Lymphatic System

Question 1

How much interstitial fluid is collected by the lymphatic system a day?

Answer 1

3 L.

(20L fluid leaves arteriolar ends of capillaries and 17L absorbed back into the venous end - remaining 3L returned to venous system by lymphatic system)

Question 2

What three things aid the movement of lymph against gravity?

Answer 2

Skeletal muscle contraction
Pressure changes in the thorax during breathing
Pulsation in adjacent arteries

Question 3

What are diffuse lymphatic tissue?

Answer 3

small concentrations of lymphoid tissue e.g. mucosal associated lymphatic tissue (MALT)

Found in the gastrointestinal tract, skin, lungs, salivary glands

Question 4

Name three locations of lymphatic nodules

Answer 4

Tonsils (3 - one at back of nose, tongue and throat)
Peters patches - in ilium
Vermiform appendix

Question 5

What is the function of a lymph node

Answer 5

To filter lymph. Consist of an apparent lymphatic vessel (lymph enters) and an efferent lymphatic vessel (lymph leaves).

Question 6

Give some examples of locations of lymph nodes

Answer 6

Throat
Arm pits
Groin

Question 7

What type of cell is abundant in the germinal centre of lymph nodes?

Answer 7

Follicular dendritic cells - bind antigen-antibody complexes. Involved in proliferation on B cells

Question 8

Lymph nodes contain professional antigen presenting cells, such as…

Answer 8

Macrophages
B cells
(Contain MHC2 on surface)

Question 9

What is the body’s initial response to an antigen?

Answer 9

Inflammation - mediated by neutrophils and macrophages (may elicit immune response)

Question 10

What cell types are involved in the immune response?

Answer 10

B cells - humoral - antibody production

T cells - cell mediated - kills infected cells

Question 11

What is lymphadenopathy?

Answer 11

Enlarged lymph nodes. As the lymph nodes fight infection, germinal centres fill with lymphocytes - causes swelling

Question 12

What functions does the spleen play?

Answer 12

Immune functions - antigen presentation ny APCs, activation and proliferation of B and T cells and removal of macromolecular antigen from blood (macrophages)

Haemopoietic functions - removal/destruction of old, damaged, abnormal erythrocytes and platelets and retrieval of iron from erythrocytes haemoglobin

Question 13

If the spleen is removed (splenectomy), what organs/cells take over its function?

Answer 13

Liver and bone marrow take over removal and destruction of ageing erythrocytes.

Question 14

The spleen may enlarge in response to systemic infections such as

Answer 14

Malaria
Glandular fever
Septicaemia

Question 15

What is the role of the thymus?

Answer 15

Maturation of bone marrow derived stem cells into immunocompetent T cells

Question 16

What happens inside a phagocyte after ingestion of a foreign body?

Answer 16

It creates an endoscope which fuses with a lysosome to form a phagosome. Material is degraded in the phagosome then exocytosed.

Question 17

What two chemical processes are active in phagosome to degrade pathogens?

Answer 17

• oxygen dependent killing mechanisms - production of reactive oxygen and nitrogen species (e.g. superoxides) produce radicals. Act as potent antimicrobials.
• oxygen independent killing mechanisms - lysosomal hydrolases, hydrologic enzymes and lysozyme work to degrade microbes. Also defending form channels in bacterial membranes

Question 18

What is opsonisation?

Answer 18

Process by which a pathogen is “marked” for destruction by a phagocyte. Involved binging of an opsonin e.g. Antibody to receptor on pathogen membrane (C3b to C3b receptor)

Question 19

What is complement?

Answer 19

A group of serum proteins that function to:

• promote inflammation
• opsonisation - enhances phagocytosis
• destroys cells - facilitates formation of a membrane attack complex

Question 20

What can complement be activated by?

Answer 20

Classical pathway: antibody- antigen complex
Alternative pathway: C3b - antigen
Lectin pathway - lectins

Question 21

What is oedema?

Answer 21

Accumulation of excessive watery fluid in cells, tissues or serous cavities

Question 22

What is lymphoedema?

Answer 22

Accumulation of large amounts of lymph (swelling) in subcutaneous tissues as a result of obstruction of lymphatic vessels/lymph nodes.

Question 23

What are starling forces?

Answer 23

Dictate whether reabsorption (into capillary) or filtration (is out of capillary) occurs based on hydrostatic and oncotic pressures in the capillary and interstitial space.

Question 24

What is hydrostatic pressure?

Answer 24

Pressure that any fluid in a confined space exerts - “pushing water out”

Often higher towards the arteriole and lower towards venous ends

Question 25

Why is lymphoedema non-pitting?

Answer 25

Because fibroblasts build “storage” for fluid meaning that when you press down there is nowhere for the fluid to move to (cannot leave compartment)

Question 26

What types of white blood cells are granulcytes?

Answer 26

Neutrophils, basophils and eosinophils

Question 27

What do natural killer (NK) cells do?

Answer 27

Stimulate apoptosis of virally infected or cancerous cells

Question 28

What is haemophilia A?

Answer 28

X linked recessive disease - causing lack of clotting factor 8

Question 29

Where is lymph drained back into blood system?

Answer 29

Right lymphatic duct (drains lymph from upper right area of torso, right arm and head) into internal jugular vein

Larger thoracic duct (drains lymph from rest if the body) into subclavian vein

Question 30

Where are follicular dendritic cells located and what’s their function?

Answer 30

Located in the germinal centre of lymph nodes/tissues, function in the proliferation of B cells (particularly memory cells)

Question 31

What happens to the capillaries during inflammation?

Answer 31

Became leaky - allow neutrophils and other proteins to site of infection, cause swelling

Question 32

What is the innate immune system?

Answer 32

First line of defence

External barriers - skin, mucus membranes, acidic environments

Internal defences - phagocytes, NK cells, antimicrobial proteins

Question 33

Where are mucous membranes found?

Answer 33

Lining open cavities (respiratory tract, GI tract, urinary tract, reproductive tract)

Question 34

List three functions of antibodies

Answer 34

Opsonisation
Neutralisation
Agglutination

Question 35

How do cytotoxic T cells kill infected cells?

Answer 35

Trigger apoptosis

Release perforins

Question 36

What is the function of helper T cells?

Answer 36

Release cytokines - which trigger other immune cells to divide and also finishes the maturation of B cells