Lymphatic System Ch. 20 Module 1: Section 20.01-20.02 Dynamic Study Module Flashcards

red lines under the skin that are sensitive to touch

Ex.

Lymphangitis presents itself as red lines under the skin that are sensitive to touch.

Like the larger blood vessels, the larger lymphatics receive their nutrient blood supply from a branching vasa vasorum. When lymphatic vessels are severely inflamed, the related vessels of the vasa vasorum become congested with blood. As a result, the pathway of the associated superficial lymphatics becomes visible through the skin as red lines that are tender to the touch. This unpleasant condition is called lymphangitis (lim”fan-ji’tis; angi = vessel).

Tonsils

Same three tunics as veins; the second-smallest lymph vessels

Ex.

Collecting lymphatic vessels contain the same three tunics as veins and are the second smallest of lymph vessels.

From the lymphatic capillaries, lymph flows through successively larger and thicker-walled channels—first collecting vessels, then trunks, and finally the largest of all, the ducts (figure below). The collecting lymphatic vessels have the same three tunics as veins, but the collecting vessels have thinner walls and more internal valves, and they anastomose more. In general, lymphatics in the skin travel along with superficial veins, while the deep lymphatic vessels of the trunk and digestive viscera travel with the deep arteries. The exact anatomical distribution of lymphatic vessels varies greatly between individuals, even more than it does for veins.

Smallest lymphatic vessel that collects excess tissue fluid

Ex.

Lymphatic capillaries are the s mallest lymphatic vessel that collects excess tissue fluid.

The transport of lymph begins in microscopic blind-ended lymphatic capillaries. These capillaries weave between the tissue cells and blood capillaries in the loose connective tissues of the body. Lymphatic capillaries are widespread, but they are absent from bones and teeth, bone marrow, and most of the central nervous system (where the excess tissue fluid drains into the cerebrospinal fluid).

As blood circulates through the body, nutrients, wastes, and gases are exchanged between the blood and the interstitial fluid. The hydrostatic and colloid osmotic pressures operating at capillary beds force fluid out of the blood at the arterial ends of the beds (“upstream”) and cause most of it to be reabsorbed at the venous ends (“downstream”). The fluid that remains behind in the tissue spaces, as much as 3L daily, becomes part of the interstitial fluid.

This leaked fluid, plus any plasma proteins that escape from the bloodstream, must somehow be returned to the blood to ensure that the cardiovascular system has sufficient blood volume. This problem of circulatory dynamics is resolved by the lymphatic vessels, or lymphatics, elaborate networks of drainage vessels that collect the excess protein-containing interstitial fluid and return it to the bloodstream.

A type of loose connective tissue called reticular connective tissue; dominates all lymphoid organs except the thymus

Ex.

Lymphoid tissue is a type of loose connective tissue called reticular connective tissue. It dominates all lymphoid organs except the thymus.

Lymphoid tissue is an important component of the immune system, mainly because it:

• Houses and provides a proliferation site for lymphocytes
• Furnishes an ideal surveillance vantage point for lymphocytes and macrophages

Lymphoid tissue, largely composed of loose connective tissue called reticular connective tissue, dominates all the lymphoid organs except the thymus. Macrophages live on the fibers of the reticular connective tissue network. Huge numbers of lymphocytes squeeze through the walls of postcapillary venules coursing through this network. The lymphocytes temporarily occupy the spaces in the network before leaving to patrol the body again (figure below). The cycling of lymphocytes between the circulatory vessels, lymphoid tissues, and loose connective tissues of the body ensures that lymphocytes reach infected or damaged sites quickly.

Transport of chyle

Ex.

It is not common to both lymphatic vessels and veins to transport chyle.

A special set of lymphatic capillaries called lacteals (lak’tealz) transports absorbed fat from the small intestine to the bloodstream. Lacteals are so called because of the milky white lymph that drains through them (lact = milk). This fatty lymph, called chyle (“juice”), drains from the fingerlike villi of the intestinal mucosa.

return of tissue fluid to the cardiovascular system

Ex.

A major function of the lymphatic system is to return tissue fluid to the cardiovascular system.

