question: How do things you ingest (pills, specific foods like fish, etc) make their way up to the brain?
comment: Your stomach acid breaks down the food you eat. The broken down food next goes to the intestines. The intestines absorb nutrients from broken down food. The microscopic nutrients pass through microscopic channels in the intestines to enter the blood stream. The blood carries the nutrients all through the body. Some of these nutrients can pass through the blood brain barrier. If they make it past, they can be distributed to the brain.
passages: Along with social environmental factors, ingestive behaviors are also influenced by atmospheric environmental factors. Atmospheric factors include:
  
  Section::::Initiating ingestion.:Signals from stomach.
   BULLET::::- Taste receptors in the gustatory system: The primary use of gustation as a type of chemoreception is for the detection of tasteants. Aqueous chemical compounds come into contact with chemoreceptors in the mouth, such as taste buds on the tongue, and trigger responses. These chemical compounds can either trigger an appetitive response for nutrients, or a defensive response against toxins depending on which receptors fire. Fish and crustaceans, who are constantly in an aqueous environment, use their gustatory system to identify certain chemicals in the mixture for the purpose of localization and ingestion of food.
   In most vertebrates, digestion is a four-stage process involving the main structures of the digestive tract, starting with ingestion, placing food into the mouth, and concluding with the excretion of undigested material through the anus. From the mouth, the food moves to the stomach, where as bolus it is broken down chemically. It then moves to the intestine, where the process of breaking the food down into simple molecules continues and the results are absorbed as nutrients into the circulatory and lymphatic system.
   Section::::Possible solutions.:Nanoparticles.
   Section::::Systematic response.:Digestive-system response.:Enteric nervous system.
  
  The digestive system is also able to respond to internal stimuli. The digestive tract, or enteric nervous system alone contains millions of neurons. These neurons act as sensory receptors that can detect changes, such as food entering the small intestine, in the digestive tract. Depending on what these sensory receptors detect, certain enzymes and digestive juices from the pancreas and liver can be secreted to aid in metabolism and breakdown of food.
  
  Section::::Research methods and techniques.
  
  Section::::Research methods and techniques.:Clamping techniques.
   Within this network, central inhibitory connections play a major role, producing a rostrocaudal inhibition that parallels the rostrocaudal anatomy of the swallowing tract. Thus, when the neurons controlling the proximal parts of the tract are active, those that command more distal parts are inhibited. Apart from the type of connection between the neurons, intrinsic properties of the neurons, especially those of NTS neurons, probably also contribute to the shaping and timing of the swallowing pattern.
   Section::::Vitamins.:Vitamin A.:Spatial memory.
   BULLET::::- Narcosis Narcosis refers to the general depression of biological activity from exposure to a nonspecifically acting toxicant. Toxicants that induce narcosis are known as narcotics or anesthetics. Alcohol is an example of a narcotic and can result in intoxication, a form of narcosis. Using the FATS approach, researchers are able to predict toxicity by assessing responses elicited by narcotics.
   Section::::Possible solutions.:Peptide masking.
   Section::::Initiating ingestion.:Metabolic signals.
  
  Hunger is the result of a fall in blood glucose level or depriving cells of the ability to metabolize fatty acids—glucoprivation and lipoprivation, respectively, stimulate eating. Detectors in the brain are only sensitive to glucoprivation; detectors in the liver are sensitive to both glucoprivation and lipoprivation outside the blood–brain barrier. However, no single set of receptors is solely responsible for the information the brain uses to control eating.
  
  Section::::Satiety signals.
   There are several sets of receptors located in the head: eyes, nose, tongue, and throat. The most important role of head factors in satiety is that taste and odor can serve as stimuli that permit learning about caloric contents of different foods. Tasting and swallowing of food contributes to the feeling of fullness caused by the presence of food in the stomach.
  
  Section::::Satiety signals.:Short-term signals.:Gastric and intestinal factors.
   Ingestion
  
  Ingestion is the consumption of a substance by an organism. In animals, it normally accomplished by taking in the substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms, ingestion can take place through taking the substance through the cell membrane.
  
  Besides nutritional items, other substances which may be ingested include medication (where ingestion is termed oral administration), recreational drugs, and substances considered inedible such as foreign bodies or excrement. Ingestion is a common route taken by pathogenic organisms and poisons entering the body.
   Jaws allow fish to eat a wide variety of food, including plants and other organisms. Fish ingest food through the mouth and break it down in the esophagus. In the stomach, food is further digested and, in many fish, processed in finger-shaped pouches called pyloric caeca, which secrete digestive enzymes and absorb nutrients. Organs such as the liver and pancreas add enzymes and various chemicals as the food moves through the digestive tract. The intestine completes the process of digestion and nutrient absorption.
   The digestive system can respond to external stimuli, such as the sight or smell of food, and cause physiological changes before the food ever enters the body. This reflex is known as the cephalic phase of digestion. The sight and smell of food are strong enough stimuli to cause salivation, gastric and pancreatic enzyme secretion, and endocrine secretion in preparation for the incoming nutrients; by starting the digestive process before food reaches the stomach, the body is able to more effectively and efficiently metabolize food into necessary nutrients. Once food hits the mouth, taste and information from receptors in the mouth add to the digestive response. Chemoreceptors and mechanorceptors, activated by chewing and swallowing, further increase the enzyme release in the stomach and intestine.
   Section::::Effects of drugs.
   Drug delivery to the brain
  
