Question

diffrentiate the composition of lymph and blood . specify the origin and flow pathway for both through gheir respective vessels

Answer 1

• Blood is red in color, whereas lymph is slight yellowish white in color.
• Blood have RBCs, whereas lymph does not have.
• Blood has more neutrophils, whereas lymph has more lymphocytes.
• Oxygen content is more in blood than lymph.
• CO2 content is less in blood , whereas it is more in lymph.
• Protein is more in blood than in lymph.
• Lymph has less protein content compared to blood because of presence of water.
• There is less protein in the lymph when compared to blood.
• There is high osmotic pressure in the blood than in lymph due to more protein content.
• The ratio of albumin to globulin will be more in lymph compared to to blood, because only small sized proteins can be leaked out from the blood through the pores of capillary walls.
• Blood circulatory system is a closed system where as lymphatic system is not closed. Blood vessels starts and ends in heart ; lymphatic system start in the interstitium and ends in veins.
• Heart pumps blood through artery, arteriole, reaching capillaries near the tissues. At the capillary bed exchange of oxygen and nutrients and removal of waste products occurs and passes into the small venules and eventually to the larger veins and to the heart.

LYMPHATIC CIRCULATION

Lymph is the fluid leaked out from capillaries near the tissues into the interstitial space, containing water, small proteins (mainly albumin), pathogens, cells of lymphatic system, cell products (example: hormones) and cell debris (No RBCs). Blood contains Water, Blood cells (RBCs, WBCs and platelets), Proteins (Albumin, Globulin, Fibrinogen). It is similar to blood but low in protein. Lymph is contained most in lymphatic vessels. It is a clear colorless fluid. The function of lymph is to return excess body fluid back to the circulation, transportation of fat from intestine to the blood and act as a major part of immunological defence system to resist the body against infections. Lymph plays an important role in immune function. Lymphoid organs remove foreign material from to keep it from entering the bloodstream.
Hundreds of lymph nodes cluster along the lymph vessels. Lymph nodes can be felt in neck and armpit and groin. The lymph nodes present in the intestinal wall are called peyer's patches. When infection occurs the pathogen can be drained to the lymph vessels and then to lymph nodes, where pathogen is detected by the dendritic cells.

Some fluid is getting lost from the blood through the single layer walls of capillaries in the interstitium or extracellular space. When the pressure in the interstitial space is higher than that in the lymphatic capillaries the endothelial mini valves open up allowing the fluid to get in. This fluid is picked up by lymphatic capillaries or plexus passing through afferent lymph vessels done to the lymph nodes. From where it passes through efferent lymph vessels, lymph trunk and lymphatic duct back to the heart to mix with venous system. There is no pump pushing the lymph through the lymphatic system. smooth muscles in the lymphatic capillaries react to the arterial pulse near to the lymph vessels squeezing to move the lymph eventually reaching the lymphatic trunk. to prevent the back for there are valves present inside the lymphatic capillaries just like veins. The lymphatic trunks are named in various parts of body from where the lymph is drained from.

• A pair of Lumbar trunks
• A pair of broncho-mediastinal trunk
• A pair of subclavian trunks
• A pair of jugular trunks
• An intestinal trunk

From there the lymph is drained to either to the right lymphatic duct which collects lymph from right arm and right side of neck and chest or the thoracic duct which collects lymph from rest of the body. The right lymphatic duct joins the right jugular vein and right subclavian vein. Thoracic duct drains lymph to the same junction on the left side of the body. Out of 100% blood reaching the tissues 90 % goes back through veins and 10% goes to lymph vessels. Laterals are special type of lymphatic vessels found in the villi of small intestine that will drain to lymphatic vessels and then to the big veins. This lymphatic system is major route of transport of fat absorbed by gastrointestinal tract. The function of lymph nodes are like interrogation rooms, that act on pathogen to destroy them so that bacteria cannot enter the blood circulation. Lymphatics are all over the body except CNS, bone, bone marrow, teeth, cartilage and epithelium. There are two types of lymphatic vessels - superficial and deep. Superficial vessels are in the subcutaneous tissue and accompanying veins. Deep muscles accompany the arteries and receive internal organ's drainage.

