LYMPHATIC VESSEL (anatomical view)

-Amirah Nu’aimi Binti Zakaria

-Siti Sarah Amiza Binti Md Amin

• A vessel that carries fluid only away from tissues. This fluid is a pale, watery substance known as lymph. • Act as reservoirs for plasma and other substances including cells that have leaked from the vascular system and transport lymph fluid back from the tissues to the circulatory system. • In anatomy, lymph vessels are lined by endothelial cells, and have a thin layer of smooth muscles, and adventitia that bind the lymph vessels to the surrounding tissue. •There are three main types of lymphatic vessels which are lymph capillaries, lymphatics and lymph ducts. • There is no pump in the lymphatic system like the heart in the cardiovascular system. The pressure gradients to move lymph through the vessels come from : 1. the skeletal muscle action, 2. respiratory movement, 3. contraction of smooth muscle in vessel walls.

LYMPHATIC VESSEL

LYMPHANGION

• Is a functional unit of a lymph vessel which is the segment between two valves.

• Have valves to prevent backflow of blood.

• Smooth muscles in the walls of the lymphatic vessels cause the angions to contract sequentially to aid the flow of lymph toward the thoracic region.

LYMPHATIC CAPILLARIES

• The smallest lymph vessels are the lymph capillaries, which begin in the tissue spaces as blind-ended sacs.

• Found in all regions of the body except the bone marrow, central nervous system, and tissues, such as the epidermis, that lack blood vessels.

• Mainly concerned with absorption of interstitial fluid from the tissues.

• Lymph vessels that carry lymph to a lymph node are called the afferent lymph vessel. • One that carries it from a lymph node is called the efferent lymph vessel, from where the lymph may travel to another lymph node, may be returned to a vein, or may travel to a larger lymph duct.

LYMPHATICS

LYMPHATIC DUCTS

Right Lymphatic Duct Thoracic Duct

Collects lymph from the right side of the head, the right neck, the right upper limb and the right side of the chest.

Collects all the lymph from the hind limbs and alimentary canal. Also receives the left cervical duct which collects lymph from the left forelimb, left side of the neck and chest.

Empties into the venous system at the right subclavian vein and internal jugular vein.

Opens into the venous system at the junction of the left internal jugular vein and subclavian vein.

• Lymph ducts drain the lymph into one of the subclavian and internal jugular veins and thus return it to general circulation

Histology of Lymph Vessels BY

KHIRROL NIZAM D11A014 NUR ALYAA D11023

• found in all tissues except the CNS, cartilage, bone and bone marrow, thymus, teeth, and placenta

• difficult to demonstrate satisfactorily in normal tissues

• frequently collapse to the point of invisibility during tissue processing

• easily visualized and studied during pathological processes (e.g., inflammation)

• blind-ended lymphatic capillaries which coalesce to form lymphatic vessels and finally empty into the circulation via the lymphatic ducts (thoracic and right lymphatic).

•convey fluids from the tissues to the bloodstream

•in contrast to blood vessels, which carry blood to and from tissues, lymphatic vessels are unidirectional due to the presence of valves which direct the flow of lymph

•more permeable than blood vessels

•lymphatic capillaries – smallest lymphatic vessels

•numerous in loose connective tissues of the skin and in mucous membranes

•converge into larger vessels that ultimately unite to form two main channels that empty lymph into the blood stream

•Top photo - small lymphatic vessel next to a small vein - not contain RBCs, but a few lymphocytes

•Bottom photo - a valve present within the lymphatic vessel

Slide : spermatic cord.

•lymphatic vessels of the spermatic cord

•like the veins (pampiniform plexus) of the spermatic cord, these lymphatic vessels have unusually thick walls

•note the valve leaflets of this vessel

Dilated Lymphatic Vessel

•Fibrous connective tissue is full of little endothelially-lined, thin-walled channels

•tubes of endothelium

•Easy to see when distended - draining excess tissue fluid.

•section of fibrous tissue from a patient with some extra tissue fluid that needed draining

see:

•big dilated lymphatic

•less-filled lymphatic

•the endothelium of both lymphatic

Another Big Lymphatic

dilated lymphatic in the serosa of the colon in a person who had peritonitis

See:

•big lymphatic

•endothelial cell nuclei

•Valve

•pus in the left lower corner

•smooth muscle at the top

A Slender Lymphatic Vessel

•lymphatic vessel under a bit of ciliated epithelium

•from oviduct

•no valves visible here

found:

•the lymphatic vessel

•its endothelium

•the little blood vessels near it

A Collapsed Lymphatic Vessel

•dense irregular connective tissue

Cancer Cells in a Lymphatic Vessel

•cancer cells are easy to spot even at low power

•their nuclei are very large

•most of the common cancers spread via the lymphatic vessels

•this is a lymphatic with cancer in it

See:

•the large lymphatic

•cancer cells in the center of lymphatic vessel

•reinforced by a bit of smooth muscle

Lymphatic Channel in Inflammation

•Inflammation is the stereotyped tissue response to injury

•the vessels let protein leak out

•If the tissue damage is severe enough, some of the local structural proteins may be solubilized as well

•Normally the fluid in the lymphatic vessels is scanty and contains very little protein

•This changes when a lymphatic vessel drains an area where soluble proteins have accumulated in an area because of inflammation.

This is a lymphatic vessel draining an inflamed area

•lymphatic vessel

•some inflammatory cells in its lumen the protein-rich fluid in its lumen

•the edema fluid in the tissue surrounding the lymphatic vessel

Sections of small intestine

•villi extending into the lumen of the jejunum

•In some of the villi - fairly large open spaces, which are surrounded by a layer of flattened endothelial cells

•not contain any red blood cells

•these openings represent the blind end of lymph capillaries which originate in the villi.

•lacteals - is derived from the milky appearance of the lymph - suspended lipid droplets which enter these lymph capillaries.

LYMPHATIC VESSEL-LACTEAL

BY NUR FARHANA OTHMAN D11A026

• Present in the gastrointestinal tract

• Most nutrients that are absorbed by the SI will be carried by portal vein to the liver

• Absorption of fat takes place in the duodenum and is transported into lymphatic system

• First, fat droplets which consists mainly of triglycerides will be emulsified by bile salts

• Then, lipase produced by pancreas will digest the emulsified fat into fatty acids and monoglyceride

• The fatty acids and monoglycerides leave the micelle and enter the epithelial cell.

• Inside the epithelial cell the fatty acids and monoglycerides combine with protein to form chylomicrons (lipid + proteins).

• Lastly, the chylomicrons are secreted into the lymphatic system

Lymphatic Vessels in Physiological View

Nur Farhana binti Othman

Nur Athirah binti Mohd Azhar

• Moves in one-way (towards the heart)

• Assisted by muscular contractions, rhythmic contraction of lymphatic vessel walls and pressure changes in thoracic cavity during respiration

• Have valves to prevent backflow

How does it flow

• Excess fluid that is that is drained into blind-ended lymph capillaries is called the lymph.

• „ The lymph starts at the capillary beds, where they enter the lymph capillaries and later merges with the lymph vessels

• Lymph vessels have smooth muscles around them that contract, keeping the lymph flow upward

Lymph capillaries Lymph nodes

Lymphatic vessels

Left and right thoracic duct

Left and right subclavian vein