Topic 10 -Lymphatic System

Question 1

General characteristics of lymphatic system?

Answer 1

Function is same across all species, structure may be different
Partner w/ circulatory system
extensive network of 1-way vessels
provide accessory route by which interstitial fluid can be returned back to plasma
Collect lymph resorbed by lymphatic capillaries & return it to venous circulation near precaval & postcaval veins

Question 2

What are lymphatic vessels?

Answer 2

blind-ended tubular system that recirculates fluid from tissues back to cardiovascular system

Question 3

Hydrostatic pressure w/in arterioles is generated by…?

Answer 3

force from ventricular contraction

Question 4

Osmotic pressure w/in arterioles results from…?

Answer 4

unequal concentrations of protein w/in the arteriole & outside in surrounding tissue fluid
-as consequence fluid moves from surrounding tissue into blood

Question 5

Describe lymph fluid

Answer 5

Carried by lymphatic system
Consists mostly of water & few dissolved substances such as electrolytes & proteins
No RBC’s

Question 6

Name the major vessels of the lymphatic system and where they are situated

Answer 6

Jugular lymphatics (head & neck)
Subclavian lymphatics (anterior appendage)
Lumbar lymphatics (posterior appendage)
Thoracic lymphatics (trunk, viscera (body cavity), tail)

Question 7

Describe the adaptation of some bony fish in regards to lymph sys.

Answer 7

Lymph hearts -lack cardiac muscle, striated muscles develop pulses of pressure to drive lymph

Question 8

General body movements aid in…?

Answer 8

movement of lymph

Question 9

Lymphatic system includes…?

Answer 9

lymphatic tissue, collection of connective tissues & free cells

Question 10

A bit about lymph nodes

Answer 10

collection of lymphatic tissue wrapped in a capsule of fibrous connective tissue.
Located w/in channels of lymphatic vessels along route of returning lymph
-birds have lymph nodules
-reptiles have lymph sacs or cisterns

Question 11

Describe primary lymphatic organs

Answer 11

sites where stem cells divide & become immunocompetent

Include red bone marrow & thymus

Question 12

Describe secondary lymphatic organs

Answer 12

where most immune responses occur

Includes lymph nodes, spleen & lymphatic nodules

Question 13

A bit about the thymus?

Answer 13

Large in newborn animals, then disappears (atrophies)

Before atrophy, populates secondary lymphatic organs w/ T cells

Question 14

A bit about the spleen?

Answer 14

Largest single mass of lymphatic tissue
Filters blood
consists of white & red pulp

Question 15

Describe the white pulp of the spleen

Answer 15

consists of lymphocytes & macrophages
B cells & T cells carry out immune functions
Macrophages destroy pathogens

Question 16

Describe the red pulp of the spleen

Answer 16

consists of blood-filled venous sinuses & splenic cords (Billroth’s cords)
removal of old/worn out RBC’s by macrophages
Storage of platelets
production of blood cells (haematopoesis

Question 17

A bit about lymphocytes

Answer 17

React against foreign antigens
produced in bone marrow
circulate in blood & lymph
3 major classes:
-T cells
-B cells
-NK (null) cells

Question 18

A bit about B cells?

Answer 18

produced & mature in bone marrow
HUMORAL IMMUNITY
secrete & produce antibodies that bind specifically to antigens (immunoglobulins)
act as antigen presenting cells

Question 19

A bit about T cells?

Answer 19

CELL-MEDIATED IMMUNITY
secrete proteins known as cytokines
cytotoxic t cells kill infected or abnormal cells

Question 20

A bit about NK (null) cells?

Answer 20

involved in non-specific immunity

destroy virus-infected cells & cancer cells

Question 21

Name 3 ways in which immunity can be generated

Answer 21

natural exposure to pathogen
vaccination
to fetus from dam through passively acquiring antibodies in utero

Question 22

A bit about natural immunity?

Answer 22

Can be:
passive (does not require immune sys to respond, no B memory cells, short-term response)
active (immune response required)

Question 23

Colostrum contains?

Answer 23

High concentration of IgG
also contains:
anti-infection agents, digestive enzymes, hormones, growth factors, bioactive peptides

Question 24

A bit about colostrum and calves?

Answer 24

immunoglobulin in calf’s serum must reach 10mg/ml to provide minimal protection
maximum protection provided by 3-5L
Maximum absorption in first 6-8hrs
Little or no absorption after 24-36hrs

Question 25

A bit about auto immune diseases?

Answer 25

Immune system fails to display self-tolerance & attacks own tissues
Bind to & stimulate or block self antigens

SLE (system lupus erythematosus)
-excessive activation of B cells
attacks vital systems, organs (especially kidneys)

Question 26

What affects the quality of colostrum?

Answer 26

Age
Dry periods too short or too long
exposure to antigens & vaccinations