Chapter 21: The Lymphoid and Immune Systems

Merged flashcards from Chapter 21, McGraw Hill Anatomy and Physiology Tenth Edition, by Kenneth S. Saladin.

Microbiome

Microorganisms that reside on and in the human body; most are beneficial but some are harmful

Immune system

Cell population that inhabits all organs and defends the body from disease agents

Lymphoid system

System for immune cells that recover fluid, inspect for disease, activate responses, and return fluid

Lymphedema

Swelling due to impaired lymphoid drainage

Immune surveillance

Filtering fluid through the lymph nodes for immune responses

Lipid absorption

Absorption of lipids by the lymphoid system in the small intestine

Lymphoid system components

• Lymph

• Lymphatic vessels

• Lymphoid tissue

• Lymphoid organs

Lymph

A clear, colorless fluid similar to plasma but low in protein that serves as tissue fluid in the lymphatic vessels

Lymphatic vessels (lymphatics)

Transport lymphoid system’s lymph

Lymphoid tissue

Aggregates of lymphocytes and macrophages within the organs

Lymphoid organs

Organs where lymphoid cells are concentrated; surrounded by connective tissue capsules

Lymphatic capillaries

Microscopic vessels that allow bacteria and cells to enter via intercellular clefts

Intercellular clefts

Gaps between lymphatic capillary cells to allow bacteria and cells to enter

Lymphatic drainage

Done through collecting vessels that converge to larger lymphatic trunks

Collecting ducts (lymphoid ducts)

Where the lymphatic trunks converge (thoracic and right)

Right lymphatic duct

Recieves lymph from the right arm, right side of head and thorax; empties into right subclavian vein

Thoracic duct

Larger than right lymphatic duct; recieves lymph from below diaphragm, left arm, left side fo head, neck, and thorax; empties into left subclavian vein

Subclavian veins

Veins below the clavicle that collect from the collecting ducts, passes through lymph nodes

Glymphatic system

Lymphatic-resembling vessels associated with neuroglia to deliver nutrients and drain wastes

Neutrophil

White blood cell type associated with the lymphoid system

Natural killer cells (NK cells)

Lymphocytes that attack and destroy infected host cells, cancerous cells

T lymphocytes (T cells)

Lymphoid system cells that mature within the thymus

B lymphocytes (B cells)

Lymphoid cells that activate to proliferate and differentiate into antibody-producing plasma cells

Macrophages

Large phagocytic cells that present antigens to alert other immune cells

Dendritic cells

Antigen-presenting cells found in the skin, mucous membranes, and lymphoid organs

Diffuse lymphoid tissue

Tissue with scattered lymphocytes; prevalent in exterior-facing body passages (respiratory, digestive, urinary, reproductive)

Aggregated lymph nodes

Clusters of lymphoid nodules in the small intestine

Primary lymphoid organs

Includes the red bone marrow and thymus; are sites where T and B cells become immunocompetent

Secondary lymphoid organs

Include lymph nodes, tonsils, and spleen; are sites where immuncompetent cells migrate and populate

Red bone marrow

Soft and loosely organized material separated from bone tissue for hematpoiesis and immunity

Thymus

A bilobed organ in the superior mediastinum; houses developing T cells and secretes hormones regulating activity

Involution

Degeneration and shrinkage; happens with age to the thymus

Lymph nodes

Bean-shaped structures that cleanse lymph and are sites of lymphocyte activation; ~450 in young adult

Afferent lymphatic vessels

Lymphatic vessels that lead into the lymph node

Efferent lymphatic vessels

Lymphatic vessels that lead out of the lymph node

Lymphadenitis

Swollen lymph nodes in response to antigens

Lymphadenopathy

Term for all lymph node diseases

Metastasis

Condition where cancerous cells travel to other sites for reestablishment; easy in lymphatic vessels

Tonsils

Patches of lymphoid tissue at the entrance to the pharynx; guards against ingested or inhaled pathogens

Tonsillitis

Inflammation of the palatine tonsils

Pharengeal tonsil

Tonsil on the wall of the pharynx

Palatine tonsils

Two tonsils on the posterior margin of the oral cavity

Lingual tonsils

Numerous tonsils on the base of the tongue

Spleen

The largest lymphoid organ

Purposes include:

• RBC recyclation

• Fetal blood production

• Blood volume stabilization via plasma transfers

Splenectomy

Removal of the spleen in response to rupture; increases chances of future infections and premature death

Pathogens

Agents capable of producing disease

• Viruses

• Bacteria

• Fungi

• Other microbes

First line of defense

Skin and mucous membranes, which serve as barriers to pathogens — keratin, lysozymes, and hyaluronic acids

Second line of defense

Protections against pathogens that break the skin or mucous barriers, such as leukocytes, antimicrobial proteins, fevers, inflammation, and NK cells

Third line of defense

Adaptive immunity to specific pathogens that leave a memory

Immune system

Population of cells, chemicals, physical barriers, and physiological responses broken up into innate and adaptive immunity

