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Anatomy of the lymphatic system

The left panel shows a female human body, and the entire lymphatic system is shown. The right panel shows magnified images of the thymus and the lymph node. All the major parts in the lymphatic system are labeled.
Lymphatic vessels in the arms and legs convey lymph to the larger lymphatic vessels in the torso.

A major distinction between the lymphatic and cardiovascular systems in humans is that lymph is not actively pumped by the heart, but 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. Lymph flows from the lymphatic capillaries, through lymphatic vessels, and then is dumped into the circulatory system via the lymphatic ducts located at the junction of the jugular and subclavian veins in the neck.

Lymphatic capillaries

Lymphatic capillaries , also called the terminal lymphatics, are vessels where interstitial fluid enters the lymphatic system to become lymph fluid. Located in almost every tissue in the body, these vessels are interlaced among the arterioles and venules of the circulatory system in the soft connective tissues of the body ( [link] ). Exceptions are the central nervous system, bone marrow, bones, teeth, and the cornea of the eye, which do not contain lymph vessels.

Lymphatic capillaries

This image shows the lymph capillaries in the tissue spaces, and a magnified image shows the interstitial fluid and the lymph vessels. The major parts are labeled.
Lymphatic capillaries are interlaced with the arterioles and venules of the cardiovascular system. Collagen fibers anchor a lymphatic capillary in the tissue (inset). Interstitial fluid slips through spaces between the overlapping endothelial cells that compose the lymphatic capillary.

Lymphatic capillaries are formed by a one cell-thick layer of endothelial cells and represent the open end of the system, allowing interstitial fluid to flow into them via overlapping cells (see [link] ). When interstitial pressure is low, the endothelial flaps close to prevent “backflow.” As interstitial pressure increases, the spaces between the cells open up, allowing the fluid to enter. Entry of fluid into lymphatic capillaries is also enabled by the collagen filaments that anchor the capillaries to surrounding structures. As interstitial pressure increases, the filaments pull on the endothelial cell flaps, opening up them even further to allow easy entry of fluid.

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.

Larger lymphatic vessels, trunks, and ducts

The lymphatic capillaries empty into larger lymphatic vessels, which are similar to veins in terms of their three-tunic structure and the presence of valves. These one-way valves are located fairly close to one another, and each one causes a bulge in the lymphatic vessel, giving the vessels a beaded appearance (see [link] ).

The superficial and deep lymphatics eventually merge to form larger lymphatic vessels known as lymphatic trunks    . On the right side of the body, the right sides of the head, thorax, and right upper limb drain lymph fluid into the right subclavian vein via the right lymphatic duct ( [link] ). On the left side of the body, the remaining portions of the body drain into the larger thoracic duct, which drains into the left subclavian vein. The thoracic duct itself begins just beneath the diaphragm in the cisterna chyli    , a sac-like chamber that receives lymph from the lower abdomen, pelvis, and lower limbs by way of the left and right lumbar trunks and the intestinal trunk.

Questions & Answers

what is the difference between a neuron and nerve?
Tonny Reply
Neurons are specialized cells which are capable of transmitting signals between different parts of the body. Nerve is a bundle of fibers composed of neurons. Therefore, neurons and nerves are closely related.
acquosuah
wow
Andy
what are the first aid procedures
Andy
what is a positive and negative feedback and give examples of both positive and negative feedback
esther Reply
Positive feedback is a feedback that tends to magnify its output. An example of positve feedback is the release of oxytocin from the pitutary gland during child birth. Negative feedback regulates a stimulus to cause a opposite effect. An example of this is when you eat your blood sugar rises,which
Camello
is sensed by the nervous system. specialized cells in the pancreas sense the increase and release the hormone insulin.
Camello
merci beaucoup
esther
what then is Pathological anatomy
acquosuah Reply
anatomy study about normal human organ... pathological anatomy study of diseased organ
Aswin
thanks
acquosuah
wow
Morshed
that's are good
Morshed
why oral glucose make insulin response in 1 phase but IV glucose make insulin response in 2 phase?
qwe Reply
what is anatomical position?
Kakande Reply
it's de description of any region or part of the body in specific strance
Andy
the standard anatomical position is standing straight with your hand an feet forward and the neck straight and face facing forward
Lubabah
how many cell do we have in our body
Sawmtei Reply
around 37.2 trillion
Jeremiah
how do you know when a women is lying
Hernandez
go with your gut
Stephanie
what is a positive and negative feedback and give examples of negative and positive feedback
esther Reply
messa I didn't understand this too
Shammy
and would love to know as well
Shammy
what are the various types of white blood cells
Andy Reply
what is cpr in first aid
Andy
various whiteblood cells includes Granulocytes (neutrophils,basophils ana eosinophils) and Agranulocytes (monocytes and lymphocytes)
Waziri
Cardiopulmonary resuscitation (cpr) is an emergency procedure. Uses chest compressions with artificial ventilation in an effort to preserve brain function until further measures are taken to restore blood circulation and breathing in a person who is in cardiac arrest.
Jeremiah
wow thanks alot
Andy
respiration is not just taking in of oxygen and bringing out Co2. that is called INHALATION AND EXHALATION. BUT RESPIRATION IS THE BREAKDOWN OF LARGE MOLECULES OF GLUCOSE OR OTHER SUBSTRATES IN THE PRESENCE OF OXYGEN AND SUBSEQUENT REMOVAL OF WASTE PRODUCT
Osuji Reply
why study anatomy?
esther Reply
to know the detailed functioning of the internay body organs
Jam
we study anatomy to know about the structure of the organs which in turn help to study physiology which is the knowledge related to function of the vital organ,and when we know the normal functionality we can understand the abnormalities in that organ,and the study of disease is called pathology
Lubabah
why is it so hard to know the spelling and words
Sawmtei
they were made so that only the best and thr brightest would understand.
Senen
thank you
esther
to know the internal structure of the human body and how it function
Jaafar
whats antonmy
Jaan Reply
the study of structure and function of internal body parts
Jam
is a branch of biology which describes the structures of the body and relationship from one part to another
esther
I believe it is the scientific study of body structures that are both macro and micro.
acquosuah
wat the question is tis ! without knowing tis simple thing.. y didn't install tis app ..
Aswin
what is anatomy and physiology
mwitwa Reply
Anatomy is the study of structures of the body
Zunehri
Physiology the study functions of the body
Zunehri
anatomy is study of structure of body nd physiology is study of function of body.
PRIYANKA
anatomy is the study of internal body structures and physiology is the functioning of these structures in the body
Jam
what is lungs
Shipon Reply
it an organ found in our thoracic cavity
Richard
lungs are spongy organs where our respiration takesplace
Maryama
Lungs is a spongy organs located in the chest , is an a primary organs of respiration in human body and other Animals
Zunehri
lungs thorex me present hote hai ye organ hai and gas exchange (o2,co2 exchange)inka inka function hai.
PRIYANKA
lungs ka function hai
OM
pls am a student I don't know
Mavis
main function is respiration
faheem
respiration is the taking ing of oxygen by the body tissues and the removal of carbondioxide from the body tissues
Jam
what is heart beat,?
Naqeeb Reply
heart beat is the process briting
Mavis
what functions of heart
Muthu Reply
To circulate the blood
Arshad
it pump blood to the lungs
Laura
very twiest
Shipon

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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