A&p II lymph system chap 22 slides

What are the 3 major functions of the lymphatic system?

Fluid balance, lipid absorption, and defense.

What happens to excess interstitial fluid in the lymphatic system?

It enters lymphatic capillaries and becomes lymph.

What is the role of the lymphatic system in fluid balance?

It returns excess interstitial fluid and leaked proteins to the blood.

What are lacteals

and what do they absorb?, Lacteals are lymphatic capillaries in the digestive tract that absorb fats and other substances.

What is fatty lymph called?

Chyle.

How does the lymphatic system contribute to defense?

Lymph nodes filter microorganisms and foreign substances from lymph, while the spleen filters the blood.

What are the major components of the lymphatic system?

Lymph, lymphatic vessels, lymphatic tissues, lymphatic nodules, lymph nodes, tonsils, thymus, and spleen.

Are the terms lymphoid and lymphatic often used interchangeably?

Yes. The term lymph can also be used as a shortened version of these terms.

What is lymph?

A watery fluid formed when excess tissue fluid, primarily blood plasma that leaked from blood capillaries, enters lymphatic capillaries.

What does lymph contain?

Large amounts of water, proteins, lipids, and other materials.

Where does lymph eventually return?

To the cardiovascular system through lymphatic vessels.

What does lymph return to the blood?

Excess interstitial fluid and leaked proteins.

What is edema?

Swelling caused by an abnormal increase in interstitial fluid volume.

What is the overall function of lymphatic vessels?

To carry fluid away from tissues and ultimately return it to the blood.

Why does lymph need special mechanisms to move through lymphatic vessels?

There is no pump to move lymph through the vessels, so other mechanisms are needed, especially to move lymph against gravity.

What prevents lymph from flowing backward?

One-way valves.

What causes smooth muscle contraction in lymphatic vessels to help move lymph?

Contraction of smooth muscle in the vessel walls.

How does body movement help move lymph?

Skeletal muscle contractions compress lymphatic vessels and move lymph.

How does breathing help move lymph?

Pressure changes during breathing help move lymph through the vessels.

What is the general order of lymphatic vessels from smallest to largest?

Lymphatic capillaries → lymphatic vessels → lymphatic trunks → lymphatic ducts.

How are lymphatic capillaries different from blood capillaries in permeability?

Lymphatic capillaries are more permeable.

How does fluid enter lymphatic capillaries?

Flap-like endothelial cells act as one-way valves that allow fluid to enter.

What does it mean that lymphatic capillaries are blind-ended?

They end rather than forming a closed circuit like blood vessels.

Where are lymphatic capillaries found?

Almost everywhere except the nervous system, bone marrow, and avascular tissues.

How are larger lymphatic vessels formed?

Lymphatic capillaries join together to form larger lymphatic vessels.

What blood vessels are lymphatic vessels structurally similar to?

Veins.

What structures are located along lymphatic vessels?

Lymph nodes, which filter lymph.

What are lymphatic trunks?

Larger vessels formed when lymphatic vessels join together.

What do lymphatic trunks drain?

Specific large areas of the body.

Where can lymphatic trunks deliver lymph?

Some carry lymph directly to veins, while others join together to form lymphatic ducts.

What does the jugular trunk drain?

The head and neck.

What does the subclavian trunk drain?

The upper limbs, superficial thoracic wall, and mammary glands.

What does the bronchomediastinal trunk drain?

The deep thoracic organs and deep thoracic wall.

What does the intestinal trunk drain?

The abdominal organs.

What does the lumbar trunk drain?

The lower limbs, pelvic and abdominal walls, and pelvic organs.

Where do lymphatic ducts return lymph to the bloodstream?

At the junction of the internal jugular and subclavian veins.

What does the right lymphatic duct drain?

The right side of the head, right upper limb, and right side of the thorax.

What does the thoracic duct drain?

The rest of the body.

What are primary lymphoid organs?

Areas where T cells and B cells mature and become immunocompetent.

Where do B cells mature?

Red bone marrow.

What are secondary lymphoid organs and tissues?

Areas where mature lymphocytes first encounter their antigen and become activated.

What are the major secondary lymphoid organs and tissues listed in the slides?

Lymphatic tissues, thymus, lymphatic nodules, lymph nodes, tonsils, and spleen.