Innate immunity

Defenses one is born with that protect one from a broad spectrum of disease agents; defends at point of invasion, is nonspecific, and lacks memory to pathogens

Adaptive immunity

Defenses against specific pathogens, developed only upon exposure while maintaining a memory

Keratin

Hard and easily replaced protein on skin that maintains a dry and nutrient-poor surface

Acid mantle

Thin film of lactic and fatty acids from sweat and sebum that inhibits bacterial growth

Mucous membranes

Covers the digestive, urinary, respiratory, and reproductive tracts to trap microbes

Lysozyme

Enzymes in the mucous membrane that destroys bacterial cell walls in the first line of defense

Hyaluronic acid

Acid that serves as a barrier to prevent bacterial growth in the first line of defense

Phagocytes

Cells that engulf foreign matter

Leukocyte types

1. Neutrophils (bacterial)

2. Eosinophils (parasitic)

3. Basophils (dilation)

4. Monocytes (macrophages)

5. Lymphocytes (memory)

Neutrophils

Type of leukocyte that wanders in connective tissue, killing bacteria either through phagocytization or chemicals

Eosinophils

Type of leukocyte found in mucous membranes to guard against parasites (tapeworms, roundworms) and allergens

Basophils

Type of leukocyte that secretes chemicals aiding mobility and action, such as histamine (vasodilation) and heparin (stops blocking clots)

Lymphocytes

Type of leukocyte that includes T and B cells for adaptive immunity and NK cells for innate immunity

Monocytes

Type of leukocyte that emigrates from the blood into connective tissue to transform into macrophages

Macrophage system

Includes all phagocytic cells except leukocytes — includes monocytes, macrophages, dendritic cells, and others

Interferons

Proteins secreted by virally infected cells and immune cells to “alarm” nearby cells, which bind to nearby receptors for antiviral protein production and NK cell/macrophage stimulation

Natural killer cells (NK cells)

Type of cell on continuous patrol for pathogens, diseased host cells for destruction through binding

Perforins

Proteins released by NK cells to created holes in an infected cell’s plasma membrane

Granzymes

Protein-degrading enzymes that degrade cellular enzymes and induce apoptosis

Fever (pyrexia)

An abnormal elevation of body temperature caused from trauma, infections, and drug reactions to promote interferon activity, metabolic rate

Febrile

Pertaining to fever

Antipyretics

Fever-reducing medications; may slow down recovery

Exogenous pyrogens

Fever-producing agents originating outside the body, such as glycolipids on bacteria and viruses

Endogenous pyrogens

Fever-producing agents originating from within the body, increasing the set point

Fever stages

1. Onset

2. Stadium

3. Defervescence

Onset

The first stage of a fever where the body temperature rises

Stadium

The second stage of a fever where the body temperature oscillates around a higher set point

Defervescence

The third and last stage of a fever where body temperature returns to normal

Reye syndrome

Disorder in children younger than 15 following an acute viral infection like chickenpox or influenza

Involves swelling of neurons, fatty liver, and swelling brain pressure triggered by aspirin usage

Inflammation

Local defensive response to tissue injury, including trauma and infection for pathogen spread limitation and debris removal

Inflammation signs

1. Redness

2. Swelling

3. Heat

4. Pain

Hypermia

Increase of blood flow during inflammation, causing increased redness and heat

Swelling (edema)

Accumulation and enlargement of body due to increased fluid filtration from capillaries during inflammation

Inflammation pain

Caused by nerve injury, pressure, and stimulation by toxins

Pus

Yellow accumulation of dead neutrophils, bacteria, cellular debris, and tissue fluid

Abscess

Accumulation of pus in a tissue cavity

Adaptive immunity

The third line of defense in the body with a systemic effect, specificity, and memory to distinguish it from innate immunity

Systemic effect

Property of active immunity meaning that it acts throughout the body

Specificity

Property of adaptive immunity meaning that it creates protection to pathogens individually

Memory

Property of adaptive immunity meaning that it recognizes previous pathogens for quick reactions

Active immunity

The body does work to create antibodies

Natural active immunity

The body produces its own antibodies or T cells as a result of infection or exposure to antigen

Artificial active immunity

The body produces antibodies or T cells a result of vaccination against disease

Vaccine

Injection consisting of dead or weakened to stimulate immune responses for antibodies without causing disease

Booster shots

Additional injections on top of vaccinations to restimulate immune memory

Passive immunity

Something outside the body produces and transfers antibodies or T cells

Natural passive immunity

Temporary immunity from antibodies from another person; most common example is through antibody transfer in placenta and breast-feeding

Artificial passive immunity

Temporary immunity from injection of immune serum from another person or animal; emergency treatment for bites, botulism, tetanus, rabies, and other diseases

Antigen (Ag)

Any molecule that can bind an antibody; helps distinguish bodily from foreign cells

Antibodies (immunoglobulins)

Proteins that play defensive roles, some on immune cell membranes