Histo-Lymphatic Organs

Front 1

What is the lymphatic system?

Back 1

A closed system of lymphatic vessels with associated lymphatic organs

Front 2

What are some examples of lymphatic organs?

Back 2

lymph nodes
spleen
thymus
tonsils

Front 3

What are three functions of the lymphatic system?

Back 3

1. returns to the blood the fluid and plasma protein that escape from the circulation.
2. returns to the blood the lymphocytes of the recirculating pool
3. adds to the blood antibodies that are formed in the lymph nodes

Front 4

What type of tissue are all lymphoid organs made of?

Back 4

lymphatic/lymphoid or adenoid tissue

Front 5

What type of tissue is the back bone for all lymph tissue?

Back 5

reticular connective tissue

Front 6

What is a general definition of lymphatic tissue/adenoid tissue?

Back 6

has a connective tissue backbone in which various cells are suspended

Front 7

What do reticular cells form?

Back 7

reticular CT

Front 8

What do reticular cells look like?

Back 8

-star shape w/ cell processes= stellate in shape
-cytoplasm is weakly basophilic
-has a large pale staining nucelus

Front 9

What is the reticular cell "fishnet framework"

Back 9

-knots of the net are the cell bodies
-strings are the cell processes
-there are numerous holes formed in between the strings where other cells are found

Front 10

What holds reticular cell processes together within the CT framework?

Back 10

-reticular fibers
-they are not held together by junctional specializations such as desmosomes

Front 11

What is the most numerous cell present in lymphoid tissue?

Back 11

lymphocytes

Front 12

Are there several different classes of lymphocytes depending on their rolls in the immune response?

Back 12

yes

Front 13

What two classes of lymphocytes have immune responses that overlap?

Back 13

-T cell
-B cell

Front 14

What happens when an unsensitized T-cell and an antigen come into contact?

Back 14

The unsensitized T-cell will differentiate into a lymphoblast, which then differentiates into lymphokines, killer cells, and memory cells

Front 15

What is cellular immunity?

Back 15

T-lymphocytes recognize the antigens and initiate the direct destruction of the antigen by the formation of killer cells and the release of lymphokines

Front 16

What are cytokines?

Back 16

chemical mediators released by cellular elements of the immune system, but are not antigen specific
**when these are released by the lymphocytes, they are called lymphokines

Front 17

What are lymphokines?

Back 17

chemical mediators released by cellular elements of the immune system, but are not antigen specific
**when these are released by the lymphocytes, they are called lymphokines

Front 18

What are killer cells?

Back 18

immune cells that directly attack a cell that contains an antigen

Front 19

What are memory cells?

Back 19

cells that reduces the responce time to the second presence of an antigen: the response is quicker

Front 20

What is humoral immunity?

Back 20

Immunity that involves the formation of antibodies and B-cells

Front 21

What is the function of B-cells?

Back 21

- recognize the antigen and initiate the destruction of the antigen by the formation of antibodies on their cell surface

Front 22

What happens when a B-cell comes into contact with a macrophage that is presenting an antigen?

Back 22

the undifferentiated B-cell will differentiate into a lymphoblast, the lymphoblast then differentiates into plasma cells and memory cells

Front 23

What do macrophages do in the humoral response?

Back 23

macrophages act as antigen presenting cells

Front 24

What role do T- helper cells play in humoral immunity?

Back 24

-T-helper cell aid B-cells in the recognition of the antigen

Front 25

What role do T- suppressor cells play in humoral immunity?

Back 25

T-suppressor cells recognize our own cells and do not see them as foreign so we don't destroy ourselves

Front 26

What is the function of plasma cells?
What makes plasma cells?

Back 26

-they produce antibodies
-B-cells

Front 27

What is the function of monocytes?

Back 27

differentiate into a variety of macrophages for phagocytosis

Front 28

What are granulocytes?
Do these cells differentiate?