What cells are found in lymphoid tissue?

Lymphocytes, macrophages, dendritic cells, reticular cells, and other cell types.

What do fine collagen reticular fibers do in lymphoid organs and tissues?

They act as filters that trap microorganisms and other particles.

Are lymphoid organs encapsulated?

Yes, except the thymus; lymphoid organs have a connective tissue capsule.

Are lymphoid tissues encapsulated?

No. Lymphoid tissues do not have a connective tissue capsule.

What does MALT stand for?

Mucosa-associated lymphatic tissue.

What structures are examples of MALT?

Tonsils, Peyer's patches, and the appendix.

What are tonsils?

Groups of lymphatic nodules associated with the digestive and respiratory mucosa and are part of MALT.

What is the function of the tonsils?

They protect against pathogens entering through the nose and mouth.

Where are the tonsils located?

They form a ring around the border between the oral cavity and pharynx.

What is the pharyngeal tonsil and where is it located?

One large tonsil called the adenoids, located in the pharyngeal region.

Where are the palatine tonsils located?

Two tonsils located on the sides of the throat.

Where is the lingual tonsil located?

One large tonsil located at the base of the tongue.

Where are Peyer's patches located?

In the distal end of the small intestine.

What are Peyer's patches structurally similar to?

Tonsils.

What is the function of Peyer's patches?

They destroy pathogens in the intestine to prevent them from passing through the intestinal wall into the lymph, blood, or tissue spaces.

What is the appendix?

A worm-like structure that hangs off the cecum at the proximal end of the large intestine.

What does the appendix contain?

A large number of lymphoid follicles.

What is the function of the appendix?

It has the same function as Peyer's patches: destroying pathogens in the intestine.

Why is the appendix prone to infection?

Its structure makes it prone to trapping pathogens and becoming infected.

What are lymph nodes?

Small, round or bean-shaped structures responsible for filtering lymph.

How large are lymph nodes?

Approximately 1-25 mm long.

Where are lymph nodes located?

Both deep and superficially throughout the body.

Where are superficial lymph nodes especially abundant?

The axillary, cervical, and inguinal regions.

What happens to substances removed by lymph nodes?

They are removed by phagocytosis or stimulate lymphocytes to proliferate in germinal centers.

Where is the spleen located?

In the left upper quadrant of the abdomen, tucked behind the stomach.

What does the spleen filter?

Blood, not lymph.

What role do macrophages in the spleen have?

They destroy old and defective red blood cells and remove other debris from the blood.

What happens to the breakdown products of red blood cells in the spleen?

They are stored to be recycled.

What else does the spleen store?

Platelets.

When is the spleen a site of red blood cell production?

During fetal development.

What is the thymus?

A bilobed gland located in the superior part of the mediastinum, just anterior to the heart.

How does the thymus change with age?

It grows rapidly during the first year of life and then gradually atrophies with age.

When does the thymus work the hardest?

During the first year of life, when it establishes its part of the immune system.

Does the thymus stop functioning completely as we age?

No. It maintains its part of the immune system for the rest of life, although less use leads to atrophy.

What is the main function of the thymus?

It is the site where T cells mature.

What does the thymus secrete?

Thymosin, which is important for T-cell development.

How do lymphatic capillaries and vessels contribute to lymph flow?

They remove excess fluid from tissues, forming lymph.

What do lymph nodes do during lymph flow?

They filter lymph and provide sites where lymphocytes respond to infections.

What do lacteals do?

They absorb lipids in the small intestine, forming chyle.

Where does lymph/chyle travel before entering the blood?

Through the thoracic duct or right lymphatic duct.

Where do the lymphatic ducts empty into the blood?

At the junction of the internal jugular vein and subclavian vein on either side.

What additional function does the spleen have besides filtering blood?

It is a site where lymphocytes respond to infections.

Where do lymphocytes originate?

From stem cells in the red bone marrow.

Where do pre-B cells mature?

In the red bone marrow before being released into the blood.

Where do pre-T cells go after originating from the red bone marrow?

They migrate to the thymus.

What happens to pre-T cells in the thymus?

They increase in number and mature before being released into the blood.

What eventually happens to B cells and T cells after entering the blood?

They leave the blood and enter lymphatic tissues, where they either remain or leave to respond to infections throughout the body.