1. The lymphatic system Objectives:
know all the structures within the system and how they relate to the function

2. What is the function of the lymph system?
The lymphatic system
The circulatory system is a vital system, and its constant movement of blood allows for gases and nutrients to be exchanged so the trillions of cells in your body can carry out their important functions.
However, there's an unsung hero of the cardiovascular system that you don't always hear about, and it's called the lymphatic system.
Without this system, the cardiovascular system would stop working, because it is this system of vessels that picks up fluids leaked from blood vessels and returns them to the blood.
What is the function of the lymph system?

3. The lymphatic system
The lymphatic system belongs to the circulatory system.
The lymph system is a second pathway back to the heart, parallel to the blood system.
In contrast to the blood circulation, which uses the pumping of the heart to circulate its flow, lymph is propelled through the vessels primarily by the rhythmic contractions of tiny muscular units.
The lymphatic system has a slow rhythm, low velocity and low pressure
How does it work?

4. The lymphatic system: How does fluid leak out?
Why is the lymphatic System important?
The super-thin walls of the blood capillaries are a little bit leaky. The pressure of the blood entering forces fluids out of the capillaries and into the tissue spaces.
This adds up to about three litres of fluid. Considering that the average human body only has about five or six litres of blood, you can begin to understand the importance of the lymphatic system.
These leaked fluids, along with any blood proteins that were forced out of the bloodstream, must be returned to the blood to maintain adequate blood volume.

5. The lymphatic system: What would happen if the fluid didn’t return to the circulatory system?
If the fluids remained in the tissue spaces, it would accumulate and lead to edema, which is an excessive accumulation of fluid in tissue spaces. This edema would show up as swelling in the legs and other areas of your body.
What is an edema?

6. The lymphatic system: how does this fluid return to the bloodstream?
Well, that's the job of the microscopic lymphatic capillaries.
What are Lymphatic Capillaries? How do they work?
Lymphatic capillaries are the smallest lymphatic vessels and collect fluid from the surrounding tissues. They're cast like a spiderweb among the capillary beds.

7. What are the function of Lymph Nodes?
lymphatic capillaries are more permeable, and therefore they're more prone to allow the passage of proteins or even larger particles such as bacteria and viruses.
To prevent the system spreading disease the fluid within the lymphatic system must travel through lymph nodes, which are small, bean-shaped organs that act as filters of disease-causing agents like bacteria and viruses.
Lymph nodes are widely distributed throughout your body, and though they're part of the lymphatic system, they're often considered organs of your immune system because they contain immune cells.
What are the function of Lymph Nodes?

8. How does the Lymph actually get back into the circulatory System?
The lymphatic vessels direct lymph toward the upper chest, where they finally return to the venous blood system through one of two large ducts.
The right lymphatic duct is a short vessel that drains lymph from the right arm and the right side of the head and chest.
The right lymphatic duct empties lymph into the right subclavian vein near the shoulder, where it's only a short distance back to the heart.
The thoracic duct drains lymph from all other areas of the body and empties the lymph into the left subclavian vein at the opposite shoulder.

9. Other Lymphoid Organs
Thymus - secretes hormones, it is found in the inferior neck and it increases in size and is most active during childhood
Spleen - Cleanses the blood: extracts aged and defective blood cells and platelets.
Tonsils - gathers and removes pathogens entering the pharynx from food and inhaled air

10. Plenary: Read notes and be prepared to discuss your answers.
What is the function of the lymph system?
How does it work?
Why is the lymphatic System important?
What is an edema?
What are Lymphatic Capillaries? How do they work?
What are the function of Lymph Nodes?
How does the Lymph actually get back into the circulatory System?