MDS PREP
What is the primary role of the cephalic phase of gastric acid secretion?
1) Stimulation of gastrin release in the stomach
2) Secretion of gastric juices in response to the thought or smell of food
3) Increase in gastric motility
4) Secretion of gastric juices in response to food entering the duodenum
Physiology
Answer: 2
The cephalic phase of gastric acid secretion is initiated by the parasympathetic system and is triggered by the sight, smell, or thought of food. It accounts for approximately 20% of total acid secretion and prepares the stomach for digestion even before food arrives.
What is the effect of oxytocin on the myoepithelial cells of the mammary gland?
1) Contraction to facilitate milk ejection
2) Relaxation to facilitate milk secretion
3) Increase in cellular metabolism
4) Growth and proliferation of myoepithelial cells
E. Inhibition of milk secretion
Oxytocin causes contraction of the myoepithelial cells surrounding the mammary alveoli, which presses milk into the larger ducts and leads to the milk let-down reflex. This is essential for milk ejection during lactation.
Which cranial nerve is NOT involved in the parasympathetic control of the eye?
1) Oculomotor nerve (CN III)
2) Facial nerve (CN VII)
3) Trigeminal nerve (CN V)
4) Vagus nerve (CN X)
The vagus nerve is involved in the parasympathetic control of various visceral organs, but not the eye. The oculomotor nerve (CN III) innervates the pupillary sphincter and ciliary muscle for pupil constriction and accommodation, which are parasympathetic functions.
What is the primary neurotransmitter involved in the pupil dilatation during the fight-or-flight response?
1) Acetylcholine
2) Epinephrine
3) Norepinephrine
4) Dopamine
Answer: 2) EpinephrineExplanation: During the fight-or-flight response, epinephrine is released from the adrenal medulla and acts on the pupillary dilator muscles to cause mydriasis (dilatation of pupils). This effect is mediated by beta-adrenergic receptors on the smooth muscle of the iris, leading to increased pupil size to allow more light in for better vision.
What is the primary site of vitamin B12 absorption in the intestine?
1) Stomach
2) Duodenum
3) Jejunum
4) Ileum
Physiology
Answer: 4
The ileum is the primary site of vitamin B12 absorption, facilitated by intrinsic factor binding to specific receptors.
What is the primary role of sleep spindles during sleep?
1 ) To facilitate memory consolidation
2) To maintain muscle tone
3) To regulate body temperature
4) To initiate REM sleep
Sleep spindles are associated with the transition from stage 1 to stage 2 NREM sleep and are thought to play a role in memory consolidation and the integration of new information.
What is the effect of vitamin E deficiency on cell membranes?
1) Increased fluidity
2) Decreased fluidity
3) No change in fluidity
4) Unknown
Physiology
Answer: 2
Vitamin E is an important antioxidant that protects unsaturated fats in cell membranes from oxidation. Without vitamin E, these fats can become oxidized, leading to decreased fluidity and altered function of membranes.
What is the primary function of the sympathetic nervous system during the fight-or-flight response?
1) Facilitation of digestive processes
2) Diverting blood flow to the gastrointestinal tract
3) Preparing the body for rest and digestion
4) Mobilizing energy and preparing the body for immediate action
Answer: 4) Mobilizing energy and preparing the body for immediate actionExplanation: The sympathetic nervous system is activated during the fight-or-flight response to mobilize energy and prepare the body for immediate action. It does this by increasing heart rate, dilating pupils, and diverting blood flow to muscles and the brain, among other effects.