Lymph

Ever wonder how your body recovers tissue fluid? Or how is fat absorbed? What helps defend against infection? The answer lies in lymph. It is a nearly clear fluid that circulates through the lymphatic system. It balances fluids and supports immunity. Let’s go through the important concepts related to lymph!

What is Lymph?

Lymph starts as interstitial fluid, which is the fluid surrounding tissue cells. Around 3 litres per day escape from blood capillaries and enter lymph capillaries, becoming lymph. It is:

Colourless or pale yellow
It is alkaline and is slightly different from blood plasma
A mix of water, proteins, salts, fats (in chyle), and immune cells

Formation and Flow of Lymph

To know completely how lymph works in terms of fluid balance and immunity part taker, learn about its formation and flow. Here’s how the process works step by step.

Formation: Blood plasma leaks into tissues → most returns to blood; the remaining ~10% goes into lymph capillaries.
Capillaries merge into larger vessels → lymph nodes filter debris and microbes.
Major trunks (thoracic duct, right lymphatic duct) empty into the bloodstream near the subclavian veins.
Movement occurs via muscle contractions, vessel valves, and breathing, not a pump

Composition of Lymph

Component	Description
Water	94%; the bulk of the lymph
Proteins	Lower than plasma; includes antibodies (globulins)
Ions and Nutrients	Similar ions to plasma; fats in intestinal lymph (chyle)
Cells	Mainly lymphocytes and macrophages
Waste and Debris	Tissue waste, pathogens, and occasionally cancer cells

Functions of Lymph

Let’s break down its key functions.

1. Fluid Balance

Lymph collects excess fluid and proteins from tissues, returning them to the blood and maintaining plasma volume.

2. Fat Absorption

Special lymph capillaries (lacteals) in the small intestine absorb fats and fat-soluble vitamins. This fatty lymph (chyle) travels to the bloodstream.

3. Immunity

Lymph transports lymphocytes and antibodies. Lymph nodes filter out pathogens, triggering immune responses.

4. Waste Removal

Removes dead cells, pathogens, and debris from body tissues. It keeps them away from tissues thanks to lymph node filtration.

Lymphatic Organs and Tissues

Primary lymphoid organs: Bone marrow (B-cells), thymus (T-cells)
Secondary organs:

Lymph nodes: Bean-shaped filters full of B-cells, T-cells, and macrophages
Spleen, tonsils, Peyer’s patches, adenoids: Filter blood and support immune responses.

Important Notes:

The lymphatic system is open-ended and works slowly, relying on body movement, not a pump.
Chyle: A milky lymph rich in fats from digestion
Lymphedema: Swelling due to blocked lymph vessels.
Nodes often swell during infections.

Box to Remember

Fluid: Interstitial fluid → lymph
Main components: Water, proteins, lipids, lymphocytes
Key functions: Fluid balance, fat absorption, immunity, waste removal
Movement is driven by muscles and breathing
Organs: Capillaries → vessels → nodes → ducts → blood

Summing Up

Lymph is an important fluid that maintains fluid balance, transports fats, and supports immunity. It circulates through a system of vessels and nodes. It filters, cleans and returns vital substances to the bloodstream. Understanding how lymph connects body fluids, immunity, and nutrition is a core part of physiology and anatomy.