Hunger, Eating and Health Flashcards
(85 cards)
The prevalence of eating disorders suggests that
mechanisms regulating eating are complex.
- Over half of the adult population in the U.S. meets clinical criteria for obesity.
- 3% of U.S. adolescents suffer from anorexia nervosa.
Diet must provide energy but also
nutrients (bricks and mortar) for growth, maintenance and repair of body structure (muscles, bones, etc).
Diet must provide:
- Nine essential amino acids (from the 20 in the body)
- A few fatty acids
- About 15 vitamins
- Several minerals
Available energy is used for
- Processing newly ingested food = 8%
- Basal metabolism (body heat, gland secretions, action potentials, etc) = 55%, depending on body weight
- Active behavior = 12-13%
Purpose of eating is to provide the body with
molecular building blocks and energy.
Digestion
breaking down food and absorbing its constituents.
After digestion, energy is delivered to the body as
lipids (fats), amino acids (proteins), and glucose (carbohydrates: starches, sugar).
first step in digestion
Chewing breaks up food and mixes it with saliva.
second step in digestion
Saliva lubricates food and begins its digestion.
third step in digestion
Swallowing moves food and drink down the esophagus to the stomach.
fourth step in digestion
The primary function of the stomach is to serve as a storage reservoir. The hydrochloric acid in the stomach breaks food down into small particles and pepsin begins the process of breaking down protein molecules into amino acids.
fifth step in digestion
The stomach gradually empties its contents through the pyloric sphincter into the duodenum, the upper portion of the intestine where most of the absorption takes place.
sixth step in digestion
Digestive enzymes in the duodenum, many of them from the gall bladder and pancreas, break down protein molecules to amino acids, and starch and complex sugar molecules to simple sugars. Simple sugars and amino acids readily pass through the duodenum wall into the bloodstream and are carried to the liver.
seventh step in digestion
Fats are emulsified (broken into droplets) by bile, which is manufactured in the liver and stored in the gall bladder until it is released into the duodenum. Emulsified fat cannot pass through the duodenum wall and is carried by small ducts in the duodenum wall into the lymphatic system.
eighth step in digestion
Most of the remaining water and electrolytes are absorbed from the waste in the large intestine, and the remainder is ejected from the anus.
energy stored as
fats, glycogen and proteins.
fats are the
most efficient for energy storage.
one gram of fat stores
twice as much energy as one gram of glycogen.
fat does not attract and hold as much
as glycogen.
glycogen
Glycogen, a polymer of glucose, referred as animal starch, made primarily in the liver and muscles.
If all fat calories were stored as glycogen, one would weight about 600 pounds (275 Kg).
energy metabolism
Chemical changes that make energy available for use.
cephalic phase (1st phase of energy metabolism)
preparation for eating (seeing, smelling food).
absorptive phase (2nd phase of energy metabolism)
food absorbed meets immediate energy needs.
fasting phase (3rd phase of energy metabolism)
Withdrawing energy from reserves, weight loss. Ends with next cephalic phase. Insulin is low, so glucose cannot be used by cells in the body, but brain cells do not need insulin to use glucose, so glucose is reserved for the brain.
three phases of energy metabolism controlled by two pancreatic hormones
insulin and glucagon