed framework: reticular cells and fibers

Free cells:
Mature lymphocytes, lymphocytes in various stages of development, macrophages and plasma cells

Question 5

Macrophages function

Answer 5

Phagocytize foreign substances

Activate T cells

Question 6

Dendritic cells: appearance and function

Answer 6

Spiny-looking

Function is similar to macrophage

Question 7

Reticular cells

Answer 7

Fibroblast-like cells
Make stroma or network
Supports other cells types in lymphoid organs

Question 8

Nodules

Answer 8

Solid, spherical bodies

Tightly packed reticular elements and cells

Question 9

Tonsils

Answer 9

Simplest lymphoid organ

Forms ring of lymphatic tissue around nose and mouth (pharynx)

Question 10

3 Types of tonsils. Which one is referred to as people getting their “tonsils removed?”

Answer 10

Palatine
Lingual
Pharyngeal

Palatine tonsils = tonsils that people get removed

Question 11

Locations of the three tonsils

Answer 11

Palatine:
Both sides of posterior end of oral cavity (back of mouth)

Lingual:
Base of the tongue

Pharyngeal:
Posterior wall of the nasopharynx
(If enlarged, that obstruct nasal openings and are called adenoids)

Question 12

Tonsils

Answer 12

Lymphoid tissue of tonsils have germinal center

Epithelial tissue overlying tonsil masses invaginates - makes blind-ended crypts

Crypts: trap and destroy bacteria and matter

Question 13

Lymph node - Hilus

Answer 13

Indentation on 1 side of node

Blood vessels and lymphatics enter and leave node via hilus

Question 14

Lymph node - cortex

• location
• regions

Answer 14

Under the capsule

Divided into outer and inner region
- outer: B-lymphocyte area
- inner: deep cortex (paracortinal zone);
Thymus dependent area and has T-lymphocytes

Question 15

Lymph node - medulla

• Medullary cords

Answer 15

Inner node

Made by diffuse lymphatic tissue in the form of strands or cords called medullary cords

Question 16

Lymph nodes - sinsuses

Answer 16

Spaces between adjacent cords of lymph tissue OR

Spaces between lymph tissue and connective tissue

Question 17

Sinuses

Answer 17

Channels for lymph flow through node

Crisscrossed by reticular fibers

Lymph gets filtered here by: macrophages that are suspended in the reticular framework

Slow lymph flow –> Ag interact with lymphocytes

Question 18

3 Sinuses - named by location

Answer 18

Subcapsular (marginal sinus)
- between capsule and lymph tissue of outer cortex

Intermediate (cortical, trabecular) sinuses
- btwn connective tissue and lymph tissue of cortex

Medullary sinuses
- between medullary cords

Question 19

Lymphatics - afferent vessels

Answer 19

Lymph nodes are the only organs with afferent

Numerous vessels

Bring lymph to the lymph nodes for filtering

Question 20

Efferent vessels

Answer 20

Few in number

Carry lymph away from the lymph nodes (E= EXIT)

Efferent of one node can become the afferent of another node

Question 21

Pattern of lymph flow through node

Answer 21

Afferent lymphatics > subscapular sinus > cortical sinus > medullary sinus > efferent lymphatic

Lymph only flows in ONE direction bc of the valves in afferent and efferent lymphatics

Question 22

Functions of lymph node

Answer 22

Filter lymph and phagocytosis of particulate matter
Lymphocytopoiesis
Humoral and cellular immune responses of B and T cells

Question 23

Spleen - size and main function

Answer 23

Largest lymphatic organ

Main function = FILTER blood (does not filter lymph, lymph nodes filter lymph)

Question 24

Structure of spleen

Answer 24

Splenic pulp = parenchyma of spleen

- Divided into red and white pulp

Question 25

White pulp of spleen

Answer 25

Lymphatic tissue - mostly lymphocytes involved in immune responses

Question 26

Red pulp of spleen

Answer 26

Part that filters blood Deals with disposing worn-out RBCs and bloodborne pathogens

Question 27

Spleen functions | - CHIPS

Answer 27

``` Cleanses blood Hematopoietic organ in fetal life Immune surveillance and response Platelet storage Storage site for RBCs ```

Question 28

Thymus functions

Answer 28

Lymphopoiesis - T-lymphocytes only | Production of thyroid hormone, thymosin

Question 29

Thymus size and age

Answer 29

Size varies with age: Increases in childhood and is most active Stop growing during adolescence and then atrophies

Question 30

Thymus differences vs. other lymphatic organs

Answer 30

Functions strictly in T-lymphocyte maturation | Does not directly fight antigens

Question 31

Involution (shrinkage) of thymus

Answer 31

Max weight occurs at puberty After puberty, gradual loss of lymphocytes and reticular cells are replaced by adipose tissue

Question 32

Lymphatic vessels - Direction of flow - What do they include

Answer 32

One way system in which lymph flows to the heart Lymph vessels include: Microscopic, permeable, blind ended capillaries (sealed at one end) Lymphatic collecting vessels Trunks and ducts

Question 33

Lymphatic capillaries - Characteristics - 1 way gates

Answer 33

Permeable Loosely joined endothelial minivalves Withstand interstitial pressure and remain open Minivalves function as 1 way gates: - Allow fluid to enter capillaries - Do not allow lymph fluid to escape from capillaries

Question 34

Efferent lymph capillaries

Answer 34

Drain organs Begin as blind-ended capillaries Drain lymph away from the organ: in direction retrograde to arterial flow

Question 35

Lymphangitis | Lymphadenitis

Answer 35

- gitis = inflammation of lymph vessels | - denitis = inflammation of lyph nodes

Question 36

During inflammation, what can lymph capillaries absorb? | What are lacteals?

Answer 36

Absorb: cell debris, pathogens, cancer cells Lacteals - specialized lymph capillaries present in intestinal mucosa Absorb digested fat and deliver chyle to blood

Question 37

Name the major lymphatic trunks

Answer 37

``` Paired lumbar Bronchomediastinal trunk Subclavian Jugular Single intestinal trunk ```

Question 38

Drainage of lymph from: Both sides of the lower half of body: Gut

Answer 38

- Lumbar lymph trunks | - intestinal lymph trunk

Question 39

Right lymphatic duct

Answer 39

Drains upper right arm and right side of head and thorax