PHYSIOLOGY REVIEW - EXERCISE 01
Parathyroid hormone (PTH) is a peptide hormone responsible for increasing the concentration of calcium in the blood. This is accomplished by stimulating the activity of osteoclasts and removing calcium from the bones. If a person has low blood calcium levels, what would you expect the level of PTH to be in the body? Normal levels of parathyroid hormone would be seen as it works to restore normal calcium levels. Parathyroid hormone would be lower than normal in the blood. Parathyroid levels will fluctuate until normal calcium levels are restored. Parathyroid hormone would be higher than normal in the blood. Normal levels of parathyroid hormone would be seen as a different hormone works to restore normal calcium levels.
Parathyroid hormone would be higher than normal in the blood. EXPLANATION: A critical concept to understand about hormones in the body is negative feedback. Remember that hormones are not causing the body's condition, but rather, are responding to the body's condition. As a result, parathyroid hormone would be higher than normal in order to increase the concentration of calcium currently in the blood, correcting the existing deficiency.
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are both released from the anterior pituitary. The hypothalamus regulates their release through release of __________. Corticotropin-releasing factor (CRF) Growth hormone-releasing hormone (GHRH) Thyroid-stimulating hormone (TSH) Gonadotropin-releasing hormone (GnRH)
Gonadotropin-releasing hormone (GnRH) EXPLANATION: Gonadotropin-releasing hormone (GnRH), released from the hypothalamus, is responsible for regulating follicle-stimulating hormone and luteinizing hormone release. Growth-hormone-releasing hormone (GHRH) regulates release of growth hormone (GH), and corticotropin-releasing factor (CRF) regulates adrenocorticotropic hormone (ATCH) release from the anterior pituitary. Thyroid-stimulating hormone (TSH) is released from the anterior pituitary and stimulates release of T3 and T4 from the thyroid.
Which of these hormones stimulates secretion of cortisol? Cortisone Thyroid stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle stimulating hormone (FSH) Human growth hormone (hGH)
Adrenocorticotropic hormone (ACTH) EXPLANATION: Cortisol is a hormone secreted by the adrenal cortex. The adrenal cortex is first stimulated by adrenocorticotropic hormone, which is secreted from the anterior pituitary gland.
A certain molecule is known to signal through an autocrine mechanism. What does this tell us about the hormone's behavior? The molecule is released by a certain cell and acts on receptors on that same cell The molecule is released by a certain cell, travels through the bloodstream, and acts on receptors on distant cells The molecule is released by a certain cell and acts to mediate release of more of the same hormone The molecule is released by a certain cell, travels through the bloodstream, and acts on receptors in the hypothalamus The molecule is released by a certain cell and acts on receptors on nearby cells
The molecule is released by a certain cell and acts on receptors on that same cell. EXPLANATION: To answer this question, you must have an understanding of the differences between endocrine, paracrine, and autocrine functioning. This example, in which a molecule exhibits autocrine behavior, means that a cell releases a hormone that acts on itself. In paracrine signaling, the molecule does not act on the same cell, but does diffuse through tissue to reach nearby target cells. Finally, endocrine signaling refers to hormone molecules that are released and transported through the bloodstream to act on more faraway target cells in distant regions.
Which one of the following vitamins can be produced by the human body? Vitamin A Vitamin C Vitamin E Vitamin D
Vitamin D EXPLANATION: Vitamin D is the only vitamin that can be produced endogenously via UV activation of 7-dehydrocholesterol in the skin. All other vitamins must be obtained from outside sources, namely the digestion of other organic matter.
Which of the following is not true of hormones? Hormones affect only one specific tissue at a time. Hormones are released directly into body fluids and tissues. All of these are true of hormones. Hormones are relatively slow acting compared to neurotransmitters. Hormones affect a wider range of the body compared to neurotransmitters.
Hormones affect only one specific tissue at a time. EXPLANATION: Hormones are generally slow acting, spread throughout the body by the blood, and can affect a variety of tissues at once. Neurotransmitters on the other hand, are quick acting, localized, and affect only a specific cell. We would not expect hormones to affect only one cell or tissue at a time, as their wide distribution allows them to have multiple target areas.
Where in the body is core temperature regulated? Anterior pituitary Posterior pituitary Hypothalamus Thalamus
Hypothalamus EXPLANATION: The hypothalamus is a structure in the brain responsible for homeostatic control over much of the body. It is responsible for maintaining core body temperature within normal levels. There are special neurons located within the hypothalamus that respond to changes in body temperature. The hypothalamus then sends out signals to the result of the body in response to changes in temperature.
Which endocrine gland in the brain regulates the release of hormones from the anterior pituitary? Hypothalamus Pineal gland Thyroid gland Posterior pituitary
Hypothalamus EXPLANATION: The hypothalamus releases hormones that control the release of hormones from the anterior pituitary, which in turn controls the release of hormones from other endocrine glands. The anterior pituitary is also controlled by several negative feedback systems based on hormones released throughout the body and their effects.
Which of the following provides the correct sequence of signaling for a hormone cascade pathway? Anterior pituitary, endocrine gland, hypothalamus, target cells Hypothalamus, anterior pituitary, endocrine gland, target cells Anterior pituitary, hypothalamus, endocrine gland, target cells Hypothalamus, endocrine gland, anterior pituitary, target cells
Hypothalamus, anterior pituitary, endocrine gland, target cells EXPLANATION: Groups of hormones from the hypothalamus, anterior pituitary, and individual endocrine glands are often organized into a hormone cascade pathway. The flow of such a cascade occurs as follows: 1. Signals or sensory cells in the brain trigger the hypothalamus to secrete a hormone (example: thyroid-releasing hormone) that either stimulates or inhibits release of a particular hormone from the anterior pituitary. 2. The anterior pituitary hormone (example: thyroid-stimulating hormone) acts on a target endocrine tissue (example: thyroid gland) 3. The endocrine tissue secretes a systemic hormone (example: thyroid hormone/T4) that creates a physiological response. 4. The physiological response by the target cells provides negative feedback to the brain to curtail the cascade.
