Digestive Flashcards
What is the main purpose of the digestive system?
Prepares nutrients for absorption and use by body cells
What are the two main portions of the digestive system?
Alimentary canal- continuous hollow tube
Accessory organs
What are the 7 organs of the alimentary canal?
Mouth Pharynx Esophagus Stomach Small intestine Large intestine Anus
From the innermost to outermost, what are the layers of the alimentary canal?
Mucosa
Submucosa
Muscularis (muscle)
Serosa (peritoneum)
What is the main purpose of the mouth?
Mastication
Mixed food with saliva for chemical digestion in addition to mechanical digestion
Taste
Swallowing with tongue
What is the main purpose of the pharynx?
Tube going from mouth to esophagus
What is the purpose of the esophagus?
First segment of DIGESTIVE TUBE
Food propelled by peristalsis
What are some main characteristics of the stomach?
Capacity about 1-1.5 L
-position changing during deep breaths and after eating (related to dyspnea)
Lesser (lengthier) curvature
Greater (shorter) curvature
What are the different components of the stomach?
Lower esophageal sphincter allows foot to enter
From top to bottom, regions are :
Cardiac region
Fundus (expands and collapses)
Body
Pylorus- funnel shaped end
What is the sphincter between the stomach and the small intestine?
Pyloric sphincter
What is produced in the stomach?
Chyme
What are the folds in the stomach called and what is their purpose?
Rugae - allow for expansion
Is anything absorbed in the stomach?
Only alcohol and aspirin
What is the mucosa in the stomach?
Gastric mucosa
Simple columnar epithelium
What are the layers of the gastric mucosa from innermost to outermost?
Mucosa neck cells- produces alkaline mucus to protect from stomach acids
Chief cells- produce proteins: pepsinogen and rennin
Parietal cells- produces HCl
Enteroendocrine cells- stimulate gastrin to release digestive chemicals
What are the holes in the stomach called?
Gastric pits- folding in mucosa layer to house various gastric glands
Is the stomach chemical or mechanical digestion?
Both. Enzymes and physical churning
What is GERD?
Heart burn
Gastroesophegeal reflux disease
Backwards flow of stomach acid through lower esophageal sphincter into esophagus
What is the purpose of the stomach?
Acts as storage tank
Churns to mix contents
Site of food breakdown
Chemical breakdown of protein begins with PEPSINOGEN
Releases gastrin to regulate digestive functions
Delivers chyme to small intestines
What are some characteristics of the small intestine?
Long muscular tube roughly 2.5 cm diameter and 6m long
- MAJOR digestive organ
- site of nutrient absorption
- ends at ileocecal valve (attachment to large intestines)
What are the divisions of the small intestine?
- duodenum- 25cm, shaped like a C. Attached to stomach.
- jejunum - attached to duedenum (2.5 m long)
- ileum - from jejunum to large intestines(3.5 m long)
What are the organs of absorption in the small intestine?
Deep folds in mucosa and su mucosa (plicae folds) have VILLI
villi- finger like projections use to increase surface area and increase absorption
Each villi has lacteal vessels, arterioles, and venules- also covered in BRUSH BORDER, 1700 ultrafine microvilli PER CELL
What are the structures of the villi?
Absorptive cells- ENTEROCYTES (microvilli. Main site of absorption
Blood capillaries
Lacteals
Peyers patches (lymphatic tissue in submucosa to fight bacterial invasion) - most numerous at end of small intestine
Where does the most digestion occur?
Duodenum
What are some characteristics of the large intestine?
Larger than small intestine in diameter
Have microvilli, but no villi
Site of WATER ABSORBTION
What are the components of the large intestine?
Cecum- saclike
Appendix- protrusion. Reservoir for gut bacteria. Accumulation of lymphatic tissue
Ascending colon (transverse)
Descending colon (sigmoid)
Rectum
Anus
What are the main functions of the large intestine?
Eliminates indigestible food
Does NOT digest food
Contains goblet cells- intestinal mucous cells that produce alkaline mucous that coats feces and reduces acidity.
What are the 5 accessory organs to digestion?
Salivary glands
Teeth
Pancreas
Liver
Gall bladder
What are the three Salvatore glands and what is their purpose?
Paranoid, submandibular, sublingual
Produce saliva that contains salivary amylase- begins starch digestion
Dissolved so chemicals can be tasted
What is the main purpose of teeth?
Mastication
Mechanical digestion
What are the two portions of the pancreas and what do they do?
Exocrine portion- tiny ducts unite to form pancreatic duct, which secreted enzymes into duodenum
Endocrine portion- cells in pancreas that produce insulin and glucagon into blood stream
What is the overall function of the pancreas?
Produce digestive enzymes that break down ALL food
Pancreatic AMYLASE, TRYPSINS, LIPASES, NUCLEASES
Alkaline fluid secreted to neutralize acid in chyme from stomach
What is the difference between digestion and metabolism?
Digestion- break down of ingested food and absorption of nutrients into blood
Metabolism- production of ATP (both anabolic and catabolic activities)
What are some characteristics of the liver?
Largest gland in body (1.5kg)
Right side of body under diaphragm
Connected to gallbladder at HEPATIC DUCT
What is the relationship between the liver and the gallbladder?
Gallbladder is found embedded in a hollow fossa of the liver
CYSTIC DUCT extends from gall bladder, which COMMON HEPATIC DUCT extends from liver.
