ESS 3 Lecture Notes - Lecture 2: Subclavian Vein, Chyme, Probiotic
Digestion
Appetite: the psychological desire to consume specific foods
➔Environmental cues stimulate appetite
◆Stress, boredom, smell
➔Triggers (foods stimulate our 5 senses)
◆Appearance (color, shape)
◆Aroma
◆Sweetness
◆Texture
◆Sound of foods eaten or prepared
Hunger: the physiological drive for food that occurs when our body sense that we need to eat
➔Hypothalamus triggers the feeling of hunger or satiation (fullness)
◆Signals from 3 sources
● Nerve cells
● Hormones
● Amount and type of food we eat
Nerve cells
➔Nerve cells lining the stomach and small intestine detect changes in pressure according
to whether the organ is empty or full
➔The nerve cells cells relay the information to the hypothalamus which prompts you to
feel hungry
Alcohol and the liver
➔Liver functions to filter the blood from toxins
➔1 drink per hour
➔When it is exceeded, liver becomes overwhelmed and cells are damaged
◆Scar tissue forms that blocks blood flow through the liver
Digestive disorders
➔Acid reflux
➔Gallstones
◆Small pebble-like particles that harden and cannot pass through gallbladder
➔Hemorrhoids
◆Swollen and inflammation in the anus and lower rectum
➔Gastric inflammation
Gluten
➔Celiac disease (gluten intolerance)
◆Immune response to gluten found in wheat, barley, and rye
◆Affects the small intestine
◆If untreated, impairs digestion resulting in malabsorption and malnutrition
◆Treatable by avoiding gluten
Primary function of the digestive system is to break down nutrients in food into compounds
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small enough to be absorbed and utilized by the body
➔Carbohydrates → single sugar units
◆Salivary amylase break down carbs
➔Proteins → amino acids
➔Fats → fatty acids and glycerol
➔Vitamins and minerals are released during digestion
The Role of Hormones
Hormones: chemicals produced in glands that travel in the bloodstream to target organs in other
parts of the body
➔Stimulate food intake and produce a feeling of satiety
➔Body uses hormones to maintain homeostasis
Insulin and glucagon are responsible for maintaining blood glucose levels
➔Glucose: body’s most readily available fuel supply
◆No food → glucose levels drop → insulin and glucagon levels change →
message is sent to hypothalamus which prompts hunger
The Role of Amount and Type of Food
Foods with protein have the highest satiety value
➔Enters bloodstream more slowly
Fiber and water in the food
➔The bulkiness of the food affects hunger
➔Fiber is found in whole grains and leafy vegetables
➔Bulky meals stretch the stomach → sends signals to hypothalamus → stop eating
Body organization
➔From smallest functional units to functional systems
➔Atoms: smallest units of matter
◆Bind together to form molecules
◆Every bite of food is composed of molecules
➔Cells: smallest functional unit
➔Tissue: collection of cells with a similar origin
◆Organized to form organs
➔Organ systems: group of organs that function together
Stages of digestion
Ingestion: taking food into the body
Digestion: food is mechanically and chemically broken down into absorbable units
Absorption: nutrients are absorbed into the bloodstream
➔Small intestine = majority of absorption
➔Active transport : carrier and energy are required
➔Passive transport : higher to lower gradient
◆Simple diffusion
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Document Summary
Appetite: the psychological desire to consume specific foods. Hunger: the physiological drive for food that occurs when our body sense that we need to eat. Hypothalamus triggers the feeling of hunger or satiation (fullness) Amount and type of food we eat. Nerve cells lining the stomach and small intestine detect changes in pressure according to whether the organ is empty or full. The nerve cells cells relay the information to the hypothalamus which prompts you to feel hungry. Liver functions to filter the blood from toxins. When it is exceeded, liver becomes overwhelmed and cells are damaged. Scar tissue forms that blocks blood flow through the liver. Small pebble-like particles that harden and cannot pass through gallbladder. Swollen and inflammation in the anus and lower rectum. Immune response to gluten found in wheat, barley, and rye. If untreated, impairs digestion resulting in malabsorption and malnutrition.
