Caffeine in food• Natural sources of caffeine include coffee beans, tea leaves, kola nuts, guarana berries and cacao pods.• Caffeine is most well known for being a natural component of chocolate, coffee and tea.• It is also added to colas and energy drinks.• Around 90 percent of Americans consume caffeine every single day in one form or another.
Cell Signalling• To understand a “caffeine jolt” we must first understand the pathways which the body’s cells respond to certain signals in their environment. There are three sequential processes involved in the cell’s response to any signal. 1) The signal binds to a receptor protein. 2) The binding of the signal causes a message to be conveyed to the cell’s cytoplasm and amplified. 3) The cell changes its activity in response to the signal
Caffeine as a drug• Caffeine is chemically known as 1,3,7-trimethylxanthine.• It is an odourless white crystalline powder that has the ability to stimulate the central nervous system.• Caffeine enters the bloodstream through the stomach and small intestine, causing its effects in just 15 minutes after consumption. It stays in the body for quite a long time with a half-life of around 6 hours.• Caffeine has a similar structure to adenosine, which is a naturally occurring neurotransmitter in the brain, so it occupies the adenosine receptors and inhibits brain cell function so alertness is restored.• The role of adenosine is to suppress neural activity in the brain, increase blood flow throughout the body and contribute towards energy metabolism.
Effects of Caffeine on the Nervous SystemBy suppressing these actions of adenosine, caffeine has the following effects:• It increases neural activity in the brain - leading to a temporary increase in mental alertness and thought processing swell as reducing drowsiness and fatigue.• It decreases energy metabolism in the body- (after long-term consumption) leads to adrenal fatigue.• It reduces blood flow to the brain- leading to headaches, dizziness and reduced fine motor coordination.Other nervous system effects of caffeine include:• Increased heart rate• Increased thirst and hunger• Anxiety and nervousness• Dilation of air passages• Insomnia• Release of glucose from liver
In more detail..•Caffeine inhibits the action of an enzyme, (phosphodiesterase), resulting in anincreased intracellular concentration of -(cyclic AMP)- in the axon.•This can result in the release of increased amounts of excitatory transmittersubstances in the brain and has a mild stimulatory effect, increasing alertness.•Simply, caffeine causes more transmitters to be released, which will in turn causeions to move in and out of the post-synaptic neurone, making it depolarised(more positive inside the axon than the outside).
Caffeine Dependence• Some studies show that caffeine causes physical dependence.• One way to tell if someone is dependent is to remove caffeine from their diet and see if they have any withdrawal symptoms.• Withdrawal symptoms include headache, fatigue and muscle pain within 24 hours after the last dose of caffeine.• One study has stated that the minimum consumption of caffeine for physical dependence is 4 cups of coffee per day.• Caffeine can be lethal at dosages over 10g for the average adult. This is equivalent to drinking at least 80 cups of coffee in quick succession.