A&P II Exam #4

primary function of lymphatic system

production & distribution of lymphocytes

• lymphocytes provide defense against infections & environmental hazards

lymphatic capillaries

close-ended

• in SI, called lacteals

lymphatic vessels

• have epithelial cells overlapping to create valves

• have fluid carrying viruses & bacteria

• carry lymph (includes lipids otherwise same as plasma)

lymph pathway

capillaries→larger lymphatic vessels→lymph nodes→thoracic duct→empties into L subclavian vein

t-cells

formed in bone marrow & mature in thymus gland

b-cells

form & mature in bone marrow

cytotoxic t-cell

attack foreign cells or body cells infected by virus

• killer

• damage control

helper & suppressor t-cells

help: stimulate t & b

suppress: inhibit t & b

• control sensitivity of immune response (homeostasis)

nk-cells

attack foreign, infected, or cancer cells

lymphocyte life span

4-20 yrs.

lymphoid tissues

clusters of lymphocytes

nodules

deep to epithelium of respiratory, urinary, & digestive tracts

• in submucosa

tonsils

large nodules in oral & nasal cavities w/ inhaled/ingested foreign substances→attack

• pharyngeal→ in nasopharynx

• palatine→on sides of soft palate

• lingual→@ base of tongue

lymphoid organs

• nodes

• thymus gland

• spleen

nodes

• throughout body, some group together (cervical, axillary, inguinal)

• consist of b-cells & plasma cells

• lymph filters thru nodes & traps foreign substances→desroyed by lymphocytes

metastatic cancer

produces clusters of tumor cells in nodes along way

thymus gland

• deep to sternum

• large during infancy→shrinks & turns into fat

spleen

red pulp: venous sinuses

white pulp: lymphocytes

• filters blood & looks for bacteria/viruses & worn out blood cells to phagocytize

• initiates immune response

• very fragile→if damaged, can cause internal bleeding

innate defenses

born w/ these; general responses not immune

physical barriers

• skin & mucus membrane: tightly packed cells microbes can’t cross

  • sweat, oil, & mucus: trap & wash away microbes & chemicals

  • stomach mucosa: produces HCl acid enzymes to destroy bacteria

• hair

phagocytes

• neutrophils: eosinophils circulate in blood

• fixed macropages: stay in blood tissue

• free macrophages: travel thru body to injury site

immunological surveillance

instant monitoring of normal tissues by nk-cells

• respond immediately & recognize abnormal Ags on surface of foreign cell

• produce

perforins

• produced by nk-cells

• poke holes in abnormal cell’s PM→cell death

interferons

cells infected by viruses produce these→bind to uninfected cells→stimulated to produce antiviral proteins

inflammation

response of body to stress of tissue damage by microbes of physical/chemical agents

• redness, pain, heat, & swelling

• removes foreign substance & prevent spread

steps of inflammation

1. after injury, damaged cells release histamine, heparin, & prostaglandins

2. histamine increases capillary permeability→clotting factors enter injured area→swelling

3. heparin increases blood flow to tissues→removes toxins→heat

4. neutrophils attracted by chemotaxis

5. dead cells & debris form pus

fever

• above 99 F

1. macrophages secrete interleukin-1 →circulates to hypothalamus→”thermostat” is reset higher

2. increased body temp→increases tissue defense→increases repair

adaptive defenses

*immunity

• acquired & developed after exposure to specific Ags

adaptive properties

specificity: t & b-cells respond to molecular structures of a specific Ag

versatility: can react to any Ag @ any time

memory: remembers Ags it has encountered

tolerance: t & b-cells ignore normal Ags

cell-mediated immunity

1. Ag presentation

2. Ag recognition

3. activation of t-cells

Ag presentation

body cells produce MHC proteins that bind to Ags

• self MHC: ignored by t-cells

• non-self MHC: presented outside & activates t-cells

Ag presenting cells(II): macrophages eat foreign substances & recognizes later to kill

Ag recognition

t-cells recognize & bind to certain Ag

activation of t-cells

undergo proliferation & differentiation into diff. types

• cytotoxic seek out & destroy abnormal