ANATOMY - Term Test 4 (Lymphatic System)

Question 1

Two most important functions of the lymphatic system?

Answer 1

1) maintenance of fluid balance in internal environment
2) immunity

* 3rd less important function: absorption of lipids from digested food in the small intestine and its transport to large systemic veins

Question 2

How does the lymphatic system maintain fluid balance in the internal enironment?

Answer 2

1) plasma filters into interstitial spaces from blood flowing through capillaries
2) most of this IF^ is absorbed by tissue cells or reabsorbed by the blood before it flows out of the tissue BUT a small % of IF remains behind
3) if IF just stays there it would cause massive edema of the tissue leading to tissue destruction or even death

therefore: lymphatic vessels exist to act as “drains” to collect excess tissue fluid and return it to venous blood just before it reaches the heart

Question 3

True or False. Lymphatic system is a component fo the circulatory system.

Answer 3

True - because it consists of a moving fluid (lymph) dervied from blood and tissue fluid and a group of vessels (lymphatics) that return the lymph to the blood

However, it differs from true “circulation” of blood seen in the CV system because lymphatic vessels do not run in a closed loop but instead begin blindly in intercellular spaces of soft tissues of the body

Question 4

Lymphoid tissue

Answer 4

type of lymphoid tissue that contains lymphocytes and other defensive cells

Question 5

Aggregated lymphoid nodules

Answer 5

isolated nodules of lymphatic tissues in the intestinal wall (Peyer’s patches)

Question 6

Lymphoid structures

Answer 6

tonsils

thymus

spleen

bone marrow

Question 7

Lymph/lymphatic fluid

Answer 7

• clear, watery-appearing fluid found in lymphatic vessels
• along with IF, lymph closely resembles blood plasma in composition (main difference is that they contain a lower % of proteins than does plasma)
• isotonic and almost identical in chemical composition to IF

Question 8

What would happen is there was a loss of lymphatic fluid?

Answer 8

• if damage to lymphatic trunks (such as in penetating injury) occurs, flow of lymph must be stopped or it can be fatal
• it is impossible to maintain adequte plasma protein concentration by dietary means if significant loss of lymph continues over time
• As lymph is lost, rapid emaciation occurs, progressive and eventually fatal decrease in total blood fat and protein concentration

Question 9

Lymphatic vessels originating in the villi of the small intestine are called:

Answer 9

lacteals

Question 10

Wall of each lymphatic capillary

Answer 10

single layer of large but very thin and flattened endothelial cells; also has clefts (openings) between endothelial cells which allow for increased permeability

Question 11

Main lymphatic trunks

Answer 11

right lymphatic duct

thoracic duct

Question 12

Lymph from where drains into thoracic duct?

Answer 12

Lymph from entire body (except for upper right quadrant); eventually drains into thoracic duct which then drains into left subclavian vein (where it joints left internal jugular vein)

Question 13

Lymph from the upper right quandrant of the body empties into….?

Answer 13

right lymphatic duct → then into right subclavian vein

Question 14

Cisterna chyli

Answer 14

an enlarged pouch on the thoracic duct that serves as a storage area for lymph (fatty lymph - chyle) moving toward its point of entry into the venous system

Question 15

Lymphatics resemble veins in structure, with what exceptions?

Answer 15

1) lymphatics have thinner walls
2) lymphatics contain more valves
3) lymphatics contain lymph nodes located at certain intervals along their course

Question 16

As lymph flows from the thin-walled capillaries into vessels with a larger diameter (0.2 to 0.3 mm), how do the walls change?

Answer 16

become thicker and exhibit the three coats, or layers, typical of arteries and veins

Question 17

Function of lymphatic vessels

Answer 17

• involved in homeostatic mechanisms
• high degree of permeability allows for large molecules (that cannot be absorbed into a blood capillary) to be removed from interstitial spaces by lymphatics
• proteins that accumulate in tissue spaces can return to blood ONLY via lymphatics

Question 18

If lymphatic return was blocked, what would happen?

Answer 18

if anything blocks lymphatic return, blood protein concentration and blood osmotic pressure soon fall below normal; fluid imbalance and death will result

Question 19

Function of Lacteals

Answer 19

absorption of fats and other nutrients

milky lymph found in lacteals after digestion has 1-2% fat (called chyle)

Question 20

Lymph flows through thoracic duct and reenters general circulation at a rate of _____ per day.

