Human Lymphatic System: Definition, Diagram, Functions
The human lymphatic system is a vital part of both the immune and circulatory systems, transporting lymph, filtering pathogens, and maintaining fluid balance. It consists of lymph, lymph nodes, vessels, and lymphoid organs that provide immunity and prevent tissue swelling. This guide covers structure, functions, disorders, lymphatic diseases, diagrams, NEET FAQs, and MCQs.
This Story also Contains
- What Is The Human Lymphatic System?
- Structure Of The Lymphatic System
- Lymphoid Organs (Primary & Secondary)
- Functions Of The Lymphatic System
- Disorders Of The Lymphatic System
- Lymphatic System and Diseases
- Maintaining a Healthy Lymphatic System
- Human Lymphatic System NEET MCQs (With Answers & Explanations)
- Video Recommended On Human Lymphatic System
What Is The Human Lymphatic System?
The human lymphatic system forms part of the immune and circulatory systems of the body. It consists of vessels, nodes, and organs to which it gives one-way circulation—the lymph. It is a transparent fluid containing white blood cells (WBCs). This system plays either a major or very significant role in maintaining fluid balance, defending against pathogens, and absorbing dietary fats from the gastrointestinal tract.
It becomes important because it helps in returning the excess interstitial fluid into the blood circulation, thereby avoiding tissue swelling and maintaining blood volume. Another major function it carries out is the filtering of noxious substances by the lymph nodes which produces and circulates lymphocytes required for immune responses. This interrelation thus makes sure that development from fluids is undertaken effectively and that the body is guarded against various infectious diseases.
Structure Of The Lymphatic System
The lymphatic system is made up of various components that serve unique functions, all of which interplay to achieve the duties of this complex system.
Lymphatic Vessels
These are thin-walled vessels that transport lymph.
They are similar to veins, with more valves to prevent backflow.
They are not blood vessels; they transport lymph, not blood.
They collect and filter the interstitial fluid and return it into the bloodstream.
Lymph
Lymph is a clear fluid with a high composition of WBCs and mainly with predominant lymphocytes.
It assists in the movement of immune cells and products of waste removal from tissues.
Lymph is similar to blood plasma but has a lesser amount of proteins and more WBCs.
Blood plasma travels within the blood vessels, and lymph flows through lymphatic vessels.
Lymph Nodes
Small, oval structures that occur along the course of lymphatic vessels
They occur in groups in the neck, armpits and groin area
They filter lymph returning to the bloodstream which traps bacteria, viruses as well as other foreign substances.
They contain lymphocytes that mount responses against pathogens.
Lymphoid Organs (Primary & Secondary)
The lymphoid organs are divided into two parts:
Primary Lymphoid Organs
Primary lymphoid organs are where lymphocytes originate and mature. These are classified as :
Bone Marrow
Differentiates into all blood cells, including lymphocytes.
Site of B-lymphocyte maturation.
Thymus
An organ in the chest above the heart.
Plays a vital role in developing and maturing T-cells, a type of lymphocyte.
Secondary Lymphoid Organs
Secondary lymphoid organs are where they become activated to initiate immune responses. These are classified as:
Spleen
Above the left upper abdomen.
It filters the blood, removing old red blood cells, and it helps your body defend against infection.
Tonsils and Adenoids
They are tissues in the throat and nose.
They trap pathogens from food and air.
Peyer's Patches
These are found in the small intestine.
Monitor the bacteria that reside in the intestines and keep the growth of pathogenic bacteria at bay.
Functions Of The Lymphatic System
The lymphatic system performs some very crucial functions, integral to keeping the body in good health.
Fluid Balance
Picks up the excess of interstitial fluid from tissues.
Returns fluid into the bloodstream to avoid oedema.
Lymphatic capillaries pick up fluid from the interstitium.
Transportation of fluid along lymphatic vessels to the lymph nodes where it is emptied into the circulatory system.
Immune System Support
Lymph nodes filter pathogens from lymph.
Infection response of lymphocytes within nodes.
Transport by lymphocytes to sites of infection.
Allows for interchange and communication between immune cells.
Fat Absorption
Specialised lymphatic capillaries in the intestinal villi.
They absorb dietary fats before passing them into the bloodstream.
Fatty acids and glycerol are absorbed by lacteals.
Absorbed and transported as chyle, a milky fluid, to the thoracic duct and into the bloodstream.
Disorders Of The Lymphatic System
Different disorders may affect the functioning of the Lymphatic System.
Lymphedema
Blockage or damage to lymphatic vessels causes
Symptoms include swelling, pain, limited movement of limbs
Treatment is done by compression garments, physical therapy, surgery.
Massage for lymphatic drainage to reduce swelling.
