MCAT Biology › Endocrine System
A patient is admitted to the hospital after a traumatic injury to her adrenal cortex. Which of the following hormones is most likely to be present at normal levels?
Antidiuretic hormone (ADH)
Adrenocorticotropic hormone (ACTH)
Cortisol
Aldosterone
Corticotropin-releasing hormone (CRH)
Of all the hormones listed, antidiuretic hormone (ADH) is the only one that neither acts on, nor is released by, the adrenal cortex. ADH is released from the posterior pituitary and causes the kidneys to retain more water.
Aldosterone (a mineralcorticoid) and cortisol (a glucocorticoid) are both incorrect choices because they are released by the adrenal cortex and would be greatly affected by trauma to that area. ACTH is released by the anterior pituitary and acts to stimulate the adrenal cortex; these hormones act as part of a negative feedback chain, so damage to the target area would temporarily cause more ACTH to be produced. The same goes for CRH, which is released by the hypothalamus and stimulates secretion of ACTH.
What is the most likely hormonal response immediately following a significant blood loss?
Increased level of ADH
Increased level of ACTH
Decreased level of insulin
Increased level of calcitonin
Decreased level of ADH
Significant amount of blood loss results in a sudden and large drop in blood pressure due to the decreased fluid volume in the body. To compensate for this change, the body will attempt to increase fluid retention. This is directly accomplished by increasing the level of ADH (anti-diuretic hormone) that allows reabsorption of water in the kidneys. Therefore, increased ADH level is the best response.
A patient is admitted to the hospital after a traumatic injury to her adrenal cortex. Which of the following hormones is most likely to be present at normal levels?
Antidiuretic hormone (ADH)
Adrenocorticotropic hormone (ACTH)
Cortisol
Aldosterone
Corticotropin-releasing hormone (CRH)
Of all the hormones listed, antidiuretic hormone (ADH) is the only one that neither acts on, nor is released by, the adrenal cortex. ADH is released from the posterior pituitary and causes the kidneys to retain more water.
Aldosterone (a mineralcorticoid) and cortisol (a glucocorticoid) are both incorrect choices because they are released by the adrenal cortex and would be greatly affected by trauma to that area. ACTH is released by the anterior pituitary and acts to stimulate the adrenal cortex; these hormones act as part of a negative feedback chain, so damage to the target area would temporarily cause more ACTH to be produced. The same goes for CRH, which is released by the hypothalamus and stimulates secretion of ACTH.
A patient is admitted to the hospital after a traumatic injury to her adrenal cortex. Which of the following hormones is most likely to be present at normal levels?
Antidiuretic hormone (ADH)
Adrenocorticotropic hormone (ACTH)
Cortisol
Aldosterone
Corticotropin-releasing hormone (CRH)
Of all the hormones listed, antidiuretic hormone (ADH) is the only one that neither acts on, nor is released by, the adrenal cortex. ADH is released from the posterior pituitary and causes the kidneys to retain more water.
Aldosterone (a mineralcorticoid) and cortisol (a glucocorticoid) are both incorrect choices because they are released by the adrenal cortex and would be greatly affected by trauma to that area. ACTH is released by the anterior pituitary and acts to stimulate the adrenal cortex; these hormones act as part of a negative feedback chain, so damage to the target area would temporarily cause more ACTH to be produced. The same goes for CRH, which is released by the hypothalamus and stimulates secretion of ACTH.
What is the most likely hormonal response immediately following a significant blood loss?
Increased level of ADH
Increased level of ACTH
Decreased level of insulin
Increased level of calcitonin
Decreased level of ADH
Significant amount of blood loss results in a sudden and large drop in blood pressure due to the decreased fluid volume in the body. To compensate for this change, the body will attempt to increase fluid retention. This is directly accomplished by increasing the level of ADH (anti-diuretic hormone) that allows reabsorption of water in the kidneys. Therefore, increased ADH level is the best response.
What is the most likely hormonal response immediately following a significant blood loss?
