Lymphatic System and Digestive System: Lecture Exam 5 Study Guide, Exercises of Acting

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Lecture Exam 5 Study Guide

• TOPICS: The Lymphatic System and The Digestive System

What is the Lymphatic System?

• The lymphatic system is a series

of vessels , ducts, and trunks that remove interstitial fluid from the tissues and return it the blood.

Functions of the lymphatic

system

• Carries excess fluids to the

bloodstream

• Filters pathogens from the blood
• Lymph nodes swell during an

infection

• Transports immune cells (white

blood cells or lymphocytes)

Lymphatic System – Fluid Transport

• A major function of the lymphatic system is to drain body fluids and return them to the bloodstream. - Blood pressure causes leakage of fluid from the capillaries, resulting in the accumulation of fluid in the interstitial space. - Once this filtrate is out of the bloodstream and in the tissue spaces, it is referred to as interstitial fluid.

Functions of

the Lymphatic

System

~20 liters of fluid (plasma) diffuses

out of the blood vessels at the level

of the capillaries

~17 liters of this interstitial fluid is

reabsorbed directly by the blood

vessels.

~3 liters is brought back to the

blood vessels through lymphatic

vessels - via a series of vessels,

trunks, and ducts.

Primary lymphoid organs

• Primary lymphoid organs include:
  • the bone marrow
  • The thymus gland
  • The bone marrow and thymus are the locations where lymphocytes of the adaptive immune system proliferate and mature.

lymphatic fluid

• Lymph or lymphatic

fluid is the term used

to describe interstitial

fluid once it has

entered the lymphatic

system.

Lymphatic Capillaries

• lymph is not actively pumped by the heart
• lymph is forced through the vessels by… - the movements of the body- the contraction of skeletal muscles during body movements, and breathing. - One-way valves (semi-lunar valves) in lymphatic vessels keep the lymph moving toward the heart.

Lymphatic Capillaries

• Lymphatic capillaries, also called the terminal lymphatics, are vessels where interstitial fluid enters the lymphatic system to become lymph fluid.
• Lymphatic capillaries are interlaced among the arterioles and venules of the circulatory system in the soft connective tissues of the body.

lacteals

• In the small intestine, lymphatic

capillaries called lacteals are critical for

the transport of dietary lipids and lipid-

soluble vitamins to the bloodstream.

• In the small intestine, dietary

triglycerides combine with other lipids

and proteins, and enter the lacteals to

form a milky fluid called chyle.

• The chyle then travels through the

lymphatic system, eventually entering

the liver and then the bloodstream.

lymph nodes

• Cells of the immune system also use lymph nodes as major staging areas for the development of critical immune responses.
• A lymph node is one of the small, bean-shaped organs located throughout the lymphatic system.

Lymphatic Vessels

• The lymphatic vessels begin as capillaries, which feed into larger and larger lymphatic vessels, and eventually empty into the bloodstream by a series of ducts.