Unit 2- Chapter 3 Flashcards
Digestion system
What are the various stimulants that cause eating?
The Hypothalamus is responsible for prompting us to seek food due to various signals from nerve cells and chemicals in our bodies. The hypothalamus has feeding and satiety centers that help regulate our intake of food.
Hunger which is a nonspecific psychologic drive for food occurs due to various signals in our bodies.
Appetite is a specific psychological drive for food that occurs due to social and cultural desires. Such as wanting to have popcorn at the movies or cake at a birthday party.
What are the organs in the GI tract?
The mouth, esophagus, stomach, small intestine, large intestine, and anus.
What are the accessory organs in the GI tract?
Salivary glands in the mouth
Pancreas
Gallbladder
Liver
What digestion takes place in the mouth?
Mechanical breakdown of food also known as mastication.
Chemical digestion where the salivary glands produce salvia and mixes with the food to form bolus.
Saliva contains enzymes amylase to break down starch and lingual lipase to break down lipids.
What takes place before digestion even starts?
Cephalic phase, which helps prepare the GI tract for digestion. It is started due to our senses such as smelling food, thinking about food, or tasting food.
Where does the bolus go after it gets swallowed?
The bolus is moved into the esophagus due to peristalsis and reaches the lower esophageal sphincter which connects to the stomach.
What can happen if the lower esophageal sphincter does not work properly?
If the LES fails to close after the food reaches the stomach, then the person can develop GERD or acid reflex. This can cause the feeling of heartburn or feeling like the food is going to come back up.
Digestion in the stomach
Once food reaches the stomach, the organ will start churning the food and producing gastric juices.
The mixing of the churned food with the gastric juices produces what is called CHYME.
The job of the stomach is to store chyme until it is ready to reach the small intestine.
Partial digestion and absorption takes place here.
What are the two types of cells that the gastric glands are lined with?
parietal cells and chief cells
What does the parietal cells secrete?
hydrochloric acid
this acid helps kill any harmful bacteria that may be present from the food as well as denature and break down proteins for digestion.
intrinsic factor which helps in the absorption of vitamin b12
What does the chief cells secrete?
Pepsinogen
hydrochloric acid turns pepsinogen into the active form pepsin which will start the digestion of proteins.
Gastric Lipase
an enzyme active in lipid digestion
only partial digestion of lipids until they reach the small intestine.
What protects the stomach from the acidity of the gastric juice?
Mucous cells line the stomach to help protect from gastritis or an ulcer due to acidic nature. Other cells also secrete bicarbonate which helps neutralize the acids in the stomach.
What is absorbed in the stomach?
Most absorption occurs in the small intestine, but the stomach can absorb some substances through the stomach lining and into the blood. These can include water, fluoride, some lipids, some lipid soluble drugs like aspirin and alcohol.
What is the capacity of the stomach and how long does chyme remain in there before being released into the small intestine?
The capacity of the stomach is about 1 gallon.
Chyme will still in the stomach for about 2 hours before being periodically released into the duodenum.
What sphincter connects the stomach to the small intestine which allows the chyme to pass through?
pyloric sphincter
Where does most digestion and absorption take place?
The small intestine
The longest portion of the GI tract.
What are the three sections of the small intestine?
- Duodenum
- Jejunum
- Ileum (last portion)
What are the accessory organs of the small intestine?
Gallbladder
Pancreas
Liver
What is the accessory organ of the mouth?
Salivary gland
What is the gallbladder’s main purpose in digestion?
The gallbladder is responsible for storing bile made by the liver. Bile emulsifies lipids in the small intestine. The gallbladder helps aid in the digestion of fats.
What does the pancreas do in digestion?
- Manufactures, stores, and secretes digestive enzymes to catalyze the digestion of carbohydrates, lipids, and proteins.
- Manufactures insulin and glucagon. Which are responsible for regulating hunger and satiety. As well as regulating the amount of glucose in the blood.
- Secretes bicarbonate into the duodenum. Neutralizes acidic chyme in the small intestine.
What does the liver do in digestion?
The liver is the largest digestive organ in the body and also is considered a gland.
Cleans toxins (harmful substances) out of the blood.
Gets rid of old red blood cells.
Makes bile, a fluid that helps the body digest (break down) food.
Metabolizes proteins, carbohydrates and fats so your body can use them.