Answer 20

3 liters

Question 21

What mechanisms establish the lymph pressure gradient?

Answer 21

1) breathing movements: inspiration causes increased intrabdominal pressure as intrathoracic pressure decreases (diaphragm is pushed down)

• this simultaenously causes pressure to increase in abdominal portion of thoracic duct while decreasing in thoracic portion
• thus estbalishing a pressure gradient in thoracic duct to cause upward flow of lymph
• rate of flow/ejection of lymph into venous circulation is proportional to depth of inspiration (thus total volume of lymph entering central veins during a given period depends on depth of inspiration phase and RR)

2) skeletal muscle contractions: as muscles contract, they “milk” the lymphatics to push lymph forward (thus lymph flow increases during exercise)

• small amount of smooth muscle exists in the walls of the large lymphatic trunks that when contracted cause lymphatics to pulse rhythmically and thus help move lymph from one valved segment to the next

Question 22

Lymphokinetic factors

Answer 22

anything that affects movement of lymph such as:

IF pressure (directly proportional to lymph flow), arterial pulsations, postural changes, and passive compression (massage) of body soft tissues

Question 23

True or Fale. Lymph may enter circulation system at different rates during the day.

Answer 23

True/ Rate of return depends on physical activity, changes in IF pressure, RR and depth of respiration

Question 24

Lymph nodes - what is it and describe the flow of lymph through it

Answer 24

• oval/bean-shaped structures of varying side; each enclosed by a fibrous capsule
• lymph moves into a node via afferent lymphatic vessels; emerges at the notch/hilum via efferent vessels
• once lymph enters, it “percolates” slowly throuhg sinuses before draining out single efferent exit vessel
• cotnain lymphocytes that get released in the presence of infection (B cells begin their final stages of maturation within less dense germinal center of nodule and then pushed to outer layers as they mature to become antibody-producing plasma cells)

Question 25

Preauricular lymph nodes

Answer 25

located just in front of the ear; these nodes drain the superficial tissues and skin on the lateral side of the head and face

Question 26

Submental group and submandibular group of lymph nodes

Answer 26

in the floor of the mouth; lymph from the nose, lips, and teeth drains through these nodes

Question 27

Superficial cervical lymph nodes

Answer 27

in the neck along the sternocleidomastoid muscle, these nodes drain lymph (which has already passed through other nodes) from the head and neck

Question 28

Superficial cubital lymph nodes (supratrochlear lymph nodes)

Answer 28

located just above the bend of the elbow; lymph from the forearm passes through these nodes

Question 29

Axillary lymph nodes

Answer 29

• 20 to 30 large nodes clustered deep within the underarm and upper chest regions
• lymph from the arm and upper part of the thoracic wall, including the breast, drains through these nodes

Question 30

Iliac lymph nodes and Inguinal lymph nodes

Answer 30

in the pelvis and groin; lymph from the pelvic organs, legs, and external genitals drains through these nodes

Question 31

Function of lymph nodes

Answer 31

At least two distinct functions:

defense: filtration and phagocytosis

hematopoiesis

Question 32

Defense (filtration and phagocytosis) function of lymph nodes

Answer 32

• structure of sinus channels in lymph nodes slows lymph flow
• reticuloendothelial cells lining the channels have time to remove microorganisms and other things and phagocytose them (biological filtration)
• physically stops particles from progressing farther in the body (mechanical filtration)

Question 33

Adenitis

Answer 33

infection of a node - occurs when there is an excess amount of microorganisms/particles that enter the nodes to be removed but phagocytes are overwhelmed and cannot prevent injury to the node

Question 34

Why is having an understanding of the lymphatic drainage of the breast important in formulating the diagnosis and treatment of breast cancer?

Answer 34

because cancerous cells from a single “primary” tumor in the breast often spread to other areas of the body through the lymphatic system

• in mastectomies, sometimes lymphatics and lymph nodes are removed too due to extensive network of lymphatic vessels associated with the breast and cancer’s ability to spread easily through it

Question 35

How does muscle contraction affect lymphokinetic action?

Answer 35

Muscle contraction creates a “milking” effect on the lymphatic vessels, creating increased lymphatic pressure to push the lymph forward and in one direction

Question 36

Hematopoiesis - Function of lymph node

Answer 36

• lymphoid tissue of lymph nodes serve as site of final stages of maturaiton for some lymphocytes and monocytes that have migrated from bone marrow

Question 37

How is the breast (mammary glands and surrounding tissues) drained?

