Lymphatic System Lecture Notes PDF

WHAT IS LYMPHATIC SYSTEM? ► The lymphatic system is part of ▸ the circulatory system and an important ▸ part of the immune system, comprising a ▸ network of lymphatic vessels that carry a ▸ clear fluid called lymph (from Latin, lympha meaning "water") directionally towards the heart. Formation o...

WHAT IS LYMPHATIC SYSTEM? ► The lymphatic system is part of ▸ the circulatory system and an important ▸ part of the immune system, comprising a ▸ network of lymphatic vessels that carry a ▸ clear fluid called lymph (from Latin, lympha meaning "water") directionally towards the heart. Formation of lymph As blood circulates through the body, most components of blood plasma such as nutrients, gases, and hormones filter through blood capillary walls to form interstitial fluid and reabsorbed back by venous capillaries. The excess filtered fluid (about 3 liters per day) drains into lymphatic vessels and becomes lymph. ie. the interstitial fluid enters into lymphatic vessels is called lymph  Lymph: ► The interstitial fluid picked up by lymphatic capillaries is known as lymph. Lymph very closely resembles the plasma found in the veins: it is a mixture of about 90% water and 10% solutes such as proteins, cellular waste products, dissolved gases, and hormones. Lymph may also contain bacterial cells that are picked up from diseased tissues and the white blood cells that fight these pathogens. In late-stage cancer patients, lymph often contains cancerous cells that have metastasized from tumors and may form new tumors within the lymphatic system.  LYMPH VESSELS These originate as blind end tubes in the interstitial spaces. Structurally, they are same as blood capillaries. Lymphatic vessels begin as lymphatic capillaries, which join up to form lymphatic vessels. Larger lymphatic vessels unite to form lymphatic trunk. Lymphatic trunk opens into two large lymphatic duct - right lymphatic duct and thoracic (left lymphatic)duct. Their walls are more permeable to all interstitial fluid including proteins and cell debris.. Lymph vessels have numerous cup shaped valves that prevent back flow of movements of lymph in vessels. In small intestine, specialized lymphatic capillaries called lacteals absorb dietary lipids into lymphatic vessels and ultimately into the blood. The presence of these lipids causes the lymph draining from the small intestine to appear creamy white. Such lymph is referred to as chyle  LYMPH NODES All the small and medium size lymph vessels open into lymph nodes. The size of a node arise from pin head to the largest is about the size of an almond Structure Has a fibrous capsule, dips down into the node forming trabecula that divide the node into compartments. Below the capsule is sub capsular substance. The outer portion is called cortex. The inner portion is called medulla  Flow of lymph inside a node Lymph enters into node through Afferent lymphatic vessel ↓ Subcapsular sinus ↓ Trabecular sinus ↓ Medullary sinus ↓ Efferent lymphatic vessel And finally leaves the node. LYMPH NODES compartments. LYMPH NODES It has tightly packed. Found lymphocytes, macrophages and plasma cells. Macrophages. Within the lymph nodes are macrophages, which engulf and destroy bacteria, viruses, and other foreign substances in the lymph before it is returned to the blood. Lymphocytes. Collections of lymphocytes (a type of white blood cell) are also strategically located in the lymph nodes and respond to foreign substances in the lymphatic stream.. A lymph node Located along lymph vessels About 600 lymph nodes in body. Usually occur in groups. Lymph nodes are major sites of B, T and other immune cells It can be seen widely in cervical, auxiliary and inguinal regions Functions Phagocytic action. Production of antibodies. Enlargement of lymph nodes, when the area of drainage is infected. Activate T and B lymphocytes. Filtration of lymph(Extra fluid from tissue in the body drains into and flows through small lymph vessels. This fluid is filtered through the lymph nodes, and drains back into the bloodstream. FLOW/TRANSPORT/CIRCULATION OF LYMPH Lymphatic capillaries have greater permeability than blood capillaries. Greater pressure in interstitial fluid opens lymph valves and fluid enters into lymphatic capillaries. Lymph passes from lymphatic capillaries into lymphatic vessels and