L17- Lymphatic system Flashcards

1
Q

function of the lymphatic system

A

1) Fluid balance 2) transport of fats and fat-soluble vitamins 3) Defence against invading pathogens and disease 4) storage of and destruction of aged erythrocytes

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2
Q

Fluid balance

A
  • Returns fluid to the heart from tissues o Collecting excess interstitial fluid and returning it to the blood
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3
Q

Transport of fats and fat-soluble vitamins

A

Quickest way to send lipid soluble materials from the digestive system to the venous circulation

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4
Q

Defence against invading pathogens and disease

A

a. Lymph nodes and other lymphatic organs filter the lymph to remove microorganisms, parasites, foreign particles and [cancer cells] b. ‘Visiting’ T and B lymphocytes and macrophages

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5
Q

Storage of and destruction of aged erythrocytes

A

a. The spleen is responsible for this role – liver can take over after splenectomy

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6
Q

organisation of the lymph nodes

A

(1) Lymph (fluid) (2) Lymphatic vessels (3)Lymphoid tissues and organs (lymph nodes etc) (4) Cells contained within tissues and organs

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7
Q

lymphatics in the CNS?

A

no

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8
Q

lymph

A

Fluid which flows through the lymphatic vessels and lymph nodes

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9
Q

how much lymph produced each day

A

3-4 litres

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10
Q

what does lymph resemble and what is its pH

A

plasma- pH7.4

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11
Q

how does lymph differ from plasma

A

less protein

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12
Q

how is chyle different to lymph

A

lymph that arises in GI tract

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13
Q

what does chyle look like

A
  • White and cloudy (fats and dissolved lipids- chylomicrons and fat-soluble vitamins)
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14
Q

the lymphatic system is not a

A

closed loop

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15
Q

lymphatic capillaries are

A

blind ended- meaning that all left over lymph is dumped into veins

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16
Q

lymphatic capillaries structure

A

smallest lymphatic vessel, endothelial cells line tightly together with some overlapping at the ends to create valves.

found penetrating into lymphatic tissue –> draining system

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17
Q

lymphatic capillaries are in some way comparable to

A

veins

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18
Q

how are lymphatic capillaries comparable to veins

A
  • Low pressure system - Valves
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19
Q

how are lymphatic capillaries different to veins

A
  • BUT NO CELLS NORMALLY (e.g. no RBC or WBC) - Lymph vessels have less smooth muscle
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20
Q

what do lymphatic capillaries do broadly

A
  • Absorb excess interstitial fluid from interstitial tissue
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21
Q

how do lymphatic capillaries absorb excess interstitial fluid

A
  • Highly porous due to Gaps in lymphatic vessels- formed between endothelial cells
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22
Q

what forces lymph into capillaries

A

oncotic pressure= when it reaches a certain level the gaps between the endothelial cells are forced open

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23
Q

what prevents lymph flowing in the wrong direction

A

the way the epithelial cells are layered forms a kind of valve- flow of fluids away from the terminals of the capillary- unidirectional

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24
Q

what anchors lymphatic vessels in place

A

endothelial cells produce RETICULIN (type 3 collagen)

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25
Q

once lymph has entered the capillaries outline its journey

A

Capillaries –> Trunks –>Ducts –> Veins

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26
Q

how is lymph moved unidirectionally around lymphatic vessels

A

Lymphatic vessels lie adjacent to capillaries, arteries and veins.

Lymphangion- compression by local veins and arteries propels lymph through the vessels

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27
Q

Like veins, lymphatic vessels are arranged into

A

superficial and deep.

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28
Q

deep lymphatics

A

e.g. in the limbs, use muscle contraction to aid lymph movement

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29
Q

superficial lymphatic vessels use what to move lymph

A

lymphangion

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30
Q

lymphangion

A

compression by local veins and arteries propels lymph through the vessels

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31
Q

larged lymphatic vessels are called

A

duct and trunks

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32
Q

how are ducts and trunks different to smaller lymphatic vessels

A

contain smooth muscle cells in their walls e.g. abdomen and thorax

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33
Q

ducts and trunks are quivalent to

A

larger veins

  • Larger fibrocartilaginous valves
  • Skeletal muscle and organ movement for flow
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34
Q

cisterna chyli

A

large container of chyl from GI tract (recveive lumph drainng from GI organs

35
Q

the abodomen can be split into

A

4 quadrants

  1. right upper quadrant
  2. left upper quadrant
  3. right lower quadrant
  4. left lower quadrant
36
Q

the upper right quadrant drains into

A

the right subclavian veins

37
Q

the rest of the body drains into the

A

left subclavian vein

38
Q

as lymph passes through the body is is filtered by

A

lymph nodes (600-700 in the body)

39
Q

which lymph nodes are clinically important

A

neck (cervical), grain (inguinal) and armpit (axillae)

