Chapter 22: Lymphatic System And Immunity Flashcards
Immunity
Is the ability to ward off damage or disease through our defenses.
2 types-
1. Innate: refers to defenses that are present at birth. Does not involve specific recognition of a microbe and acts against all microbes in the same way.
2. Adaptive : refers to defenses that involve specific recognition of a microbe once breached the innate immunity defenses. Based on a specific repose to a specific microbe.
Susceptibility
Vulnerability or lack of resistance.
Lymphatic System
Consists of:
-a fluid called lymph
-lymphatic vessels that transports the lymph
-A number of structures and organs containing lymphatic tissue and red bone marrow.
-Assists in circulating body fluid that helps defend the body against disease causing agents.
Lymph
Interstitial fluid that passes into lymphatic vessels.
Found in: lymphatic vessels and lymphatic tissue.
Is clear, pale yellow fluid.
Lymphatic Tissue
A specialized form of reticular connect tissue that contains large numbers of lymphocytes.
2 types of lymphocytes participate in adaptive immune responses:
B cells and T cells
Functions of Lymphatic System
- Drains excess interstitial fluid: drains excess fluid from tissue spaces and returns it to blood. This function links it with CVS
- Transport dietary lipids: lymphatic vessels transport lipids and lipid soluble vitamins A, D, E, K absorbed by the GI tract.
- Carries out immune responses: lymphatic tissue initiates highly specific responses directed against particular microbes or abnormal cells.
Lymphatic Capillaries
Lymphatic vessels begins as capillaries. Capillaries unite to form larger lymphatic vessels.
Capillaries are located in the spaces between cells and are closed at one end.
Have greater permeability than blood capillaries and can absorb large molecules such as proteins and lipids.
Lacteals
Specialized lymphatic capillaries in the small intestine.
Carry dietary lipids into lymphatic vessels and ultimately into the blood.
Chyle
A presence of dietary lipids causes the lymph draining from the small intestine to appear creamy white.
Lymph Trunks
Formed as lymphatic vessels that exit lymph nodes in a particular region of the body.
Principal trunks:
-lumbar: drains lymph for lower limbs, wall and viscera of pelvis, kidneys, adrenal glands and abd wall.
-intestinal: drains lymph from the stomach, intestines, pancreas, spleen and part of the liver.
-bronchomediastinal: drain lymph from thoracic wall, lung and heart.
-subclavian: drain the upper limbs
-jugular: drains head and neck
Formation of Lymph
Formed by excess of interstitial fluid about 3 L/day drains into lymphatic vessels to form lymph.
Proteins can move readily thought more permeable lymphatic capillaries into lymph.
Lymphatic Vessels
Formed by lymph capillaries.
Important function: to return the lost plasma proteins and plasma to the blood stream.
Contains: valves, ensures one way movement of lymph.
Flow of Lymph
Blood capillaries - interstitial spaces (fluid)- lymphatic capillaries (lymph) - lymph vessels (lymph) - lymphatic trunks or ducts (lymph) - junction of the internal jugular and subclavian veins (blood).
Pumps that Maintain Flow of Lymph
- Respiratory Pump: flow of lymph is maintained by pressure changes that occurs durning inhalation. Flows from abd region where pressure is higher towards the thoracic region where it is lower. During exhalation, the valves in lymphatic vessels prevent back flow of lymph.
- Skeletal Muscle Pump: the milking action of skeletal muscle contractions compresses lymphatic vessels and forces lymph towards the junction of the internal jugular subclavian veins.
Primary Lymphatic Organs
Sites where stem cells divide and become immunocompetent ( capable of mounting an immune response).
1. Red bone marrow: in flat bones and epiphyses of long bones of adults. Pluripotent stem cells in marrow give rise to mature immunocompetent B cells and to pre-t cells.
2. Thymus: pre-T cells migrate to thymus where they become immunocompetent T cells.
Secondary Lymphatic Organs
Sites where most immune response occur.
1. lymph nodes
2. spleen
3. lymphatic nodules (follicles)-non organ.
Lymph nodes, spleen as surrounded by CT capsule.
Lymphatic nodules as they lack a capsule.
Thymus
Largest functional capacity is a puberty.
Organ located in the mediastinum between the sternum and aorta.
Where T cells mature.
Extends from the top of sternum to the 4th costal cartilages, anterior to the top of the heart and its greats vessels.
Parts of the Thymus
Capsule: CT encloses each lobe separately
Trabeculae: extensions of the capsule
Lobules: trabeculae penetrate inward and divide each lobe
Cortex: composed of large numbers of T cells and scattered dendritic cells, epithelial cells and macrophages.
Medulla: consists of widely scattered, more mature T cells, epithelial cells, dendritic cells and macrophages.
Thymic Corpuscles: clusters of some epithelial cells become arranged into concentric layers of flat cells that degenerate, become killed with keratohyalin granules and keratin. Site of T cell death in the medulla.