then through lymph nodes. Later drains into lymphatic trunk. Lymph passes from lymphatic trunks into two main ducts, the thoracic duct and the right lymphatic duct, and then drains into venous blood at the junction of internal jugular and subclavian veins  The sequence of lymph flow is Blood capillaries (blood) ↓ Interstitial spaces (interstitial fluid) Lymphatic capillaries (lymph) Lymphatic (afferent) vessels (lymph) ↓ Lymph node (lymph)→ ↓ Lymphatic (efferent) vessels (lymph) ↓ LYMPHATIC TISSUE OR LYMPHATIC ORGANS The lymphatic organs are found in a number of situations n the body. such as (i) Tonsils (ii)Spleen (iii) Bone Marrow (iv)Thymus Gland (i)tonsils Lingual Tonsils are the paired and lie at the base of the tongue. Your nervous system is your body’s command center. It’s made up of your brain, spinal cord and nerves. Your nervous system works by sending messages, or electrical signals, between your brain and all the other parts of your body. These signals tell you to breathe, move, speak and see, for example. Your nervous system keeps track of what’s going on inside and outside of your body and decides how to respond to any situation you’re in. The nervous system is a complex network of nerves and nerve cells (neurons) that carry signals or messages to and from the brain and spinal cord to different parts of the body. Has two main division Central nervous system ,Peripheral nervous system, the nervous system can be further divided into the somatic nervous system, which controls voluntary activities, and the autonomic nervous system, PRIMARY FUNCTIONS OF NERVOUS SYSTEM Sensing the world Vision, Hearing, Smell, Taste, Touch Transmitting information Processing information Producing a response Central Nervous System The central nervous system (which consists of the brain and spinal cord) is composed of 2 major cell types; the neuron and the neuroglia. Neurons are the nerve cells, the structural and functional units of the nervous system. They conduct impulses that enable the body to interact with its internal and external environments.  Neurons Cell Body ➤ The main processing center of the cell. Dendrites ➤ Thin branching extensions of the cell body that conduct nerve impulses toward the cell body. Axon ➤ A single branch (in most neurons) which conducts nerve impulses away from the cell body. ➤ Myelin sheath and neurilemma are coverings. Neurons ➤ Impulse Transmission ➤ Terminal end fibers are located at the ends of the axon and they transmit impulses leaving the neuron across a synapse to the next neuron. Central Nervous System The central nervous system is composed of two major interconnected organs:  The brain  The spinal cord. These organs work together to integrate and coordinate sensory and motor information for the purpose of controlling the various tissues, organs, and organ systems of the body. The central nervous system is responsible for higher neural functions, such as memory, learning, and emotion. Spinal Cord Extends from the medulla oblongata of the brain to the area around the first or 2nd lumbar vertebra in the lower back. Nerves from the peripheral nervous system extend out from the spinal cord. Protected by: Vertebral column Cerebrospinal fluid Meninges Meninges are three layers of membranes ➤ Dura mater ➤ Outer tough fibrous membrane. Arachnoid mater ➤ Middle weblike membrane containing CSF. Pia mater ➤ Innermost layer containing several blood vessels. Peripheral Nervous System The peripheral nervous system (PNS) is a collection of peripheral nerves, ganglia and specialized sensory structures that, as a system, carries sensory and motor information between the central nervous system and all other organs and tissues of the body. The peripheral nervous system is functionally divided into two major divisions: The Sensory or Afferent Division The Motor or Efferent Division The Somatic Nervous System The Autonomic (Visceral) Nervous System. -Spinal Cord Peripheral nerves Somatic Nervous System Responsible for receiving and processing sensory input from the skin, muscles, tendons, joints, eyes, tongue, nose and ears as well as excite the voluntary contraction of skeletal muscles. Autonomic Nervous System ➤ Carries impulses from the central nervous system to glands, various smooth muscles, cardiac muscle and various membranes. Stimulates organs, glands, and senses.