M26: Lymphatic System

Question 1

4 main components of lymphatic system

Answer 1

• lymphatic tissue
• red bone marrow
• lymph
• lymphatic vessels

Question 2

what is the main purpose of the lymphatic system?

Answer 2

the body system that carries out immune responses

Question 3

lymphatic tissue

Answer 3

• reticular CT with lymphocytes: B cells and T cells
• found in many structures and organs

Question 4

primary vs secondary lymphatic organs/tissues

Answer 4

PRIMARY:
where stem cells divide to create the immuno-response cells
- RED BONE MARROW
- THYMUS

SECONDARY
where immune responses happen
- SPLEEN
- LYMPH NODES
- TONSILS

Question 5

difference between tonsils and lymph nodes

Answer 5

• tonsils don’t have a capsule surrounding them
• not a lymphatic organ, just a mass of lymphatic cells

Question 6

when lymphatic cells aren’t surrounded by a capsule it’s not considered an organ but…

Answer 6

lymphatic tissue

Question 7

what makes lymphatic vessels different from small veins?

Answer 7

they’re very similar other than
thinner walls
more valves

Question 7

what structures do lymphatic vessels follow in the body?

Answer 7

• superficial vessels tend to follow superficial veins
• deep vessels tend to follow arteries

Question 8

cisterna chyli

Answer 8

• dilation in lymphatic vessels
• caused by merge in lumbar and intestinal trunks
• start of the thoracic duct

Question 9

where does the thoracic duct attach to the vascular system

Answer 9

left subclavian vein

Question 10

where is lymph drained from R side of body?

Answer 10

right lymphatic duct
right subclavian vein

Question 11

functions of lymphatic system

Answer 11

1. drains excess interstitial fluid
2. transports dietary fats and lipid-soluble vitamins (A, D, E, K)
3. carry out immune responses (targets microbes and abnormal cells)

Question 12

lymphatic capillaries

Answer 12

• located between cells of many tissues
• larger and more permeable than blood capillaries
• endothelial cells organized for one-way flow of lymph
• merge to form lymphatic vessels

Question 13

anchoring filaments

Answer 13

extensions of lymphatic capillary endothelial cells that attach it to neighbouring cells

Question 14

special features of endothelial cells in lymphatic capillary to prevent backflow

Answer 14

overlapping endothelial cells
- when lymphatic capillary gets to full, openings will close off

Question 15

name the 2 primary lymphatic organs

Answer 15

• thymus
• red bone marrow

Question 16

difference between lymphatic capillary and blood capillary

Answer 16

lymphatic are larger in diameter and more permeable

Question 17

flow of lymph

Answer 17

interstitial fluid
lymphatic capillaries
lymphatic vessels
lymph nodes
lymph trunks
lymph ducts (thoracic duct OR “right lymphatic duct”)
most people have drainage on R side of body go straight to R subclavian vein
subclavian veins

Question 18

5 principle lymph trunks

Answer 18

main lymphatic trunks
LUMBAR: drains lower limbs, kidneys, adrenals, portions of pelvic and abdominal walls
INTESTINAL: drains stomach, intestine, pancreas, spleen, part of liver
BRONCHOMEDIASTINAL: drains thoracic walls, lungs, heart
SUBCLAVIAN: drains upper limbs
JUGULAR: drains head and neck

Question 19

routes of lymph drainage

Answer 19

MOST OF BODY
- R and L lumbar merge with intestinal trunk at the cisterna chyli to form the thoracic duct
- merges with L jugular trunk and L subclavian trunk
- attaches to L subclavian vein (right at its junction with the L internal jugular vein)
- L bronchiomediastinal trunk attaches independently to L subclavian vein

UPPER RIGHT BODY
- R jugular, R subclavian and R brochiomediastinal trunk join independantly to R subclavian vein
small # of people will have these merge, called the right lymphatic duct

Question 20

what lymphatic vessel does not join thoracic trunk and attaches to L subclavian vein independanty?

Answer 20

L bronchiomediostinal trunk

Question 21

lymph nodes

Answer 21

filters for lymph
- remove foreign substances through filtering, phagocytosis and immune reactions

Question 22

immunocompetent

Answer 22

cells that are able to create an immune response

Question 23

where is thymus located

Answer 23

mediastinum
left side of body

Question 24

anatomy of thymus

Answer 24

- bilobed (each lobe surrounded by a capsule, so its considered an organ) - TRABECULAE: extensions that divide lobes into lobules - LOBULES - CORTEX: pre-T cells begin to mature - MEDULLA: mature T cells

Question 25

red bone marrow produces...