  Drug delivery to the brain is the process of passing therapeutically active molecules across the blood–brain barrier for the purpose of treating brain maladies. This is a complex process that must take into account the complex anatomy of the brain as well as the restrictions imposed by the special junctions of the blood–brain barrier.
  
  Section::::Anatomy.
   Section::::Anatomy and physiology.:Digestion.
  
  Jaws allow fish to eat a wide variety of food, including plants and other organisms. Fish ingest food through the mouth and break it down in the esophagus. In the stomach, food is further digested and, in many fish, processed in finger-shaped pouches called pyloric caeca, which secrete digestive enzymes and absorb nutrients. Organs such as the liver and pancreas add enzymes and various chemicals as the food moves through the digestive tract. The intestine completes the process of digestion and nutrient absorption.
  
  Section::::Anatomy and physiology.:Excretion.
   In mormyrid fish (a family of weakly electrosensitive freshwater fish), the cerebellum is considerably larger than the rest of the brain put together. The largest part of it is a special structure called the "valvula", which has an unusually regular architecture and receives much of its input from the electrosensory system.
  
  Section::::Memory.
   Each sensory system begins with specialized receptor cells, such as light-receptive neurons in the retina of the eye, or vibration-sensitive neurons in the cochlea of the ear. The axons of sensory receptor cells travel into the spinal cord or brain, where they transmit their signals to a first-order sensory nucleus dedicated to one specific sensory modality. This primary sensory nucleus sends information to higher-order sensory areas that are dedicated to the same modality. Eventually, via a way-station in the thalamus, the signals are sent to the cerebral cortex, where they are processed to extract the relevant features, and integrated with signals coming from other sensory systems.
   Insufficient intake of selected vitamins, or certain metabolic disorders, may affect cognitive processes by disrupting the nutrient-dependent processes within the body that are associated with the management of energy in neurons, which can subsequently affect synaptic plasticity, or the ability to encode new memories.
  
  Section::::Nutrients needed for memory development.
  
  Section::::Nutrients needed for memory development.:Choline.
   Section::::More recent studies.:The Impact of Different Drugs on Latent Learning.
  
  Many drugs abused by humans imitate dopamine, the neurotransmitter that gives humans motivation to seek rewards. It is shown that zebra-fish can still latently learn about rewards while lacking dopamine if they are given caffeine. If they were given caffeine before learning, then they could use the knowledge they learned to find the reward when they were given dopamine at a later time. 
   The gut flora can produce a range of neuroactive molecules, such as acetylcholine, catecholamines, γ-aminobutyric acid, histamine, melatonin, and serotonin, which is essential for regulating peristalsis and sensation in the gut. Changes in the composition of the gut flora due to diet, drugs, or disease correlate with changes in levels of circulating cytokines, some of which can affect brain function. The gut flora also release molecules that can directly activate the vagus nerve which transmits information about the state of the intestines to the brain.
   BULLET::::1. In neurons that are involved in chemical synaptic transmission, neurotransmitters are synthesized either in the neuronal cell body, or within the presynaptic terminal, depending on the type of neurotransmitter being synthesized and the location of enzymes involved in its synthesis. These neurotransmitters are stored in synaptic vesicles that remain bound near the membrane by calcium-influenced proteins.
  
  BULLET::::2. In order to trigger the process of chemical synaptic transmission, upstream activity causes an action potential to invade the presynaptic terminal.
   Section::::Nervous system.:Cerebellum.
  
  The circuits in the cerebellum are similar across all classes of vertebrates, including fish, reptiles, birds, and mammals. There is also an analogous brain structure in cephalopods with well-developed brains, such as octopuses. This has been taken as evidence that the cerebellum performs functions important to all animal species with a brain.
   Microarray analysis of gene expression shows the brain is active at the molecular level in the forebrain, midbrain and hindbrain of common carp and rainbow trout. Several genes involved in mammalian nociception, such as brain-derived neurotrophic factor (BDNF) and the cannabinoid CB1 receptor are regulated in the fish brain after a nociceptive event.
  
raw_presuppositions: Ingested materials can move specifically to the brain.
raw_corrections: The blood carries materials all through the body including to the brain.