While walking home from class one afternoon, you take a shortcut that leads you in front of a house that is guarded by a huge, barking dog. Unfortunately, you are terrified of dogs! Though the dog is unable to escape its yard, as you walk past you notice yourself breathing more quickly than normal and you can feel your heart racing and your palms sweating. Which of your glands is most likely responsible for your physiological reaction to the dog? Adrenal cortex Pineal gland Anterior pituitary Adrenal medulla
Adrenal medulla EXPLANATION: The adrenal gland is almost certainly responsible for your reaction, as this gland contains the adrenal medulla, which is capable of releasing epinephrine. During stressful situations, the sympathetic nervous system triggers the fight-or-flight response. During this response, sympathetic nerves stimulate the adrenal medulla, which then releases epinephrine. Epinephrine raises blood sugar levels and increases blood pressure, brain oxygen consumption, and heart rate. It prepares an individual to either fight a threat (such as a dog), or run away from it. The anterior pituitary is capable of releasing a number of hormones including growth hormone, thyroid-stimulating hormone, and prolactin. The pineal gland is involved in biorhythms and sleep patterns. The adrenal cortex is stimulated by adrenocorticotropic hormone and releases corticosteroids in response to long-term stress, such as sleep or food deprivation.
How might Grave's disease cause hyperthyroidism? Antibody binding and inactivation of thyroid-stimulating hormone A cellular immune response selectively destroys thyroid-stimulating hormone producing cells in the pituitary A cellular immune response selectively destroys cell in the parathyroid glands Antibody binding and activation of thyroid-stimulating hormone receptors
Antibody binding and activation of thyroid-stimulating hormone receptors EXPLANATION: Hyperthyroidism is an over-secretion of the thyroid hormones, resulting in an increase in metabolism and energy consumption. Grave's disease is the most common cause of hyperthyroidism. It is an autoimmune disorder in which the body's immune system produces antibodies that bind to the thyroid-stimulating hormone (TSH) receptor. The binding of the antibody to the receptor serves as a non-hormonal activation of the receptor and thyroid hormone continues to be produced, even when TSH is not present. The normal negative feedback mechanism to maintain thyroid hormone levels is bypassed. Inactivation of thyroid-stimulating hormone or its receptors would cause a decrease in the production of thyroid hormone, known as hypothyroidism. The parathyroid glands are not directly involved in regulating thyroid hormone.
Which pituitary hormone is responsible for regulating the water volume in blood? Aldosterone Glucagon Insulin Oxytocin Antidiuretic hormone
Antidiuretic hormone EXPLANATION: Antidiuretic hormone (ADH) is secreted by the posterior pituitary and acts on the kidney tubules, increasing the water retention in blood and decreasing the water volume in urine. It works by increasing the number of aquaporins (water channels in the plasma membrane) in the collecting duct of the kidney nephrons. Water flows down its osmotic gradient out of tubule, and into the blood for circulation. Aldosterone also functions to regulate water volume in the blood, and is associated with the renin-angiotensin-aldosterone system (RAAS). Aldosterone functions by increasing sodium reabsorption. This increases the solute concentration in the blood, passively causing water to diffuse out of the filtrate and into the blood. Though aldosterone and antidiuretic hormone have similar functions, aldosterone is secreted by the adrenal cortex, not the pituitary. Oxytocin stimulates uterine contractions and milk release in the mammary glands. Glucagon and insulin are involved in the regulation of blood sugar levels.
Glucocorticoid release by the adrenal glands functions to mobilize fuel for the body in what way? Direct stimulation of a feedback loop to the hypothalamus Breakdown of proteins from skeletal muscle Signaling the pancreas to secrete glucagon Conversion of stored fat to glucose
Breakdown of proteins from skeletal muscle EXPLANATION: Glucocorticoids are produced from the adrenal gland. Their primary effect increases energy and glucose metabolism by making more glucose available from non-carbohydrate sources. Glucocorticoids stimulate gluconeogenesis. One way this is accomplished is through activation of the glucocorticoid receptors within skeletal muscle, which signal the breakdown of muscle proteins to their corresponding amino acids. The amino acids are then transported to the liver and kidneys where they are converted to glucose, which is released into the bloodstream. The ability to make glucose from muscle proteins can provide additional fuel when the body needs more glucose (under stress conditions) than the liver can mobilize from the glycogen it has stored. The process, however, can be detrimental if stimulated for extended periods of time.
Amy has osteoporosis, which is a disease that affects the bone. It occurs in individuals with low calcium levels in their bones. The bones become weak, brittle and may break. Which of the following hormones would she need to produce to help reduce the problems associated with osteoporosis? Growth hormone Calmodulin Calcitriol Parathyroid hormone Calcitonin
Calcitonin EXPLANATION: Calcitonin is the hormone in charge of taking calcium ions from the bloodstream and incorporating them into the matrix of the bone. This allows the bone to produce hydroxyapatite crystals from the calcium, which can strengthen the matrix of the bone and reduce the effect of osteoporosis. Parathyroid hormone and calcitriol (vitamin D) have opposite effects as calcitonin - they increase the blood calcium levels through breaking down bone and increasing the absorption of calcium in the gut. Growth hormone is responsible for normal growth and development of the body, especially bones and skeletal muscles. It is not involved in regulation of minerals such as calcium. Calmodulin is a calcium binding protein that regulates many intracellular processes.
