Renin hydrolyzes angiotensinogen, which is released from the _______ to form angiotensin I.
Lungs
Kidneys
Liver
Heart
spleen
The Correct Answer is C
A. Lungs: The lungs are the primary site for the activity of Angiotensin-Converting Enzyme, which transforms angiotensin I into angiotensin II. While they are central to the RAAS pathway, they do not synthesize the precursor protein angiotensinogen. Their role is enzymatic conversion rather than substrate production.
B. Kidneys: The juxtaglomerular cells of the kidneys secrete the enzyme renin in response to low blood pressure. While the kidneys initiate the cascade, they are the source of the enzyme, not the protein substrate angiotensinogen. The kidneys react to the substrate produced by a different organ.
C. Liver: This organ constitutively synthesizes and releases the alpha-2 globulin known as angiotensinogen into the systemic circulation. This protein serves as the essential substrate upon which renin acts to produce angiotensin I. It is the primary biosynthetic source of this precursor molecule.
D. Heart: The heart produces atrial natriuretic peptide in response to atrial stretch, which generally opposes the effects of the RAAS pathway. It does not produce the angiotensinogen required for the initiation of angiotensin I formation. Cardiac tissue is a target rather than a source for this substrate.
E. spleen: The spleen serves primarily as a lymphoid organ and a site for erythrocyte recycling. It does not possess the secretory capacity or the metabolic machinery to produce systemic hormonal precursors like angiotensinogen. It is not a component of the renin-angiotensin-aldosterone system.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+: This equation represents the primary equilibrium for maintaining physiological acid-base homeostasis. Carbon dioxide reacts with water to form carbonic acid, which subsequently dissociates into bicarbonate and hydrogen ions. It accurately depicts the reversible hydration of carbon dioxide catalyzed by carbonic anhydrase.
B. CO2 + H2O ⇌ HCO3- + H+ ⇌ H2CO3: This sequence incorrectly places the ionic dissociation products before the formation of the weak acid intermediate. Chemical equilibrium follows a specific pathway where the hydration of carbon dioxide must produce carbonic acid first. The arrangement does not reflect the standard biochemical progression of this buffer system.
C. H2CO3 ⇌ CO2 + H2O ⇌ HCO3- + H+: This arrangement suggests that carbonic acid is the primary precursor to both carbon dioxide and the dissociated ions simultaneously. While the reaction is reversible, the standard physiological representation starts with the respiratory gas component. This layout disrupts the logical flow of the carbon dioxide-bicarbonate equilibrium.
Correct Answer is C
Explanation
A. prolactin (PRL): This hormone is synthesized and secreted by lactotrophs located within the anterior pituitary gland. Its release is regulated by dopamine from the hypothalamus, which acts as an inhibitory signal. The posterior pituitary does not possess the glandular tissue required to produce or release prolactin.
B. adrenocorticotropic hormone (ACTH): ACTH is produced by corticotrophs in the adenohypophysis, or anterior pituitary, in response to corticotropin-releasing hormone. It targets the adrenal cortex to stimulate the release of glucocorticoids. It is a product of glandular epithelial cells, which are absent in the neurohypophysis.
C. oxytocin (OT): This peptide hormone is synthesized by neuronal cell bodies in the paraventricular nuclei of the hypothalamus. It travels down axons through the hypothalamo-hypophyseal tract to be stored in the posterior pituitary. It is released into the bloodstream to facilitate uterine contractions and milk ejection.
D. thyroid hormone (TH): Thyroid hormones, specifically thyroxine and triiodothyronine, are synthesized and secreted by the follicular cells of the thyroid gland. Their release is stimulated by thyroid-stimulating hormone from the anterior pituitary. The posterior pituitary has no role in the direct synthesis or release of TH.
E. growth hormone (GH): GH is secreted by somatotrophs in the anterior pituitary gland and is essential for stimulating tissue growth and protein synthesis. Its secretion is managed by hypothalamic releasing and inhibiting hormones. It is not stored in or released by the neural tissue of the posterior pituitary.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.