Lymphatic System

LYMPHATIC SYSTEM The lymphatic system communicates between the blood and tissue fluids. The lymphatic system consists of: 1. 2. 3. 4. 5. 6.

Lymph capillaries Lymph vessels The thoracic duct The right lymphatic duct Lymph nodes The other lymphatic tissue

Lymph capillaries are small fine capillary vessels within the tissue spaces which have to drain water and particles from the tissue spaces. The lymph capillaries are more permeable than blood capillaries. Capillaries join together to form larger lymphatic vessels. The fluid which flows inside the lymphatic capillaries and vessels is known as Lymph. The lymph is returned to the venous blood through two large lymphatic vessels, namely thoracic duct and right lymphatic duct, which opens into the left and right subclavian veins respectively. The lymph vessels have numerous nodular bodies like the beads in the strings. These beads are known as lymph nodes. Lymph nodes are the bean or kidney shaped bead found in the lymphatic vessels. They vary in size from as small as pin head to as large as size of an almond. Each node has concave surface called hilum. At the hilum the blood vessels supplying the node enter ad leave. The lymph enters the gland by afferent vessels and leaves the nodes by efferent vessels. The lymph nodes are arranged in deep and superficial groups. The lymph nodes lie in axilla, neck, abdomen, and groin. FUNCTIONS 1. Lymph nodes filter the lymph leaving behind the particles which would not normally be found in serum. 2. The lymph nodes provide an effective barrier against the spread of noxious particulate matter.

3. Lymph nodes are involved in the production of lymphocytes and antibodies. SPLEEN Spleen is the largest lymphatic organ of the body. It is slightly oval in shape.

The spleen lies in the left hypochondriac region of the abdominal cavity between fundus and diaphragm. It varies in size but usually it is about 12 cm long, 7 cm wide and 2.5 cm thick. The spleen is covered by fibroelastic capsule which extends into the organ to form the trabeculae. The cellular element of spleen is known as splenic pulp.

FUNCTION 1. Phagocytosis: Spleen destroys the worn out RBC , bacteria and platelets. 2. Haemopoietic organ: Spleen is involved in the production of small mount of RBC in the fetus. 3. Reservoir of RBC: Spleen sores blood which it liberates during condition of stress. 4. Formation of Antibodies and Anti toxins: Spleen provide defense against infections by producing antibodies and antitoxins. VARIOUS LYMPHOID TISSUES OF THE BODY 1. 2. 3. 4. 5.

Lymph nodes Tonsils Payer's patches Spleen Thymus

LYMPH The fluid within the lymph capillaries and vessels is known as lymph

The lymph is similar in composition to blood but concentration of various constituents is different. The lymph has no blood platelets but has lymphocytes. FUNCTIONS 1. The lymph gland functions as filters for microbes. 2. Lymph gland provides lymphocytes to the blood. 3. Lymph transports nutrients and oxygen from blood to the tissues and removes waste products from the tissues to the blood. 4. The lacteals help in the absorption of fats and carry it to systemic circulation. THYMUS Thymus gland is situated in the upper part of the mediastinum behind the sternum. At birth its weight is about 12 gm, and then it increases in size and puberty it weighs between 30-40 gm s. And then shrinks again. The thymus is a

bi lobed gland covered by a fibrous capsule which extends into the gland forming lobules. The lobules are divided into the inner medulla and outer cortex. FUNCTION z

Thymus gland controls the production of T Lymphocytes by bone marrow and production of antibodies.

Multiple Choice Questions: 1. Plasma represents ___% of total blood volume a) 35% b) 45% c) 55% d) 65%

2. Albumin/ Globulin is a) 1:1 b) 1.2 :1 c) 1.7 :1 d) 2:1

3. pH of blood is a) 7.0 b) 7.2 c) 7.4 d) 7.6 4. Colloidal osmotic pressure is controlled by following protein a) Prealbumin b) Albumin c) Fibrinogen d) Prothrombin

5. Function of transferrin is a) Binds with copper b) Growth promoting protein c) Antiinfective protein d) Regulates and controls iron absorption from GIT

6. Prealbumin functions a) Blood clotting b) Controls colloidal osmotic pressure c) Binds T3 and T4 d) Transports iron in blood

7. Cyanosis is due a) Reduced Hemoglobin levels, >0.5gm% b) Reduced Hemoglobin levels, >1.5 gm% c) Reduced Hemoglobin levels, >2.5 gm% d) Reduced Hemoglobin levels, >3.5 gm%

8. Life span of RBC is a) 60 days b) 80 days c) 100 days d) 120 days

9. Hb F disappears by a) Birth b) 1 month c) 3-4 months d) 1 year

10. Following statements about HbF is true a) Life span of fetal RBC is 120 days b) HbF is less resistant to alkalies than HbA c) Greater affinity for 2,3 DPG d) Formed of α2β2 chains

11. Hb concentration in a single RBC is called a) MCH b) MCV c) MCHC d) None

12. All are granulocytes except a) Monocytes b) Eosinophils c) Neutrophils d) Basophils

13. Life span of platelets is a) 2-5 days b) 8-12 days c) 15-20 days d) 20-25 days

14. Platelets release a) ATP b) PDGF c) 5-HT d) All o the above

15. Natural anticoagulants are all except a) Heparin b) Protein C c) Dicoumarol d) Antithrombin

16. Prothrombin is a) Coagulation factor I b) Coagulation factor II c) Coagulation factor III d) Coagulation factor IV

17. One of the following does not constitutes lymphoid organs of the body a) Spleen b) Liver c) Thymus d) Tonsil

18. Iron in Heme is in the form of a) Ferrous ions b) Ferric ions c) Both d) None

19. Serum is a) b) c) d)

Fibrinogen - plasma proteins. Plasma – Fibrinogen +plasma proteins. Plasma – plasma proteins. Plasma - Fibrinogen.

20. Destruction of platelets occur in a) spleen b) blood. c) bone marrow. d) liver.