Question

The right pinky finger : Describe the formation of lymph within right pinky finger , relating that to blood vessels within the right pinky finger and addressing the physical forces that lead to lymph production. How would the lymph that is formed in right pinky finger be returned to the blood supply? What vessels and lymph organs would it travel through? For the second part of your discussion imagine that there is a potential pathogen within your identified region - what involvement of other lymph organs or individual immune cells would you expect?

Answer 1

Introduction:

The lymphatic system is a complex network of thin vessels, valves, ducts, nodes, and organs.

Lymph: It is the fluid, formed from the interstitial fluid due to the permeability of the lymph capillaries it flows through the lymphatic system.

Formation:

When blood passes via blood capillaries through tissues, 9/10 of fluid passes into the venous end of capillaries from the arterial end.

And remaining 1/10 of the fluid passes into lymph capillaries.

Composition:

It contains 96% water, 4% solids and some blood cells.

Solids include Protein, Lipids, Urea, creatinine, Amino acids, Electrolytes, and Lymphocytes.

Functions:

• Return protein from tissue spaces into blood.
• Redistribution of fluid in the body.
• Removal of bacteria, toxins and other foreign bodies/
• Maintenance of structural and functional integrity of the tissue.

Lymphatic drainage of the right pinky finger:

• The lymphatic system arises from tissue spaces as a meshwork of delicate vessels.
• These vessels are called lymph capillaries.
• Lymphatic capillaries are the sites of lymph fluid collection and are distributed throughout most tissues of the body, particularly connective tissue.
• Lymphatic capillaries reabsorb excessive tissue fluid and interstitial fluid from the blood capillaries and transport the fluid through the lymphatic pathway, and ultimately dispose it into the blood.
• In the case of the right pinky finger, the capillaries would arise from the digital branch of the ulnar artery.
• This fluid is mainly water from plasma from the blood capillary that leaks into the interstitial space in the tissues due to pressure forces exerted by capillaries (hydrostatic pressure) or through osmotic forces from proteins (osmotic pressure).
• When the pressure for interstitial fluid in the interstitial space becomes large enough it leaks into lymph capillaries, which are the site for lymph fluid collection.
• When pressure is greater in the interstitial fluid than in lymph, the minivalve cells (present in the lymph capillaries and acting as a valve) separate slightly and interstitial fluid enters the lymphatic capillary. When pressure is greater inside the lymphatic capillary, the cells of the minivalves adhere more closely, and lymph cannot flow back into the interstitial fluid.
• The lymph vessels that receive lymph fluid from many capillaries are called collecting vessels.
• Lymphatic capillaries are slightly larger in diameter and have greater oncotic pressure than blood capillaries.
• The lymph capillaries feed into larger lymph vessels
• Lymph flows in one direction toward the heart.
• Lymph vessels become larger, with better developed smooth muscle and valves to keep lymph moving forward despite the low pressure and adventitia to support the lymph vessels.
• As the fluid increases, the lymph vessels become larger their function changes from collecting fluid from the tissues to propelling fluid forward.
• The fluid reaches the nearest lymph node.
• These capillaries form large lymphatic vessels.
• The lymph nodes are present along the course of lymphatic vessels.
• Lymph nodes work like a biological filtering system of the lymph.

Filtration of lymph:

In the case of the right pinky finger, the lymph would be transported to the lateral group of the axillary lymph nodes.

• Lymph circulates to the lymph node via afferent lymphatic vessels and drains into the lymph node in the subcapsular sinus.
• Small glands called lymph glands or lymph nodes are interposed during the course of lymph vessels.
• When lymph passes through lymph nodes, it is filtered i.e, the water and electrolytes are removed. But, the proteins and lipids are retained in the lymph.
• The bacteria and other toxic substances are destroyed by macrophages.
• Because of this, lymph nodes are called defense barriers.
• Each lymph node is formed by a cortical sinus and a medullary sinus.
• The cortex contains collections of lymphocytes. These contain predominantly B-lymphocytes and some T-lymphocytes.
• The medullary sinus is lined by phagocytes.
• The lymph vessel reaching a node is called the afferent vessel.
• It divides into many small channels, which open through cortical sinuses.
• The sinuses open into medullary sinuses.

• When the body is invaded by foreign organisms, the painful swelling sometimes felt in the neck, armpits, groin, or tonsils comes from the microorganisms being trapped inside collections of lymph cells or nodes.

• Eventually, these organisms are destroyed and eliminated by cells that line the walls of the lymph nodes and the swelling and pain subside.

• The nodes contain white blood cells that can attack any bacteria or viruses they find in the lymph as it flows through the lymph nodes.
• From medullary sinuses, 1 or 2 efferent vessels arise and leave the node.

Collecting ducts: Formed by the convergence of larger lymphatic vessels called lymphatic trunks.

• In the case of the right pinky finger, the efferent vessels from lateral axillary nodes and form the right lymphatic duct and it returns lymph to the right subclavian vein which then merges into the vena cava, the large vein that brings deoxygenated blood to the heart.

In the case of a pathogen present.

• Lymph contains lymphocytes.
• they recognize the proteins on surface of the pathogens called antigens.
• Lymphocytes recognize that these are foreign and produce antibodies.
• The antibodies cause pathogens to stick together and make it easier for phagocytes to engulf them.
• They can also be drained to the lymph node as explained above.