Lecture 9 Flashcards Preview

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Flashcards in Lecture 9 Deck (22):
1

Lymphatic System:

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

2

lymph:

Organs, vessels and a fluid
similar to interstitial fluid

3

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

lymphaticvessels:
resemble veins with thinwalls & more valves

4

Fluid flows through

lymph nodes towards large veins above the heart
lymph emptied into bloodstream

5

Lymphatic Capillaries:

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)

6

Lymph Trunks & Ducts

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

7

Formation & Flow of Lymph:

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

8

Functions of the Lymphatic System

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

9

Lymphatic Organs & Tissues

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

10

Thymus Gland

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

11

Cortex:

tightly packed lymphocytes &macrophages

12

Medulla

reticular epithelial cells produces thymic hormones
Hassall’s corpuscles

13

Lymph Nodes flow in:

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

14

Lymph Nodes are:

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

15

Stroma

is capsule, trabeculae & reticular fibers

16

Parenchyma is divided into 2 regions:

cortex
medulla

17

cortex in nodes

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

18

medulla in nodes

contains B cells & plasma cells in medullary cords

19

Metastasis Through Lymphatic System:

-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

20

Lymphatic Nodules:

-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

21

Spleen:

-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

22

Parenchyma consists of white pulp and red pulp:

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