What is the hormone responsible for decreasing blood levels of calcium? Calcitonin Melatonin Triiodothyronine Parathyroid hormone (PTH) Thyroxine
Calcitonin EXPLANATION: The hormone responsible for the reduction of calcium in the blood is calcitonin. This hormone promotes the assimilation of calcium ions into the bone matrix from the blood. This reduces the concentration of calcium ions in the blood and increases the concentration found in the bone. Meanwhile, PTH has the opposite effect by taking calcium ions from the bone matrix and releasing them into the blood.
Which hormone is most likely to be produced in order to decrease plasma calcium levels? Melatonin Antidiuretic hormone Parathyroid hormone Oxytocin Calcitonin
Calcitonin EXPLANATION: The two hormones known for their effect on plasma calcium levels are calcitonin and parathyroid hormone (PTH). When calcium levels are high, calcitonin is released by the thyroid gland to stimulate the uptake of serum calcium into bone. This effectively decreases calcium levels in the blood. PTH has the opposite effect and is released by the parathyroid gland. The three remaining answer choices are not known for their effect on calcium levels in the blood.
Which of the following is most directly regulated by parathyroid hormone (PTH)? Glucose Corticosteroids Thyroid hormone Calcium ions
Calcium ions EXPLANATION: Calcium ions are essential for normal cellular function. Parathyroid hormone is released when blood calcium levels fall below a threshold of about 10mg per 100mL. Parathyroid hormone acts to raise blood calcium through multiple mechanisms. It works directly to increase blood calcium by causing demineralization of bone and by directly stimulating ion reabsorption in the kidneys. It also acts indirectly by stimulating conversion of vitamin D, which acts on the intestines to stimulate the uptake of calcium ions from food.
The corpus luteum releases progesterone to prevent menstruation from occurring; if an ovum is not fertilized, then menstruation occurs. What happens to progesterone levels if the ovum is not fertilized? Increase Progesterone levels stay the same Progesterone levels will depend on relative estrogen levels Decrease
Decrease EXPLANATION: In order for menstruation to occur, progesterone levels must decrease. When fertilization does not occur, the corpus luteum ceases progesterone production, initiating menstruation. The corpus luteum then transitions into the corpus albicans and removed from the ovary in preparation for the new menstrual cycle.
Which of the following is a hormone that is directly regulated by the nervous system? Estrogen Melatonin Calcitonin Epinephrine
Epinephrine EXPLANATION: Epinephrine, or adrenaline, is regulated by the nervous system when an environmental stress occurs. Nerve signals travel through the spinal cord to the adrenal medulla, which secretes epinephrine and norepinephrine. Release of epinephrine is not caused by a tropic hormone or other cell signal, but by direct neural stimulation. Release of epinephrine is a short-term stress response that increases blood pressure, breathing rate, glycogen break down to glucose, and metabolic rate. This increases alertness, and decreases digestive, excretory and reproductive system activity. Epinephrine is essentially responsible for the effects of the sympathetic nervous system, which is active during the "fight or flight" response.
__________ is a critical hormone that controls heart rate and constriction of blood vessels. It is crucial in the fight-or-flight response. Insulin Cortisol Epinephrine Glucagon
Epinephrine EXPLANATION: Epinephrine, released from the adrenal gland, is important for the fight-or-flight response. During moments of stress, heart rate increases, pupils dilate, and blood vessels constrict in order to prepare for danger. All of this is controlled by epinephrine and norepinephrine, and is part of the sympathetic nervous system.
Which of the following is does not describe an endocrine interaction? All of these are endocrine interactions Insulin is secreted by the pancreas to lower blood-glucose levels Adrenocorticotropic hormone is secreted to stimulate secretion of cortisol Epinephrine is secreted into a synapse to excite a post-synaptic neuron
Epinephrine is secreted into a synapse to excite a post-synaptic neuron EXPLANATION: Endocrine interactions involve a molecule (hormone) being secreted into the bloodstream to trigger a response in target cells in a different location. Reduction of blood-glucose levels by insulin and stimulation of cortisol release by adrenocorticotropic hormone are both examples of endocrine function. Though epinephrine can act as a hormone when secreted by the adrenal medulla, the answer option indicates that it is being secreted by a neuron into a synapse. In this case, epinephrine would be acting as a neurotransmitter, causing an effect on a neighboring post-synaptic neuron. This answer does not describe an endocrine interaction.
Which of the following is produced by the pituitary gland? Estrogen Follicle-stimulating hormone Epinephrine Insulin Testosterone
Follicle-stimulating hormone EXPLANATION: The hormones secreted by the pituitary gland are FLAT PEG: Follicle-stimulating hormone, luteinizing hormone, adrenocorticotropic hormone, thyroid-stimulating hormone, prolactin, endorphins, and growth hormone. Testosterone is produced in the testes in males, and in the adrenal gland in both males and females. Insulin is produced by the pancreas. Estrogen is produced by the ovaries in females, and in the adrenal gland in both males and females.
