Chapter 3 - The Human Body Flashcards
(36 cards)
Appetite
Psychological desire to consume specific foods
Hunger
Physiological drive for food
Anorexia
Physiological need for food, yet no appetite
Hypothalamus
- Triggers feelings of hunger or satiation (fullness)
- Located above the pituitary gland and the brain stem in an area of the brain that regulates involuntary activities
- Integrates signals from nerve cells, chemical messengers (hormones), and the types of food consumed
Role of nerve cells and hunger
- Special sells lining the stomach and small intestine
- Detect changes in pressure which indicate whether the organ is empty or distended with food
Hormones
- Chemical messengers secreted into the bloodstream by endocrine glands to help regulate body functions
- -Pancreatic hormones, insulin and glucagon, maintain blood glucose levels
- -Feeling full results from signals from the stomach no a raise in blood glucose
Roles of food type on hunger (protein, high-fat diets, bulky meals, solid foods)
- Proteins have the highest satiety value
- High-fat diets have a higher satiety value that high-carb diets
- Bulky meals (high in fiber and water) distend the stomach and promote a sense of satiety
- Solid foods are more filling than semisolid foods or liquids
Why do we want to eat?
- Foods stimulate our senses (sight, smell, taste, texture, hearing)
- Social and cultural cues
- Learned experiences
Digestion
Large food molecules are broken down to smaller molecules, mechanically and chemically
Absorption
Process of taking the digested products through the intestinal wall
Elimination
Undigested portions of food and waste products are removed from the body
Gastrointestinal Tract
- A series of organs arranged in a long tube that work together to process foods
- Sphincters: muscles that control the passage of food material from one GI organ to the next
Cephalic phase of digestion
- Hunger and appetite work together to prepare the GI tract for digestion
- First thought of food (nervous system)’stimulates the release of digestive juices
Digestion begins in the mouth
- Chewing moisten the food and mechanically breaks it into smaller pieces
- Saliva contains digestive juices secreted by the salivary gland in the mouth
- Taste receptors detect distinct tastes
Components of saliva
- Enzymes are complex chemical that induce chemical changes in other substances to speed up bodily processes
- Bicarbonates neutralize acids
- Mucus moistens the food and oral cavity
- Antibodies and lysosomes fight oral bacteria
Bolus
The mass of food chewed and moistened in the mouth
Epiglottis
Covers the opening to the trachea during swallowing
Peristalsis
The muscular contraction that move food through the GI tract
The pH scale
- Stands for potential of hydrogen
- Measures the potential of a substance to release or take up hydrogen ions in solution
- Tissues lining the stomach are generally protected from the effects of acidity
Gastrin
A hormone secreted by stomach lining cells that stimulates the gastric glands to produce gastric juice
Gastric glands
- Parietal cells secrete HCL and intrinsic factor
- Chief cells secrete pepsinogen and gastric lipase
Contents of gastric juice
- HCl denatures proteins and activates pepsin
- Pepsin - enzyme to digest protein
- Gastric lipase - enzyme to digest fat
- Intrinsic factor - protein to absorb vitamin B12
Mechanical digestion
Occurs as the stomach mixes and churns the food and gastric juices
Chyme
Liquid product of mechanical and chemical digestion in the stomach
