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THE L-ATIC SYSTEM AND IMMUNITY

Chapter 14

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ORGANIZATION OF THE L-ATIC SYSTEM1. Vessels

L-atic vessels, or L-atics – go from peripheral tissues and end at connections to the venous system.

2. FluidsL – resembles plasma, but with a lower concentration of proteins

3. L-ocytesspecialized cells that perform varied, specific functions in the body

4. L-oid tissues and organsL-oid tissues – collections of loose connective tissue and L-ocytes. These are in structures called L-oid nodules (e.g. the tonsils).L-oid organs – more complex structures, contain large numbers of L-ocytes and are connected to L-atic vessels (e.g. spleen).

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ORGANIZATION OF THE L-ATIC SYSTEM• Functions of the L-atic system (454)• The production, maintenance, and distribution of L-cytes• The return of fluid and solutes from peripheral tissues to the blood.• The distribution of hormones, nutrients, and waste products from their

tissues of origin to the general circulation

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ORGANIZATION OF THE L-ATIC SYSTEM• L-ATIC VESSELS• Lymphatic capillaries• Thoracic duct• Right lymphatic duct

Blockage of the lymphatic drainage from a limb can cause a limb to swell due to the accumulation of interstitial fluid. This is called lymphedema.

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ORGANIZATION OF THE L-ATIC SYSTEML-OCYTES

• Respond to the presence of • 1) invading pathogens (e.g. bacteria, viruses)• 2) abnormal body cells (e.g. virus-infected cells, cancer cells)• 3) foreign proteins, such as the toxins produced by some bacteria

• Respond through a combo of physical and chemical actions.• Specific defenses of the body are known as an immune response.• Immunity is the body’s ability to resist infection and disease

through the activation of specific defenses.

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ORGANIZATION OF THE L-ATIC SYSTEML-OCYTES

• Migrate throughout the body.• Have relatively long lifespans.

• Roughly 80% live for 4 years.• Some live up to 20+ years.

• 3 Classes:• T Cells

• Thymus-dependent• ~80%

• B Cells• Bone marrow-dependent• 10-15%

• NK Cells• Natural Killer cells• 5-10%

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ORGANIZATION OF THE L-ATIC SYSTEML- NODULES

• Pharynx• The 5 Tonsils

• Intestines• Peyer’s patch• Appendix

Tonsillitis, appendicitis

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ORGANIZATION OF THE L-ATIC SYSTEM• L-OID ORGANS:• L- nodes• Thymus• Spleen

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ORGANIZATION OF THE L-ATIC SYSTEM• L- NODES

• Filter and purify the L- before it reaches the venous system.• At least 99% of antigens are removed.

• Their detection and removal stimulates T and B cells, initiating an immune response.

• THYMUS• Site of T-cell production and maturation.

• Lobules• Thymosins, produced in each lobule, stimulate cell divisions and T-cell maturation.

• Septae (septum; walls)

• SPLEEN• Largest collection of L-oid tissue in the body.• Filters blood, not L-

• Stores Fe• Removes abnormal blood cells

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ROLES OF THE L-ATIC SYSTEM IN BODY DEFENSES

1. Nonspecific defenses nonspecific resistance• Physical barriers• Phagocytic cells• Immunological surveillance• Interferons• Complement• Inflammation• Fever

2. Specific defenses specific resistance• dependent on L-ocyte activity

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ROLES OF THE L-ATIC SYSTEM IN BODY DEFENSES• Physical barriers

• The skin and hair (integument) and inner linings• Secretions

• Flush away microorganisms and chemical agents• Contain lysosomes (destructive enzymes), specific pH, antibodies

• Phagocytic cells• First line of cellular defense

• Microphages• Neutrophils and eosinophils

• Macrophages • Can be free or fixed• Some have special names in some organs (e.g. microglia in CNS, Kupffer cells in and around the

liver)• Can move via diapedesis or attracted/repelled via chemotaxis

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ROLES OF THE L-ATIC SYSTEM IN BODY DEFENSES• Immunological Surveillance

• Constant monitoring of tissues involving NK cells• Kill via perforins, which perforates the cell membrane in the abnormal cell• Cell escape can cause cancer cells to multiply and spread unabated

• Interferons• Released by activated l-ocytes, macrophages, and virus-infected tissue cells• Example of cytokines – chemical messengers

• Complement• Plasma has 11 special complement proteins• Complement activation is known to

• Attract phagocytes• Stimulate phagocytosis• Destroy cell membranes• Promote inflammation

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ROLES OF THE L-ATIC SYSTEM IN BODY DEFENSES

• Inflammation• Inflammatory response• Mast cells are pivotal here• Purposes:

• Temporary repair and prevent further pathogen access• Slow pathogen spread from the injury site• Mobilize defenses and aid permanent tissue repair (regeneration)

• Cell death• Necrosis

• Organized cell death (of injured cells)• Pus

• Debris and dead cells• Accumulation in a closed space is an abscess

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ROLES OF THE L-ATIC SYSTEM IN BODY DEFENSES

• Fever• Inflammatory response• Pyrogens (fire-makers) reset the hypothalamus’ thermostat• Normally 99°-104° F

• This can be beneficial – speeds up metabolism and chemical reactions

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SPECIFIC DEFENSES: THE IMMUNE RESPONSE

• Specific resistance/immunity:• Cellular/Cell-mediated

• Abnormal cells• Pathogens in living cells

• Humoral/Antibody-mediated• Antigens• Pathogens in fluids• Why would anti-bodies be humoral?

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SPECIFIC DEFENSES: THE IMMUNE RESPONSE

• Types of immunity• Innate

• Genetic (i.e. people don’t get the same diseases as goldfish)• Acquired

• Not present at birth• Arises by either means:

• Active• Passive

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SPECIFIC DEFENSES: THE IMMUNE RESPONSE

• Acquired - ANTIBODIES• Active

• Like preventative maintenance; you are actively seeking out protection• Appears after exposure to antigens• NATURALLY ACQUIRED

• Exposure to antigens naturally• Like vocab development

• INDUCED• Exposure to vaccines (immunization/vaccination) before infection

• Passive• Happens to you after the fact• Mechanical xfer of antibodies to an individual• NATRUALLY ACQUIRED

• Mom to baby• INDUCED

• Exposure to antibodies after infection

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SPECIFIC DEFENSES: THE IMMUNE RESPONSE

2. Properties of immunitySpecificity – antigen recognitionVersatility – confront any antigen at ant timeMemory – memory cellsTolerance – ignores certain cells (e.g. your own cells)

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SPECIFIC DEFENSES: THE IMMUNE RESPONSE

3. An overview of the immune response• to pathogens, abnormal cells, foreign molecules…

inactivate ordestroy

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SPECIFIC DEFENSES: THE IMMUNE RESPONSE

4. T Cells and Cell-mediated immunityCytotoxicHelperMemorySuppressor

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SPECIFIC DEFENSES: THE IMMUNE RESPONSE

5. B Cells and antibody-mediated immunityB Cell sensitization and activation Antibody structure

immunoglobulins – IgG

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SPECIFIC DEFENSES: THE IMMUNE RESPONSE

6. Hormones of the immune system