Back 28

eosinophils, basophils,neutrophils
-these cells contain specific granules
-no

Front 29

What are the three types of lymphatic tissue based on their cellular content?

Back 29

-loose lymphatic tissue
-dense lymphatic tissue
-nodular lymphatic tissue

Front 30

What is loose lymphatic tissue composed of?

Back 30

predominatly meshwork of reticular cells

Front 31

What is dense lymphatic tissue composed of?

Back 31

predominatly lymphocytes(free cells), a few reticular cells
-often cannot see reticular cells due to lymphocytes

Front 32

What is nodular lymphatic tissue composed of?
What does nodular lymphatic tissue look like?

Back 32

-free cells predominate
-appear typically as spherical structures/circular structure

Front 33

What does non-encapsulated lymphatic tissue mean and where can it be found?

Back 33

-means there is no CT capsule surrounding the tissue
-found in the lamina propria of the GI tract, respiratory system and urinary system

Front 34

What does MALT stand for?
What does GALT stand for?
What does BALT stand for?

Back 34

-mucosa associated lymphatic tissue
-gut associated lymphatic tissue
-bronchiole associated lymphatic tissue

Front 35

In the lamina propria of the GI tract, respiratory system and urinary system, where is the loose connective tissue located?

Back 35

directly under the epithelium

Front 36

Why is the loose connective tissue of the lamina propria in the GI tract, respiratory system and urinary system considered part of the lymphatic system?

Back 36

-because numerous lymphocytes can be found here
- the loose CT is not highly organized and lymphocytes can enter and function here.

Front 37

What is a solitary lymph nodule?

Back 37

a dense aggregation of lymphatic tissue forming a spherical mass

Front 38

What does a solitary lymph nodule contain?

Back 38

-reticular cells
-reticular fibers
-lymphocytes that are suspended in cells and fibers

Front 39

Is a solitary lymph nodule a permanent sturcture? Why?

Back 39

-No
-they increase w/ humoral immune response and decrease after the response is over

Front 40

Where are solitary lymph nodules located?

Back 40

in the lamina propria of the GI tract, urinary and respiratory systems

Front 41

What is the general structure of a solitary lymph nodule?

Back 41

contains a Cortex(corona) and a Germinal center with no capsule

Front 42

What is the cortex of a lymphoid structure?

Back 42

an outer dense staining region that contains small T-lymphocytes, mostly
T-helper cells

Front 43

What is the germinal center of a lymphoid structure?

Back 43

a lighter staining region, containing large cells undergoing proliferation and lympnoblast transformation

Front 44

Are lymphoid structers with a germinal center undergoing a cellular or humoral immune response?

Back 44

a humoral immune response

Front 45

What type of cells does a germinal center contain?

Back 45

-B-lymphocytes
-plasma cells
-reticular cells

Front 46

What is an aggregate nodule?

Back 46

an aggregation of solitary lymph nodules- up to the hundreds

Front 47

What is an example of an aggregate nodule?
Where can this example be found?

Back 47

-Peyer's patches
-in the lamina propria of the ileum on the side opposite of the attachment of the mesentaries

Front 48

What is the function of aggragate nodules (peyer's patches)?

Back 48

production of antibodies during the humoral immune response

Front 49

What are partially encapsulated lymphatic organs?

Back 49

lymphatic organs that are not totally surrounded by a capsule

Front 50

What is an example of the partially encapsulated lymphatic organs?

Back 50

tonsils

Front 51

What are some general characteristics of tonsils (partially encapsulated lymphatic organs)?

Back 51

-the surface that faces the throat wall is covered by epithelium, contains infoldings called crypts that are lined w/ epithelium
-the surface facing into the throat contains CT
-some coarse internal framework called trabeculae is present

Front 52

What are crypts?

Back 52

epithelial lined infoldings on tonsils

Front 53

What three tonsillar groups form a ring about the entrance of the throat- are associated with the nasal pharynx and where are they located?