Produces substances to help blood clot.
Regulates the amount of blood in the body.
Stores glycogen (an energy source) and vitamins to be used by the body later.
Three structural features of the small intestine?
1.) circular folds
2.) villi
3.) microvilli
Circular folds
heavy folds within the small intestine that result in increased surface area therefore allowing for better absorption.
Villi
small fingerlike projections within the circular folds.
the constant movement of the villi allow them to encounter and trap nutrient molecules.
Enterocytes
Specialized absorptive cells in the villi of the small intestine.
What is inside each Villus?
Capillaries and Lacteal.
The capillaries absorb water soluble nutrients into the bloodstream. Whereas the lacteal absorbs fat-soluble nutrients into lymph.
Lacteal
A small lymphatic vessel located inside the villi of the small intestine.
What does each enterocyte of each villus have?
Microvilli also known as brush border. Which is tiny brush like projections that help increase absorption.
what is brush border?
The microvilli of the small intestinal mucosa, which tremendously increase its absorptive capacity.
What are the four types of absorption in the small intestine?
Passive diffusion
Facilitated diffusion.
Active diffusion
Endocytosis
Passive diffusion
Nutrients cross into the enterocytes without the use of a carrier protein or requirement of energy. Moves from a high to low concentration gradient.
Ex: lipids, water, vitamin c
Facilitated diffusion.
Nutrients cross into the enterocytes with the help of a carrier protein but do not need energy. Moves from a high to low concentration gradient. Will not move without the carrier protein.
Ex: Fructose
Active Transport
Energy and a carrier protein are required to move nutrients against the concentration gradient. Moves from a low to high concentration gradient.
Requires the use of ATP (adenosine triphosphate)
Ex: Glucose, amino acids, certain minerals, and vitamin c).
Endocytosis
A transport process in which nutrients are engulfed by the cell membrane and are released into the cell interior (also called pinocytosis).
Ex: some proteins including the antibodies in breast milk are absorbed this way.
What are the two nutrients that transport nutrients and wastes
The blood and the lymphatic system
What are blood and the lymphatic system responsible for?
Blood travels through the cardiovascular system to transport nutrients and fluids and to pick up waste products.
Lymph travels through the lymphatic system and transports most lipids and fat-soluble vitamins.
How Does the Neuromuscular System Support the Gastrointestinal System?
Its two components, nerves and muscles, partner to coordinate and regulate the digestion and absorption of food and the elimination of waste products.
segmentation
Rhythmic contraction of the circular muscles of the small intestine, which squeezes chyme, mixes it, and enhances the digestion and absorption of nutrients from the chyme.
Peristalis
Peristalsis occurs through the actions of circular muscles and longitudinal muscles that run along the entire GI tract. These muscles continuously contract and relax, causing subsequent constriction and bulging of the tract, which pushes the intestinal contents from one area to the next.
Simple carbohydrates
A monosaccharide or disaccharide; commonly called sugar.
monosaccharide
The simplest of carbohydrates; consists of one sugar molecule; the most common is glucose.
disaccharide
A carbohydrate compound consisting of two monosaccharide molecules joined together.
fructose
The sweetest natural sugar; a monosaccharide that occurs in fruits and vegetables; also called levulose or fruit sugar.
high fructose corn syrup
A type of corn syrup in which part of the sucrose is converted to fructose, making it sweeter than sucrose or regular corn syrup.
galactose
A monosaccharide that joins with glucose to create lactose
ribose
A five-carbon monosaccharide that is located in the genetic material of cells. RNA
what are the three most common monosaccharides?
Glucose, Fructose, Galactose.
Ribose is also a common monosaccharide.
what elements do carbohydrates contain?
carbon, hydrogen, and oxygen
how are monosaccharides linked together in disaccharides?
alpha or beta bonds
alpha bonds
Alpha bonds are easily digestible by humans.
beta bonds
beta bonds are not easily digestible by humans.
