CHAPTER 22 Flashcards
Lymph
Fluid similar to plasma (without plasma proteins)
Lymphatic Vessels
a. lymphatic capillaries
b. lymphatic trunks
c. lymphatic ducts
Cells in the lymphatic system
lymphocytes, phagocytes, other cells
Lymphoid tissues
EX
a) tonsils
b) MALT (mucosa associated lymphatic tissue)
Lymphoid organs
spleen, thymus, lymph nodes
What does the lymphatic system do?
Protect us against disease
What do lymphatic system calls respond to?
Pathogens (viruses, bacteria, fungi, parasites)
Toxins
abnormal body cells such as cancers.
What is immunity, and what is involved in the immune system?
immunity is the ability to resist infection and disease
all cells and tissues are involved in production in immunity, NOT just lymphatic system
Which is greater, immune or lymphatic system?
IMMUNE SYSTEM
Specific defenses of lymphocytes
part of the immune response
identify, attack, and develop immunity to a specific pathogen
Non-specific defenses
block or attack any potential infectious organism. cannot distinguish one attack from another
Function of the lymphatic system
To produce, maintain, and distribute lymphocytes
Lymphocyte production
lymphocytes are produced in:
- lymphoid tissues (tonsils)
- lymphoid organs (spleen, thymus)
- red bone marrow
Lymphocyte circulation
from blood to interstitial fluid thru capillaries
-returns to venous blood thru lymphatic vessels
Fluid circulation
- from blood plasma to lymph and back to the venous system
- transports hormones, nutrients, and waste products
Difference between lymphatic and blood capillaries
lymphatic capillaries:
a. originate as pockets
b. large diameter
c. thinner wall
d. irregular shape in cross section
e. have lymphatic valves
Lymph flow
from lymphatic capillaries to larger lymphatic vessels containing one way valves
Lacteals
special lymphatic capillaries in small intestine, transport lipids from digestive tract
2 lymphatic ducts:
thoracic and right lymphatic duct
Thoracic duct
a. drainage areas including the left upper and whole lower body
b. entering venous system in the left subclavian vein, the superior vena cava and right atrium
c. enlarged site is called cisterns chyli
Right lymphatic duct
a. drainage areas including right upper of the body
b. entering right subclavian vein, then superior vena cava and right atrium
What percent of white blood cells are lymphocytes?
20-30% of WBC
T cellls
80% thymus dependent cells
a. cytotoxic t cells: cell mediated immunity
b. helper t cells: stimulate t and b cells
c. suppressor t cells: inhibit t and b cells
B cells
(10-15%) bone marrow derived cells
- antibody (Ab) - mediated immunity (humoral immunity)
- differentiate into plasma cells to produce Ab
- ab also called immunoglobulins
- life span of b lymphocytes4-20 years
NK cells
5-10% natural killer cells
a. also called: large granular lymphocytes
b. act as immunological surveillance
Cytotoxic T Cells
- attack cells infected by viruses
- produce cell mediated immunity
Memory T cells
formed in response to foreign substance
- remain in body to give immunity
Helper T cells
simulate function of t cells and b cells
Suppressor t cells
inhibit function of t cells and b cells
regulatory t cells
- are helper and suppressor t cells
- control sensitivity of immune response
What is lymphopoeisis
lymphocyte production
- lymphocyte production in red bone marrow
Hemocytoblasts-> Lymphoid stem cells = NK cells and B cells
- lymphocyte production in thymus (blood thymus barrier)
Lymphoid stem cells ————-> mature T cells
^ Thymic hormones (thymosins)
Lymphocyte production
called lymphopoiesis, involves
- bone marrow
- thymus
- peripheral lymphoid tissues
Hemocytoblasts differentiate into 2 groups
group 1. lymphoid stem cells:
remains in bone marrow and develop with help of stromal cells
-produces b cells and natural killer cells
group 2 lymphoid stem cells
- migrates to thymus
-produces t cells in environment isolated by blood thymus barrier
Lymphoid tissues
(storage of lymphocytes) without fibrous capsule
- lymphoid nodules:
a. respiratory tract
b. digestive t- ex. payer’s patch, appendix (MALT)
c. urinary tract
Tonsils
a. pharyngeal tonsil (adenoid tonsil) single
b. palatine tonsils: a pair (R & L)
c. Lingual tonsils: a pair (R & L)
Lymphoid organs
covered with capsule
1 lymph nodes:
2. thymus:
3. Spleen:
Mucosa Associated lymphoid tissues (MALT)
- lymphoid tissues associated with the digestive, respiratory, urinary, and reproductive tracts
ex. aggregated lymphoid nodules= peyer’s patch : cluster deep to intestinal epithelial lining - Appendix (vermiform appendix): contains a mass of fused lymphoid nodules
Lymph Nodes: Anatomy:
a. capsule= trabecular
b. afferent vessels
c. sub capsular sinus: d cells
Cortex:
a. outer cortex- D cells, b cells
b. germinal center- b cells
c. deep cortex- t cells
Medulla: b cells, plasma cells
Efferent vessel
Hilus
- D cells: dendritic cells
- function: initiating immune response
Functions of lymph nodes
a. acting as a filter, purifying lymph before it reaches the venous system
b. providing an early warning system for immune responses (by d cells)
c. producing antibodies (by b cells and plasma cells)
Important lymph nodes
a. Cervical lymph node
b. axillary lymph node
c. inguinal lymph node (groin areas)
lymph nodes in gut and trachea
Lymphadenopathy
enlargement of lymph node (sign of infection, cancer or endocrine disorder)
Lymph nodes and cancer cells
lymph nodes serve as “way stations” for migrating cancer cells (bc lymphatic capillaries offer litter resistance to the passage of cancer cells)
Thymus anatomy
Location: in the mediastinum
weight: 40 g (2 year old)–> 12 g (50 year old)
capsule –> 2 thymic lobes
*many lobules
Thymus cortex
(immature t cells, reticular epithelial cells) producing thymosins