Back 53

-palatine tonsils, on either side of the throat
-lingual tonsils, on either side of the uvula on the tongue
-pharyngeal tonsils, a ring of lymphoid tissue encircling the throat

Front 54

Where are palatine tonsils located?

Back 54

laterally at the enterance of the throat between the two folds in the pharyngeal wall

Front 55

What types of lymphatic tissue is in the palatine tonsils?

Back 55

dense lymphatic tissue and nodular lymphatic tissue arranges around the enfolding of the epithelium

Front 56

What type of epithelium is on the surface of palatine tonsils?

Back 56

stratified squamous epithelium

Front 57

What are some characteristics of crypts in palatine tonsils?

Back 57

-10-20 finger-like invaginations of the epithelium surrounded by lymphatic tissue
-on the slide, crypts can go down through the surface or they can be seen in cross section,can tell those in cross section by noticing the stratified squamous epithelium

Front 58

In palatine tonsils, a partial capsule is also known as what?

Back 58

hemi-capsulation

Front 59

In palatine tonsils, what is trabeculae?

Back 59

-CT partitions seen from the CT deep into the tonsil,almost all the way to the surface crypts
-trabeculae contain blood vessels inside of them near the surface

Front 60

In palatine tonsils, where are mucous galnds located?
What are the function of the mucous glands?

Back 60

-beneath the tonsil
-they do not empty into the crypts, which is why palatine tonsils get inflamed, they are not washed out
-their functionis protective, they contribute to the saliva in the oral cavity to make it slimy

Front 61

Where are lingual tonsils located?

Back 61

on the root of the tongue behind the vallate papillae

Front 62

How are lingual tonsils arranged?

Back 62

-are actually clusters of lymphatic tissue separated from each other
-an aggregation of 35-100 individual units

Front 63

What type of lymphatic tissue is in the lingual tonsil?

Back 63

dense lymphatic tissue and noduler lymphatic tissue

Front 64

What are some characteristics of lingual tonsil crypts?

Back 64

-surface covered by stratified squamous epithelium
-there is generally a single crypt per unit of lymphatic tissue that may branch

Front 65

Where are the mucous glands of the lingual tonsil located?
Where do they empty into?

Back 65

-beneath the tonsils, embedded in the skeletal muscle of the tongue
-empty into the base of the crypts
**possible reason lingual tonsils are seldom removed- crypts are cleaned by mucous

Front 66

Where are pharyngeal tonsils located?

Back 66

posterior wall of the nasopharynx

Front 67

What type of lymphatic tissue is in pharyngeal tonsils?

Back 67

dense lymphatic tissue and nodular lymphatic tissue

Front 68

What type of epithelium covers the surface of pharyngeal tonsils?

Back 68

pseudostratified columnar epithelium with cilia
**this is how you distinguish the palatine tonsil

Front 69

Do pharyngeal tonsils contain crypts?

Back 69

No- they contain folds but no crypts

Front 70

What type of gland is associated with the pharyngeal tonsil that is different from the others?
Where are they located?
Where do the gland empty?

Back 70

-sero-mucous glands
-beneath the tonsil
-empty into the troughs of the folds

Front 71

What is the function of tonsils?

Back 71

-lymphopoiesis
-antibody production

Front 72

What are examples of encapsulated lymphatic organs?

Back 72

lymph nodes
spleen
thymus

Front 73

What are five characteristics of lymph nodes?
-shape
-yes,no encapsulated
-structure
-sinuses
-types of lymphatic vessels

Back 73

1. kidney bean shaped
2. encapsulated
3. contains cortex (outer layer) and medulla (inner layer)
4. lymph sinuses are cleaned w/ lymph
5. contain afferent and efferent lymphatic vessels

Front 74

What do afferent lymphatic vessels do?
What do efferent lymphatic vessels do?

Back 74

-bring lymph to a lymph organ
-take away lymph from a lymph organ

Front 75

What is the parenchyma of the lymph nodes?

Back 75

functional units of the lymph organ

Front 76

What is the stroma of the lymph organ?