Answer 37

• drained by two sets of lymphatic vessels:
  
  • lymphatics that originate in and drain skin over the breast (with exception of areola and nipple) → vessels converge to form cutaneous lymphatic plexus
  • lymphatics that originate in and drain the underlying substance of the breast itself, as well as skin of areola and nipple

Question 38

More than ____% of lymph from breast enters lymph nodes of the axillary region. Remainder enters lymph nodes along ______________.

Answer 38

85; lateral edges of sternum

Question 39

What about the lymphatic structures of the breast make cancer/infectious cells easy to spread?

Answer 39

• There are several large nodes in axillary region that are in actual physical contact with extension of breast tissue (axillary tail/tail of Spence) that allows for cancer and infectious cells to spread by lymphatic extension and contiguity of tissue
• other nodes in axilla or chest wall will enlarge and swell after being “seeded” with malignant cells or bacteria, as lymph from cancerous/infected breast flows through them

Question 40

Sentinel lymph node (SLN)

Answer 40

first lymph node to which a cancerous tumor can spread

Question 41

Tonsil

Answer 41

• Masses of lymphoid tissue located in a protective ring (pharyngeal lymphoid ring) under mucous membranes in mouth and back of throat
• ring of tonsils helps protect against bacteria that may invade tissues in the area around the openings between nasal and oral cavities

Question 42

Palatine tonsil

Answer 42

located on each side of the throat

Question 43

Pharyngeal tonsils

Answer 43

known as adenoids when swollen

near posterior opening of the nasal cavity

Question 44

What is the type of blood cells produced by the lymph nodes?

Answer 44

lymphocytes

monocytes

Question 45

Lingual tonsils

Answer 45

located near base of the tongue

Question 46

Tubal tonsils

Answer 46

located near opening of auditory (eustachian) tube

Question 47

Function of tonsils

Answer 47

serves as first line of defence from exterior and as such as subject to chronic infection (tonsillitis)

sometimes removed surgically if antibiotic therapy is not successful or if swelling impairs breathing

Question 48

Thymus

Answer 48

• primary organ of lymphatic system
• two pyramidal lobes with delicate and finely lobulated surfaces
• located in the mediastinum, extending up into neck as far as lower edge of thyroid gland & inferiorly as far as 4th costal cartilage
• size relative to rest of body is largest in a child ~2 years of age
• absolute size is largest at puberty
  
  • after this, it gradually atrophies until in advanced old age, it may be largely replaced by fat
  • by 60, lymphoid tissue is about half its max size
  • virtually gone by 80

Question 49

Involution

Answer 49

process of shrinkage of an organ

Question 50

Colour of thymus - childhood vs aging

Answer 50

In early childhood - pinkish gray

Advancing age - yellowish - replaced by fat

Question 51

Structure of thymus

Answer 51

• lobes of thymus subdivided into small lobules by connective tissue septa that extend inward from fibrous covering capsule
• each lobule is composed of dense cellular cortex & inner, less dense medulla
• composed of lymphocytes
• medullary tissue contain thymic corpuscles (onion like appearence)
  
  • area to break down dead, keratinized epithelial cells migrating inward from outer parts of each lobules
  • also secrete regulatory molecules that affect WBC development

Question 52

Function of thymus

Answer 52

Two important functions:

1) serves as final site of lymphocyte development before birth (fetal bone marrow forms immature lymphocytes which then move to the thymus)
2) soon after birth, thymus begins secreting group of hormones (thymosin) and other regulators that enable lymphocytes to develop into mature T cells

Question 53

Location of spleen

Answer 53

left hypochondrium of abdominopelvic cavity (directly below diaphragm)

just above most of left kidney and secnding colon, behind fundus of stomach

common to find “accessory spleens” embedded in double fold of serous membrane that connects the spleen and stomach - these accessory spleens often form from splenic stem cells released from the spleen during minor injuries to spleen

Question 54

Structure of spleen

Answer 54

• varied size in different people or at diff times in the same person; roughly ovoid shape
• surrounded by fibrous capsule with inward extensions that divide the organ into compartments
• white pulp: dense masses with developing lymphocytes
• red pulp: outer regions of each compartment - made up of network of fine reticular fibers submerged in blood hat comes form nearby arterioles
• after passing through reticular meshwork, blood collects in venous sinuses and returns to heart through veins

