Presentation on theme: "Chapter 2 - Caffeine. Absorption Absorbed through linings of the stomach (slowly). Most absorbed through small intestine. Full effect: 30-60 min. (depending."— Presentation transcript:
Chapter 2 - Caffeine
Absorption Absorbed through linings of the stomach (slowly). Most absorbed through small intestine. Full effect: min. (depending on food in stomach) Metabolized by liver; excreted through kidneys Half-life: approx 3 hrs.
Mechanism of Action Blocks adenosine receptors Adenosine: inhibitor; caffeine prevents it from working 200 mg – brain arousal 500 mg - + heart rate and breathing Dilates blood vessels; constricts blood vessels in the brain
Tolerance and Dependence Tolerance develops to some effects Dependence hrs. after last cup- headaches and fatigue
Effects on the Body Heart: increase heart rate; irregular heart beat; heart disease: conflicting results; may increase blood pressure Cholesterol: may raise LDL (not filtered coffee) Kidneys: contain adenosine receptors; diuretic Digestive System: gastritis; contributes to problems with ulcers (doesn’t cause them). Respiratory System: Theophylline (asthma)
Reproductive System: reduces chances of pregnancy; lower birth weight; fibrocystic disease Eyes: Constricts vessels, decreased nutrients Stress: increases adrenaline (increased blood pressure) Panic Attacks: 700+ mg – panic attacks in people who don’t have panic disorder
Enhancement of Physical Performance: delays fatigue; may help muscle performance; mixed results from studies; fat burners?; may dehydrate Lowers calcium levels Caffeine content – coffee p. 74 Caffeine content – energy drinks & soda p. 77 Caffeine content – over-the-counter drugs p. 78