Back 76

the CT framework of a lymph organ

Front 77

What are the components of the stroma of the lymph organ

Back 77

-Capsule=fibroelastic CT and some smooth muscle, on outside of organ

-trabeculae= CT projections from the capsule which partially subdivide the organ

-reticular CT= CT of stroma

Front 78

What are lymph sinuses in lymph nodes?

Back 78

-located under the capsule
-are spaces for the movement of lymph through the node
-are not lined by endothelium
-are looser areas of lymphatic tissue surrounded by many reticular cells that are surrounded by reticular fibers

Front 79

What is the cortex of a lymph node and what composes it?

Back 79

-the outer region of the lymph node
-lymph nodules, the paracortical region/deep cortex, the sucapsular sinuses and peritrabecular sinuses

Front 80

What are some characteristics of the paracortical region/deep cortex?

Back 80

-located between the lymph nodules and the medulla
-contains an abundance of T-lymphocytes
-contains postcapillary venules

Front 81

What are post-capillary venules in lymph nodes?

Back 81

-venules on the venuous side on the capillary bed
-lined by simple cuboidal epithelium (not simple squamous)
-allows T-lymphocytes to enter the lymph node from the peripheral blood

Front 82

Where are subcapsular sinuses located?
Where are peritrabecular sinuses located?

Back 82

-under the capsule
-around the CT trabeculae

Front 83

Where is the medulla of the lymph nodes and what composes it?

Back 83

-is the center portion of the organ
-contains medullary cords, and medullary sinuses

Front 84

What are medullary cords?

Back 84

cords of lymphatic tissue surrounding blood vessels that contain B-lymphocytes, plasma cells, macrophages, and reticular cells

Front 85

What are medullary sinuses?

Back 85

-large irregular spaces between the cords
-forms a complex of vessels that exit the hilus as the efferent lymph vessels
-contains reticular cells and lymphocytes

Front 86

What are the two types of lymphatic vessels?

Back 86

-afferent vessels
-efferent vessels

Front 87

What are some characteristics of lymphatic vessels?

Back 87

-have similar structure to veins
-contain valves
-lumen contains precipitated lymph-light pink
-is embedded in CT of the lymph organ
-sometimes has red blood cells but not often

Front 88

Where do afferent vessels enter lymph nodes?
Where do efferent vessels exit lymph nodes?

Back 88

-pass through the capsule,opposite the hilus
-exit the hilus

Front 89

What is the filtration of lymph pathway?

Back 89

-afferent vessel
-subcapsular sinus
-peritrabecular sinus
-medullary sinus
-parenchema
-efferent vessel

Front 90

Where do blood vessels enter lymph nodes?
How do blood vessels get to parenchyma tissue?

Back 90

-at the hilus
-travel through the trabeculae
*** there is no communication between the lymph sinuses and the blood vessels

Front 91

What type of nerves are in lymph nodes and where are they located?

Back 91

-vasomotor only
-the nerves innervate the smooth muscle of the blood vessels

Front 92

How is lymph filtered in lymph nodes?

Back 92

by the phagocytosis of particles by macrophages which are found along the lymph sinuses

Front 93

In the spleen, what compses the stroma?

Back 93

-capsule
-trabeculae
-reticular CT

Front 94

In the spleen, what is the capsule composed of?
What is the smooth muscle for?

Back 94

-fibro-elastic CT w/ some smooth muscle
**fribro=collagen
-smooth muscle can squeeze RBC's out of the spleen

Front 95

In the spleen, what is the trabeculae composed of?

Back 95

dense CT containing blood vessels

Front 96

In the spleen, what cells are suspended in the reticular CT?

Back 96

lymphocytes

Front 97

What two components make up the parenchyma of the spleen?

Back 97

-white pulp
-red pulp

Front 98

What is white pulp of the spleen?
What is its function?

