Digestive System Flashcards
0
Q
Absorption
A
Movement of nutrients into the bloodstream
1
Q
Ingestion
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Taking in food
2
Q
Defecation
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Rids the body of indigestible waste
3
Q
Mechanical digestion
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Breaking down physically
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Q
Chemical digestion
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Break down chemically
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Q
Alimentary canal (GI tract)
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Continuous hollow tube that runs from mouth to anus
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Accessory digestive organs
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Organs that the food doesn’t directly enter but helps with digestion
Ex: liver, pancreas
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Q
Organs of the alimentary canal
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Mouth to pharynx to esophagus to stomach to small intestine to large intestine to anus
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Q
Mouth anatomy: lips
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Protect anterior opening
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Mouth anatomy: cheeks
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Form the lateral walls
10
Q
Mouth anatomy: hard palate
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Forms anterior roof
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Mouth anatomy: soft palate
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Forms posterior roof
12
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Mouth anatomy: uvula
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Fleshy projection of the soft palate
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Mouth anatomy: tongue
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Attached at hyoid bone and styloid processes of the skull and by the lingual frenulum to the floor of the mouth
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Mouth anatomy: tonsils
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Palatine lingual
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Q
Pharynx physiology
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Serves as a common passageway for air and food
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Pharynx physiology
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Serves as a common passageway for air and food
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Q
Esophagus: Anatomy
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About 10 in long
Runs from pharynx to stomach through the diaphragm
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Q
Esophagus: physiology
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Conducts for peristalsis (slow rhythm squeezing)
Passageway for food only (respiratory system branches off after the pharynx)
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Q
Stomach anatomy
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Located on the left side of the abdominal cavity
Food enters at the cardiac sphincter (valve)
Food empties into the small intestine at the pyloric sphincter (valve)
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Q
Regions of the stomach
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Cardiac region
Fundus
Body
Pylorus
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Q
Cardiac region
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near the heart
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Fundus
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Expanded portion lateral to the cardiac region
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Q
Body
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Mid portion
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Layers of peritoneum attached to the stomach
Lesser omentum
| Greater omentum
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Lesser omentum
Attaches to the liver to the lesser curvature
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Greater omentum
Contains fat to insulate, cushion, and protect abdominal organs
Attaches the greater curvature to the posterior body wall
Has lymph nodules containing macrophages
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Stomach physiology
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Temporary storage tank for food
Site of food breakdown
Chemical breakdown of proteins begin
Delivers chyme (processed food) to the small intestine
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Structure of the stomach mucosa
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Mucosa is simple columnar epithelium
Mucous neck cells
Gastric glands
Chief cells
Parietal cells
Enteroendocrine cells
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Mucosa neck cells
Produce a sticky alkaline mucus
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Gastric glands
Situated in gastric pits and secrete gastric juice
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Chief cells
Reduce proteins digesting enzymes (pepsinogens)
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Parietal cells
Produce hydrochloric acid
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Enthroned octane cells
Produce gastrin
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Small intestine
The bodies major digestive organ
Site of nutrient absorption into the blood
Muscular tube extending from the pyloric sphincter to the ileocecal valve
Suspended from the posterior abdominal wall by then mesentiery
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Subdivisions of the small intestine
Duodenum
Jejunum
Ileum
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Duodenum
10 inches long
Attached to the stomach
Curves around a hold of the pancreas
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Jejunum
8 feet long
| Attaches anteriorly to the duodenum
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Ileum
12 feet long
| Extends from jejunum to large intestine
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Chemical digestion begins in the small intestine
Enzymes are produced by intestinal cells and the pancreas
Pancreatic ducts carry enzymes to the small intestine
Bile, formed by the liver, enters via the bile duct
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Small intestine anatomy
Structural modifications that increase surface area
Micro villi
Villi
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Microvilli
Tiny projections of the plasma membrane (create a brush border appearance)
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Villi
Fingerlike structures formed by the mucosa
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Large intestine
Large in diameter, but shorter in length, then the small intestine
Frames the internal abdomen
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Large intestine anatomy
Cecum: saclike first part of the large intestine
| Appendix
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Appendix
Accumulation of lymphatic tissue that sometimes becomes inflamed (appendicitis)
Hangs from the Cecum
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Ascending colon
Travels up right side of abdomen
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Transverse colon
Travels across the abdominal cavity
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Descending colon
Travels down the left side
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Sigmoid colon
Enters the pelvis
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Anus
Opening of the large intestine
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External anal sphincter
Formed by skeletal and under voluntary control
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Internal anal sphincter
Formed by smooth muscle
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Anal sphincters
These sphincters are normally closed except during defecation
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Large intestine anatomy continued
No villi present
| Goblet cells produce alkaline mucus which lubricates the passage of feces
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Accessory digestive organs
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Liver
Teeth
Gallbladder
Pancreas