What key factor distinguishes type 1 diabetes from type 2 diabetes? In type 1 diabetes, the body remains responsive to insulin Type 1 diabetes is usually associated with being overweight Type 2 diabetes usually occurs after age 40, when insulin production decreases Type 2 diabetes is an autoimmune disorder
In type 1 diabetes, the body remains responsive to insulin EXPLANATION: Type 1 diabetes, also known as insulin-dependent diabetes, is an autoimmune disease in which the body attacks and destroys the beta cells within the islet of Langerhans. These cells produce insulin, which normally works in a regulated feedback mechanism with glucagon to maintain glucose homeostasis. Type 1 diabetes usually occurs in children and is treatable with injectable insulin shots. Glucose levels need to be monitored frequently to know when insulin needs to be given/taken to maintain proper glucose levels. In type 1 diabetes, the determining factor is the inability to produce insulin due to destruction of the beta cells. The body remains responsive to insulin. In type 2 diabetes the body is still capable of producing insulin, but the tissues of the body have become unresponsive and do not remove glucose from the bloodstream. Type 2 diabetes generally begins during adulthood and is not caused by autoimmune interaction.
After a large meal, an individual's blood sugar increases. This signals an increase in which of the following hormones? Adrenocorticotropic hormone (ACTH) Insulin Glucagon Thyroxine (T4) Epinephrine
Insulin EXPLANATION: After a large meal the body must quickly remove glucose from the blood. Insulin facilitates the entry of glucose into a variety of body cells, particularly hepatocytes in the liver. Once inside the cell, glucose is either stored as a polymer (glycogen) or reduced into carbon dioxide and water to produce a usable form of energy (ATP) for the cell. Glycogen is stored in the liver until blood glucose levels become low, at which point it can be converted back to glucose and released to maintain homeostasis. This process, known as glycogenolysis, is stimulated by the release of glucagon. Together, insulin and glucagon create a negative feedback loop to regulate glucose in the blood. Thyroxine (T4) regulates metabolic rate, and is released from the thyroid. Adrenocorticotropic hormone (ACTH) is released from the anterior pituitary and stimulates the release of glucocorticoids (like cortisol) from the adrenal glands. The release of epinephrine is tightly linked to the sympathetic nervous system, and is involved in the immediate stress response.
Following a large meal, which of the following biological changes occurs? Glucagon levels spike, promoting the breakdown of glycogen Glycogenolysis begins to occur Insulin levels spike, facilitating the storage of glucose into cells Gluconeogenesis activity increases Insulin levels drop, facilitating the release of glucose from cells
Insulin levels spike, facilitating the storage of glucose into cells EXPLANATION: Following a large uptake of glucose, the body will begin to release insulin to facilitate storage of the glucose molecules within the cells of the liver, as well as skeletal muscles. Glucagon is released when blood glucose levels are low and promotes an increase in free blood glucose. The breakdown of glycogen into free blood glucose is a process known as glycogenolysis; this process is stimulated by glucagon and inhibited by insulin. Gluconeogenesis is the generation of glucose from non-carbohydrate carbon substrates; it is also stimulated by glucagon and inhibited by insulin.
What type of receptor does this lipid-soluble molecule activate? Second messenger receptor Cell surface (transmembrane) receptor Post-synaptic receptor Intracellular receptor
Intracellular receptor EXPLANATION: This molecule is estrogen, a lipid-soluble endocrine hormone. Estrogen acts a classic endocrine hormone. It is secreted and diffuses into the bloodstream to trigger a physiological response in target cells anywhere in the body that possess estrogen receptors. Estrogen is a steroid hormone. Its nonpolar nature and small size allow it to diffuse through the membrane of target cell, binding to receptors within the cytoplasm. The estrogen receptor is an intracellular receptor whose activation through ligand binding typically results in alteration of gene expression.
Which of the given elements is a component of thyroid hormone? Zinc Iodine Copper Potassium
Iodine EXPLANATION: There are two types of thyroid hormone: T3 and T4. Both hormones are derived from the amino acid tyrosine, and are created by the addition of iodine atoms to the amino acid structure. The full name of T3 is triiodothyronine (three iodine atoms) and the full name of T4 is tetraiodothyronine (four iodine atoms). Because iodine is specific to the production of thyroid hormone, radioactive iodine is used to gather images of the thyroid gland. If iodine levels are low, the thyroid cannot produce sufficient thyroid hormone. The result is hypothyroidism. Symptoms of hypothyroidism include weight gain, lethargy, and intolerance to cold. In extreme cases, the thyroid will enlarge in an attempt to produce more hormone, resulting in a goiter.
What aspect of growth hormone differentiates it from other anterior pituitary hormones? It is the only glycoprotein hormone It produces both tropic and non-tropic effects It is a steroid hormone It provides negative feedback directly to the hypothalamus
It produces both tropic and non-tropic effects EXPLANATION: Non-tropic hormones are hormones that directly stimulate target cells to induce effects. For example, aldosterone acts directly on the kidney to promote reabsorption of sodium, which causes an increase in blood pressure. This differs from tropic hormones, which act on other endocrine glands to stimulate (or inhibit) release of a second hormone. For example, thyroid-stimulating hormone is responsible for stimulating the release for thyroid hormone by acting on the thyroid gland. Growth hormone (GH) stimulates growth through both tropic and non-tropic mechanisms. Growth hormone's major tropic effect is to stimulate the release of insulin-like growth factors (IGFs) from the liver, which causes bone growth. Growth hormone also stimulates a number of tissues through non-tropic mechanisms to affect metabolism and raise blood glucose levels.
The pancreas is responsible for regulating blood sugar levels through the release of insulin and glucagon. In Type I Diabetic individuals the body has high blood sugar due to the inability to produce insulin, which is responsible for lowering blood sugar. In an individual with Type II Diabetes the body produces insulin, however, the receptors have become insensitive to the presence of insulin. What effect will injecting additional insulin have in an individual with Type II Diabetes? It will have little to no effect It will reduce blood sugar levels It will increase blood sugar levels It will reduce glucagon levels
It will have little to no effect EXPLANATION: Because insulin receptors have been desensitized to insulin, the addition of more insulin will not have any effect. This is why Type II Diabetes is much more difficult to treat than Type I. The recommended course of action for individuals with Type II diabetes is to eat healthy and exercise.