Back 98

-lymphatic portion/region of the spleen,dark area with white circles
-filtration of the blood

Front 99

What are the arteries called in the center of the white pulp in the spleen?

Back 99

-central arteries, may be more than one

Front 100

What is a layer of dense lymphatic tissue called surrounding the central artery in the spleen?

Back 100

periarterial sheath

Front 101

What are two characteristics of the periarterial sheath in the spleen?

Back 101

-rich in T-lymphocytes
-may contain germinal centers when infected/inflamed

Front 102

What is the red pulp in the spleen?

Back 102

-blood vascular portion of the spleen
**lymph nodes filter lymph, spleen filters blood

Front 103

What are splenic or billroth's cords?

Back 103

-cords of lymphatic tissue in the red pulp
-composed of several cells macrophages, B-lymphocytes,reticular cells, and blood cells

Front 104

What are venous sinusoids?

Back 104

-spaces in between the billroth's cords in the spleen
-are endothelial lined blood vessels that look like white spaces between Bilroth's cords
-are dialated capillaries after the capillary bed

Front 105

Is the tissue of the spleen organized around the blood vessels?

Back 105

yes

Front 106

What are the arteries of the spleen?

Back 106

-trabecular arteries
-central artery of the pulp
-penicillar arteries/arteries of the red pulp

Front 107

Where does the trabecular artery branch from?

Back 107

-it is a branch of the splenic artery, from the celiac trunk
-is inside the trabeculae of the spleen

Front 108

Where does the central artery of the pulp in the spleen branch from?

Back 108

-is a branch from the trabecular artery
-is surrounded by the periarterial sheath

Front 109

Where does the penicillar arteries in the spleen branch from?

Back 109

-it branches from the central artery that enters the red pulp after the central artery leaves the periarterial sheath

Front 110

What are the three extensions of the penicillar artery?

Back 110

-pulp arterioles
-sheathed arterioles
-terminal capillaries

Front 111

What is a characteristic of pulp arterioles?

Back 111

they are surrounded by smooth muscles

Front 112

What is a characteristic of sheathed arterioles?

Back 112

they are surrounded by reticular cells

Front 113

What is a characteristic of terminal capillaries?

Back 113

they are joined with the venous sinusoids

Front 114

What are venous sinusoids in the spleen?

Back 114

-they are a system of endothelial lined tunnels within the red pulp
-they are a true blood vessel, unlike lymph sinusoids

Front 115

What is the function of venous sinusoids?

Back 115

-to slow the blood down so it can be filtered in the spleen
-phagocytize old RBC's
-to get nutrients out of the blood in the hepatic sinusoids

Front 116

What are some characteristics of the venous sinusoids?

Back 116

-barrel shaped in general
-endothelial cells are rod-shaped
-reticular fibers encircle cells to render support
-basal lamina is fenestrated, ther is a free flow of cells in and out of the sinusoid
-are leaky structures

Front 117

What types of veins are in the spleen?

Back 117

-venous sinusoids
-splenic veins
-trabecular veins
-pulp veins

Front 118

What is the open theory of arterio-venous communication?

Back 118

The arterial capillaries open into the parenchyma(splenic cords) of the organ, and blood passes between the cells of thesplenic cords to enter the venous sinusoids

Front 119

What is the closed theory of arterio-venous communication?

Back 119

Arterial capillaries are continous with the venous sinusoids and thus blood passes directly into the venous sinusoids

Front 120

Are lymphatic vessels in the spleen efferent, afferent or both?

Back 120

efferent only
-the only lymph organ that has efferent and afferent vessels is the lymph node

Front 121

What nerves are in the spleen?

Back 121

-vasomotor
-innervates smooth muscle

Front 122

What are the five functions of the spleen?

Back 122

1. filters the blood
2. hemopoieses- mainly lymphocytes and monocytes
3. phagocytosis of RBC's-old & damaged
4. antibody production- germinal centers
5. blood reservoir

Front 123

What are the characteristics of the thymus that are only seen until a person hits puberty?