Salivary glands
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Teeth function
Masticate (chew) food
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Humans have two sets of teeth
Deciduous
| Permanent
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Deciduous teeth
Baby or milk teeth
| 20 teeth fully formed by age two
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Permanent teeth
Replace deciduous teeth between six and 12
Full set is 32 teeth that some people don't have wisdom teeth
If they do emerge, the wisdom teeth appear between ages 17 and 25
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Classification of teeth
Incisors: cutting
Premolars: grinding
Canines: tearing or piercing
Molars: grinding
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Salivary glands
Three pairs of salivary glands empty secretion into the glands
Parotid
Submandibular
Sublingual
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Saliva
Mixture of mucus mad serous fluid
Helps to form a food bolus
Contains salivary amylase to begin starch digestion
Dissolves chemicals so they can be tasted
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Pancreas
Found posterior to the parietal peritoneum
Extends across the abdomen from spleen to duodenum
Produces a wide spectrum of digestive enzymes that break down all categories of food
Enzymes are secreted into the duodenum
Hormones produced by the pancreas insulin
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Liver
Largest gland in the body
Located on the right side of the body under the diaphragm
Consists of four lobes suspended from the diaphragm and abdominal wall by the falciform ligament
Connected to the gallbladder via the common hepatic duct
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Bile
Produced by cells in the liver
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Bile composition
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Bile salts
Bile pigments (mostly bilirubin from the breakdown of hemoglobin)
Cholesterol
Phospholipids
Electrolytes
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Bile function
Emulsify (break apart) fats by physically breaking fat globules into smaller ones
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Gallbladder
When no digestion is occurring, bile backs up the cystic duct for storage in the gallbladder
Sac found in hollow fossa (hole) of liver
When digestion of fatty food is occurring, bile is introduced into the duodenum from the gallbladder
Gallstones are crystallized cholesterol which can cause blockages
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Propulsion
Moving foods from one region of the digestive system to another
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Peristalsis
Alternating waves of contraction and relaxation that squeezes food along the GI tract
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Chemical digestion
Enzymes break down food molecules into their building blocks
Each major food group uses different enzymes
Carbs broken to simple sugars, proteins to amino acids, fats to fatty acids and alcohol
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Absorption
End products of digestion are absorbed in the blood or lymph
| Food must enter mucosal cells and then into blood or lymph capillaries
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Defection
Elimination of indigestible substances from the GI tract in the form of feces
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Digestive activities of the mouth: chemical
Food mixed with saliva
| Starch is broken down into maltose by salivary amylase
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Hydrochloric acid
Makes the stomach contents very acidic
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Acidic pH
Activates pepsinogen to pepsin for protein digestion
| Provides a hostile environment for microorganisms
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Protein digestion enzymes
Pepsin: an active protein digesting enzyme
Rennin: works on digesting milk protein in infants, not adults
Alcohol and asprin are the only items absorbed into the stomach
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Propulsion in the stomach
Food must first be well mixed
| Stomach empties in 4-6 hours
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Rippling perstalsis
Occurs in the lower stomach
80
The pylorus
Real eases chyme into the small intestine (30 mL at a time)
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Digestion in the small intestine
Help complete digestion of starch (pancreatic amylase)
Alkaline content neutralizes acidic chyme
Carry out about half of all protein digestion
Digest fats using lipases from the pancreas
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Food breakdown and absorption in the large intestine
No digestive enzymes are produced
Resident bacteria digest remaining nutrients
Release gases
Water is absorbed
Remaining materials are eliminated via feces
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Carbohydrates
Most are derived from plants
| Exceptions: lactose from milk and small amounts of glycogens from meats
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Major nutrients
Carbohydrates
Lipids proteins
Water
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Minor nutrients
Vitamins
| Minerals
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Nutrient
Substance used by the body for growth, maintenance, and repair
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Lipids
Saturated fats from animal products
Unsaturated fats from nuts, seeds and vegetable oil
Cholesterol from egg yolk, meats and milk products
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Proteins
Complete proteins: contain all essential amino acids
Most from animal products
Legumes and beans also have proteins, but are incomplete
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Vitamins
Most used as coenzymes
| Found in all major food groups
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Minerals
Play many roles in the body
| Most mineral rich foods are vegetables, legumes, milk and some meats
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Lysozyme
Enzyme in saliva that fights infection by digesting the cell walls of bacteria
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Alimentary canal
One way tube that passes through the body
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Bile
Fluid that prepares fat molecules to be broken down by enzymes
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Gastric glands
Microscopic structure that releases a number of substances into the stomach
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Islets of langerhans
Small clusters of cells, some of which produce insulin, that are located inside the pancreas
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Mouth
Alimentary canal begins
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Glucagon
Hormone that enables the body to break down glycogen and fats, and release sugars in the blood
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Villus
Projection in the lining of the small intestine
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Peristalsis
Contractions of smooth muscle that move food through the alimentary canal
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Small intestine
Part of the digestive system that consists of the duodenum, jejunum, and ileum
Region of the digestive system where most of the chemical work of digestion takes place
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Esophagus
Tubelike structure through which food passes btwn the mouth and stomach
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Large intestine
Region of the digestive system where in digested wastes are prepared for removal from the body
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Pepsin
Protein digesting enzyme produced by gastric glands
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Insulin
Polypeptide hormone that enables the body to convert sugar in the bloodstream into stored glycogen and fat
105
Salivary gland
Structure that produces a fluid that helps to moisten food
106
Pancreas
Gland located just below the stomach that produces enzymes and other substances essential for digestion
107
Stomach
Large sac that mixes food with acids and enzymes to produce chyme
108
Liver
Gland that produces bile
109
Amylase
Enzyme in saliva that breaks the chemical bonds in starches
