MDS PREP
What are the two major functions of GH?
1) Stimulation of growth hormone-dependent lipolysis and glycogenolysis
2) Stimulation of gluconeogenesis and growth of the skeletal system
3) Stimulation of cortisol synthesis and thyroid hormone release
4) Regulation of insulin secretion and cardiovascular function
Answer: 2) The two major functions of GH are the growth of the skeletal system and metabolic effects, including gluconeogenesis.
A lowering of serum calcium is the stimulus for the endogenous release of
1. thyroid hormone
2. adrenocortical hormone
3. insulin
4. parathyroid hormone
Physiology Answer: 4
Parathyroid hormone (PTH) levels are mainly controlled by a feedback loop of calcium levels in your blood to your parathyroid glands. In other words, low calcium levels in your blood stimulate parathyroid hormone release, whereas high calcium levels in your blood prevent your glands from releasing parathyroid hormone.
What is the role of gastrin in the gastric phase of gastric acid secretion?
1) It directly stimulates the release of HCl from parietal cells.
2) It inhibits the release of HCl from parietal cells.
3) It activates the myenteric plexus to enhance intestinal motility.
4) It promotes the release of bicarbonate into the stomach lumen.
E) It is not involved in the gastric phase of acid secretion.
Gastrin is a hormone released by G cells in the gastric antrum in response to the presence of food, especially protein. It acts on parietal cells in the gastric glands, stimulating them to produce and secrete hydrochloric acid (HCl) and intrinsic factor, which is essential for vitamin B12 absorption. Gastrin is a critical component of the gastric phase, which is responsible for the bulk of gastric acid secretion.
What is the primary function of chymotrypsin in the digestive process?
1) Converting chymotrypsinogen into chymotrypsin
2) Breaking down proteins into peptides
3) Catalyzing the hydrolysis of disulfide bonds in proteins
4) Activating pepsinogen into pepsin
E) Releasing gastrin from gastric mucosa
Chymotrypsin is an endopeptidase enzyme that plays a crucial role in the digestive system by breaking down proteins into smaller peptides. It is activated from its precursor chymotrypsinogen by the enzyme trypsin. Once active, chymotrypsin hydrolyzes the peptide bonds at the carboxyl side of aromatic and bulky amino acids, such as phenylalanine, tryptophan, and tyrosine. This process is essential for the further digestion and absorption of dietary proteins.
The osmolarity of the tubular fluid in the medullary collecting duct is primarily controlled by which hormone?
1) Aldosterone
2) Atrial Natriuretic Peptide (ANP)
3) Antidiuretic Hormone (ADH)
4) Renin
The osmolarity of the tubular fluid in the medullary collecting duct is primarily controlled by Antidiuretic Hormone (ADH), which increases water reabsorption.
Which of the following substances does NOT directly depolarize taste cells during the sensation of bitter taste?
1) Increased intracellular calcium (Ca+) concentration
2) Activation of amiloride-sensitive Na+ channels
3) Closure of K+ channels
4) Release of neuronal glutamic acid
Bitter taste is mediated by the activation of bitter receptors, which are G protein-coupled and result in an increase in intracellular Ca+2 and subsequent neurotransmitter release, not by the activation of sodium channels as seen in salty taste transduction.
What is the primary effect of excitatory postsynaptic potentials (EPSPs) on the excitability of a neuron?
1) Depolarization
2) Hyperpolarization
3) No change in excitability
4) Initiation of an action potential
Answer: 1) DepolarizationExplanation: EPSPs occur when the neurotransmitter binds to postsynaptic receptors that open sodium channels, allowing sodium ions to flow into the neuron and causing the membrane to depolarize. This increases the excitability of the neuron, bringing the membrane potential closer to the threshold for action potential firing.
What is the role of ghrelin in the control of food intake?
1) It stimulates the release of growth hormone
2) It suppresses the secretion of gastric acid
3) It inhibits food intake
4) It increases the sensation of hunger
Physiology
Answer: 4
Ghrelin is a hormone produced mainly by the stomach that stimulates appetite and food intake. It acts on the hypothalamus to increase hunger and is often referred to as the "hunger hormone." It also stimulates growth hormone secretion from the pituitary gland.