Back 123

1. bilobed
2. has a cortex and medulla w/ no germinal centers
3. no lymphatic nodules
4. hassall's body or thymic corpuscles

Front 124

What distinguishes the thymus from a lymph node?

Back 124

the thymus has no lymphatic nodules

Front 125

Does the thymus participate in humoral immunity?

Back 125

no, the thymus produces T-lymphocytes

Front 126

What are the components of the stroma of the thymus?

Back 126

-capsule
-septae
-epithelial-reticular cells
***these are different from other organs

Front 127

What are epithelial-reticular cells in the thymus?

Back 127

these cells from the supporting system for the lymphatics of the thymus

Front 128

What makes epithelial-reticular cells different from the reticular cells found in all of the other lymphatic organs?

Back 128

-they come from endoderm and do not have the ability to produce reticular fibers

Front 129

What hold the cell processes of the epithelial-reticular cells together?

Back 129

epithelial-reticular cell processes are held together by desmosomes because there are no reticular fibers to hold them together

Front 130

What is the parenchyma of the thymus composed of?

Back 130

-cortex
-medulla

Front 131

What is the cortex of the thymus composed of?

Back 131

-dense lymphatic tissue, no lymphatic nodules
-contain thymocytes

Front 132

What are thymocytes?

Back 132

is another term for T lymphocyted in the thymus

Front 133

What composes the medulla of the thymus?

Back 133

-lots of epithelial-reticular cells, is a lighter staining region
-thymocytes
-hassall's body or thymic corpuscles

Front 134

What is hassall's body or thymic corpuscles?

Back 134

-flattened concentric arrays of individual epithelial reticular cells
-these undergo kertinization
-these undergo calcification with age

Front 135

How is the blood distributed in the thymus?

Back 135

blood vessels travel in the septae to capillaries in the parenchyma

Front 136

Are there efferent or afferent lymphatics in the thymus?

Back 136

efferent only

Front 137

What types of nerves are in the thymus?

Back 137

vasomotor nerves only

Front 138

What are the functions of the thymus?

Back 138

1. lymphopoiesis
2. maturation of the T-lymphocytes
**80% of the peripheral lymphocytes are T-lymphocytes

Front 139

In what stage of life is the thymus most important?

Back 139

-from birth to puberty
-because by then we have built up a population of T-cells in all areas of the body
-at puberty the thymus begins to shrink and T-cells proliferate by mitosis

Front 140

What is the progression of cells that form the monomuclear phagocytic system?

Back 140

-precursor cells in bone marrow
-promonocytes
-monocytes in blood
-macrophages in tissue

Front 141

What is the mononuclear phagocytic system?

Back 141

-involves all of the macrophages in the body
-all have a common precursor cell found in the bone marrow

Front 142

What is the macrophage of the mononuclear phagocytic system found in the connective tissue?

Back 142

histocytes or macrophages

Front 143

What is the macrophage of the mononuclear phagocytic system found in the liver?

Back 143

kupffer cells

Front 144

What is the macrophage of the mononuclear phagocytic system found in the lung?

Back 144

alveolar macrophage or dust cell

Front 145

What is the macrophage of the mononuclear phagocytic system found in the spleen and lymph nodes?

Back 145

free and fixed macrophages

Front 146

What is the macrophage of the mononuclear phagocytic system found in the bone marrow?

Back 146

macrophage

Front 147

What is the macrophage of the mononuclear phagocytic system found in the serous cavity?

Back 147

pleural and peritoneal macrophages

Front 148

What is the macrophage of the mononuclear phagocytic system found in the nervous system?

Back 148

microglia

Front 149

What is the macrophage of the mononuclear phagocytic system found in the bone?

Back 149

osteoclast

Front 150

What is the macrophage of the mononuclear phagocytic system found in the cementum?

Back 150

cementoclast

Front 151

What is the macrophage of the mononuclear phagocytic system found in the skin?

Back 151

langerhans cell