Ch. 14 Lymphatic System

Question 1

The lymphatic system is also named..

Answer 1

(Reticuloendothelial system, defensive system, immune system)

Question 2

The lymphatic system is also known as..

Answer 2

A 2nd circulatory system

Question 3

Lymphatic vessels collect and carry away excess tissue fluid from..

Answer 3

Interstitial spaces, eventually returning it to the blood

Question 4

Lymph nodes, which are situated along lymphatic vessels, contain..

Answer 4

Lymphocytes, which help defend body against infection

Question 5

The lymphatic pathway is..

Answer 5

Arterioles (blood) —> Capillaries (Vein-Blood) —> Tissue (Interstitial fluid) —> Lymphatic capillaries (Lymph) —> Lymph node —> Lymphatic ducts —> Either RT Lymphatic duct or Thoracic duct which drain into the RT or LT Subclavian vein

Question 6

Lymphatic capillaries:

Answer 6

• Tiny, closed-ended tubular vessels that extend into interstitial spaces, paralleling the blood capillaries
  
  • Found all over body, except in central nervous system
  • Receive tissue (interstitial) fluid through their thin walls and slits between cells
  • Once inside a lymphatic capillary, tissue fluid is called lymph

Question 7

Lymphatic capillaries: Tiny, closed-ended tubular vessels that extend into..

Answer 7

Interstitial spaces, paralleling the blood capillaries

Question 8

Lymphatic capillaries: Found all over body, except in..

Answer 8

Central nervous system

Question 9

Lymphatic capillaries: Receive tissue (interstitial) fluid through their..

Answer 9

Thin walls and slits between cells

Question 10

Lymphatic capillaries: Once inside a lymphatic capillary, tissue fluid is called..

Answer 10

Lymph

Question 11

Lymphatic vessels:

Answer 11

• Walls of lymphatic vessels are thinner than those of veins, but they are constructed with the same 3 layers
• Have flaplike valves on the inside, like veins
  - Prevent backflow
• Larger lymphatic vessels pass through organs called lymph nodes, and then merge to form larger lymphatic trunks

Question 12

Lymphatic vessels: Walls of lymphatic vessels are thinner than those of veins, but they are constructed with..

Answer 12

The same 3 layers

• (1) Tunica interna
  
  • Inner layer
  • Made of simple squamous epithelium
  • Also called endothelium
  • Direct contact with blood
  • Prevent blood clotting
• (2) Tunica media
  
  • Middle layer
  • Thickest layer
    
    • Consist 2 layers: (1) Elastic connective tissue, (2) Smooth muscle
    • [Tube-like structures are made up of smooth muscle]
  • Functions: (1) Elasticity/contractibility, (2) Help maintaining blood pressure
• (3) Tunica externa (Tunica adventitia)
  
  • Formed by fibrous connective tissue
  • Very strong
    
    • Prevent rupturing of the blood vessel because of pressure beared from the left ventricle

Question 13

Lymphatic vessels: Have flaplike valves on the inside, like veins to

Answer 13

Prevent backflow

Question 14

Lymphatic vessels: Larger lymphatic vessels pass through organs called..

Answer 14

Lymph nodes, and then merge to form larger lymphatic trunks

Question 15

Lymphatic trunks:

Answer 15

• Drain lymph from the lymphatic vessels
  
  • Named for the regions they drain

Question 16

Trunks empty into 1 of 2 collecting ducts:

Answer 16

Thoracic or right lymphatic duct

Question 17

Right lymphatic duct: Drains..

Answer 17

Right side of head and neck, right arm, and right thorax, and empties into right subclavian vein

Question 18

Thoracic duct:

Answer 18

Larger collecting duct, drains rest (majority) of the body, and empties into left subclavian vein

Question 19

Lymph:

Answer 19

• Tissue fluid that has entered a lymphatic capillary
  
  • Lymph formation depends on tissue fluid formation

Question 20

Tissue fluid formation:

Answer 20

• Tissue fluid is made up of water and dissolved substances that leave blood capillaries by filtration and diffusion

    - [Diffusion: Movement from high to low concentration]
    - [Filtration: Water and dissolved material forced through a membrane from high to low pressure]

Question 21

Fluid that does not return to the capillaries becomes..

Answer 21

Tissue fluid

Question 22

Lymph also transports foreign particles, including bacteria and viruses, to the lymph nodes for..