Lymph Nodes
600 bean shape, located along lymphatic vessels.
Function: act as a type of filter.
Scattered throughout the body, both superficially and deep, usually occurs in groups.
Larges groups are present near mammary glands, axilla, and groin.
Parts of Lymph Nodes
Capsule: covering of dense CT, extends into node.
Trabeculae: capsular extension, divide the node into compartments, provide supports and route for blood vessels into the interior of node,
Cortex: consists of inner and outer.
Inner Cortex: do not contain lymphatic nodules. Consists of mainly T cells and dendritic cells that enter a lymph node other tissues.
Outer cortex: egg shaped aggregates of B cells called lymphatic nodules.
Primary Lymphatic Nodule
Smaller than lymph nodes
A lymphatic nodule consisting chiefly of B cells.
Secondary Lymphatic Nodules
Smaller than a lymph node
Most lymphatic nodules are in the outer cortex.
Form in response to an antigen and are sites of plasma cell and memory B cell formation.
Medulla of Lymph Node
Contains B cells. Antibody producing plasma cells that have migrated out of the cortex into the medulla and macrophages.
Afferent Lymphatic Vessels
Carry towards
Lymph flows though a node in one direction.
Enters several of these vessels which penetrate the convex surface of the node at several points.
Contains valves that open towards venter of the node directing the lymph inward.
Sinuses
A series of irregular channels that contain branching reticular fibers, lymphocytes and macrophages.
Efferent Lymphatic Vessels
To carry away.
Medullary sinuses drain into these vessels.
Are wider and fewer in number than afferent vessels.
Contain valves that open away from the center of the lymph node to convey lymph, antibodies and activated T c cells out of the node.
Hilum
Slight depression where efferent lymphatic vessels emerge from one side of the lymph node.
Where blood vessels enter and leave the node.
Spleen
Oval shaped.
Largest single mass of lymphatic tissue in the body.
Function: removes worn out blood cells.
Located: left hypochondrias region between stomach and diaphragm.
Parenchyma of Spleen
Consists of 2 different kinds of tissue.
1. White Pulp: lymphatic tissue, most of lymphocytes and macrophages arranged around branches of splenic artery known as ventral arteries
2. Red Pulp: consists of blood filled venous sinuses and cords of splenic tissue known as splenic cords.
Splenic cords consists of RBC, macrophages, lymphocytes, plasma cells and granulocytes.
Veins are closely associated with this pulp.
Mucosa Associated Lymphatic Tissue (MALT)
Lymphatic Nodules found in mucous membrane lining the GI, GU, Resp and resp airways.
Tonsils
Form a ring at the junction of the oral cavity and oropharynx and junction of nasal cavity and nasopharynx.
Positioned to participate in immune responses against inhaled or injected foreign substance.
Types of Tonsils
- Pharyngeal tonsil: (adenoid) single, embedded in the posterior walls of nasopharynx
- Palatine tonsils: paired, lie at posterior region of the oral cavity, one on each side. These are removed in tonsillectomy.
- Lingual tonsils: located at the base of the tongue. May also need removal during tonsillectomy.
Innate (nonspecific) Immunity
Depends against all types of invaders
A defense that you have since birth.
1.First line of defense: Includes the external physical and chemical barriers provided by the skin and mucous membrane.
-When a pathogen penetrate the fist line they met the second
2.Second line of defense: various deference as anti microbial substances: interferons, natural killer cells, phagocytes, inflammation and fever.
First Line of Defense for Immunity
Skin and mucous membranes.
Provide physical and chemical barriers to discourage pathogens and foreign substance from penetrating the body.
Consists of :
1. Hairs: traps and filter microbes.
2. Cilia: hairline projects that remove dust.
3.lacrimal apparatus: produce treats to remove irritants.
4. Saliva: washes mirrors from the surface of the teeth and mouth.
4. Flow of urine: removes microbes from Gu system
5. Vaginal secretions: moves micro out of the body
6. Defecation and vomiting; expel microbes.
7. Sebum: forms a protective acidic film/layer on the skin to prevent bacteria growth
Second Line of Defense: Internal
Occurs when pathogens penetrate the first line of defense of the skin and mucous membranes physical and chemical barrier.
Includes:
1. internal anti microbial substance: antibodies and interferons
2. phagocytes
3. natural killer cells
4. Cyctoxic cells
5. inflammation.
4 Main Types of Antimicrobial Sustances
- Interferons (IFNs): lymphocytes, macrophages and fibroblasts infected with viruses that produce proteins.
- Complements System: group of non active proteins in blood plasma and on plasma membranes. When activated complements or enchanted certain immune reactions.
- Iron Binding Proteins: inhibit growth of certain bacteria by producing the amount of available iron.
- Antimicrobial Proteins: short peptides that have a broad spectrum of Antimicrobial activity.
