Digestive system Flashcards
What are the two groups of organs?
Alimentary canal
Accessory digestive organs
What is contained in the alimentary canal of the digestive system?
Mouth to anus
What does the alimentary canal do? (gi tract)
Digests food and absorbs fragments
What are the accessory digestive organs
Teeth
Tongue
Gallbladder
Digestive glands (salivary glands, liver, pancreas)
What are 6 essential activities of the digestive process?
- Ingestion
- Propulsion
- Mechanical breakdown
- Digestion
- Absorption
- Defecation
The enteric nervous system is supplied by _________ of alimentary canal
Intrinsic nerve supply
The enteric nervous system is linked to the CNS via the ______ fibers?
Afferent visceral fibers
Stomach digest ____ to _____
Bolus to chyme
The stomach has ____ tunics
Four
What does the muscularis externa allow the stomach to do?
Churn
Mix
Move
Physically break down food
What does the mucosa contain in the stomach?
Mucosal cells that secrete two layer coat of alkaline mucus
Gastric glands that produce gastric juice
What are the 4 cell types in gastric glands?
Mucous neck cell
Parietal cells
Chief cells
Enteroendocrine cells
What are the parietal cell secretions?
HCl
Intrinsic factor (needed for absorption of vitamin B12)
What do chief cells secrete?
Pepsinogen
Lipase (digest lipids)
What are the secretions of the enteroendocrine cells?
Chemical messengers
Paracrines (serotonin and histamine)
Hormones (somatostatin and gastrin)
What makes up the mucosal barrier of the stomach?
Thick layer of bicarb rich mucus
Tight junctions between epithelial cells
What are the 4 steps to digestive process in the stomach?
Mechanical breakdown
Denaturation of proteins by HCl
Enzymatic digestion of proteins by pepsin
Delivery of chyme to small intestine
What is the only stomach function that is essential to life?
Secretion of intrinsic factor (needed for vitamin B 12 absorption)
What nervous system is involved in the neural control of gastric secretion?
The autonomic nervous system
(vagus nerve stim that increases stimulation)
(Sympathetic stim that decreases stimulation)
What hormone is responsible for regulation of gastric secretion?
Gastrin (increases enzyme and HCl secretion)
What are the three phases of gastric secretion?
Cephalic phase
Gastric phase
Intestinal phase
What happens during the cephalic phase?
It is triggered by aroma, taste, sight, thought
What stimulates the gastric phase?
Distension, peptides, low acidity, gastrin
What does the intestinal phase do?
Partially digested foods enter the small intestine with a brief intestinal gastrin release
What kind of effects happen during the intestinal phase?
Inhibitory effects (by chyme, fats, peptides, irritating substances)
What are three chemicals that stimulate parietal cells through secondary messengers?
ACh
Histamine
Gastrin
What releases enterogastrones in the intestinal phase?
Enteroendocrine cells
What are enterogastrones?
Secretin, CCK, vasoactive intestinal peptide
They all inhibit gastric secretion
What is dumping syndrome
Happens if the small intestine is pushed to accept more chyme
Nausea and vomiting
Common in gastric reduction for weight loss
Enterogastric reflex is part of the ____ ____ of gastric secretion
Intestinal phase
What do enterogastric reflexes do?
Inhibit vagal nuclei
Inhibit local reflexes
Activate sympathetic nerve fibers
_____ cells pump H+ into stomach lumen
Parietal cells
What moves food throughout the stomach to the plyorus?
Peristaltic waves
Basic electrical rhythm is set by ______ _____ ____.
Enteric pacemaker cells
What are pacemaker cells linked by?
Gap junctions
____ and ____ increase force of contraction
Distention
Gastrin
TF: Fatty chyme is moved quicker through the duodenum than carb-rich chyme?
False
What are the subdivisions of the small intestine?
Duodenum
Jejunum
Ileum
What is the major organ of digestion and absorption?
Small intestine
What controls entry of bile and pancreatic juices into the duodenum?
Hepatopancreatic sphincter
What part of the small intestine joins the large intestine
Ileum
What are the three components of the small intestine that help increase surface area for better absorption?
Circular folds
Villi
Microvilli (brush border)
TF: intestinal juice is slightly alkaline
True
The Intestinal Juice is largely ____
water`
What facilitates transport and absorption of nutrients?
Intestinal juice
What is the main function of the liver?
Digestive function
Bile production (fat emulsifier)
What is the main function of the gall bladder?
Bile storage
What is the largest gland in the body?
Liver
What do hepatocytes do?
They are liver cells
Filter and process bloodborne nutrients
Store fat-soluble vitamins
Perform detoxification
Produce bile
What do Kupffer cells in the liver do?
Remove old RBCs
What connects the liver to the gallbladder?
Bile duct
What is contained within bile?
Bile salts (cholesterol derivative that functions in fat emulsification and absorption)
Bilirubin (brown color in feces)
Cholesterol, Triglycerides, phospholipids, and electrolytes
How does the gallbladder release bile?
Muscular contraction
What happens to bile salts when there is too much cholesterol?
Too few bile salts so gallstones are formed
TF: the pancreas has an endocrine and exocrine function
True
What is the endocrine function of the pancreas?
Pancreatic islets secrete insulin and glucagon
What is the exocrine function of pancreas?
Acini secrete pancreatic juices
What is pancreatic juice?
Watery alkaline solution with a high pH to neutralize chyme
Contains electrolytes (HCO3-)
Enzymes (amylase, lipase, nucleases and proteases)
Where do proteases get activated?
Duodenum
What is the most common motion of small intestine
Segmentation
What initiates segmentation of the small intestine
Intrinsic pacemaker cells
What stimulates peristalsis in the small intestine?
Rise in the hormone motilin
What are the 5 regions of the large intestine?
Cecum
Appendix
Colon
Rectum
Anal canal
What is the cecum
The first part of the large intestine
What is the appendix?
Masses of lymphoid tissue (bacterial storehouse (immune function))
What are the 4 colons?
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
How many rectal valves stop feces from being passed with gas?
three
What is the last segment of the large intestine?
Anal canal
What opens the body to the exterior in the digestive system?
Mouth and anus
What kind of muscle is found in the internal anal sphincter
Smooth muscle (involuntary)
What kind of muscle is found in the external anal sphincter?
Skeletal muscle
What is reclaimed during the digestive process in the large intestine?
Vitamins
water
electrolytes
What is the major function of the large colon?
Propulsion of feces to anus
Defecation
TF: the colon is essential for life
False
What are the contractions of the colon called?
Haustral contractions
What initiates the gastrocolic reflex?
Presence of food in the stomach
What is defecation?
Mass movements force feces to rectum
What initiates spinal defecation reflex?
Distension