-Joining of two ducts forms BILE DUCT into duodenum
(Liver secretes bile, gallbladder stores it)
Used for emulsification of fats
What is bile made up of and what is its purpose?
- bile salts
- bile pigment- BILIRUBIN (yellow breakdown of heme)
- cholesterol
- phospholipids
- electrolytes
What are the metabolic roles of the liver?
- removes amino acids, fatty acids, Glucose from blood
- stores and activates vitamins, minerals, and drugs
- stores glucose as glycogen
- maintains blood glucose levels by converting between glucose and glycogen
- synthesizes non essential amino acids
- produces blood proteins
- manufactures heparin
- makes cholesterol
- forms bile for fat emulsification
- bile excretes bilirubin, cholesterol, phospholipids, and electrolytes
- degrades hormones and bilirubin
- detoxifies ammonia into urea
- produces enzymes to detoxify drugs and alcohol
- liver will store poison to prevent circulation
What is cirrhosis?
Chronic liver disease
-degeneration of cells, inflammation, fibrous thickening of tissues
Usually result of hepatitis or alcoholism
DEATH OF LIVER CELLS
What is hepatitis?
Inflammation of liver caused by virus, poison, or autoimmune condition
What is the main purpose of the digestive function?
To bring essential nutrients into internal environment for body cells.
What are the three mechanisms of digestion?
Ingestion- food into mouth
Digestion- breakdown of complex nutrients into smaller ones (mechanical and chemical)
Secretion- release of digestive fluids
What some examples of mechanical digestion?
ALL MOVEMENT THROUGH DIGESTIVE TRACT
mixing of food- in mouth by tongue
Churning of food- in stomach
Segmentation- broken into small pieces in S Intestine
What is segmentation?
Forward and back movement to aid with mixing food into gastric juices
What are the broken down forms of each of the major nutrients?
Carbohydrates- simple sugars
Proteins- amino acids
Fats- monoglycerides, fatty acids, glycerol
What are some factors influencing chemical digestion and what do they do?
Saliva- amylase (starch) and lingual lipase (lipids)
Gastric juice(stomach)- pepsin and HCl?(proteins)
Rennin- milk proteins
Pancreatic juice- pancreatic lipase(fat)
Pancreatic amylase (starch)
Trypsin (protein)
Nuclease (nucleic acid)
Gallbladder(Into duodenum)- bile(fat emulsification)
Small intestine- peptidases, sucrase, Maltase, lactase (all found in brush border
What are the duodenal hormones?
Gastrin- stimulates HCl and Pepsin
Secretin- increases pancreatic juice and bile secretion
Cholecystokinin (CCK)- stimulates bile from gallbladder and secretion of pancreatic juice
Gastrin inhibitory peptide- inhibits gastric secretion: stimulates insulin release to uptake glucose
What are some physical mechanisms of digestion?
Motility (propulsion)- moving food from one part of system to another
- swallowing
- peristalsis- wavelike- SINGLE DIRECTION
How does movement in the stomach work?
Peristaltic contractions happen, mixing food well with acids, creating CHYME before passing through pyloric sphincter
Enters S intestine 30ml at a time.
Stomach empties in 4-6 hours
How does movement in the small and large intestines work?
Peristalsis and segmentation in small,
sluggish peristalsis in large- 3/4 time a day
What are some mechanisms of absorption?
Simple sugars, amino acids, and fatty acids enter GI mucosa into lymph or blood capillaries
Where does the majority of digestion take place?
Small intestines
Absorbed and transported to liver via HEPATIC PORTAL VEIN
What are the absorptive traits of the large intestine?
No digestive enzymes
Ideal pH is 5.9-6.9
Resident bacteria digest remaining nutrients
Mostly water absorption (also vit K and B)
What is defecation?
Elimination of indigestible substance
Water, inorganic salts, bacteria, cells, undirected food, products of decomposition
What controls digestive activity?
Duodenal hormones
Parasympathetic nervous system
Chemical and mechanical reactions during digestion
What are the types of nutrients? What is a nutrient?
Substances used by the body for growth, maintenance, and repair
Macronutrients- LARGE AMOUNTS needed (carbohydrates, lipids, proteins
Micronutrients- SMALL AMOUNTS needed (vitamins, minerals)
Also need water
What is a calorie?
Amount of heat required to raise temp of 1kg water by 1 degree C
What are some sources of carbohydrates?
Sugars and starches:
Polysaccharides
Cellulose
Disaccharides
Monosaccharides
Glucose
EXCEPTION- lactose in milk
What is a dietary source of lipids?
Triglycerides
Saturated- animal products and coconut
Unsaturated- nuts, seeds, vegetable oils
What is a dietary source of proteins?
Proteins make up 50% of organic matter in body
Complete proteins- all 20 amino acids- animal products
Incomplete proteins- plant foods (legumes or beans)
What is gastrin?
Stomach secretes when digesting
Stimulates secretion of gastric juice rich in pepsin and HCl
What is GIP?
Intestinal mucosa in response to nutrients
Inhibits gastric secretion and enhancing insulin secretion
What does secretin do?
Secreted by intestines in response to acid
Inhibits gastric secretion, stimulates secretion of pancreatic juice high in alkalinity
What is cholecystokinin?
Secreted by intestines in response to nutrients
Stimulates bile ejection
What hormones are responsible for digesting proteins?
Pepsin (activated by HCl from PEPSINOGEN), trypsin
