MOD 6 : Function & Structure Of Lymphatic System

Question 1

Lymphatic system

3 main functions

Answer 1

1. 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
2. Remove waste products from tissue and cooperate with immune system in destroying invading pathogens
3. Return filtered lymph to the veins at base of neck.

Question 2

a. Interstitial fluid and

b. Lymph creation

Answer 2

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

Question 3

Structure of lymphatic system

Question 4

Lymphatic circulation

Answer 4

• 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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Question 5

Lymphatic capillaries

Answer 5

• 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

Question 6

Lymphatic vessels and ducts , nodes

Answer 6

• 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

2. 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

1. CERVICAL LYMPH NODES
   - located along sides of neck
2. AXILLARY LYMPH NODES
   - Under arms
3. INGUINAL LUMPH NODE
   - groin area

Question 7

Lymphocytes

Answer 7

• • 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

1. Natural killer cells - lymphocytes that are matured and differentiated to kill cancer cells and cells infected by virus
2. 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
3. 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

Question 8

Lymphoid

Answer 8

• ## the structures of the the lymphatic system are made of lymphoid tissue

Question 9

Tonsils

Answer 9

• 3 masses of lymphoid tissue
• protective ring around back of nose and upper throat
• tonsils prevent pathogens from entering respiratory system while breathing

1. ADENOIDS
   - know as ‘nasopharyngeal tonsils’
   - located in nasopharynx (upper part of pharynx)
   -
2. 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
3. LINGUAL TONSILS
   - located at base of tongue
   - not readily visible
   - ‘lingual’ means pertaining to tongue

Question 10

Thymus gland

Answer 10

• 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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Question 11

The Vermiform Appendix

Answer 11

• • appendix
• hangs from lower portion of cecum(first section of large intestine )
• appendix may play important role in immune system

Question 12

The Spleen

Answer 12

• 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

Question 13

Lymphadenitis

Lymphaden= lymph nodes

Answer 13

• known as ‘ swollen glands ‘

- inflammation of lymph nodes

Question 14

Lymphangioma

Answer 14

• tumor

Question 15

Lymphadenopathy

Answer 15

Any disease affecting lymph node

Question 16

Rupture spleen causes splenorrhagia

Question 17

Lymphoscintigraphy

Answer 17

• diagnostic test
• detect damage or malformation of lymphatic vessels
• radioactive substance injected into lymph ducts
• scanner or probe is used .

Question 18

Lymphedema

Answer 18

• swelling of tissues due to abnormal accumulation of lymph fluid within tissue
• edema due to lymph not draining properly
  1. Primary edema
• hereditary
• from feet to ankle to leg

2. Secondary lymphedema
   - due to cancer treatment , surgery, trauma

Question 19

Bioimpedance spectroscopy

Answer 19

• non invasive method
• diagnose lymphedema
• electric current passed through affected limb
• more resistance buildup of lymph