(Lecture 13, Chapter 15) Lymphatics

Question 1

How does the body respond to damage to its tissues and/or cells?

Answer 1

Inflammation, swelling due to accumulation of ECF

Question 2

ECF = _____ + ________ ____

Answer 2

plasma + interstitial fluid

Question 3

What is lymph/lymph fluid?

Answer 3

• Plasma and water move into surrounding interstitial fluid from blood in the capillaries
• IF is collected into lymphatic vessels, and then known as lymph

Question 4

Where is lymph collected and released?

Answer 4

• Collected at peripheral tissues

- Empties into the venous system

Question 5

Is the lymphatic system an open or closed system?

Answer 5

Open; lymphatic vessels aren’t directly connected to capillaries

Question 6

Fluid is collected, filtered in ____ ___, and returned to the blood

Answer 6

lymph nodes

Question 7

What are the responsibilities of cells, tissues, and organs in the lymphatic system? (2)

Answer 7

• Drainage (returning IF to the bloodstream)

- Immunity (enhancing the body’s ability to defend against infection, illness, and disease)

Question 8

T/F: Lymph doesn’t have to be replenished/regenerated

Answer 8

False

Question 9

Lymphatic Vessels

Answer 9

Carry lymph and lymphocytes from peripheral tissues to the veins

Question 10

Lymph Nodes

Answer 10

• Monitor the composition of lymph
• engulf pathogens
• stimulate immune response

Question 11

Spleen

Answer 11

• Monitors circulating blood
• Engulfs pathogens
• Recycles RBCs
• Stimulates immune response

Question 12

Thymus

Answer 12

Controls development/maintenance of T cells

Question 13

Lymphocytes

Answer 13

• Main cell type in lymphatic system
• Surrounded by lymph
• Respond to invading pathogens, abnormal body cells, foreign proteins

Question 14

Lymph Capillaries

Answer 14

• Open-ended
• Surround blood capillaries
• Embedded in capillary bed

Question 15

Structure of lymphatics

Answer 15

• Lymphatics have valves that form from overlapping epithelial cells, creating bulges
• Valves ensure that flow of lymph is unidirectional
• No tight junctions or basement membranes; they would prevent the flow of lymph

Question 16

Lymph flow

Answer 16

• Aided by slow/sporadic contraction of skeletal muscle
• Movement is independent of a pump (unlike the cardiovascular system)
• Valves open when the pressure of IF in interstitial space exceed that in lymphatic capillaries

Question 17

T/F: Proteins can enter both lymphatic and blood capillaries

Answer 17

False, they can only enter lymphatic capillaries

Question 18

Substances that can easily enter/exit lymphatic capillaries (3):

Answer 18

• Larger particles
• Cell debris
• Pathogens

Question 19

Thoracic Duct

Answer 19

Collects lymph from below and above/to the left of the diaphragm

Question 20

Right Lymphatic Duct

Answer 20

Collects lymph from above/to the right of the diaphragm

Question 21

What blood vessels do the thoracic duct and right lymphatic duct drain into?

Answer 21

Thoracic Duct: left subclavian vein

Right Lymphatic Duct: right subclavian vein

Question 22

Functions of lymph nodes

Answer 22

• Macrophages in lymph nodes remove/destroy microorganisms and debris
• Lymph nodes filter macrophages and debris, preventing them from going to other body parts
• Activate immune mechanisms; nodes are located where lymphocytes often encounter antigens and foreign particles

Question 23

How does bottleneck flow occur in lymph nodes? Why is it beneficial?

Answer 23

• There are many afferent lymphatic vessels and only one efferent lymphatic vessel per lymph node
• Increased residence time = more time for immune function to work

Question 24

List of lymphoid organs (5)

Answer 24

• Spleen
• Thymus
• Tonsils
• Peyer’s patches
• Appendix

Question 25

Where are Peyer’s patches located? What is significant about this?

Answer 25

• Located in the small intestine
• Lots of absorption occurs in the small intestine, so there are more opportunities for pathogens (and other stuff that has to be filtered out) to be absorbed

Question 26

Edema

Answer 26

Lymphatics fail to collect and drain fluid, causing it to accumulate

• causes pressure/pain, can be severe if it occurs around the heart or nerves
• Drained with a needle
• e.g. hyperthyroidism/goiters