Chapter 3 Flashcards
Atoms
Elements
Chemical bonds
Molecules
Smallest unit of an element that still retain properties of that element
Substances that cannot be broken down into products with different properties
Forces that hold atoms together
Units of two or more of the same or different elements bonded together
Cells
Organs
The basic structural and functional units of plants and animal life
Discrete structures composed of more than one tissue that perform a specialized function
4 types of tissue
Muscle
Nerve
Epithelial
Connective
Two functions of digestive system
Digestion: the process of breaking down food into components small enough to be absorbed into the body
Absorption: the process of taking substances into the interior of the body
Feces
Body waste; unabsorbed food, bacteria, mucus, and dead cells which is excreted from the GI by passing through the anus
Gastrointestinal tract
A hollow tube consisting of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus, in which digestion and absorption of nutrients occurs
The tube is not inside your body…but food can be absorb less into the body
Transit time
The time between the ingestion of food and the elimination of the solid waste from that food.
24-72 hours in healthy adults
Mucosa
The layer of tissue lining the GI tract and other body cavities.
- protective layer
- absorption of the end products of digestion
- in direct contact with digestive enzymes and churning therefore cells only live 2-5 days
Layers of tissue of GI tract
- mucosa: cells to absorb nutrients
- connective tissue with nerve and blood vessels (support, controls muscles)
- involuntary smooth muscle/peristalsis (breaks up food)
- connective external layer provides support and protection
Mucus
A viscous fluid secreted by glands in the GI tract and other parts of the body, which acts to lubricate, moisten, and protect cells from harsh environments
Enzymes
Protein molecules that accelerate the rate of specific chemical reactions without being changed themselves
- some only affect fat
- some only affect carbs
Salivary amylase
Rennin
Pepsin
Mouth-breaks starch (large carb to smaller carbs molecules)
Stomach-cause the milk protein casein to curdle
Stomach-breaks proteins into polypeptides and amino acids
Trypsin
Chymotrypsin
Carboxypepidase
Pancreas
- breaks proteins and polypeptides into shorter polypeptides
- same as above
- breaks polypeptides into amino acids
Carboxypeptidase
Pancreatic lipase
Pancreatic amylase
Pancreas
- polypeptides into amino acids
- breaks triglycerides into monoglycerides, fatty acids and glycerol
- breaks starch into shorter glucose chains and maltose
Carboxypepidase
Aminopeptidase
Dipeptidase
Small intestine
-breaks polypeptides into amino acids
Lipase
Sucrase
Lactase
Small intestine
- monoglycerides into fatty acids and glycerol
- sucrose into glucose and fructose
- lactose into glucose and galactose
Maltase
Dextrinase
Small intestine enzyme
- breaks maltose into glucose
- breaks short chains of glucose into individual glucose molecules
Hormones
Chemical messengers that are produced in one location, released into the blood, and elicit responses at other locations in the body
Gastrin
Digestive hormone from stomach mucosa that stimulates secretion of HCL and pepsinogen by gastric glands in the stomach and increases gastric motility and emptying
Very important!!!
Somatostatin
Hormone from stomach and duodenal mucosa that inhibits stomach secretion, motility, and emptying, pancreatic secretion, absorption in the small intestine, gallbladder contraction and bile release
Secretin
Hormone released by the duodenum that signals the release of pancreatic juice rich in bicarbonate ions and stimulates the liver to secrete bile into the gallbladder.
Cholecystokinin (CCK)
Hormone released by the duodenum that stimulates the release of pancreatic juice rich in digestive enzymes and causes the gallbladder to contract and release bile into the duodenum
Gastric inhibitory peptide
Hormone from duodenal mucosa that inhibits gastric secretion and motility
Barrier function
The protective role that gastrointestinal cells have in limiting the absorption of harmful substances and disease-causing organisms
The GI tract limits the absorption of toxins and disease-causing organisms
Antigen
Antibody
A foreign substance (almost always has a protein) that, when introduced into the body, stimulates an immune response
Proteins produced by cells of the immune system that destroy or inactivate foreign substances in the body
Allergen
What are allergies
A substance, usually a protein, that stimulates an immune response.
An allergic reaction occurs when the immune system produces antibodies to a substance called an allergen
Saliva
Salivary amylase
A watery-fluid produced and secreted into the mouth by salivary glands. Contains lubricants, salivary amylase and lysozyme (inhibit bacteria growth in mouth).
An enzyme secreted by the salivary glands that breaks down starch (carbohydrates)
Lysozyme
An enzyme in saliva, tears and sweet that is capable of destroying certain types of bacteria
-helps prevent tooth decay
Pharynx
A funnel-shaped opening that connects the nasal passages and mouth to the respiratory passages and esophagus. It is a common passageway for food and air and is responsible for swallowing
Epiglottis
A piece of elastic connective tissue at the back of the throat that covers the opening of the passageway to the lungs during swallowing
Esophagus
What pushed food down???
A portion of the GI tract that extends from the pharynx to the stomach
Peristalsis: coordinated muscular contractions that move food through the GI tract
Sphincter
A muscular valve that helps control the flow of materials in the GI tract
Chyme
A mixture of partially digested food and stomach secretions
How many smooth muscle layers does the stomach have?
3
Parietal cells
Cells in the stomach lining that make HCL and intrinsic factor (needed for absorption of B12) in response to nervous or hormonal stimulation