Complex carbohydrates
include oligosaccharides and three types of polysaccharides: starch, glycogen, and fiber.
lactose
Also called milk sugar, a disaccharide consisting of one glucose molecule and one galactose molecule
Maltose
A disaccharide consisting of two molecules of glucose; does not generally occur independently in foods; also called malt sugar
fermentation
The anaerobic process in which an agent causes an organic substance to break down into simpler substances and results in the production of ATP.
sucrose
A disaccharide composed of one glucose molecule and one fructose molecule; sweeter than lactose or maltose.
oligosaccharides
complex carbohydrate that contains 3 to 10 monosaccharides.
raffinose
An oligosaccharide composed of galactose, glucose, and fructose. Also called melitose. It is commonly found in beans, cabbage, brussels sprouts, broccoli, and whole grains.
stachyose
An oligosaccharide composed of two galactose molecules, a glucose molecule, and a fructose molecule. Found in many beans and legumes.
polysaccharide
A complex carbohydrate consisting of long chains of glucose.
starch
The storage form of glucose (as a polysaccharide) in plants.
amylose
a straight chain of glucose molecules
amylopectin
is highly branched.
more rapidly digested than amylose and raises blood glucose levels more quickly due to increased surface area.
Starch
Storage form of glucose in plants; found in grains, legumes, and tubers such as sweet potatoes.
Glycogen
Storage form of glucose in animals; stored in liver and muscles.
Fiber
Forms the support structures of leaves, stems, and plants
Dietary fiber
The nondigestible carbohydrate parts of plants that form the support structures of leaves, stems, and seeds.
plants skeleton.
Functional fiber
The digestible forms of carbohydrate that are extracted from plants or manufactured in the laboratory and have known health benefits.
Total fiber
The sum of the functional fiber and the dietary fiber.
Soluble fibers
dissolve in water, are viscous, and can be digested by bacteria in the colon.
ex: dissolvable laxatives, citrus fruits, berries, oat products, and beans
reduces the risk of CVD and type two diabetes.
insoluble fibers
do not dissolve in water, are not viscous, and cannot be digested.
not known for reducing cholesterol levels but is helpful for reliving constipation and increasing bowl movements.
fiber-rich carbohydrates
A group of foods containing either simple or complex carbohydrates that are rich in dietary fiber. These foods, which include most fruits, vegetables, and whole grains, are typically fresh or moderately processed.
salivary amylase
An enzyme in saliva that breaks starch into smaller particles and eventually into the disaccharide maltose.
pancreatic amylase
An enzyme secreted by the pancreas into the small intestine that digests any remaining starch into maltose.
maltase
A digestive enzyme that breaks maltose into glucose
sucrase
A digestive enzyme that breaks sucrose into glucose and fructose.
lactase
A digestive enzyme that breaks lactose into glucose and galactose.
does carbohydrate digestion take place in the stomach?
NO
which two hormones are responsible for our flight or fight response?
Epinephrine and norepinephrine
what monosaccharide does not stimulate insulin release?
Fructose
glycemic index
A rating of the potential of foods to raise blood glucose and insulin levels.
glycemic load
The grams of carbohydrate in a serving of food multiplied by the glycemic index of the carbohydrate and divided by 100.
ketosis
The process by which the breakdown of fat during fasting states results in the production of ketones.
ketones
Substances produced during the breakdown of fat when carbohydrate intake is insufficient to meet energy needs; provide an alternative energy source for the brain.
ketoacidosis
Excessive blood ketone level, which causes the blood to become very acidic and can be fatal.
The RDA for carbohydrate
130 g per day
The AMDR for carbohydrate
45% to 65% of total energy intake.
The Adequate Intake for fiber
25 g per day for women and 38 g per day for men, or 14 g of fiber for every 1,000 kcal per day that a person eats.
nutritive sweeteners
Sweeteners, such as sucrose, fructose, honey, and brown sugar, that contribute energy.
non-nutritive sweeteners
Also called alternative sweeteners or high-intensity sweeteners; manufactured sweeteners that provide little or no energy.
Acceptable Daily Intake (ADI)
An estimate made by the Food and Drug Administration of the amount of a non-nutritive sweetener that someone can consume each day over a lifetime without adverse effects.
hyperglycemia
A condition in which blood glucose levels are higher than normal.
diabetes
A chronic disease in which the body can no longer regulate blood glucose.
type 1 diabetes
A disorder in which the pancreas cannot produce enough insulin.
hypoglycemia
A condition marked by blood glucose levels that are below normal fasting levels.
lactose intolerance
A disorder in which the body does not produce sufficient lactase enzyme and there-fore cannot digest foods that contain lactose, such as cow’s milk.
