Lymphatic System

Question 1

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

Answer 1

Lymphatics

Lymphocytes

Question 2

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

Answer 2

Lymphocytes

Question 3

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 _____________

Answer 3

Lymph

Question 4

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

Answer 4

One

Heart

Question 5

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

Answer 5

Venous

Question 6

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

Answer 6

Less than

Question 7

Explain this figure.

Answer 7

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

Question 8

What happens to fluid that is not reabsorbed by capillaries?

Answer 8

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

Question 9

________________ __________ carry lymph from peripheral tissues

Answer 9

Lymphatic vessels

Question 10

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

Answer 10

Capillaries

Question 11

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 ________________

Answer 11

Thinner

Tunics

Question 12

To what does the V point?

Answer 12

Lymphatic valve

Question 13

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

Answer 13

Superficial lymphatics

Deep lymphatics

Question 14

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

Answer 14

Thoracic duct

Right lymphatic duct

Question 15

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

Answer 15

Thoracic duct

Question 16

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

Answer 16

Right lymphatic duct

Question 17

What are some characteristics of lymphoid tissues?

Answer 17

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

Question 18

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

Answer 18

Free cells

Type III collagen

Question 19

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

Answer 19

Reticular cells

Question 20

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

Answer 20

Macrophages

Lymphocytes

Question 21

What is the largest lymphoid organ?

Answer 21

Mucosa-associated lymphoid tissue (MALT)

Question 22

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

Answer 22

Sites exposed to the external environment

Question 23

What are two specific types of MALT discussed in class?

Answer 23

Tonsils

Peyer’s patches (GI)

Question 24

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

Answer 24

Tonsils

Question 25

What are the five tonsils named?

Answer 25

Left and right palatine tonsils Paryngeal tonsil Lingual tonsils (two)

Question 26

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

Answer 26

Stratified squamous keratinized epithelium Dense connective tissue capsule

Question 27

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ _________ are pockets or folds that occur naturally in the tonils

Answer 27

Tonsillar cypts

Question 28

The average adult tonsil has between __ and __ crypts

Answer 28

10 and 20

Question 29

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

Answer 29

Tonsil stones

Question 30

What often occurs to the epithelium surrounding tonsillar crypts?

Answer 30

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

Question 31

Where would you find Peyer's patches?

Answer 31

Ileum

Question 32

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

Answer 32

Columnar

Question 33

\_\_\_\_\_\_\_\_\_\_\_\_\_\_ __________ are small, oval lymphoid organs covered by a capsule

Answer 33

Lymph nodes

Question 34

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

Answer 34

Dense irregular connective tissue

Question 35

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

Answer 35

Reticular fibers

Question 36

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?

Answer 36

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

Question 37

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

Answer 37

Afferent Hilum Efferent

Question 38

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

Answer 38

Germinal centers

Question 39

The paracortex is densely packed with \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 39

Lymphocytes

Question 40

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

Answer 40

1. Medullary cords 2. Medullary sinuses

Question 41

What are medullary cords?

Answer 41

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

Question 42

What are medullary sinuses?

Answer 42

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

Question 43

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

Answer 43

Subcapsular sinus

Question 44

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

Answer 44

Thymus

Question 45

The functional tissues of the thymus are the \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 45

Lobules

Question 46

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

Answer 46

Epithelial reticular cells Outer cortex Central medulla

Question 47

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

Answer 47

T cells

Question 48

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 _________________ \_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 48

Central self-tolerance

Question 49

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

Answer 49

Positive selection

Question 50

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ _________________ removes thymocytes that are capable of strongly binding with "self" MHC peptides.

Answer 50

Negative selection

Question 51

Where does positive selection occur?

Answer 51

Thymic cortex

Question 52

Where does negative selection occur?

Answer 52

Thymic medulla

Question 53

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 ___ \_\_\_\_\_\_\_\_\_

Answer 53

T cells

Question 54

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

Answer 54

Thymocytes Epithelial reticular cells

Question 55

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

Answer 55

Cortex

Question 56

How are lobes divided in the thymus?

Answer 56

Via connective tissue septa

Question 57

What are the two key identifying features of the thymus?

Answer 57

1. Lack of lymphatic nodules 2. Hassall's corpuscles

Question 58

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ ______________ 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

Answer 58

Hassall's corpuscles Pharyngeal

Question 59

Where are Hassall's corpuscles located?

Answer 59

Thymic medulla

Question 60

Fewer lymphocytes are present in the thymic \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 60

Medulla

Question 61

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

Answer 61

Negative selection

Question 62

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

Answer 62

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

Question 63

What are the three crucial functions of the spleen?

Answer 63

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

Question 64

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

Answer 64

Dense irregular

Question 65

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

Answer 65

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

Question 66

What is the white pulp of the spleen?

Answer 66

An accumulation of lymphocytes

Question 67

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

Answer 67

B cell Central arteries