Which of these hormones is responsible for the secretion of testosterone in males? Follicle stimulating hormone (FSH) Luteinizing hormone (LH) Human growth hormone (hGH) Oxytocin
Luteinizing hormone (LH) EXPLANATION: Luteinizing hormone is responsible for the secretion of testosterone from leydig cells in the testes. FSH is responsible for the proliferation of sertoli cells, which nurture sperm cell precursors. hGH is responsible for body growth, and is not responsible for testosterone formation. Oxytocin is responsible for increasing uterine contractions during pregnancy.
__________ causes testosterone production in males and triggers ovulation in females. Testosterone Luteinizing hormone (LH) Estrogen Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH) EXPLANATION: The hormone described in the question is luteinizing hormone (LH). If fertilization occurs, the LH levels will decrease and human chorionic gonadotropin (hCG) is released from the placenta to simulate LH function.
Which of the following hormones is not secreted by the pituitary gland? Growth hormone Adrenocorticotropic hormone Prolactin Melatonin Follicle-stimulating hormone
Melatonin EXPLANATION: Melatonin is secreted by the pineal gland, which is also in the brain. The function of melatonin is not yet certain, but current research hints that it plays functions in regulation of the circadian rhythm. All other hormones are indeed secreted by the pituitary gland.
Which of the following statements is not true of melatonin? Melatonin is structurally similar to corticosteroids Melatonin affects skin pigmentation Melatonin is produced in the pineal gland Melatonin's main function is to regulate functions related to light and changes in day length
Melatonin is structurally similar to corticosteroids EXPLANATION: Melatonin is a modified amino acid that is secreted by the pineal gland. The pineal gland contains light-sensitive cells and has nervous connections to the eyes that affect its secretory activity. As a result, melatonin regulates functions related to light, circadian rhythm, and seasonal alterations based on the amount of daylight. Melatonin is secreted at night, and the amount released depends on the length of the night. In winter, for example, more melatonin is released. Melatonin is believed to target a group of neurons in the hypothalamus called the suprachiasmatic nucleus (SCN), which functions as a biological clock. Melatonin also affects skin pigmentation in many vertebrates. Since melatonin is a modified amino acid, its structure is very different from that of corticosteroids, which are synthesized from the lipid cholesterol. Melatonin has two rings (similar to tryptophan), a modified ether group (from the carboxylic acid of the amino acid), and an amide group (from the amine group of the amino acid). Corticosteroids have four rings and multiple hydroxyl and ketone groups.
Vasopressin is released when sensory neurons in the hypothalamus detect a rise in the osmolarity of the blood. When secreted, this hormone causes changes in water reabsorption by the kidneys. This is an example of what type of signaling? Synaptic signaling Autocrine signaling Neuroendocrine signaling Paracrine signaling
Neuroendocrine signaling EXPLANATION: Neuroendocrine signaling describes the process when specialized neural sensors, usually in the brain, detect changes in the body. These sensors stimulate the release of a hormone to help correct deviations. The hormone can travel via the bloodstream to affect distant tissues. In this example, sensor neurons in the hypothalamus trigger the release of the hormone vasopressin to affect the kidney.
Where is the hormone melatonin produced? Adrenal gland Pineal gland Posterior pituitary Anterior pituitary Pancreas
Pineal gland EXPLANATION: Melatonin is produced in the pineal gland which is a gland in the brain responsible for the body's circadian rhythms and sleep/wake cycle. The concentration of melatonin peaks at night and causes us to fall asleep. Melatonin is degraded while we sleep so that when we wake up in the morning we start to produce it again throughout the day.
Which anterior pituitary hormone regulates blood glucose control by the pancreas? Antidiuretic hormone None of the answers provided Adrenocorticotropic hormone (ACTH) Glucagon
None of the answers provided EXPLANATION: The maintenance of blood glucose homeostasis is not controlled by the pituitary gland. It is controlled through a continuous sensory and feedback mechanism by the pancreas and its two hormones, glucagon and insulin. When blood glucose levels rise above a threshold point, insulin is produced/released to drive uptake of glucose from the blood. Conversely, when blood glucose levels drop below a threshold point, glucagon is released to promote release of glucose into the bloodstream from glucagon stores. Each of these two hormones is produced in by specific cells in the islets of Langerhans in the pancreas; alpha cells produce glucagon and beta cells produce insulin.
Which of the following hormones is not released by the anterior pituitary gland? Oxytocin Thyroid-stimulating hormone (TSH) Prolactin Growth hormone (GH)
Oxytocin EXPLANATION: The anterior pituitary is responsible for releasing a large number of hormones; however, oxytocin is released by the posterior pituitary. Two of oxytocin's most important functions include stimulating uterus contractions and stimulating milk production by the mammary glands. Prolactin stimulates milk release from the mammary glands. Thyroid-stimulating hormone stimulates the release of hormones from the thyroid gland. Growth hormone stimulates the growth of bones and stimulates the liver to release insulin-like growth factors. It is important to note that at least one hormone from the hypothalamus is used to regulate each of the hormones released by the anterior pituitary—for example, the anterior pituitary gland will only release prolactin if the hypothalamus releases prolactin-releasing hormone.
