18A/B: Digestive System Flashcards
Explain the process of peristalsis
- peristalsis: moving bolus along digestive tract by coordination of smooth muscle contractions
1. bolus of food arrives
2. circular muscle contracts behind the bolus
3. longitudinal muscle contracts ahead of the bolus
4. contractions of circular muscle push bolus forward
Explain segmentation
- rhythmic cycles of contraction in most areas of small and some areas of large intestine for mechanical digestion
- don’t follow a set pattern; doesn’t push materials in any one direction
- churns and fragments bolus
Explain the process of degluttion
- swallowing
1. buccal phase: bolus compresses against hard palate; tongue retracts; bolus moves into oropharynx; soft palate elevates to seal off nasopharynx (voluntary phase)
2. pharyngeal phase: tactile receptors in uvula stimulated; larynx elevated; epiglottis folds over it; palatal muscles elevate uvula and soft palate to block nasopharynx; bolus forces through pharynx
3. esophageal phase: bolus pushed through esophagus by peristalsis; triggers opening of lower esophageal sphincter
rugae
temporary mucosal folds in the stomach lining that can flatten to expand the stomach
Describe the structures and functions of the following teeth structures: dentin, enamel, gingival sulcus, root canal
- dentin: mineralized matrix that makes up the bulk of each tooth, similar to bone but does not contain cells
- enamel: covers dentin in the grown; contains calcium phosphate
- gingival sulcus: surrounds neck of the tooth
- root canal: narrow tunnel within root of the tooth, supplies blood vessels and nerves
mumps
viral disease causing swelling of parotid salivary glands in the face
hepatitis
inflammation of liver
cirrhosis
hepatocytes die faster than they are replaced; hardening of liver
major functions of the liver
- produces bile
- filters blood coming from the digestive tract
Describe the functional anatomy of the liver.
- blood enters sinusoids through interlobular artery and interlobular vein
- as blood flows through sinusoids, adjacent hepatocytes regulate nutrient levels, absorbing/secreting solutes
- stellate macrophages line sinusoids and engulf pathogens
- central vein collects blood from sinusoids, merge into hepatic veins, which empties into inferior vena cava
- hepatocytes secrete bile (containing bile salts) for fat digestion
pancreatitis
inflammation of the pancreas due to blockage of excretory ducts
Name the cells of the gastric gland and their secretions.
- parietal cells: HCl
- G cells: gastrin
- chief cells: pepsinogen
gastrin
- stimulates acid production of parietal cells and gastric motility
- food in stomach
GIP (gastric inhibitory peptide)
- stimulates release of insulin from pancreas
- inhibits gastrin
- chyme in duodenum
secretin
secretion of bile and pancreatic buffers
VIP (vasoactive intestinal peptide)
- dilation of intestinal capillaries
- facilitates nutrient absorption
enterocrinin
- stimulates production of alkaline mucus to neutralize acidic chyme
Discuss the cephalic phase of gastric activity regulation.
- the first phase
- prepares the stomach to receive food
- directed by CNS to stimulate submucosal plexus and stimulate secretions of parietal cells, chief cells, G cells and mucous cells
Discuss the gastric phase of gastric activity regulation
- the second phase
- when food arrives in the stomach
- stimulation of submucosal and myenteric plexuses
- secretory cells activated and powerful contractions produced
Discuss the intestinal phase of gastric activity regulation
- the third (last) phase
- controls rate of gastric emptying
- when chyme enters duodenum
- secretion of CCK, GIP and secretin inhibit chief cells and parietal cells
- inhibition of myenteric plexus stops muscle contractions
- duodenal stretch and chemoreceptors stop peristalsis
__ tells the liver to make more bile, while __ stimulates the release of stored bile.
secretin; CCK
CCK
secretion of pancreatic enzymes and contraction of gallbladder (release of bile)