BLOOD CIRCULATION

There are 2 types of circulation mainly:

• Pulmonary circulation (to the lungs)and
• Systemic circulation(to body organs)

Pulmonary circulation

When the right ventricle contract, the deoxygenated blood from the right ventricle enters to the pulmonary artery through the semilunar valve and takes the blood into the lungs.As the blood goes through the lung, it is oxygenated by the gas exchange inside the lungs.The oxygenated blood enters back into the heart to the left atrium through the pulmonary vein.

Systemic circulation

The oxygenated blood enters the left ventricle when atrial contraction occurs: by the opening of the bicuspid valve present between the left atrium and ventricle.,When the ventricular contraction occurs, it enters into the aorta by opening of the semilunar valve.Then the blood travels through the large arteries into the various parts of the body.Then it branches to the smaller arteries and finally the arterioles near the tissues, where the oxygen and nutrients are delivered to the tissues and the waste material like CO2 are recieved.Then the Deoxygenated blood enters to the venules and go through the various veins ultimately reaching the superior and inferior vena cava taking the blood to the right atrium.The atrial contraction occurs and the blood enters to the right ventricle by the opening of the tricuspid valve.

The blood from aorta goes to arms via brachial artery carrying the oxygenated blood to arms. It becomes deoxygenated and drains to cephalic vein and ultimately to the superior venacaval.

The other blood from the aorta goes to the large arteries in the head; carotid arteries, which become Deoxygenated as go through the tissue and drains to jugular vein and ultimately drain to the superior vena cava to the right atrium.

The some of the blood from the aorta goes to the liver via hepatic artery and, the deoxygenated blood from the liver drains to the right atrium through the inferior vena cava.

The oxygenated blood goes to GIT via mesenteric artery, and it will become deoxygenated, but not directly drained into systemic circulation; instead it drains to the liver and from there it joins the hepatic vein. (Hepatic portal Circulation)

Some of the blood goes to kidney through the renal artery and drains to the inferior vena cava by the renal vein.

The blood goes down to the tissues of the leg and supplies oxygen via femoral arteries and drains back to the inferior vena cava via the femoral veins.

Superior vena cava - Right atrium - Tricuspid valve cross - Right ventricle - Pulmonary semilunar valve cross - Pulmonary artery - Lung (alveoli) - Receives oxygen - Pulmonary vein - Left atrium - Bicuspid valve cross - Left ventricle - Aortic semilunar valve - Aorta - to body tissues

Right side

Inferior vena cava and superior vena cava are the main veins that bring the blood into the right atrium of the heart from the tissues.There is another opening that opening into the right atrium called coronary sinus.There is a hole found between the right atrium & the left atrium(during birth). This foramen ovale will be turned into the scar tissue during the development called fossa ovalis. SA node is found (a bunch of neural cells) found near the right atrium which help in the cardiac rhythm.

Left side

The left pulmonary veins bringing oxygenated blood from the left lung, and the right pulmonary veins drain the oxygenated blood from the right lung to the left atrium.

Valves:

Tricuspid valve are found in between the right atrium and ventricle. The bicuspid (mitral )valve is found in between the left atrium and ventricle.There are collagen structures that connects the valves to the inner wall of the ventricle called chorda tendinae. The papillary muscles are found on the inner wall of the ventricle upon which the chorda tendinae is attached.On contraction and relaxation of these muscles, These chorda tendinae will help the respective valves to open and close whenever needed.

The right ventricle have to pump out the high volume of the blood into the pulmonary artery, where there is a valve present in the opening of the pulmonary artery, called pulmonary semilunar valve. Another one that separating the left ventricle and the aorta called aortic semilunar valve. Both function to prevent the back flow of the blood from these vessels.

The septum that separating the two ventricles is called the Interventricular septum.The septum present between the atriums is called interatrial septum.