Lymphatic System Flashcards

1
Q

What is the immune system?

A

A cell population that inhibits all organs and defends the body from agents of disease.

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2
Q

What is the lymphatic system?

A

Network or organs and vein-like vessels that recover fluid - unrecovered from capillary filtrate.

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3
Q

What are the 3 functions of the lymphatic system?

A

1) Fluid Recovery
2) Immunity
3) Lipid Absorption

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4
Q

What is lymph?

A

Fluid, similar to plasma, has very little protein; essentially extracellular
fluid

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5
Q

What does a lymphatic vessel do?

A

Transport the lymph; mechanisms of flow similar to venous return.

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6
Q

Characteristics of lymphatic tissues.

A

Composed of aggregates of lymphocytes and macrophages that
populate many organs in the body.

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7
Q

Characteristics of lymphatic organs.

A

Defense cells are especially concentrated in these organs; Separated from surrounding organs by connective tissue capsules

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8
Q

Examples of lymphatic organs.

A

Lymph nodes. red bone marrow, spleen, etc.

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9
Q

Describe fluid recovery.

A

Fluid continually filters from the blood capillaries into the tissue spaces. The capillaries reabsorb about 85% of it on average. The other 15% (2 to 4 L/day) is reabsorbed by the lymphatic system and returned to the blood.

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10
Q

Describe immune surveillance (immunity).

A

Excess-filtered fluid picks up foreign cells and chemicals from the
tissues. Fuild passes through the lymph nodes, where immune cells are always on the lookout for foreign matter. When they detect anything potentially harmful, they activate an immune response.

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11
Q

Describe lipid absorption.

A

In the small intestine, special lymphatic vessels called lacteals absorb dietary lipids that are not absorbed by the blood capillaries.

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12
Q

Describe lymphatic capillaries.

A

They penetrate nearly every tissue of the body but are absent from cartilage, bone, bone marrow, and the cornea. They are closely associated with blood capillaries but unlike them, they’re closed at one end and there is no through flow of fluid.

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13
Q

How do lymphatic endothelial cells differ from the endothelial cells of blood capillaries?

A

They have intercellular clefs between them so that bacteria, lymphocytes, and other cells and particles can enter along with the fluid tissue.

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14
Q

Describe the relationship between tissue pressure and the endothelial valves.

A

When the tissue pressure is high, it pushes the flaps open (inward) and fluid flows into the capillary. When the pressure is higher in the lymphatic capillary than in the tissue fluid, the flaps are pressed outward (closed).

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15
Q

What is the route from the tissue fluid back to the bloodstream?

A

Lymphatic capillaries → collecting vessels → 11 lymphatic trunks → two collecting ducts → subclavian veins.

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16
Q

Describe the flow of lymph.

A

Lymph is moved along by rhythmic contractions of lymphatic vessels. Stretching of vessels stimulates contraction and flow is aided by skeletal muscle pump. Exercise significantly increases lymphatic return.

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17
Q

Neutrophils

A

Respond to bacterial infections.

18
Q

Natural killer (NK) cells

A

Large lymphocytes that attack and destroy bacteria, transplanted tissue, host cells infected with viruses or that have turned cancerous

19
Q

T lymphocytes (T cells)

A

Lymphocytes that mature in the thymus and later depend on thymic hormones.

20
Q

B lymphocytes (B cells)

A

Lymphocytes that differentiate into plasma - connective tissue cells that secrete antibodies.

21
Q

Macrophages

A

Phagocytotic cells of the connective tissues. They arise from monocytes that have emigrated from the bloodstream and other macrophages. Phagocytize foreign matter. Process foreign matter and display antigenic fragments of it to certain T cells.

22
Q

Dendritic cells

A

Branched, mobile APCs found in the epidermis, mucous membranes, and lymphoid organs. Alert immune system to pathogens that have breached the body surface.

23
Q

Reticular cells

A

Branched stationary cells that contribute to the stroma of a lymphatic organ.

24
Q

Macrophages

A

Develop from monocytes or other macrophages; Phagocytize debris, bacteria, dead neutrophils, and foreign matter; Antigen-presenting cells

25
Q

Lymphatic tissue

A

Aggregations of lymphocytes in the connective tissues of mucous membranes and various organs

26
Q

What are lymphatic nodules?

A

Dense masses of lymphocytes and macrophages that congregate in response to pathogens - transient as pathogens are neutralized; feature of the lymph nodes, tonsils, and appendix

27
Q

What are lymphatic organs?

A

Well-defined anatomical sites and ay least a partial connective tissue capsule that separates the lymphoid tissue from neighboring tissues.

28
Q

What is the difference between primary lymphatic organs and secondary lymphatic organs?

A

Lymphocytes mature and become immunocompetent in primary organs, while immunocompetent cells occupy secondary organs.

29
Q

What are considered primary lymphatic organs?

A

Red bone marrow and thymus

30
Q

What are considered secondary lymphatic organs?

A

Lymph nodes, tonsils, and spleen

31
Q

Red bone marrow

A

Involved in hematopoiesis (blood formation) and immunity

32
Q

Thymus

A

Houses developing lymphocytes; Secretes hormones regulating their activity

33
Q

What are the two functions of lymph nodes?

A

Cleanse the lymph; Act as a site of T and B cell activation

34
Q

Structure of lymph nodes.

A

Enclosed with a fibrous capsule with
trabeculae that divide the interior into
compartments

35
Q

Lymphadenitis

A

Swollen, painful node responding to foreign antigen

36
Q

Lymphadenopathy

A

Collective term for all lymph node
diseases

37
Q

Metastasis

A

Cancerous cells break free from the original tumor, travel to other sites in the body, and establish new tumors (multiply)

38
Q

Tonsils

A

Located at the entrance to the pharynx, where they guard against ingested and inhaled pathogens.

39
Q

Tonsillar crypts

A

Bacteria gets caught – leads to tonsil removal

40
Q

What is the red pulp of the spleen?

A

Sinuses filled with erythrocytes

41
Q

What is the white pulp of the spleen?

A

Lymphocytes, macrophages surrounding small
branches of the splenic artery; Heavy vascularity