Increased level of ADH
Increased level of ACTH
Decreased level of insulin
Increased level of calcitonin
Decreased level of ADH
Significant amount of blood loss results in a sudden and large drop in blood pressure due to the decreased fluid volume in the body. To compensate for this change, the body will attempt to increase fluid retention. This is directly accomplished by increasing the level of ADH (anti-diuretic hormone) that allows reabsorption of water in the kidneys. Therefore, increased ADH level is the best response.
Calcitonin, secreted from the thyroid gland, is responsible for which of the following actions?
Decrease blood calcium
Increase blood calcium
Decrease blood phosphate
Increase blood phosphate
Calcitonin generally antagonizes the effect of parathyroid hormone (PTH). When the c-cells of the thyroid sense a high calcium level, they will secrete calcitonin. Calcitonin then serves to inhibit osteoclasts and stimulate osteoblasts, promoting osteogenesis and sequestration of blood calcium into the bone matrix.
In contrast, parathyroid hormone stimulated osteoclasts and inhibits osteoblasts, causing degeneration of the bone matrix and increase in blood calcium levels.
Which hormone is secreted from the anterior pituitary?
Follicle-stimulating hormone
Somatostatin
Oxytocin
Vasopressin
The pituitary gland is comprised for the anterior and posterior pituitary. The anterior pituitary arises from the oral ectoderm, while the posterior pituitary arises from the neuroectoderm. Hormones are secreted from the anterior pituitary in response to stress or to promote milk production, growth, or reproduction. Follicle-stimulating hormone (FSH) is required for growth of the reproductive system.
The posterior pituitary is responsible for production and secretion of neurohypophysical hormones, including oxytocin and vasopressin. Somatostatin is produced from within the digestive system, and signals to the anterior pituitary to inhibit growth hormone secretion.
The hormones of the anterior pituitary can be remembered by using the pneumonic "FLAT PEG." The anterior pituitary secretes follicle-stimulating hormone, luteinizing hormone, adrenocorticotropic hormone, thyroid-stimulating hormone, prolactin, endorphins, and growth hormone.
Both the sympathetic and the parasympathetic nervous systems are essential for homeostasis and for survival. For example, when we are trying to run away from a threat, the sympathetic nervous system is in full effect to allow us to escape from danger. However, when there is no obvious threat, the parasympathetic nervous system tends to be more in control.
There are similarities and differences between the sympathetic and the parasympathetic nervous systems. In preganglionic nerve fibers, both the sympathetic and the parasympathetic nervous system utilize the neurotransmitter acetylcholine. Closer to the target organ, the parasympathetic nervous system remains dependent on acetylcholine whereas norepinephrine and epinephrine are the predominant neurotransmitters utilized by the sympathetic nervous system.
When norepinephrine and epinephrine bind to their receptors, different effects are carried out based on the type of receptor, affinity, and location of the receptor. For example, epinephrine has a higher affinity for the beta-2 receptor. When epinephrine binds to the beta-2 receptor, common effects include vasodilation and bronchodilation. Norepinephrine has a stronger affinity for the alpha-1, alpha-2 and beta-1 receptors. When norepinephrine binds to its receptor, common effects on the body include vasoconstriction (alpha-1), increased heart rate (beta-1) and uterine contraction (alpha-1).
Patient A has a genetic disorder which prevents him from producing sufficient amount of catecholamines. Which of the following events will be affected in this patient.
I. Digestion
II. Pupil dilation
III. Erection
II only
I only
I and II
III only
II and III
Catecholamines consist of epinephrine and norepinephrine. Without these neurotransmitter, the nervous system cannot illicit a sympathetic response. Of the answer choices, only pupil dilation is an event mediated by the sympathetic nervous system.
Which hormone is responsible for stimulating glucocorticoid release from the adrenal cortex?
Adrenocorticotropic hormone
Prolactin
Growth hormone
Thyroid-stimulating hormone
Adrenocorticotropic hormone (ACTH) is released from the anterior pituitary, and is responsible for stimulating secretion of glucocorticoids from the adrenal cortex. While cortisol is the most common and physiologically relevant glucocorticoid, others may also be synthesized. Adrenocorticotropic hormone release is stimulated by stress.