Answer 25

- B cells (already immuno-competent) - Pre-T cells (need to be matured in thymus to become immuno-competent)

Question 26

secondary lymphatic organs + tissues

Answer 26

ORGANS - lymph nodes - thymus - spleen TISSUES *LYMPHATIC NODULES (FOLLICLES): masses of lymphatic tissue without a capsule* - MUCOSA-ASSOCIATED LYMPHATIC TISSUE (MALT): mucous membranes of GI, urinary, reproductive, respiratory - TONSILS: pharyngeal, palatine, lingual - APPENDIX & AGGREGATED LYMPHATIC FOLLICLES (PEYER'S PATCHES, found in ilium of SI)

Question 27

how many lymph nodes in body

Answer 27

~600 typically occur in groups

Question 28

structure of a lymph node

Answer 28

STROMA: supporting framework - CAPSULE: outer layer of dense CT - TRABECULAE extensions divide nodes into compartments - RETICULAR FIBRES + FIBROBLASTS PARENCHYMA: functional component - CORTEX (inner and outer) - MEDULLA

Question 29

structure of outer cortex in lymph node

Answer 29

OUTER: contains LYMPHATIC NODULES: groupings of B-cells - when no foreign invaders around, nodule called PRIMARY LYMPHATIC NODULES - with invader, nodule called SECONDARY LYMPHATIC NODULE. - centre of this nodule called the GERMINAL CENTER. - makes up majority of outer cortex.

Question 30

where do afferent lymphatic vessels enetr a lymph node?

Answer 30

on the convex side of the node

Question 31

flow of lymph through lymph node

Answer 31

- afferent lymphatic vessel - subcapsular sinus - trabecular sinus - medullary sinus - efferent lymphatic vessel (only 1-2/lymph node), leave via hilum

Question 32

antigens

Answer 32

foreign substances in the body

Question 33

3 cell types in germinal centre in secondary lymphatic nodule

Answer 33

**1. B-CELLS** *when presented with antigen, proliferate and turn into 2 types of cells* a. PLASMA CELLS: create antibodies b. MEMORY B-CELLS: remembers antigen for if it comes again! **2. FOLLICULAR DENDRITIC CELLS** - collects antigens, brings them to B-cells **3. MACROPHAGES** - phagocytosis

Question 34

2 types of cells in inner cortex

Answer 34

**1. T-CELLS** *can form 2 types of cells* a. CYTOTOXIC T-CELLS: attack and destroy antigen b. HELPER T-CELLS: help cytotoxic T-cells and B-cells **2. DENDRITIC CELLS** - present antigens to T-cells

Question 35

types of cells in medulla region of lymph node

Answer 35

1. B-CELLS 2. PLASMA CELLS - produce antibodies 3. MACROPHAGES

Question 36

B-cells

Answer 36

- lymphocytes that respond to an antigen *when antigen present, proliferate and turn into 2 types of cells* a. PLASMA CELLS: create antibodies b. MEMORY B-CELLS: remembers antigen

Question 37

T-cells

Answer 37

*can form 2 types of cells* a. CYTOTOXIC T-CELLS: attack antigens b. HELPER T-CELLS: help cytotoxic T-cells and B-cells

Question 38

Dendritic cells

Answer 38

*from monocytes* present antigens to B and T cells

Question 39

Macrophages

Answer 39

do phagocytosis

Question 40

where do T-cells mature? Where are they stored?

Answer 40

Thymus - mature in the cortex - stored in the medulla

Question 41

largest mass of lymphatic tissue

Answer 41

spleen

Question 42

spleen structure + function

Answer 42

STROMA - similar to lymph node, has trabeculae - surrounded by visceral peritoneum PARYNCHYMA - WHITE PULP: surround central artery - B & T cells and macrophages - RED PULP: venous sinuses and splenic cord - macrophages remove old RBC/platelets - stores up to 1/3 supply of platelets

Question 43

bloodflow in spleen

Answer 43

- splenic artery - central artery (surrounded by white pulp) - splenic veins (surrounded by venous sinuses and red pulp)