Answer 22

Recognition and destruction

Question 23

Factors that help in the movement of lymph:

Answer 23

• Hydrostatic pressure of tissue fluid
• Muscular activity moves lymph through lymphatic vessels:
  - Skeletal muscle contraction
  - Breathing movements
  - Contraction of smooth muscle in the walls of the vessels
  - Valves prevent backflow
• Edema: Accumulation of lymph in the interstitial spaces, due to interference with flow in lymph
  - [Edema: When fluid goes between tissue]
  - EX: During surgery, such as removing cancerous breast, lymphatic vessels or tissues may be removed or disturbed; obstruction results in edema

Question 24

Lymphatic tissue contains..

Answer 24

Lymphocytes, macrophages, and other cells

Question 25

Lymphatic organs:

Answer 25

- Lymph nodes - Thymus - Spleen - Tonsils - Appendix

Question 26

Lymph nodes: Location

Answer 26

- In groups or chains along lymphatic vessels - Not found in the central nervous system - Major areas of concentration: Cervical, thoracic, axillary, supratrochlear, abdomial, pelvic, and inguinal regions

Question 27

Lymph nodes: Structure

Answer 27

- Lymph nodes are bean-shaped,(kidney-shaped— Reniform) - Blood vessels, nerves, and efferent lymphatic vessens enter or exit at the indent hilum or hilus - Afferent lymphatic vessels enter on the convex surface - Lymph nodes are covered with a connective tissue capsule, that extends inside the node and divides it into lymphatic nodules and spaces called sinuses - Lymph nodes contain both lymphocytes and macrophages; they filter the lymph as it flows through them, removing many pathogens - Filtered lymph leaves lymph node through efferent lymphatic vessels

Question 28

Lymph nodes: Function

Answer 28

- Filter lymph and remove bacteria and cellular debris before lymph is returned to the blood - Immune surveillance: Monitor body fluids; performed by lymphocytes and macrophages - Lymph nodes are also centers of lymphocyte production - Lymphocytes attack viruses, bacteria and parasitic cells that enter a lymph node - Macrophages engulf and destroy foreign particles, debris, and damaged cells

Question 29

Thymus: Location

Answer 29

- Behind the sternum - Anterior to aorta

Question 30

Thymus: Structure

Answer 30

- Soft, bi-lobed organ - Shrinks in size during the lifetime, large in children, small in adults, replaced by adipose and connective tissue in the elderly - Surrounded by a connective tissue capsule that extends inward and divides it into lobules - Lobules contain lymphocytes, some of which mature into T cells or T lymphocytes, that leave the thymus to provide immunity

Question 31

Thymus: Function

Answer 31

The thymus secretes hormones called thymosins, which influence maturation or T lymphocytes

Question 32

Spleen: Location

Answer 32

Lies in the upper left abdominal cavity (left hypochondriac region/LUQ)

Question 33

Spleen: Relational anatomy - The spleen is bordered by surrounding organs and structures: - Anterior by: - Medially by: - Posteriorly by:

Answer 33

- Anterior by: Stomach - Medially by: Left kidney, splenic flexure of colon, pancreatic tail - Posteriorly by: Diaphragm, pleura left lung, ribs

Question 34

Spleen: Structure

Answer 34

- Largest lymphatic organ in the body - Similar to a large lymph node, except it contains blood instead of lymph - Composed of white pulp, which contains many lymphocytes, and red pulp, which contains red blood cells, macrophages, and lymphocytes

Question 35

Spleen: Function

Answer 35

Filters the blood and removes damaged blood cells and bacteria

Question 36

Pathogens:

Answer 36

- Disease-causing agents - Presence and multiplication can produce an infection - Can be bacteria, viruses, fungi, or protozoans

Question 37

Two basic mechanisms of defenses:

Answer 37

- Innate (Nonspecific) defenses: - Guard against many types of pathogens; respond quickly - Include species resistance, mechanical barriers, chemical barriers, natural killer cells, inflammation, phagocytosis, and fever - Adaptive (Specific) defenses or immunity: - Respond against only a specific type of pathogen; respond more slowly - Accomplished by specialized lymphocytes, which secrete cytokines or antibodies

Question 38

Innate (Nonspecific) Defenses: Mechanical barriers

Answer 38

- The body’s first line of defense (the rest of the innate defenses are part of the 2nd line of defense - Prevent the entry of certain pathogens by providing a physical separation of pathogens and internal tissues - Includes hair, mucus, and sweat

Question 39

Innate (Nonspecific) Defenses: Chemical barriers

Answer 39

- Chemicals that kill many pathogens - Acidic environment - Enzymes— Destroy many pathogens - Interferons— Block viral replication and slow tumor growth - Complement— Attracts phagocytes and enhances phagocytosis and antibody action

Question 40

Adaptive (Specific) Defenses or Immunity:

Answer 40

- Third line of defense - Response by the body against specific pathogens, their toxins or metabolic products

Question 41

Hilum/hilus:

Answer 41

Door in which vessels move in and out