Lecture 9

Question 1

Lymphatic System:

Answer 1

red bone marrow
thymus
spleen
lymph nodes
diffuse lymphatic tissue
tonsils, adenoids & peyers patches

Question 2

lymph:

Answer 2

Organs, vessels and a fluid

similar to interstitial fluid

Question 3

Capillaries that begin asclosed-ended tubes foundin spaces between cells
Combine to form:

Answer 3

lymphaticvessels:

resemble veins with thinwalls & more valves

Question 4

Fluid flows through

Answer 4

lymph nodes towards large veins above the heart

lymph emptied into bloodstream

Question 5

Lymphatic Capillaries:

Answer 5

Found throughout thebody except in Avasculartissue (cartilage, epidermis& cornea)
Structure is designed to lettissue fluid in but not out
anchoring filaments keep tubefrom collapsing under outside pressure
overlapping endothelial cells open when tissue pressure is high (one-way valve)

Question 6

Lymph Trunks & Ducts

Answer 6

Vessels unite to form trunks & thoracic ducts
Right side head, arm & chest empty into right lymphatic duct and rest of body empties into thoracic duct
Lymph is dumped directly into left & right subclavian veins

Question 7

Formation & Flow of Lymph:

Answer 7

Fluid & proteins escaping from vascular capillaries is collected by lymphatic capillaries & returned to the blood
Respiratory & muscular pumps promote flow of lymphatic fluid
Lymphatic vessels empty into subclavian veins

Question 8

Functions of the Lymphatic System

Answer 8

Draining excess interstitial fluid & plasma proteins from tissue spaces
Transporting dietary lipids & vitamins from GI tract to the blood
Facilitating immune responses
recognize microbes or abnormal cells & responding by killing them directly or secreting antibodies that cause their destruction

Question 9

Lymphatic Organs & Tissues

Answer 9

Widely distributed throughout the body
Primary lymphatic organs
provide environment for stem cells to divide & mature into B and T lymphocytes
red bone marrow gives rise to mature B cells
thymus is site where pre-T cells from red marrow mature
Secondary lymphatic organs & tissues
site where most immune responses occur
lymph nodes, spleen & lymphatic nodules

Question 10

Thymus Gland

Answer 10

Large organ in infants (70 g) but atrophied as adult (3 g)
2 lobed organ located in mediastinum
Capsule & trabeculae divideit into lobules
Each lobule has cortex &medulla
Cortex
Medulla

Question 11

Cortex:

Answer 11

tightly packed lymphocytes &macrophages

Question 12

Medulla

Answer 12

reticular epithelial cells produces thymic hormones

Hassall’s corpuscles

Question 13

Lymph Nodes flow in:

Answer 13

-one direction:
afferent vessels lead in
sinuses lead to efferent vessels that exit at hilus
-Only nodes filter lymph

Question 14

Lymph Nodes are:

Answer 14

Bean-shaped organs, up to 1 inch long, located along lymphatic vessels
scattered throughout body but concentrated near mammary glands, axillae & groin
Stroma
Parenchyma

Question 15

Stroma

Answer 15

is capsule, trabeculae & reticular fibers

Question 16

Parenchyma is divided into 2 regions:

Answer 16

cortex

medulla

Question 17

cortex in nodes

Answer 17

lymphatic nodules with germinal centers containing dendritic cells
antigen-presenting cells and macrophages
B cells proliferate into antibody-secreting plasma cells

Question 18

medulla in nodes

Answer 18

contains B cells & plasma cells in medullary cords

Question 19

Metastasis Through Lymphatic System:

Answer 19

• Characteristic of malignant tumors
• Spread of disease from one organ to another
• -cancer cells travel via blood or lymphatic system
• -cells establish new tumors where lodge
• Secondary tumor sites can be predicted by direction of lymphatic flow from primary site
• Cancerous lymph nodes are firm, enlarged and nontender – infected lymph nodes are not firm and are very tender

Question 20

Lymphatic Nodules:

Answer 20

-Concentrations of lymphatic tissue not surrounded by a capsule scattered throughout connective tissue of mucous membranes
–mucosa-associated lymphoid tissue (MALT)
-Peyer’s patches in the ileum of the small intestine
Appendix
-Tonsils form ring at top of throat
–adenoids (pharyngeal tonsil)
–palatine tonsils (on each side wall)
–lingual tonsil in the back of the tongue

Question 21

Spleen:

Answer 21

• 5 inch organ between stomach & diaphragm
• Hilus contains blood & lymphatic vessels
• Stroma consists of capsule, trabeculae, fibers & fibroblasts
• Parenchyma consists of white pulp and red pulp

Question 22

Parenchyma consists of white pulp and red pulp:

Answer 22

• white is lymphatic tissue (lymphocytes & macrophages) around branches of splenic artery
• red pulp is venous sinuses filled with blood & splenic tissue (splenic cords)