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Histology > Lymphatic System > Flashcards

Lymphatic System Flashcards

1
Q

The lymphatic system consists of lymph, ________________, lymphoid tissues and organs, and _________________

A

Lymphatics

Lymphocytes

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2
Q

The primary function of the lymphatic system is the production, maintenance, and distrubution of __________________

A

Lymphocytes

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3
Q

The lymphatic vascular system is a system of thin-walled endothelial channels that collect excess interstitial fluid from the tissue spaces and returns it to the blood as _____________

A

Lymph

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4
Q

Unlike the circulatory system, lymph flows in _______ direction towards the _________

A

One

Heart

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5
Q

At the _______________ end of the capillary microvasculature, the rate of tissue fluid generally exceeds fluid reuptake

A

Venous

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6
Q

At the venous end of the microvasculature, the blood pressure is ___________ (less than, greater than) that of the tissue fluid, forcing some fluid to return to the capillaries

A

Less than

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7
Q

Explain this figure.

A

At the arterial end of the microvasculature, blood pressure and hypertonicity is higher than that of the tissue fluid, forcing fluid out of the capillary and into the surrounding tissue; however, at the venuous end of the microvasculature, blood pressure and hypertonicity is lower than that of the tissue fluid, forcing fluid into the capillary

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8
Q

What happens to fluid that is not reabsorbed by capillaries?

A

Excess fluid is drained by lymph capillaries and converies into progressively larger lymphatic vessels

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9
Q

________________ __________ carry lymph from peripheral tissues

A

Lymphatic vessels

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10
Q

Lymphatic _____________________ originate in the various tissues and are thin, close-ended vessels that consist of a single layer of endothelium

A

Capillaries

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11
Q

Lymphatic capillaries converge into larger lymphatic vessels with structures similar to those of veins except that they have _______________ walls and lack a clear-cut separation between ________________

A

Thinner

Tunics

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12
Q

To what does the V point?

A

Lymphatic valve

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13
Q

Two sets of lymphatic vessels collect lymph. What are they?

A

Superficial lymphatics

Deep lymphatics

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14
Q

Lymphatic vessels ultimately end up as two large trunks. What are they?

A

Thoracic duct

Right lymphatic duct

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15
Q

The ______________ duct empties lymph into the junction of the left jugular vein with the left subclavian vein, accounting for 75%of all lymph drainage

A

Thoracic duct

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16
Q

The ___________ duct empties into the confluence of the right subclavian fvein and the right internal jugular vein, accounting for approximately 25% of lymph collection

A

Right lymphatic duct

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17
Q

What are some characteristics of lymphoid tissues?

A

They are composed of connective tissues and contain a rich supply of lymphocytes

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18
Q

Lymphoid tissues are composed of ____________ and a rich network of reticular or _____________ fibers supporting lymphocytes

A

Free cells

Type III collagen

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19
Q

Reticular fibers in lymphoid tissues are produced by fibroblast-derived cells called ________________ _______________

A

Reticular cells

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20
Q

In lymphoid tissues, fibroblast-like reticular cells produce and secrete reticulin fibers to which many cells loosely attach, including ____________ and __________________

A

Macrophages

Lymphocytes

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21
Q

What is the largest lymphoid organ?

A

Mucosa-associated lymphoid tissue (MALT)

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22
Q

Mucosa-associated lymphoid tissue (MALT) can be found in what types of sites?

A

Sites exposed to the external environment

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23
Q

What are two specific types of MALT discussed in class?

A

Tonsils

Peyer’s patches (GI)

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24
Q

The _____________ are large nodules in the walls of the pharynx of which most people contain five

A

Tonsils

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25
Q

What are the five tonsils named?

A

Left and right palatine tonsils

Paryngeal tonsil

Lingual tonsils (two)

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26
Q

Tonsils contain several lymphoid nodules that are collectively covered by _______________ ______________ _____________ ______________ on one side and a ___________ _______________ ___________ _______________ on the other

A

Stratified squamous keratinized epithelium

Dense connective tissue capsule

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27
Q

___________________ _________ are pockets or folds that occur naturally in the tonils

A

Tonsillar cypts

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28
Q

The average adult tonsil has between __ and __ crypts

A

10 and 20

29
Q

Crypts in the tonsils are usually small and debris-free; however, on some occassions, ____________ ________ may develop

A

Tonsil stones

30
Q

What often occurs to the epithelium surrounding tonsillar crypts?

A

It often vecomes infiltrated with lymphocytes and neutrophils, becoming difficult to recognize histologically

31
Q

Where would you find Peyer’s patches?

A

Ileum

32
Q

The ileum is lined by an absorptive simple _______________ epithelium and intraepithelial lymphocytes are frequently present between cells

A

Columnar

33
Q

______________ __________ are small, oval lymphoid organs covered by a capsule

A

Lymph nodes

34
Q

The capsule of a lymph node is composed of what type of connective tissue?

A

Dense irregular connective tissue

35
Q

A changing population of immune cells is suspended on what type of fibers in lymph nodes?

A

Reticular fibers

36
Q

All lymph node cells are arranged in the stroma of reticulin fivers and reticular cells to form three major regions within each lymph node. What are these regions?

