Unit 2 Lecture 26 - Stomach anatomy Flashcards
What are the 4 main parts of the stomach?
- cardia
- fundus
- body
- pylorus
What is the sphincter in the stomach?
pyloric sphincter
What triggers the stomach to secrete and move fluids and stuff?
a full stomach
What does the stomach empty into?
Duodenum of the small intestine
What squirts through the pyloric sphincter?
Chyme
What is chyme?
acidic juices from the stomach
What are the cells in the stomach and what do they secrete?
- Surface mucous cells - secrete mucous
- Mucous neck cells - secrete mucous
- Parietal cells - secrete HCl and intrinsic factor
- Chief cells - secrete pepsinogen and gastric lipase
- G cells - secrete gastrin hormone
What comes in and out of parietal cells in the stomach?
HCO3- (bicarbonate) goes out of stomach and Cl- goes in
What stimulates mechanical digestion in the stomach?
Different intensities of waves
What are the 3 intensities of waves and what do they do?
- gentle mixing waves: mix bolus of food with gastric juices -> chyme
- more vigorous waves: move chyme to pyloric region
- intense waves: open pyloric sphincter
What are the two forms of chemical digestion in the stomach?
Protein digestion BEGINS and lipid (fat) digestion CONTINUES
What is involved in protein digestion in the stomach?
HCl
What does HCl do to proteins in the stomach?
- denatures (unfolds) proteins
- kills microbes in food
- activates pepsinogen into pepsin
What is pepsin?
an enzyme that breaks peptide bonds between certain amino acids
What is involved in lipid digestion in the stomach?
gastric lipase
What does gastric lipase do in the stomach?
splits triglycerides in milk fat
Where is alcohol absorbed in the body?
Stomach (and sometimes small intestine)
What slows the absorption of alcohol in the stomach?
- fat content (slows passage to intestine where its more rapid)
- eating a meal
How does food entering the stomach disrupt homeostasis?
Increases
- pH of gastric juices
- stretching of stomach walls
What does an increase in pH and stomach stretching stimulate?
chemoreceptors and stretch receptors in stomach
What do chemoreceptors and stretch receptors stimulate AND where?
Nerve impulses in the submucosal plexus
What do nerve impulses in the submucosal plexus trigger?
- parietal cells to secrete mucous
- smooth muscle to contract more vigorously
What happens when the stomach secretes more mucous and contracts?
Increases stomach acidity and mixing -> empties stomach
——> maintains homeostasis
Does the stomach have endocrine or exocrine functions?
Endocrine
What cells are stimulated due to distention and the presence of food
G cells
What do g cells secrete?
gastin
What does gastin do?
increases gastric gland secretions and movement of liquids
relaxes pyloric sphincter