Which of the following hormones is produced in the posterior pituitary gland? Epinephrine Prolactin Oxytocin Growth hormone Melatonin
Oxytocin EXPLANATION: The correct answer is oxytocin because this hormone is produced in the posterior pituitary gland along with antidiuretic hormone (ADH). Oxytocin is responsible for uterine contraction during labor in a positive feedback look mechanism.
Most hormone regulatory signaling is based on negative feedback control mechanisms. What hormone operates through a positive feedback mechanism? Insulin Oxytocin Calcitonin Vasopressin
Oxytocin EXPLANATION: The oxytocin pathway is an example of a positive feedback mechanism. Unlike negative feedback, which counteracts a stimulation, positive feedback reinforces a stimulus, leading to an even greater response. One key function of oxytocin in mammals is to regulate the release of milk during nursing. In this case, the initial stimulus in the oxytocin pathway is an infant suckling, which stimulates sensory nerve cells in the nipples. The signal is received in the hypothalamus, which signals the posterior pituitary to secrete more oxytocin. Additional oxytocin is released into the bloodstream, signaling the mammary glands to secrete milk and perpetuating the stimulation of the hypothalamus. Oxytocin participates in a similar positive feedback loop when it stimulates uterine contractions during birth. Vasopressin (antidiuretic hormone) is moderated by a negative feedback loop based on blood pressure. Based on pressure sensors in the body, vasopressin will be released or inhibited. Insulin and glucagon work in a negative feedback loop via sensors in the pancreas to moderate blood glucose levels. Calcitonin and parathyroid hormone work in a negative feedback loop to moderate blood calcium.
Which of the following is a hormone secreted by the posterior pituitary? Adrenocorticotropic hormone Growth hormone Oxytocin Prolactin Thyroid-stimulating hormone
Oxytocin EXPLANATION: The posterior pituitary only secretes oxytocin and vasopressin (antidiuretic hormone). The hypothalamus actually creates these hormones and stores them in the posterior pituitary. The anterior pituitary releases the growth hormone (GH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin. You can remember all of these hormones by using the acronym FLATPEG, where: F- FSH L- LH A- ACTH T- TSH P- Prolactin E- Endorphins G- GH
__________, released from the __________, is the hormone responsible for controlling lactation in nursing women, as well as triggering labor in pregnant women. Luteinizing hormone; posterior pituitary Follicle-stimulating hormone; hypothalamus Vasopressin; posterior pituitary Oxytocin; posterior pituitary
Oxytocin; posterior pituitary EXPLANATION: Oxytocin is responsible for lactation in nursing women. When the nipple is stimulated, oxytocin is released from the posterior pituitary to cause lactation. During labor, release of oxytocin causes positive feedback on the hypothalamus, which causes further oxytocin release. Luteinizing hormone and follicle-stimulating hormone are released from the anterior pituitary and function to regulate the menstrual cycle. Vasopressin is released from the posterior pituitary and helps to regulate blood pressure and water balance.
Which disorder is correctly matched with a probable cause? Pituitary dwarfism: hyposecretion of growth hormone Low blood calcium: hypersecretion of parathyroid hormone Diabetes: hypersecretion of insulin Enlargement of face and extremities: hyposecretion of growth hormone Enlargement of face and extremities: hypersecretion of thyroxine
Pituitary dwarfism: hyposecretion of growth hormone EXPLANATION: To answer this question, it is necessary to understand the prefixes "hyper" and "hypo." "Hyper" refers to excessive synthesis, while "hypo" refers to reduced synthesis. Growth hormone is responsible for stimulating cell growth and division throughout the body. Hyposecretion would cause a deficiency and reduce the effectiveness of growth hormone, potentially causing pituitary dwarfism. Hyposecretion of growth hormone in adults leads to poor protein synthesis, which significantly impacts the muscles and skin. Enlargement of the face and extremities is an adult condition known as acromegaly. The underlying cause is hypersecretion of growth hormone. In children, this condition can lead to gigantism if untreated. The hormone thyroxine is not involved. Parathyroid hormone elevates blood calcium levels, so hypersecretion would cause high blood calcium. Insulin functions to reduce blood glucose levels. Since diabetes is classified by high blood glucose, insulin must lose functionality to cause this disease. This means that it would be hyposecreted, rather than hypersecreted.
The hypothalamus plays a central role in vertebrates by integrating the endocrine and nervous systems. What gland receives signals from the hypothalamus? Adrenal gland Pineal gland Pituitary gland Thyroid gland
Pituitary gland EXPLANATION: Signals from the hypothalamus go to the posterior pituitary gland, which is located at the base of the hypothalamus. The pituitary consists of two lobes (anterior and posterior), which function independently. The anterior and posterior pituitary produce a collection of hormones that are key to endocrine signaling throughout the body. The posterior pituitary stores and secretes two hormones (oxytocin and vasopressin), while the anterior pituitary produces six different hormones (growth hormone, prolactin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH) and adrenocorticotropic hormone (ACTH). The posterior pituitary will only secrete hormones when stimulated by the hypothalamus.
Growth hormone (GH) stimulates the growth of bone and other tissues in the human body. The hypothalamus is very important in the release of GH through the release of growth-hormone-releasing hormone (GHRH), which causes release of GH from another endocrine gland. Thyroid Pancreas Anterior pituitary Posterior pituitary
Posterior pituitary EXPLANATION: Growth-hormone-releasing hormone (GHRH) causes release of growth hormone (GH) from the anterior pituitary. The posterior pituitary is responsible for antidiuretic hormone (ADH) and oxytocin release. The thyroid releases thyroid hormones (T3 and T4), which control metabolic rates. The pancreas releases glucagon and insulin to control blood sugar levels.