40
Q

structure of a lymph node

A
  • Shaped like a kidney
  • Each node has multiple afferent lymphatic vessels
    • Enter via the convex surface
  • A single efferent lymphatic vessel
    • Leaves via the concave hilum
  • Each lymph node has a feeding artery and a draining vein that enters and leaves via the hilum
  • Nodules on the outside of the node (cortex) with germinal centres in the middle
41
Q

nodules in the cortex of lymph nodes contain

A

germinal centres

  • which contain immune cells scuh as macrophages, dendritic cells, B and T cells
42
Q

main conenctive tissue fibre in lymph nodes

A

reticulin produced by reticular cells

capsule is covered in collagen 3 and 1

43
Q

follicular dendritic cell activation

A

Dendritic cells from the periphery use long processes to locate pathogen and phagocytose. The activated dendritic cell then travels to the lymph nodes via the afferent lymphatic vessels and activates T cells. This activates proliferation of B and T helper cells in the germinal centre- release of antibodies into blood via efferent lymphatic vessels.

44
Q

dendritic processes

A

Dendritic cells have very long processes which find pathogens and T cells and activate them. Macrophages has long processes which helps macrophages with phagocytosis

45
Q

B cells can

A

recognise antigens by themselves

46
Q

T lymphocytes

A

must be presented the antigen by an APC

47
Q
A
48
Q

lymphadenopathy

A

enlarged lymph nodes

49
Q

why does lymphadenopathy occur

A
  • As lymph nodes fight infection, germinal centres fill with increasing number of lymphocytes causing the lymph nodes to swell- painful
  • Cancers can metastases to lymph nodes via the afferent lymphatics to also cause swelling
  • Lymphoma- malignancy of lymphoid tissue itself
    • Hodgkin lymphoma
    • Non-Hodgkin lymphoma
50
Q

name 5 lymphatic organs

A

thymus

spellen

tonsils

appendix

payers patches

51
Q
A
52
Q

the spleen is the …. of lymphatic organs

A

largest

53
Q

where is the spleen loacted

A

inferior to diagram and posterior to the stomach

54
Q

why is the spleen so red

A

Rich blood supply

Stores RBC (why its so red)

55
Q

by birth the spleen is

A

fully formed and functional

56
Q

two different type of tissue in the spleen

A

white pulp- in the centre

red pulp- in the cortex

57
Q

white pulp

A

immunity

58
Q

red pulp

A

both immmune and haemopoietic systems

59
Q

function of the spleen

A
  • Filters blood in the same way that lymph nodes filter blood
    • Removal of old RBC and platelets
  • Immune function- APC
  • Haemopoietic function
    • Retrieval of iron from RBC haemoglobin
    • Erythrocytes storage
60
Q

spleen clinical correlates

A

Spleen is very soft- rich blood supply

Rupture can lead to death through exsanguination

Surgeons often remove the spleen

61
Q

after a splenectomy which organs take over removal and desctruction of ageing RBC

A

liver and bone marrow

62
Q

splenomegaly

A

enlarges in response to localised infection (just like lymph nodes) and systemic infection (glandular, malaria, septicaemia)

  • Can enlarge to 10X normal size
63
Q

the thymus is found

A

superior mediastinum

64
Q

structure of thymus

A

Has follicles with germinal centres (found through the thymus- unlike lymph nodes)

65
Q

thymus and age

A

Fully formed and functional at birth

By late teens is mostly fat

66
Q

function of thymus

A

maturation of marrow derived T cells into immune competent T cells - Thymic cell education

67
Q
A
68
Q

changes in thymus associated with

A

myasthenia gravis

69
Q

tonsils found in both

A

nasopharynx and oropharynx

70
Q

by birth tonsils are

A

fully formed and functional

  • mainly affected in childhood
71
Q

tonisl constitute

A

waldeyers ring

72
Q

structure of tonsil

A

nodule resides inferior to surface invagination (crypts)- many M cells

73
Q

funcion of tonsils

A
  • Prevent antigen ingress through oral, nasal and aural (adenoids) route
  • Crypts increase surface area
74
Q

tonsils have numerous

A

Surface of epithelia have numerous microfold (m-cells). Present antigens to underlying immune cells.

75
Q

when tonsils swell

A

due to B and T cell proliferation

76
Q

the appendix is also known as

A

the vermiform (worm like) appendix

77
Q

where is the vermiform appendix located

A

inferior to and attached tot he caecum (ascending colon)

78
Q

structure of the appendix

A
  • Nodule resides inferior to surface invagination (crypts)
  • Many M cells in epithelial surfaces
79
Q

function of appendix

A
  • Prevents pathogen ingress through GI routes
  • Prevent pathogen ingress arriving from ileum
  • Crypts increase surface area
80
Q
A
81
Q

payers patches located

A

inferior to and attached to the side of the illium

82
Q

structure of payers patches

A

Nodule reside inferior to surface domes.

Many m cells in epithelial surface

83
Q

payers patches function

A

prevent pathogen ingress throguh digestion