Eating, and Nutrition

energy sources

1. lipids (stored in adipose tissue) 2. gluconeogenesis 3. Proteins can also be converted into glucose by the liver.

digestion

1. saliva is automatically secreted when food enter the mouth (due to the ANS) 2. food mixes with saliva so it can be swallowed 3. after food is swallowed, it proceeds through the esophagus to the stomach, where it is mixed with hydrochloric acid and pepsin 4. these chemicals break down food particles into even smaller pieces 5. the partially digested food is released periodically through the duodenum into the small intestine, where the process of digestion is completed 6. Indigestible material travels on to the large intestine, where water is reabsorbed and feces are formed.

cholecystokinin (CCK)

A gut hormone released in response to the consumption of fats that also acts as a central nervous system neurotransmitter that signals satiety. -it is released when food, especially fatty food, arrives at the duodenum; it has an inhibitory effect on feeding behavior -promotes the release of insulin by the pancreas and contracts the gallbladder to release bile to help break down fats.

Peptide YY (PYY)

A hormone concerned with hunger and the lack of hunger. -secreted by cells in the intestines -Low levels before eating, rise rapidly after meal. -It also acts in opposition to ghrelin, acting as an appetite suppressor.

glucose

A type of sugar found in foods that is a major source of energy for living organisms. -digested carbohydrates are broken down into ______. -it moves from the blood to other tissues. -it is the exclusive source of energy for the brain, whereas the rest of the body can use both ______ and fatty acids. -Excess ______ is stored as fat by adipose tissue or converted by the liver into glycogen for storage.

ventromedial hypothalamus

An area within the hypothalamus that participates in satiety.

arcuate nucleus

a cluster of neurons involved with feeding located within the hypothalamus -when leptin levels are low, these neurons use neuropeptide Y and agouti-related protein to communicate with the lateral hypothalamus and the paraventricular nucleus of the hypothalamus (Consequently, the parasympathetic division of the autonomic nervous system is activated, and feeding behavior is stimulated.) -also governed by ghrelin and insulin

glycogen

a complex carbohydrate used to store energy in the liver -a form of glucose stored for a short term in the liver and muscles. -regulated by insulin -If the body requires more energy than can be supplied by the glucose circulating in the blood, such as during a period of fasting, the liver converts stored _____ back into readily available glucose. Consequently, we maintain a fairly steady level of blood glucose over time.

obestatin

a hormone encoded by same gene as ghrelin, yet has an opposite effect - decreases appetite - perhaps by binding to different receptors than ghrelin.

melanin-concentrating hormone

a hormone that interacts with leptin and plays a role in the regulation of eating -used by the lateral hypothalamus to communicate widely with the cortex: causing higher-order motivated feeding behaviors. -Mice genetically modified to be incapable of producing ______ burned energy faster, ate less, and had less body fat

ghrelin

a hormone that stimulates feeding behavior -produced primarily by the pancreas and the lining of the stomach -levels are highest during fasting and decrease following a meal -acts as a short-term circulating hormone that stimulates hunger -also appears to affect feeding by acting on brain circuits involved with memory and reward

alpha melanocyte-stimulating hormone (Alpha-MSH)

a neurochemical originating in the arcuate nucleus, believed to inhibit feeding behavior -cause the pituitary gland to release TSH and ACTH, raising body metabolic rates -also activate the sympathetic division of the autonomic nervous system, increasing metabolism and body temperature and inhibiting feeding behavior. -competes directly with AgRP for activation of the MC4 receptors; serves as an agonist at the MC4 receptor. when they activate MC4 receptors, feeding is inhibited

cocaine-and amphetamine- regulated transcript (CART)

a neurochemical, originating in the arcuate nucleus, believed to inhibit feeding behavior -cause the pituitary gland to release TSH and ACTH, raising body metabolic rates -also activate the sympathetic division of the autonomic nervous system, increasing metabolism and body temperature and inhibiting feeding behavior. -elevated levels have been observed in patients with anorexia nervosa, even after the patients reached normal weight during treatment -might also reduce the rewarding aspects of eating through its actions in the nucleus accumbens, which is part of the reward circuit implicated in addiction

glucagon

a pancreatic hormone that converts glycogen into glucose -mediates glycolysis: the process of converting glycogen back into glucose when blood glucose levels drop.

insulin

a pancreatic hormone that facilitates the movement of sugars from the blood supply into the body's tissues -levels normally increase after a meal, helping some glucose circulating in the blood supply to move into cells and the rest to be stored as glycogen. -levels are lowest during long periods of fasting.

orexin

a peptide neurochemical produced in the lateral hypothalamus that stimulates eating -aka hypocretin -release is stimulated by low levels of leptin and high levels of ghrelin -_____-releasing neurons project throughout the brain; but, unlike what it says in the book, are more related to sleep.

neuropeptide Y

a peptide neurochemical secreted by the arcuate nucleus of the hypothalamus that initiates eating and activates the parasympathetic nervous system -when it is applied directly to the hypothalamus, animals will begin eating immediately -if ____ receptors in the hypothalamus are blocked, animals will fail to eat following either food deprivation or ____ infusions -suppresses the release of TSH and ACTH

adrenocorticotropic hormone

a pituitary hormone that stimulates the adrenal glands and increases metabolic rate (so suppressing it slows the body's use of energy, allowing some of the nutrients taken in during feeding to be used to replenish the fat stores.)