As blood circulates through the body, nutrients, wastes, and gases are exchanged between the blood and the interstitial fluid. The hydrostatic and colloid osmotic pressures operating at capillary beds force fluid out of the blood at the arterial ends of the beds (“upstream”) and cause most of it to be reabsorbed at the venous ends (“downstream”). The fluid that remains behind in the tissue spaces, as much as 3L daily, becomes part of the interstitial fluid.

This leaked fluid, plus any plasma proteins that escape from the bloodstream, must somehow be returned to the blood to ensure that the cardiovascular system has sufficient blood volume. This problem of circulatory dynamics is resolved by the lymphatic vessels, or lymphatics, elaborate networks of drainage vessels that collect the excess protein-containing interstitial fluid and return it to the bloodstream.

It drains the lymph from the entire left side of the body and also the right abdomen and leg.

Ex.

The thoracic duct drains the lymph from the entire left side of the body and also the right abdomen and leg.

Lymph is eventually delivered to one of two large ducts in the thoracic region. The right lymphatic duct drains lymph from the right upper limb and the right side of the head and thorax (figure below). The much larger thoracic duct receives lymph from the rest of the body. It collects lymph from the two large lumbar trunks that drain the lower limbs and from the intestinal trunk that drains the digestive organs. In about half of individuals, the thoracic duct begins as an enlarged sac, the cisterna chyli (sis-ter’nah ki’li), located in the region between the last thoracic and second lumbar vertebrae. As the thoracic duct runs superiorly, it receives lymphatic drainage from the left side of the thorax, left upper limb, and the left side of the head. Each terminal duct empties its lymph into the venous circulation at the junction of the internal jugular vein and subclavian vein on its own side of the body.

Drains right side of the head, upper limb, and neck region

Ex.

The right lymphatic duct drains the right side of the head, upper limb, and neck region.

Lymph is eventually delivered to one of two large ducts in the thoracic region. The right lymphatic duct drains lymph from the right upper limb and the right side of the head and thorax (figure below). The much larger thoracic duct receives lymph from the rest of the body. It collects lymph from the two large lumbar trunks that drain the lower limbs and from the intestinal trunk that drains the digestive organs. In about half of individuals, the thoracic duct begins as an enlarged sac, the cisterna chyli (sis-ter’nah ki’li), located in the region between the last thoracic and second lumbar vertebrae. As the thoracic duct runs superiorly, it receives lymphatic drainage from the left side of the thorax, left upper limb, and the left side of the head. Each terminal duct empties its lymph into the venous circulation at the junction of the internal jugular vein and subclavian vein on its own side of the body.

Smallest lymphatic vessels that collect tissue fluid

Ex.

Lymphatic capillaries are the s mallest lymphatic vessels that collect tissue fluid.

As blood circulates through the body, nutrients, wastes, and gases are exchanged between the blood and the interstitial fluid. The hydrostatic and colloid osmotic pressures operating at capillary beds force fluid out of the blood at the arterial ends of the beds (“upstream”) and cause most of it to be reabsorbed at the venous ends (“downstream”). The fluid that remains behind in the tissue spaces, as much as 3L daily, becomes part of the interstitial fluid.

This leaked fluid, plus any plasma proteins that escape from the bloodstream, must somehow be returned to the blood to ensure that the cardiovascular system has sufficient blood volume. This problem of circulatory dynamics is resolved by the lymphatic vessels, or lymphatics, elaborate networks of drainage vessels that collect the excess protein-containing interstitial fluid and return it to the bloodstream.

From the lymphatic capillaries, lymph flows through successively larger and thicker-walled channels:

Lymphatic capillaries → Collecting lymphatic vessels → Lymphatic trunks → Lymphatic ducts

Lymphatic capillaries

Ex.

Lymphatic capillaries are closely associated with capillary beds.

The transport of lymph begins in microscopic blind-ended lymphatic capillaries. From the lymphatic capillaries, lymph flows through successively larger and thicker-walled channels—first collecting vessels, then trunks, and finally the largest of all, the ducts.

