Physiology Of The Stomach 2 Flashcards
Question: What processes result from the contraction and relaxation of the layers of muscle in the stomach wall?
Answer: Gastric motility involves the actions of grinding, churning, kneading, twisting, and propelling contents within the stomach.
Question: What is responsible for coordinating gastric motility?
Answer: Gastric motility is coordinated by the Myenteric plexus, which receives input from the Autonomic Nervous System (ANS).
Question: How does parasympathetic stimulation affect gastric motility?
Answer: Parasympathetic stimulation increases gastric motility.
Question: What is the impact of sympathetic stimulation on gastric motility?
Answer: Sympathetic stimulation decreases gastric motility.
Question: How does the Muscularis contribute to mechanical digestion in the stomach?]
Answer: The Muscularis enables food to be churned, especially in the antrum where the muscle wall is thicker, resulting in more powerful contractions.
Question: What is the outcome of the mixing of food with gastric juice in the stomach?
Answer: The mixing of food with gastric juice in the stomach produces a semi-liquid substance called chyme.
Question: Through which structure does chyme pass from the stomach to the duodenum?
Answer: Chyme passes through the pyloric sphincter to reach the duodenum.
Question: What enzyme is responsible for breaking down proteins in the stomach?
Answer: Pepsin is the enzyme responsible for breaking down proteins in the stomach.
Question: Under what conditions is pepsin active?
Answer: Pepsin is only active in an acidic environment.
Question: How is pepsinogen converted into pepsin?
Answer: Pepsinogen is converted into pepsin by the action of hydrochloric acid (HCl).
Question: Which enzyme facilitates the breakdown of fat in the stomach, and at what pH is it active?
Answer: Gastric lipase facilitates the breakdown of fat, and it is active at a higher pH (5-6).
Question: Why is the initiation of fat digestion important, particularly in infants?
Answer: The initiation of fat digestion, facilitated by gastric lipase, is crucial for the digestion of breast milk in infants.
Question: What initiates protein digestion in the stomach?
Answer: Gastric pepsins initiate protein digestion in the stomach.
Question: What are the products of pepsin hydrolyzing proteins, and what is their role?
Answer: Pepsin hydrolyzes proteins into polypeptides and amino acids, which further stimulate acid production
Question: At what pH is pepsin inactivated, and how can it be re-activated?
Answer: Pepsin is inactivated at a higher pH, above approximately pH 6, but can be re-activated upon re-acidification.
Question: How does the acidic environment of the stomach affect the activity of salivary amylase?
Answer: Salivary amylase, which acts on carbohydrates, is far less active in the acidic environment of the stomach due to gastric pH.
Question: What determines the force of contraction and the amount of gastric emptying in the stomach?
Answer: The force of contraction and amount of gastric emptying are determined by neuronal and hormonal input to the antral smooth muscle.
Question: What factors influence the rate of gastric emptying?
Answer: The rate of gastric emptying is influenced by the physical and chemical nature of the contents of the stomach and intestine.
Question: How does distension of the stomach impact antral contraction?
Answer: Distension of the stomach increases antral contraction.