MOD 6 : Function & Structure Of Lymphatic System Flashcards
Lymphatic system
3 main functions
- Absorb fat and fat- soluble vitamins through lacteals of small intestine
Villi- finger like projections lining small intestine- contains lacteals and blood vessels
- LACTEALS ~ specialized structure of the lymphatic system
~ absorbs fat cannot be transported by bloodstream
~ these dietary fats are transformed in the cells of the lacteals
~ lymphatic vessels return them to venous circulation and used throughout body as nutrients
- blood vessels absorb nutrients, fats and fat- soluble vitamins from digested food directly into bloodstream - Remove waste products from tissue and cooperate with immune system in destroying invading pathogens
- Return filtered lymph to the veins at base of neck.
a. Interstitial fluid and
b. Lymph creation
a. - also know as ‘ intercellular’ or ‘tissue fluid’
- is plasma from arterial blood that flows out of arterioles and into capillaries and then into spaces between the cells of tissues
- this fluid delivers nutrients , oxygen and hormones to the cells
- when thi fluid leaves the cell it brings with it waste products and protein molecules created within cells
- 90% of this fluid returns to blood stream
b.
- lymph - remaining 10% of the returning interstitial fluid
- clear, watery fluid
- contains electrolytes and proteins
- collects protein molecules created within cells as it leaves
- removes dead cells, debris, pathogens from intercellular places
- enters very small capillaries within tissue
- progresses to large vessels
- travels one way trip upward toward neck
- at this stage plays an active role with immune system
- to protect body against invading microorganisms and disease
Structure of lymphatic system
Lymphatic circulation
- lymphatic circulatory system and blood circulatory system work together
- because of this LCS also called ‘ secondary circulatory system ‘
- Blood circulates- pumping system is heart
- lymphatic system pumping system - motion of muscles to move fluid
- Lymph moves only in ONE direction- upward
- until it reaches its circulatory system at base of neck
- once lymph enters lymphatic capillary - continues its upward flow
- BLOOD - filtered by kidneys, waste products excretes by urinary system
- LYMPH- filtered by lymph nodes located along lymphatic vessels
- lymph nodes - contains specialized cells of immune system
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Lymphatic capillaries
- microscope, blind ended ( sealed in one end ) tubes
- located near surface of body with capillary walls ( one cell in thickness )
- cells separate briefly and allow lymph to enter capillary
Lymphatic vessels and ducts , nodes
- lymph flows from lymphatic capillaries to progressively larger lymphatic vessels (located deep within tissues
- large lymphatic vessels eventually join together to form TWO ducts
1. RIGHT LYMPHATIC DUCT - collects lymph from right side of head and neck, upper right quadrant of body , and right arm
- the duct drains into Right subclavian vein
- subclavian vein is proximal part of main vein of the arm
- THORACIC DUCT
- is Largest Lymphatic vessel
- collects lymph from left side of head and neck, upper left quadrant of the trunk, the left arm, entire lower portion of trunk, both legs
- drains into left subclavian vein
LYMPH NODES
- bean shaped
- contains specialized lymphocytes that destroys pathogens
- unfiltered lymph flows into nodes
- Here , lymphocytes destroy harmful bacteria, virus and malignant cells
- additional structure in nodes destroy other impurities from the lymph
- the filtered lymph continues journey to become part of venous circulation again
- 400-700 lymph nodes
- half of these are in abdomen
- CERVICAL LYMPH NODES
- located along sides of neck - AXILLARY LYMPH NODES
- Under arms - INGUINAL LUMPH NODE
- groin area
Lymphocytes
- called ‘ lymphoid cells ‘
- leukocyteyformed in bone marrow as stem cells
- these work together with body to defend against antigens
ANTIGEN
- any substance body regards as foreign
Eg . Bacteria, virus, toxins and transplanted tissues .
3 types of lymphocytes
- Natural killer cells - lymphocytes that are matured and differentiated to kill cancer cells and cells infected by virus
- B cells
- B lymphocytes
- produce antibodies
- most effective against viruses and bacteria that are circulating in the blood
- B cell confronted with an antigen it is coded to destroy it becomes a plasma cell
- plasma cells developed from B cells secrete large volume of antibodies coded to destroy specific antigens - T cells
- originate in Thymus
- main role in cell mediated immunity
a. CYTOKINES
- group of proteins
- produced primarily by T cells
- act as intercellular signals to begin immune response
b. INTERFERONS
- produced in response to antigens
- particularly virus or tumor cells
- activate the immune system
- slows virus and stops their multiplication
- signal other cells to increase defense
c. INTERLEUKINS
- multiple roles in immune system
- directing B and T cells to divide and proliferate
Lymphoid
- ## the structures of the the lymphatic system are made of lymphoid tissue
Tonsils
- 3 masses of lymphoid tissue
- protective ring around back of nose and upper throat
- tonsils prevent pathogens from entering respiratory system while breathing
- ADENOIDS
- know as ‘nasopharyngeal tonsils’
- located in nasopharynx (upper part of pharynx)
- - PALATINE TONSILS
- located in left and right side of throat in the are that is visible at the back of mouth
- palatine refer to hard and soft palate at the roof of mouth - LINGUAL TONSILS
- located at base of tongue
- not readily visible
- ‘lingual’ means pertaining to tongue
Thymus gland
- located above the heart
- reaches greatest size at puberty and becomes small with age
- Thymus - part of endocrine gland
- produces hormone that stimulates the maturation of Lymphocytes into T cells
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The Vermiform Appendix
- appendix
- hangs from lower portion of cecum(first section of large intestine )
- appendix may play important role in immune system
The Spleen
- sac like mass
- located in left upper quadrant of abdomen - just below ( inferior) diaphragm and behind (posterior) the stomach
- filters microorganism and other foreign material from blood
- forms lymphocytes and monocytes
- hemolytic function ( destroying work out erythrocytes) and reaeasing their hemoglobin for reuse
- stores extra erythrocytes
Lymphadenitis
Lymphaden= lymph nodes
- known as ‘ swollen glands ‘
- inflammation of lymph nodes
Lymphangioma
- tumor
Lymphadenopathy
Any disease affecting lymph node