These capillaries weave between the tissue cells and blood capillaries in the loose connective tissues of the body. Lymphatic capillaries are widespread, but they are absent from bones and teeth, bone marrow, and most of the central nervous system (where the excess tissue fluid drains into the cerebrospinal fluid). Although similar to blood capillaries, lymphatic capillaries are so remarkably permeable that they were once thought to be open at one end like a straw.

Lymph nodes

Ex.

The lymph nodes cleanse the lymph.

Although all lymphoid organs help protect the body, only the lymph nodes cleanse the lymph. The other secondary lymphoid organs typically have efferent lymphatics draining them, but lack afferent lymphatics.

Cervical nodes

Thoracic duct

Lymphatic capillaries have endothelial flap valves, but blood capillaries do not.

Ex.

Lymphatic capillaries are different from veins in that lymphatic capillaries have endothelial flap valves, but blood capillaries do not.

Although similar to blood capillaries, lymphatic capillaries are so remarkably permeable that they were once thought to be open at one end like a straw. We now know that they owe their permeability to two unique structural modifications:

• The endothelial cells forming the walls of lymphatic capillaries are not tightly joined. Instead, the edges of adjacent cells overlap each other loosely, forming easily opened, flaplike minivalves (figure below).

• Collagen filaments anchor the endothelial cells to surrounding structures so that any increase in interstitial fluid volume opens the minivalves, rather than causing the lymphatic capillaries to collapse.

Appendix

Capillaries, vessels, trunks, ducts

Ex.

The sequence that best describes the flow of lymph through the lymphatic system is capillaries, vessels, trunks, ducts.

The transport of lymph begins in microscopic blind-ended lymphatic capillaries. From the lymphatic capillaries, lymph flows through successively larger and thicker-walled channels—first collecting vessels, then trunks, and finally the largest of all, the ducts.

Thymus

Largest vessels; carry lymph fluid to subclavian veins

Ex.

Lymphatic ducts are the largest vessles and carry lymph fluid to the subclavian veins.

Lymph is eventually delivered to one of two large ducts in the thoracic region. The right lymphatic duct drains lymph from the right upper limb and the right side of the head and thorax (figure below). The much larger thoracic duct receives lymph from the rest of the body. It collects lymph from the two large lumbar trunks that drain the lower limbs and from the intestinal trunk that drains the digestive organs. In about half of individuals, the thoracic duct begins as an enlarged sac, the cisterna chyli (sis-ter’nah ki’li), located in the region between the last thoracic and second lumbar vertebrae. As the thoracic duct runs superiorly, it receives lymphatic drainage from the left side of the thorax, left upper limb, and the left side of the head. Each terminal duct empties its lymph into the venous circulation at the junction of the internal jugular vein and subclavian vein on its own side of the body.

Lymphatics

Ex.

Lymphatics are vessels that transport fluid that leaks from the vascular system back into the blood.

As blood circulates through the body, nutrients, wastes, and gases are exchanged between the blood and the interstitial fluid. The hydrostatic and colloid osmotic pressures operating at capillary beds force fluid out of the blood at the arterial ends of the beds (“upstream”) and cause most of it to be reabsorbed at the venous ends (“downstream”). The fluid that remains behind in the tissue spaces, as much as 3L daily, becomes part of the interstitial fluid.

This leaked fluid, plus any plasma proteins that escape from the bloodstream, must somehow be returned to the blood to ensure that the cardiovascular system has sufficient blood volume. This problem of circulatory dynamics is resolved by the lymphatic vessels, or lymphatics, elaborate networks of drainage vessels that collect the excess protein-containing interstitial fluid and return it to the bloodstream.

Inguinal nodes

Receives lymph from all but the right upper limb and right side of the head and thorax

Ex.

The thoracic ducts receives lymph from all but the right upper limb and right side of the head and thorax.