During pregnancy in mammals, which of the following hormones is directly responsible for maintaining the lining of the uterus? Growth hormone Progesterone Melatonin Prolactin Glucocorticoids
Progesterone EXPLANATION: Progesterone is a steroid hormone that supports gestation in mammalian pregnancy. After the eighth week of pregnancy, it is produced by the placenta and helps to decrease the maternal immune response to prepare for pregnancy. Melatonin is a hormone used to regulate circadian rhythm and sleep cycles. Glucocorticoids, such as cortisone and cortisol, prepare the body for long term stressors. Prolactin stimulates the production of milk in mammals. Growth hormone promotes the enlargement of various organs and stimulates cell division.
Which of the following in not a tropic hormone? Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Thyroid-stimulating hormone (TSH) Prolactin
Prolactin EXPLANATION: A tropic hormone is one that regulates the function of other endocrine cells or glands. Thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), adrenocorticotropic hormone (ACTH), and luteinizing hormone (LH) are the four topic hormones that are produced by the anterior pituitary. Prolactin is also produced by the anterior pituitary, but does not trigger a response from any other endocrine tissues. The stimulation of mammary gland growth and milk production in mammals, regulation of fat metabolism and reproduction in birds, and the regulation of salt and water balance in freshwater fish are all functions of prolactin.
Which of the following hormones is released from the anterior pituitary? Cortisol Prolactin Glucagon Insulin Epinephrine
Prolactin EXPLANATION: The anterior pituitary gland contains endocrine cells that release hormones through the hypothalamic-hypophyseal axis. Prolactin controls milk production and contributes to regulation of the immune system. Of the listed hormones, prolactin is the only hormone released from the anterior pituitary. Insulin and glucagon are secreted by the pancreas. Cortisol is released by the adrenal cortex; epinephrine is released by the adrenal medulla.
__________ is the hormone responsible for milk production in female mammals. It is released by the __________. Prolactin; mammary glands Oxytocin; posterior pituitary Prolactin; anterior pituitary Prolactin; posterior pituitary Oxytocin; anterior pituitary
Prolactin; anterior pituitary EXPLANATION: Prolactin is responsible for the production of milk, while oxytocin is responsible for the ejection of milk. The question asks for the hormone that causes production, so the answer is prolactin. Prolactin is released from the anterior pituitary. Oxytocin is released from the posterior pituitary and the mammary glands are responsible for releasing milk.
Insulin helps regulate blood sugar at homeostatic levels by stimulating which of the following processes? Activating hormone production in the posterior pituitary gland Stimulating the release of glucose from the liver Promoting the entry of glucose into cells Stimulating the breakdown of glycogen to glucose
Promoting the entry of glucose into cells EXPLANATION: Insulin works by stimulating adipocytes (fat cells), hepatocytes (liver cells), and skeletal muscle to translocate glucose transporter-rich vesicles to the cell membrane. This allows the diffusion of glucose from the blood into these tissue types after a carbohydrate-rich meal. Without insulin, even if an individual has high blood glucose levels, these three cell types would essentially be deprived of the circulating glucose. Glucagon works against insulin by increasing blood glucose levels as they decrease via gluconeogenesis and glycogenolysis.
Which of the following physiological responses is not under hormonal control? Prostaglandin stimulation of uterine smooth muscle contraction Glucagon effect of increasing blood glucose levels An insect larva transitioning to the pupa stage Calcitonin lowering of blood calcium levels
Prostaglandin stimulation of uterine smooth muscle contraction EXPLANATION: In almost all animals, the endocrine and nervous systems are integrated to respond and control physiological responses. In insects, the prothoracic gland releases a hormone called ecdysone at different times to stimulate molting and maturation. Calcitonin and glucagon are hormones that are secreted by the pancreas and thyroid gland, respectively. They produce these hormones in response to ongoing monitoring of blood levels for glucose and calcium. The hormones are secreted to produce physiological responses in order to bring a return to homeostasis. Prostaglandins are local regulators and produce rapid responses that are confined to a small area. In the example, prostaglandins in semen stimulate the smooth muscle of the uterine wall to contract to facilitate sperm reaching an egg.
Which of the following describes paracrine signaling? Secretion of molecules that diffuse locally and trigger a response on neighboring cells Secretion of molecules that diffuse locally and trigger a response in the same cells that secreted them Secretion of molecules that diffuse into the bloodstream and trigger a response in target cells anywhere in the body Secretion of neurotransmitters that diffuse across synapses and trigger a response in cells of target tissues (neurons, muscles, and glands)
Secretion of molecules that diffuse locally and trigger a response on neighboring cells EXPLANATION: Hormones and other signaling molecules generate physiological responses by binding to specific receptor proteins in or on target cells. Only cells that have receptors for the secreted molecule (hormone, neurotransmitter, neurohormone, etc.) are target cells; other cells are nonresponsive. There are five different classifications for molecular signaling. These are as follow: Endocrine signaling: Secreted molecules diffuse into the bloodstream and trigger responses in target cells throughout the body. Paracrine signaling: Signaling molecules diffuse locally and trigger a response in neighboring cells. Autocrine signaling: Secretion of molecules that diffuse locally and trigger a response on the same cells that secreted them. Synaptic signaling: Secretion of neurotransmitters that diffuse across synapses and trigger a response in cells or target tissues (neurons, glands, and muscles). Neuroendocrine signaling: Secretion of hormones from neuronal cells that diffuse into the bloodstream and trigger a response on cells throughout the body.
