Lymphatic ap150

Lymphatic system functions

• To return excess interstitial fluid (fluid between cells) to blood flow

  • Also transports absorbed lipid from GI tract

• Monitor body for pathogens and other harmful substances (by filtering lymph)

  • Immune function/initiation of immune response

What is the relationship between blood plasma, interstitial fluid, and lymph?

There is a net loss of fluids out of capillaries/blood due to filtration

The lymph system collects this fluid and returns to blood/the cardiovascular system

• Within blood vessels -> plasma

  • Plasma fluid exits capillaries and enters fluid between cells

• Between cells -> interstitial fluid

  • Interstitial fluid then flows into lymph

• Within lymphatic vessels -> lymph

  • Lymph will reunite with blood

How fluid enters lymph capillaries/the lymphatic system

Interstitial pressure pushes fluid into closed ended lymph capillaries through flap-like cell junctions

• Flap-like junctions act as valves preventing lymph from existing capillary

Flow of lymph

• The fluid lost from blood capillaries washes/flows through interstitial fluids into lymphatic capillaries

  • This carries pathogens and other substances from interstitial fluid into the lymph system

• Once in the lymph capillaries it moves to larger lymph vessels and through a series of nodes which filter the lymph and expose it to white blood cells

• The lymph system connects to the cardiovascular system at the junction of the subclavian and internal jugular veins

  • At this point lymph is dumped into veins and joins blood

Forces that propel lymph

Compression of vessels and lymph propels lymph past valves resulting in lymph movement toward the subclavian veins

• Muscle pump

• thoracic/respiratory pump

• Contraction of smooth muscle in lymphatic vessel walls

Lymphatic vessel anatomy

• One way valves created by endothelial cells

• Thin layer of smooth muscle and connective tissue

• Same three tunics as blood vessels

Lymph node anatomy

• WBC in reticular tissue 

  • Lymphocytes (T and B) and macrophages

• Surrounded by a dense connective tissue capsule

• Many afferent vessels, single efferent vessel

Lymphatic tissue

• Masses of WBC in reticular tissue (macrophage and lymphocytes)

• NOT surrounded by dense CT

• NOT connected to lymphatic vessels

• Found throughout the body at locations where outside substances gain entrance into the body

Thymus gland

• Site of maturation of T-lymphocytes

• large/active while young

• By age 40, most of it has been replaced by adipose CT

Spleen red pulp

• Red pulp

  • Removal of old RBS by macrophages

  • Associated with veins

  • Storage of RBCs

Spleen white pulp

• Associated with arteries

• Lymphatic in function as in lymphatic tissue

MALT

mucosa associated lymph tissue

• Intestines

• Respiratory tract

• Urogenital tract