Ch. 20 Lymphatic System

Question 1

Lymphatic Capillaries

Answer 1

• (include lymphatic lateals in villi)
• tiny vessels (though larger than blood capillaries)
• located in the spaces between cells

Question 2

What are the 3 functions of the lymphatic system?

Answer 2

1) drains excess interstitial fluid = extracellular fluid (ECF) from tissue spaces
2) Transports dietary lipids from lacteals in villi of the small intestine
3) Carries out immune responses

Question 3

Lymph Trunks

Answer 3

• (e.g. lumbar, intestinal, bronchomediastinal, subclavian, and jugular)
• formed by uniting of efferent lymphatic vessels

Question 4

What is the formation and flow of lymph? (4 steps)

Answer 4

1) more blood plasma, except for large plasma proteins, filters freely from blood capillaries than can be reabsorbed
2) unreabsorbed plasma and small proteins are known as interstitial fluid = extracellular fluid (ECF)
3) interstitial fluid enters lymphatic capillaries and is returned to blood circulatory system
4) return of lymph to and through right and left lymphatic ducts is by means of two pumps -milking action resulting from skeletal muscle contractions -pressure on lymphatic vessels resulting from inhalation and exhalation

Question 5

Primary lymphatic organs

Answer 5

• (e.g. red bone marrow and thymus)
• sites where stem cells divide and become immunocompetent (capable of mounting an immune response)

Question 6

Secondary lymphatic organs and tissues

Answer 6

• (e.g. lymph nodes, spleen, and lymphatic nodules = follicles)
• sites where immune responses occur

Question 7

Thymus gland

Answer 7

• organ superior to heart -consists of 2 lobes
• very large from birth through puberty (70g)
• regresses in size into old age (3.0g)

Question 8

Lymph Nodes

Answer 8

• Filters lymph
• structures assigned:
• afferent lymphatic vessels and valves,
• efferent lymphatic vessels and valves,
• capsule, hilium, cortex, medulla

Question 9

Superficial Lymph Nodes

Answer 9

located beneath skin in neck, axillary region, and pelvic region

Question 10

Spleen

Answer 10

• Filters blood
• left side of abdominal cavity between stomach and diaphragm
• largest mass of lymphatic tissue in body (2”,3”,5” same as heart size)
• carries out immune functions
• removes worn out erythrocytes
• stores platelets
• may be removed due to injury and/or to suppress immune function

Question 11

Tonsils

Answer 11

• Pharyngeal = adenod tonsil is embedded in the pharyngeal wall
• Palatine tonsils lie in the right and left lateral walls of the oropharynx
• Lingual tonsils situated at right and left base of tongue

Question 12

Peyer’s patches

Answer 12

Groups of lymph nodes forming a single layer in the mucous membrane of the ileum.

• Protect the mucous membranes of the small intestines (the ileum) from infection

Question 13

Pathway of flow of lymph from different parts of the body to the heart.

Answer 13

Lymphatic capillary → lymphatic vessel (afferent - unfiltered) → lymphatic node → lymphatic vessel (efferent - filtered) → lymphatic trunk → collecting duct → Subclavian vein

Collecting ducts = Left duct drains more than Right duct

1) R. Lymphatic duct drains into R. subclavian vein from right arm and chest.
2) Thoracic duct drains from places below diaphragm into the cisterna chyli
3) L. Lymphatic duct drains into L. subclavian vein from the cisterna chyli, clears all of the other areas of the body including both legs, the lower trunk upper left of the chest, and the left arm.