thyroid-stimulating hormone

a pituitary hormone that stimulates the growth and function of the thyroid gland, which in turn increases metabolic rate

paraventricular nucleus

a portion of the hypothalamus involved with the regulation of hunger

agouti-related protein (AgRP)

a small protein secreted by the arcuate nucleus that initiates eating and activates the parasympathetic nervous system -acts as an antagonist at a special receptor site in the lateral hypothalamus known as an MC4 receptor. When MC4 receptors are blocked, feeding is initiated. -suppresses the release of TSH and ACTH

leptin

a substance produced and secreted by fat cells into the bloodstream; helps the body regulate its fats stores -when fat stores are low, levels of circulating ____ are also low -Low levels activate the Arcuate Nucleus to release neuropeptide Y (NPY) and agouti-related peptide (AgRP) to initiate feeding. -high levels stimulate arcuate nucleus, which releases αMSH (via POMC) and CART -genetic defects in ____ production or sensitivity give a false reporting of body fat, causing animals to overeat. (obese humans don't respond to ____)

bulimia nervosa

an eating disorder characterized by a cyclical pattern of binge eating followed by purging through vomiting or use of laxatives. -the average binge session contains approximately 1,500 calories of food -far more common than anorexia, occurring in 3 percent as opposed to 0.5 to 1 percent of the American population -symptoms include: 1. fatigue 2. headaches 3. puffy cheeks (due to enlarged salivary glands) 4. loss of dental enamel through repeated vomiting of stomach acid. -bingeing rats responded to the opiate antagonist naloxone with anxiety, agitation, and chattering teeth. These symptoms are identical to the responses of rats addicted to morphine when given naloxone. People who fast and then binge on sweets might be setting up a similar addictive process that would make it difficult for them to stop bingeing.

anorexia nervosa

an eating disorder characterized by voluntary self-starvation and a grossly distorted body image -individuals maintain 85 percent or less of their normal body weight -up to 10 percent of patients eventually die from the disorder -symptoms include: 1. amenorrhea (cessation of menstruation), 2. dry or yellowed skin, 3. fine downy hair (lanugo) on the face, trunk, and limbs, 4. increased sensitivity to cold, 5.cardiovascular and gastrointestinal problems. -More than 90 percent of anorexia patients are female.

proteins

broken down into amino acids and used by muscles and other tissues for growth and protein synthesis

ketones

chemicals produced from stored fat by the liver; can supply energy -People following extremely low-carbohydrate diets, such as the Atkins diet, often rely on _____ for energy

nucleus of the solitary tract

cluster of nuclei in the medulla that communicate with other brain regions, notably with the hypothalamus. -also receives input from the taste reception system -No BBB... so can detect glucose levels in blood (glucoreceptors)

adipose tissue

fat cells that store fats that aren't used for immediate energy -lipids, for longer term storage, are deposited here

pancreas

large gland located behind the stomach

glucose transporters

membrane proteins that span the cell membrane and interact with insulin to bring glucose into the cell.

homeostasis

metabolic equilibrium actively maintained by several complex biological mechanisms that operate via the autonomic nervous system to offset disrupting changes -maintain fluid balance -maintain body temperature -defend against danger

glucoreceptor

receptor that is sensitive to the presence of glucose in the nucleus of the solitary tract in the brainstem -_______ in the liver influence the release of insulin from the pancreas and communicate with the NST via the vagus nerve.

lateral hypothalamus

serves as a hunger center for initiating eating -Rats with lesions here would starve to death in the presence of food because they would not initiate eating. -Human patients with tumors here often lose considerable weight due to loss of appetite. -Electrical stimulation of the _______ produces immediate feeding.

VMH syndrome

syndrome characterized by large weight gains and picky eating habits -produced in rats by lesions of the ventromedial hypothalamus; also result in excess insulin production

duodenum

the first section of the small intestine that connects the intestines and the stomach -when its glucoreceptors sense sugars, eating generally stops quickly.

type 2 diabetes mellitus

the form of diabetes generally diagnosed in middle-aged adults and characterized by resistance to insulin -individuals produce insulin but their bodies either do not make sufficient amounts of insulin or use insulin efficiently. After a few years of insulin resistance, the amount of insulin produced by the pancreas begins to decline. -same symptoms as other diabetes -can be prevented and treated by maintaining a healthy weight. -obesity is a major risk factor -Excess fructose in processed foods?

type 1 diabetes mellitus

the form of diabetes that appears early in life and is characterized by insufficient production of insulin -usually occurs when insulin-producing pancreatic cells are attacked and destroyed by the body's immune system. -Without insulin, glucose from food circulates through the bloodstream without being absorbed or stored by the body's tissues. The cells are literally starving while high levels of glucose are excreted in the urine. The excess circulating glucose causes an imbalance of solutes between the intracellular and extracellular compartments, producing enormous thirst. -SYMPTOMS: Fatigue, weight loss, excess drinking, and excess, sweet urination -glycogen isn't formed without the absorption of glucose

gluconeogenesis

the process of converting fat to glucose and ketones, a form of fuel, by the liver.

satiety

the sensation of being full, cessation of eating. -occurs long before sufficient nutrients make their way into cells. -stomach and intestines provide signals of fullness

lipostatic theory

theory that suggests that hunger results from low fat supplies (which causes us to search out fatty foods)