Lympathic System Part 1

What is Lymph

Leftover fluid that leaks out of blood capilaries carrying things like waste, proteins, and immune cells that your body collects and returns to your blood

What does lymph contain?

• Water

• Proteins

• Wastes

• Immune cells

• Sometimes bacteria

How is lymph produced?

Blood plasma leaks out of capillaries → becomes interstitial fluid→ enters lymph vessels → becomes lymph

What is Interstitial fluid

A watery, nutrient-rich liquid that fills the microscopic spaces between cells, tissues, and organs

What is the main function of the lymphatic system?

• Returns fluid to the blood (prevents swelling)

• Fights infection (houses immune cells)

• Absorbs fats from digestion

Why does swelling in the lymphatic system appear?

If the lymphatic system didn't drain the excess fluid, the lymph fluid would build up in the body's tissues, making them swell.

What are the main components of the lymphatic system?

• Lymph

• Lymphatic vessels

• Lymph nodes

• Lymphoid organs (spleen, thymus, tonsils)

WHY is the lymphatic system necessary if we already have blood vessels?

Blood vessels leak fluid into tissues, and the lymphatic system collects that extra fluid so your body doesn’t swell.

👉 Without it → severe swelling

What would happen if the lymphatic system stopped working? (application)

• Fluid builds up → swelling

• Waste accumulates

• Immune defense weakens → more infections

What are lymphatic vessels

thin-walled, branching network of tubes that collect excess, watery fluid (lymph) from body tissues and return it to the bloodstream

What are the 4 types of lymphatic vessels?

• Lymphatic capillaries

• Collecting vessels

• Lymphatic trunks

• Lymphatic ducts

What are lymphatic capillaries?

Tiny, blind-ended vessels that absorb excess fluid from tissues

What makes lymphatic capillaries special?

• Very permeable (let proteins, bacteria in)

• Have flap-like valves

WHY are lymphatic capillaries so permeable? (Meaning:allowing liquids or gases to pass through it.)

So they can pick up large particles like bacteria and proteins that blood capillaries cannot.

What are collecting vessels?

Vessels that carry lymph and pass it through lymph nodes

What are lymphatic trunks?

Large vessels that drain lymph from major body regions

What are lymphatic ducts?

The largest vessels that return lymph to the bloodstream

• Right lymphatic duct

• Thoracic duct

What would happen if valves in lymph vessels failed? (application)

• Lymph would flow backward

• Fluid buildup → swelling

What is the endpoint of lymph?

It returns to the subclavian veins

Describe the flow of lymph.

Tissues → lymph capillaries → collecting vessels → lymph nodes → trunks → ducts → bloodstream

WHY does lymph flow slowly?

There is no pump like the heart

👉 It relies on:

-Skeletal muscle pump

– Respiratory pump

– contraction of lymph vessel smooth muscles

What happens if you don’t move your body much? (application)

Lymph flow slows → swelling increases

What are Lacteals?

A special type of lymphatic capillary only found in the small intestine

What do Lacteals do?

They absorb fats from food and carry them into the lymphatic system to be put into the bloodstream

Why are Lacteals specialized?

Fat molecules are too large to enter blood capillaries directly, so the body uses lacteals instead

What is the function of lymph nodes?

Filter lymph and trap pathogens before re-entering the bloodstream

What is the structure of a lymph node?

• Capsule (outer layer)

• Cortex (outer region)

• Medulla (inner region)

What happens inside lymph nodes?

• Macrophages destroy pathogens

• Lymphocytes activate immune responses

How many types of Lymph nodes are there? and location

cervical (neck)

axillary (armpit)

inguinal (groin)

What is a Lymphocyte

a type of white blood cell critical to the immune system, responsible for fighting infections, viruses, and diseases like cancer

WHY do lymph nodes swell when you’re sick?

Lymph nodes swell because immune cells are multiplying and fighting infection

What happens if lymph nodes are removed? (application)

• Poor drainage

• Swelling

• Increased infection risk

What are the lymphatic organs?

Spleen

Thymus

Tonsil

How is the spleen involved with the lymphatic system?

The spleen is part of the lymphatic system because it filters blood, removes pathogens and old red blood cells, and produces/activates lymphocytes to fight infection.

The spleen filters/clean the blood alongside the lymph nodes that filter/clean the lymph then thats put BACK INTO the bloodstream.

Its a cycle.

Analogy for the spleens involvement

Like thanksgiving, and the main meal is the turkey/bloodstream prepared by the head chef/spleen, and the side dishes are made alongside by the cooks/lymph nodes, that are all served together for dinner at the end

(Referencing how the filtered blood goes back into the bloodstream to continue the cycle of filtering fluids)

Where is the spleen located?

Left upper abdomen, near the stomach

What are red pulp and white pulp?

• Red pulp → filters blood

• White pulp → immune function

What happens if the spleen is removed? (application)

• Higher infection risk

• Body compensates with liver/lymph nodes

How is the Thymus involved with the lymphatic system?

Trains immature T-lymphocytes (a type of white blood cell) to recognize pathogens, so they can defend the body once they enter the bloodstream or lymph.

Where is the thymus located?

Behind the sternum

What is the function of the thymus?

Matures T cells

What happens to the thymus with age?

It shrinks (atrophy)

WHY is the thymus larger in children?

Immune system is still developing

What happens if the thymus doesn’t work? (application)

Weak immune system

How is the Tonsils involved with the lymphatic system?

The frst line of defense at entry points, used to trap and destroy pathogens entering through the mouth and nose and help activate immune responses.

What do Tonsils contain?

They contain lymphocytes. Lymphocytes patrol the area for pathogens

What do Tonsils do with lymphocytes

When tonsils detect an infection, they activate lymphocytes that can then travel through lymph and blood to fight pathogens elsewhere

WHY do tonsils get inflamed?

Tonsils get flamed when they are actively fighting infection

What are the 3 major tonsils?

• Pharyngeal (adenoids)

• Palatine

• Lingual

What are Pharyngeal tonsils?

Tonsils that trap pathogens entering through nose

Where are Pharyngeal tonsils located?

Back of nasal cavity, above throat

Why are Pharyngeal tonsils important

First line of defense against airborne infections; can block airflow if swollen

What are Palatine tonsils

Tonsils that trap pathogens entering through mouth

Where are Palatine tonsils located?

Sides of the throat

Why are Palatine tonsils important?

Fights bacteria/viruses from food and breathing

What are Lingual tonsils

Tonsils used to trap pathogens entering through mouth and throat

Where are Lingual Tonsils located

Base of tongue

Why are Lingual Tonsils important

They supports immune surveillance in the digestive/airway entrance