A
  1. An outer cortex containing the nodules
  2. A deeper extension of the cortex called the paracortex, which lacks nodules
  3. A medulla with prominent draining sinusoids adjacent to the hilum
37
Q

A lymph node has a convex surface where ____________________ lymphatics enter and a concave depression, the __________, where an _____________________ lymphatic leaves and where an artery, vein, and nerve penetrate

A

Afferent

Hilum

Efferent

38
Q

___________________ _____________________ have a dark and light zone sthat form in the lymph node follicles (lymphoid nodules) and are a site of ___ cell activation and proliferation

A

Germinal centers

39
Q

The paracortex is densely packed with __________________

A

Lymphocytes

40
Q

The medulla of the lymph node has two major components. What are they?

A
  1. Medullary cords
  2. Medullary sinuses
41
Q

What are medullary cords?

A

They are branched cordlike masses of lymphoid tissue extending from the paracortex and contain T and B lymphocytes and many plasma cells

42
Q

What are medullary sinuses?

A

They are dilated spaces lined by discontinous endothelium that separate the medullary cords; the lumens of medullary sinuses include a meshwork of processes from reticular cells, which represent a final lymp filter

43
Q

The cortex contains the _________________ _________, immediately inside the capsule, that receives lymph from the afferent lymphatics

A

Subcapsular sinus

44
Q

What lymphoid organ is lobular and posterior to the sternum with no lymphatic nodules?

A

Thymus

45
Q

The functional tissues of the thymus are the __________________

A

Lobules

46
Q

Each thymus lobule is surrounded by a connective tissue of _________________ _____________ _______________; an ______________ _____________ of densely packed lymphocytes; and a _____________ _______________ of loosely packed cells

A

Epithelial reticular cells

Outer cortex

Central medulla

47
Q

The thymus cortex and medulla play different roles in the development of _____________

A

T cells

48
Q

The thymus is the site of T lymphocyte differentiation and the selective removal of T cells reactive against self-antigens, a key part of inducing _________________ __________ _____________

A

Central self-tolerance

49
Q

In _______________ ________________, developing thymocytes are chosen depending upon whether their T cell receptors can recognize and bind antigens on the MHC molecules properly; if they are unable to do so, they are removed

A

Positive selection

50
Q

_______________ _________________ removes thymocytes that are capable of strongly binding with “self” MHC peptides.

A

Negative selection

51
Q

Where does positive selection occur?

A

Thymic cortex

52
Q

Where does negative selection occur?

A

Thymic medulla

53
Q

About 98% of thymocytes die during the development processes in the thymus by failing either positive selection or negative selection, whereas the other 2% survive and leave the thymus to become mature immunocompetent ___ _________

A

T cells

54
Q

The thymus cortex is composed mainly of _______________ (cells) supported by a network of finel-branched _______________ _______________ ________________ that are continuous with a similar network in the medulla

A

Thymocytes

Epithelial reticular cells

55
Q

The ________________ is the location of the earliest events in thymocyte development, where T cell receptor gene rearrangement and positive selection occur

A

Cortex

56
Q

How are lobes divided in the thymus?

A

Via connective tissue septa

57
Q

What are the two key identifying features of the thymus?

A
  1. Lack of lymphatic nodules
  2. Hassall’s corpuscles
58
Q

_______________ ______________ are layered whorls of epithelial cells that increase in number throughout life; they are the remains of epithelial tubes, which grow out of the third _____________ pouches of the embryo; however, their function remains unknown as there are no such structures in mice

A

Hassall’s corpuscles

Pharyngeal

59
Q

Where are Hassall’s corpuscles located?

A

Thymic medulla

60
Q

Fewer lymphocytes are present in the thymic __________________

A

Medulla

61
Q

Thymocytes that reach the medulla have successfully undergone T-cell receptor gene rearrangement and positive selection and have been exposed to a limited degree of negative selection; the medulla is specialized to allow thymocytes to undergo additional rounds of _______________ ______________ to remove auto-reactive T cells from the mature repertoire

A

Negative selection

62
Q

What happens to the thymus as one progresses from childhood to adulthood?

A
  1. The thymus enlarges during childhood but begins to atrophy at puberty; the thymus is thus highly active at birth and early childhood, but after puberty, thymic activity declines and fewer lymphocytes remain
  2. Relatedly the structure of the thymus is reduced - the cortex and medulla become difficult to distinguish from the capsule
63
Q

What are the three crucial functions of the spleen?

A
  1. The removal of abnormal blood cells
  2. The storage of iron recycled from red blood cells
  3. The initiation of immune responses by B cells and T cells
64
Q

The spleen is an oval-shaped organ encapsulated with a _____________ _____________ connective tissue with lymphatic nodules distributed throughout

A

Dense irregular

65
Q

There are two primary “pulps” of the spleen. What are they?

A

White pulp or spots that are composed of lymphocytes

Red pulp or spots that are spaced in between white pulp and contain sinuses and cords of red blood cells

66
Q

What is the white pulp of the spleen?

A

An accumulation of lymphocytes

67
Q

The white pulp contain germinal centers, regions of _____ _______ proliferation and differentiation, and ___________ ____________, which brings blood from the splenic artery for filtration

A

B cell

Central arteries

68
Q
A

Histology (18 decks)

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