Obesity can sometimes be caused by the slowing of the thyroid gland's production of thyroid hormones III and IV (T3 and T4), a condition known as hypothyroidism. Conversely, hyperthyroidism occurs when the thyroid overproduces T3 and T4. If T3 and T4 receptors became insensitive to the hormones, what effect would this have on the body? Faster metabolism and weight gain Slower metabolism and weight gain Slower metabolism and weight loss Faster metabolism and weight loss
Slower metabolism and weight gain EXPLANATION: The question tells us that slowed output of thyroid hormones can lead to obesity. One can safely assume that receptor insensitivity will have a similar effect. In either scenario, the T3 and T4 hormones are unable to elicit the proper response form the body. Similar to individuals with hypothyroidism, individuals with insensitive receptors would show slowed metabolism and increased weight gain.
How do steroid hormones elicit a response from their target cells? Steroid hormones enter the target cell and alter the products of the cell at the transcription level. Steroid hormones enter the nucleus of the target cell and increase the creation of ribosomes by the nucleolus. This results in more proteins being made by the target cell. Steroid hormones attach to a membrane-bound receptor on the cell. This creates an intracellular second messenger which leads to a reaction cascade. Steroid hormones move freely throughout the bloodstream and attach to their target cells. This interaction increases ion permeability in the cell.
Steroid hormones enter the target cell and alter the products of the cell at the transcription level. EXPLANATION: Steroids are nonpolar, which means that they are able to pass easily through cell membranes, but require a transport protein through the hydrophilic blood in order to do so. The steroid hormone then enters the nucleus and attaches to the DNA in order to increase the desired product at the level of transcription.
Which of the following is a target of follicle-stimulating hormone (FSH)? Anterior pituitary Mammary glands Adrenal gland Testes
Testes EXPLANATION: Follicle-stimulating hormone (FSH) is a tropic hormone produced in the anterior pituitary. Its primary functions are to regulate development, growth, pubertal maturation, and reproductive processes of the human body. In males, follicle-stimulating hormone acts on the testes to promote spermatogenesis. In females, follicle-stimulating hormone is an important modulator of the menstrual cycle.
Which steroid hormone is responsible for development of the secondary sexual characteristics in males, such as facial hair and deepening of the voice? Testosterone Cortisol Estrogen Progesterone
Testosterone EXPLANATION: Testosterone is well known to be responsible for male secondary sexual characteristics. It also plays a key role in behavior, such as aggression. For example, during mating season in gorillas the testosterone levels in males raise significantly and lead to confrontations between males. Progesterone and estrogen are responsible for female secondary sexual characteristics, while cortisol plays a role in the body's response to long-term stress.
Which of the following is an endocrine organ? The appendix The gallbladder The spleen The kidney The stomach
The kidney EXPLANATION: Endocrine glands release hormones directly into the circulatory system, where they can act on target effector organs. The kidneys serve both endocrine and exocrine functions. Releasing urine filtrate through ducts is an exocrine function. Kidneys also release the hormone erythropoietin, which promotes the generation of new red blood cells.
Which of the following is not true about water-soluble hormones? Their receptors are found on the cell membrane Binding to its receptor can initiate a signal transduction cascade Tyrosine-derivative hormones are water-soluble They act as local regulators
They act as local regulators EXPLANATION: Water-soluble hormones can be either polypeptides (proteins) or tyrosine-derivatives. The binding of a water-soluble hormone to a receptor occurs on the cell membrane, and receptor binding triggers a physiological response through a signal transduction cascade. Peptide hormones include insulin, growth hormone, oxytocin, adrenocorticotropic hormone, and many more. Tyrosine-derivative hormones include epinephrine and the thyroid hormones (T3 and T4). Water-soluble hormones, like most hormones, are secreted into the bloodstream and carried throughout the body. As such, they are capable of eliciting responses in non-local regions of the body, and would not be classified as local regulators.
__________ is released in response to low blood sugar levels, while __________ is released in response to high blood sugar levels. insulin; glucagon thyroid hormones; glucagon glucagon; insulin insulin; thyroid hormones
glucagon; insulin EXPLANATION: Insulin is responsible for lowering blood sugar levels, and is therefore released when the body's blood sugar levels are too high. Glucagon is released in response to low blood sugar levels, and acts to increase sugar concentrations. Thyroid hormones (T3 and T4) are released to increase the body's metabolic rate, but are not directly influenced by blood sugar levels.
Chemical messengers released in the blood to stimulate or inhibit the function of another organs are known as __________. hormones enzymes second messengers platelets electrolytes
hormones EXPLANATION: A hormone is a chemical formed in one organ and carried by the blood to stimulate or inhibit the function of another organ. Enzymes are protein molecules that carry out catalytic functions. Electrolytes are simply ions dissolved in solution. Second messengers are relay molecules between a signal and its ultimate effect, such as the molecules that carry signals from the cell membrane to the nucleus to affect transcription. Platelets are cell fragments in the blood that help form clots to heal injuries.
The major tropic action of the growth hormone is to signal the __________ to release __________. adrenal medulla; epinephrine hypothalamus; thyroid-stimulating hormone liver; insulin-like growth factors pancreas; glucagon thyroid; T3 and T4
liver; insulin-like growth factors EXPLANATION: Growth hormone is released from the anterior pituitary, and has numerous effects on the body. One of its primary effects is to stimulate release of insulin-like growth factors (IGFs) from the liver. These compounds circulate in the blood and directly stimulate bone and cartilage growth. The release of thyroid-stimulating hormone (TSH) causes the release of T3 and T4, which help speed up metabolism. Glucagon serves to increase blood glucose level. Epinephrine is released in response to short term stress, and stimulates the sympathetic nervous system.