Question 55

Functions of spleen

Answer 55

1) Defence: as blood passes through sinusoids of spleen, reticuloendothelial cells (macrophages) lining these venous spaces remove microorganisms to phagocytose

2) Tissue Repair: monocytes in red pulp are mobilized when significant tissue damage occurs (like MI, CVA) - aid in healing and repair

3) Hematopoiesis: nongranular leukocytes (monocytes/lymphocytes) complete their development and become activated in the spleen

• before birth, RBCs are also formed in the spleen (after birth, spleen only forms RBCs in extreme hemolytic anemia)

4) RBC and platelet destruction: macrophages lining spleen’s sinusoids remove worn-out RBCs and imperfect platelets from blood and destroy them by phagocytosis

• also break apart Hb molecules from destroyed RBCs and salvage iron and globin for storage in bone marrow and liver

5) blood reservoir: ~350mL that can be decreased by ~200mL in less than 1 min after sympathetic stimulation producing marked constriction of its smooth muscle capsule

Question 56

If spleen is accidentally ruptured (such as in broken ribs), what would happen?

Answer 56

significant internal bleeding (due to spleen’s role in blood reservoir)

Question 57

The spleen ________________ during infectious diseases and ______________ in old age.

Answer 57

hypertrophies; atrophies

Question 58

Lympedema

Answer 58

• abnormal condition in which swelling of tissues in extremities occurs due to obstruction of lymphatics an accumulation of lymph
• most common type: congenital lymphedema (more often seen in females 15-25)
• Causes: obstructions; filaria (nematodes - small parasitic worms)
• obstruction can be in both lymphatic vessels and lymph nodes themselves
  
  • initial edema is soft followed by firm, painful edema that is unresponsive to tx as condition progresses
  • edema can cause limbs to look like elephant’s limbs therefore referred to as elephantiasis
  • will have chronic swelling, thickening of subQ tissue, frequent bouts of infection
• Treatment: diuretics, strict bed rest, massage, elevation of involved extremities; potential surgical removal of involved subQ tissue and fascia (if unresponsive to treatment)

Question 59

Lymphangitis

Answer 59

• acute inflammation of the lymphatic vessels
• stems from invasion of infectious organism
• characterized by thin, red streaks extending from infection region toward lymph nodes
• lymph nodes become enlarged, tender, and reddened
• necrosis and abscesse development can occur (leading to supprative lymphadenitis)
• common lymph node involvement: groin, axilla, cervical regions
• infectious agents may eventually spread to bloodstream causing septicemia and septic shock (but can be prevented with antibiotics)

Question 60

Tonsillitis

Answer 60

• infection of tonsils
• Common S/S: fever, sore throat, difficulty swallowing
  
  • enlarged pharyngeal tonsils (adenoids) may cause nasal obstruction
• infection may extend to middle ear via eustachian tubes causing acute otitis media and possible deafness if left untreated
• Treatment: antibiotics; tonsillectomy (if unresponsive to antibiotics)

Question 61

Lymphoma

Answer 61

• tumor of the cells of lymphoid tissue; often malignant but can be benign
• originate in isolated lymph nodes BUT can involve lymphoid tissue in liver, spleen, and GI tract
• widespead involvement is common - disease spreads from node to node via anastomoses
• exact cause is unknown
• Two principle categories:
  
  • Hodgkin lymphoma (HL): malignancy with uncertain etiology (potentially pathogen induced tumor of T cells or chemical/environmental esxposures)
    
    • starts with painless, nontender, enlarged lymph nodes in neck/axilla
    • lymph nodes in other regions then enlarged in the same manner
    • if involves esophagus/trachea, resulting pressure may cause difficulty breathing/swallowing
    • curable with early detection (chemo x radiation therapy)
  • non-Hodgkin lymphoma (NHL): malignancy of lymphoid tissue other than HL
    
    • unknown etiology (potentiall virus)
    • pt with immunodeficiencies such as AIDS often develop this condition
    • similar manifestations as HL but with more generalized involvement of lymph nodes
    • CNS often involved
    • TReatment: radiation and chemo

Question 62

What would happen if disease blocked the flow of lymph?

Answer 62

lymphedema and liver enlargement