Lymphoma (Hodgkin / Non-Hodgkin)
Types: Hodgins and Non-Hodgkins Lymphoma
Hodgkin lymphoma: Presence of Reed Sternberg cells
Non-Hodgkin lymphoma: Heterogeneous group of blood cancers affecting WBCs.
Symptoms include swollen lymph nodes, fatigue, and weight loss
Diagnosis by biopsy, imaging and blood tests
Lymphadenitis (Infections )
Bacterial, viral, or fungal infection.
Symptoms include swollen, tender lymph nodes Fever and chills.
Antibiotics, antiviral or antifungal medications.
Pain relievers and warm compresses for symptomatic relief.
Lymphatic System and Diseases
Various diseases, especially cancer and HIV, are associated with the lymphatic system.
Cancer Metastasis via Lymphatic System
Cancer cells can leap into lymph vessels to be then transported right to the lymph nodes.
Via the lymphatic system to other parts of the body.
Treatment includes surgery, chemotherapy, and radiation therapy.
HIV And Lymphatic System
HIV attacks and eliminates the CD4+ T-cells in lymph nodes.
Weakens immune systems, making it very hard to repel infections
Antiretroviral Therapy (ART) to control the virus growth.
Primarily, the state of immune function and general health is regularly checked.
Maintaining a Healthy Lymphatic System
The lymphatic system is very crucial to be kept fit. Here are some guidelines on how to keep it healthy.
Nutrition & Diet
Fresh fruits and vegetables
Source of omega-3 fatty acids like fish and flaxseeds
Water intake, the lymph fluid needs water to flow properly.
Prevents lymph from thickening and becoming sluggish.
Exercise & Physical Activity
Physical activity stimulates lymphatic flow.
Regular physical activity prevents lymphatic congestion.
Examples are walking, swimming, yoga, and best of all rebounding, jumping on a mini-trampoline.
Human Lymphatic System NEET MCQs (With Answers & Explanations)
Types of questions asked from this topic are:
Primary & secondary lymphoid organs
Disorders related to lymphatic system
Practice Questions for NEET
Q1. Which of the following statements are incorrect?
(i) Leucocytes disintegrate in the spleen and liver.
(ii) RBCs, WBCs and blood platelets are produced by bone marrow.
(iii) Neutrophils bring about destruction and detoxification of toxins of protein origin.
(iv) Important function of lymphocytes is to produce antibodies.
(i) and (ii)
(i) and (v)
(i) and (iii)
(ii) and (iii)
Correct answer: 3) (i) and (iii)
Neutrophils are a type of white blood cell and the first line of defense in the immune system. They are highly phagocytic, meaning they engulf and destroy invading pathogens like bacteria and fungi. Neutrophils circulate in the bloodstream and rapidly migrate to infection sites, where they release enzymes and antimicrobial substances to eliminate threats.
Hence, the correct answer is option 3) (i) and (iii).
Q2. Which Plasma proteins are important for defense?
Fibrinogen
Albumin
Gamma globulins
α and β globulins
Correct answer: 3) Gamma globulins
Explanation:
Globulins are a category of proteins, that largely transport proteins of hormones, lipids, and minerals. Among them, the gamma globulins specifically have antibody functions taking part in an immunity defence mechanism against infections. Thus, such separation would mean the major roles of globulins in serving nutrient transport mechanisms as well as the immune system for health as well as protecting the body against diseases.
Hence, the correct answer is option 3) Gamma Globulins.
Q3. Which of the following is/are a type of lymphocytes?
B-lymphocytes
S-lymphocytes
T-lymphocytes
Both 1 and 3
Correct answer: 4) Both 1 and 3
Explanation:
B-lymphocytes and T-lymphocytes.
Lymphocytes are a type of white blood cell that are crucial for the immune system helping the body fight infections and diseases.
Two essential elements of the immune system are T and B lymphocytes: T-lymphocytes contribute to cell-mediated immunity whereas B-lymphocytes are mainly engaged in the manufacture of antibodies.
Hence, the correct answer is option 4) Both 1 and 3.
Also Read:
Video Recommended On Human Lymphatic System
Frequently Asked Questions (FAQs)
The lymphatic system is responsible for maintaining fluid balance, supporting the immune system, and absorbing fats from the digestive tract.
The lymphatic system supports the immune system by filtering through the lymph nodes pathogens and producing lymphocytes that help fight infections.
The common diseases are Lymphedema, Lymphoma, and Lymphadenitis.
Follow a healthy diet, stay well-hydrated, have regular physical activity, and avoid risk factors like smoking or excessive alcohol intake.
Lymph is a clear fluid containing WBCs and some proteins; blood plasma, on the other hand, is the fluid portion of blood containing red and WBCs, platelets, and different proteins.