Natural Killer Cells
Bodies second line of defense after exposure to antigen.
Release perforin (protein) into the plasma membrane of the target cell and creates a channel in the membrane.
Lack the membrane that identify B and T cells
5-10% of lymphocytes in blood.
Also present in spleen, lymph nodes and red bone marrow.
Lack membrane molecules that identifies B and T cells.
Have ability to kill a wide variety of infected bloody cells and certain tumor cells.
Will release live pathogenic from infected cells called granzymes which are protein digesting enzymes
Perforin
Released by natural killer cells
Granules that contain proteins.
Does not contain chemicals so vasodilation and increased flow to infection does not occur.
Inserts into the plasma membrane of the target cell and creates channels in the membrane.
Causes extracellular fluid to flow into target cells and cell bursts.
Cytolysis
When cells bursts
Natural killer cells and cytosol cells can relapse performing rot cause this.
Granzymes
Relased by granules of Natural Killer cells.
Proteins digesting enzymes that induce the target cells to undergo apoptosis or self destruction.
Phagocytes
Specialized cells that perform phagocytosis.
2 major types:
1. Neutrophils
2. Macrophages
When infection occurs these 2 cell types migrate to infected area.
Wandering Macrophages
When monocytes enlarge during migration and develop into activity phagocytic macrophages.
Fixed Macrophages
Stand guard in specific tissues.
Phagocytosis Stages
- Chemotaxis: chemical stimulated movement of phagocytes to a site of damage,
- Adherence: attachment of phagocyte to the microbe or other foreign material.
- Ingestion: PM of phagocytes extends projections called pseudopods that engulf the microbe. When pseudopods meet, they fuse, surround microorganism with a space called phagosome.
- Digestion: phagosome enters cytoplasm, merges with lysosomes to form phagolysosome. Lysosome contributes lysozyme to break down microbial cell walls.
- Killing: chemical onslaught provided by lysozyme, digestive enzymes and oxidants with phagolysosome quickly kills many types of microbes.
Oxidative Burts
Process that occurs in digestion stage of phagocytosis.
Phagocytes forms lethal oxidant :superoxide, hypochlorite and hydrogen periods.
Residual Bodies
Structures that cannot be degraded further during the killing phase of phagocytosis.
Inflammation
Classified as acute or chronic
Nonspecific, defensive response of the body to tissue damage.
Condition that produces inflammation: pathogens, abrasions, chemical irritations, distortion or disturbances of cells and extreme temps.
Sign and Symptoms of Inflammation: PRISH
P: pain due to release of certain chemical
R: redness because more blood is rushed to the affected area
I: immobility that results from some loss of function in severe inflammations
S; swelling causes by accumulation of fluid
H: heat which is also due to more blood rushing to the affected area.
Inflammation: Vasodilation and Increased Blood Vessel Permeability
Two immediate changes occurs in the blood vessels in a region of tissue injury:
1. vasodilation-increase in diameter of arterioles. Allows more blood to flow through the damaged areas
2. Increased permeability of capillaries-substances normally retained in blood are permitted to pass from the blood vessel. Permits defensive proteins such as antibodies and clotting factors to enter area from blood.
Substances that Contribute to Vasodilation, Increased Permeability and Aspects of Immune Response
- Histamine: released by mast cells in CT and basophils and platelets in blood. Causes vasodilation and increased permeabiliy.
- Kinins: Inactive precursors form polypeptides in blood induce vasodilation and increased perm, serve as chemo tactic agents for phagocytes. Kinin= bradykinin.
- Prostaglandins: are released by damaged cells and intensify the effects of histamine and kinins.
- Leukotrienes: produced by basophils and mast cells
- Complement: different components of the complement system stimulate histamine.
3 Stages of Inflammation
- Vasodilation and increased permeability of blood vessel
- Phagocyte emigration
- Tissue repair
Emigration of Phagocytes during Inflammation
Depends of chemotaxis.
Phagocytes appear at site of inflammation within 1 hour.
Large amounts of blood accumulates.
Neutrophils begin to stick to the inner surface of the endothelium of blood vessels.
Neutrophils begin to squeeze through the walls of blood vessels to reach the site of damage.
Neutrophils attempt top destroy invading microbes by phagocytosis. Monocytes follow.
Neutrophils die out and monocytes transforms into wandering macrophages and engulf the damaged tissue and invading microbes.
Luekocytosis
An increase of WBC in the blood.
Pus
Collection of dead phagocytes and damaged tissue fluid that forms after the macrophages die out.
Occurs in most inflammatory responses and continues until the infection subsides.
Acute Inflammtion
Signs and symptoms develop rapidly and usually last for a few days or even weeks.
Mildly and self limiting.
Principle defensive cells: neutrophils
Chronic Inflammation
Signs and symptoms develop more slowly and can last for up to several months or years.
Often severe and progressive.
Principal deference cells: monocytes and maropahges