Nokea
Which is INCORRECT regarding nerve supply to the gut?
- A. the blood vessels are known to have enteric, parasympathetic and sympathetic innervation
- B. the myenteric plexus lies between the longitudinal and circular muscle layers
- C. parasympathetic supply is via vagal and sacral nerve
- D. sympathetic supply is often inhibitory on cholinergic postganglionic fibres
Correct Answer: A
Rationale: The correct answer is A because blood vessels in the gut are primarily innervated by sympathetic and parasympathetic fibers, not by enteric nerves. Enteric nerves are confined to the gastrointestinal tract itself and are responsible for regulating gut motility, secretion, and blood flow. Sympathetic innervation typically causes vasoconstriction, while parasympathetic innervation promotes vasodilation. The myenteric plexus (Auerbach's plexus) lies between the longitudinal and circular muscle layers, regulating gut motility. Parasympathetic supply to the gut is mainly through the vagus nerve (cranial nerve X) and sacral nerves (pelvic splanchnic nerves). Sympathetic supply can either be inhibitory or excitatory, but generally, sympathetic fibers are inhibitory on cholinergic postganglionic fibers in the gut.
You may also like to solve these questions
Regarding carbohydrate metabolism:
- A. glucokinase is increased in starvation
- B. the breakdown of glycogen is called glycolysis
- C. the direct oxidative pathway involves the breakdown of glucose through triose
- D. the conversion of pyruvate to acetyl-CoA is irreversible
Correct Answer: D
Rationale: Correct Answer: D - The conversion of pyruvate to acetyl-CoA is irreversible because it is catalyzed by the enzyme pyruvate dehydrogenase. This step is a key regulatory point in carbohydrate metabolism as it commits pyruvate to enter the citric acid cycle for further energy production. Reversing this step would disrupt the normal flow of metabolic pathways.
Summary of other choices:
A: Glucokinase is not increased in starvation; it regulates glucose uptake in the liver.
B: The breakdown of glycogen is called glycogenolysis, not glycolysis which is the breakdown of glucose.
C: The direct oxidative pathway involves the breakdown of glucose through glycolysis, not triose.
How do hormones differ from neurotransmitters?
- A. Hormones travel through the synaptic cleft while neurotransmitters travel through the bloodstream.
- B. Hormones act on receptors while neurotransmitters do not.
- C. Hormones use speedy electrical impulses, while neurotransmitters take several seconds from the gland to the target tissue.
- D. Hormones travel through the bloodstream while neurotransmitters travel across the synaptic cleft between neurons.
Correct Answer: D
Rationale: The correct answer is D. Hormones travel through the bloodstream while neurotransmitters travel across the synaptic cleft between neurons. Hormones are secreted by endocrine glands into the bloodstream to target distant tissues, while neurotransmitters are released by neurons into the synaptic cleft to transmit signals locally between neurons. Choice A is incorrect as hormones do not travel through the synaptic cleft, and neurotransmitters do not travel through the bloodstream. Choice B is incorrect as both hormones and neurotransmitters act on specific receptors. Choice C is incorrect as hormones do not use electrical impulses; instead, they travel through the bloodstream.
Several hormones are synthesized in the hypothalamus and transported to the anterior pituitary gland. The mechanism of transportation from hypothalamus to anterior pituitary gland is through the ________.
- A. hepatic portal system
- B. general circulatory system
- C. hypophyseal portal system
- D. feedback loop
Correct Answer: C
Rationale: The correct answer is C: hypophyseal portal system. This system involves a direct blood vessel connection between the hypothalamus and the anterior pituitary gland, allowing hormones synthesized in the hypothalamus to be rapidly transported to the anterior pituitary without being diluted in the general circulation. The hepatic portal system (A) involves blood flow from the digestive system to the liver. The general circulatory system (B) would dilute the hormones before reaching the anterior pituitary. A feedback loop (D) is a mechanism that regulates hormone levels but is not the primary mode of transportation between the hypothalamus and anterior pituitary.
Selective β2 agonists produce all of the following EXCEPT:
- A. Stimulate β2 > β1
- B. Bronchodilation
- C. Decrease of blood pressure
- D. Stimulate uterine contraction
Correct Answer: D
Rationale: The correct answer is D: Stimulate uterine contraction. Selective β2 agonists primarily target β2 receptors in the lungs, leading to bronchodilation. They have minimal effect on β1 receptors, thus do not significantly impact heart rate or blood pressure. However, β2 receptors in the uterus can cause uterine relaxation, not contraction. Therefore, selective β2 agonists do not stimulate uterine contractions. Choices A, B, and C are incorrect as they align with the typical effects of selective β2 agonists.
In the pancreas, which are the cells that secrete insulin, decrease the blood levels of glucose.
- A. delta.
- B. alpha.
- C. beta.
- D. beta.
Correct Answer: C
Rationale: The correct answer is C: beta cells. Beta cells in the pancreas secrete insulin, which helps decrease blood glucose levels by facilitating the uptake of glucose into cells for energy production. Delta cells (choice A) secrete somatostatin, which inhibits insulin and glucagon secretion. Alpha cells (choice B) secrete glucagon, which increases blood glucose levels. Choice D is a duplicate of choice C. Therefore, the correct answer is C as beta cells play a crucial role in regulating blood glucose levels through insulin secretion.