Lymph is eventually delivered to one of two large ducts in the thoracic region. The right lymphatic duct drains lymph from the right upper limb and the right side of the head and thorax (figure below). The much larger thoracic duct receives lymph from the rest of the body. It collects lymph from the two large lumbar trunks that drain the lower limbs and from the intestinal trunk that drains the digestive organs. In about half of individuals, the thoracic duct begins as an enlarged sac, the cisterna chyli (sis-ter’nah ki’li), located in the region between the last thoracic and second lumbar vertebrae. As the thoracic duct runs superiorly, it receives lymphatic drainage from the left side of the thorax, left upper limb, and the left side of the head. Each terminal duct empties its lymph into the venous circulation at the junction of the internal jugular vein and subclavian vein on its own side of the body.

It maintains blood volume and, hence, pressure.

Ex.

The lymphatic system's role in relation to the cardiovascular system is to maintain blood volume and, hence, pressure.

As blood circulates through the body, nutrients, wastes, and gases are exchanged between the blood and the interstitial fluid. The hydrostatic and colloid osmotic pressures operating at capillary beds force fluid out of the blood at the arterial ends of the beds (“upstream”) and cause most of it to be reabsorbed at the venous ends (“downstream”). The fluid that remains behind in the tissue spaces, as much as 3 L daily, becomes part of the interstitial fluid.

This leaked fluid, plus any plasma proteins that escape from the bloodstream, must somehow be returned to the blood to ensure that the cardiovascular system has sufficient blood volume. This problem of circulatory dynamics is resolved by the lymphatic vessels, or lymphatics, elaborate networks of drainage vessels that collect the excess protein-containing interstitial fluid and return it to the bloodstream.

A one-way system of vessels beginning with blind-ended lymphatic capillaries

Ex.

The lymphatic vessels form a one-way system in which lymph flows only toward the heart.

The transport of lymph begins in microscopic blind-ended lymphatic capillaries. These capillaries weave between the tissue cells and blood capillaries in the loose connective tissues of the body. Lymphatic capillaries are widespread, but they are absent from bones and teeth, bone marrow, and most of the central nervous system (where the excess tissue fluid drains into the cerebrospinal fluid).

Delivery of nutrients to tissues

Ex.

Lymphatic vessels do not deliver nutrients to tissues.

As blood circulates through the body, nutrients, wastes, and gases are exchanged between the blood and the interstitial fluid. The hydrostatic and colloid osmotic pressures operating at capillary beds force fluid out of the blood at the arterial ends of the beds (“upstream”) and cause most of it to be reabsorbed at the venous ends (“downstream”). The fluid that remains behind in the tissue spaces, as much as 3L daily, becomes part of the interstitial fluid.

This leaked fluid, plus any plasma proteins that escape from the bloodstream, must somehow be returned to the blood to ensure that the cardiovascular system has sufficient blood volume. This problem of circulatory dynamics is resolved by the lymphatic vessels, or lymphatics, elaborate networks of drainage vessels that collect the excess protein-containing interstitial fluid and return it to the bloodstream.

A special set of lymphatic capillaries called lacteals (lak’tealz) transports absorbed fat from the small intestine to the bloodstream. Lacteals are so called because of the milky white lymph that drains through them (lact = milk). This fatty lymph, called chyle (“juice”), drains from the fingerlike villi of the intestinal mucosa.

Lymphedema

Ex.

Tumors that block the lymphatics or lymphatics are removed during cancer surgery may result in what condition termed lymphedema.

Anything that prevents the normal return of lymph to the blood—such as when tumors block the lymphatics or lymphatics are removed during cancer surgery—results in shortterm but severe localized edema (lymphedema). In some cases, the lymphedema improves if some lymphatic pathways remain and can enlarge.

Axillary nodes

Collect lymph fluid draining from lymphatic capillaries

Ex.

Lymphatic collecting vessels collect lymph fluid draining from lymphatic capillaries.

From the lymphatic capillaries, lymph flows through successively larger and thicker-walled channels—first collecting vessels, then trunks, and finally the largest of all, the ducts. The collecting lymphatic vessels have the same three tunics as veins, but the collecting vessels have thinner walls and more internal valves, and they anastomose more. In general, lymphatics in the skin travel along with superficial veins, while the deep lymphatic vessels of the trunk and digestive viscera travel with the deep arteries. The exact anatomical distribution of lymphatic vessels varies greatly between individuals, even more than it does for veins.

Peyer's patches

Cisterna chyli