chapter 16 review
Define diabetes mellitus.
Diabetes mellitus is an endocrine disorder characterized by elevated blood glucose levels resulting from inadequate insulin production or diminished cell sensitivity to insulin.
What effects would increased circulating levels of glucocorticoids have on the pituitary secretion of ACTH?
Increased circulating levels of glucocorticoids inhibit the release of CRH by the hypothalamus.
Differentiate between a first messenger and a second messenger.
A first messenger is a hormone whose binding to a protein receptor in the plasma membrane gives rise to a second messenger in the cytoplasm. A second messenger changes the rate of various metabolic reactions by acting as an enzyme activator, an enzyme inhibitor, or a cofactor.
Define hormone receptor.
A hormone receptor is a protein molecule, located either on the plasma membrane or inside the cell, that binds to a specific hormone.
Define regulatory hormone.
A regulatory hormone is a hormone secreted by the hypothalamus that controls endocrine cells in the anterior lobe of the pituitary gland.
Define synergistic effect.
A synergistic effect is when two hormones have an additive effect so that the net result is greater than the effect each would produce alone.
What condition is characterized by increased body weight due to Na+ and water retention and a low blood K+ concentration?
Aldosteronism is characterized by increased body weight due to Na1 and water retention and a low blood K 1 concentration.
Which of the four hormonal effects are involved in a negative feedback response?
Antagonistic effects are involved in a negative feedback response.
What thyroid hormone aids in calcium regulation?
Calcitonin aids in calcium regulation.
Decreased blood calcium levels would result in increased secretion of which hormone?
Decreased blood calcium levels result in increased secretion of PTH.
Identify several hormones necessary for normal growth and development.
Hormones necessary for normal growth and development include GH, thyroid hormones, insulin, PTH, calcitriol, and reproductive hormones.
What kind of effect do hormones have if they produce different but complementary effects?
Hormones producing different but complementary effects are described as having integrative effects.
In a dehydrated person, how would the amount of ADH released by the posterior lobe of the pituitary change?
In a person who is dehydrated, the amount of ADH released by the posterior lobe of the pituitary gland increases in response to increased blood osmotic pressure resulting from an increase in solute concentration. The lack of CRH decreases the secretion of ACTH from the pituitary gland, so ACTH levels would decrease.
List three functions of melatonin.
In humans, melatonin may affect the timing of sexual maturation, protect against free radical damage, and maintain circadian rhythms.
What effect would increased cortisol levels have on blood glucose levels?
Increased cortisol levels would result in increased blood glucose levels, because cortisol decreases the use of glucose by cells while increasing both the available glucose (by promoting the breakdown of glycogen) and the conversion rate of amino acids to carbohydrates.
What is the effect of increased glucagon levels on the amount of glycogen stored in the liver?
Increased levels of glucagon stimulate the conversion of glycogen to glucose in the liver, which in turn decreases the amount of glycogen stored in the liver.
The secretion of which hormone lowers blood glucose concentrations?
Insulin secretion lowers blood glucose concentrations.
Describe the resistance phase.
The resistance phase is characterized by long-term metabolic adjustments, including mobilization of remaining energy reserves, conservation of glucose, increased blood glucose concentrations, and conservation of salts and water coupled with the loss of K 1 and H1
Increased amounts of light would inhibit the production of which hormone?
Melatonin secretion is influenced by circadian rhythms, the daily changes in physiological processes that follow a regular day/night pattern. Increased amounts of light would inhibit the production (and release) of melatonin from the pineal gland, which receives neural input concerning the presence of light or darkness from visual pathway collaterals.
Why do signs and symptoms of decreased thyroxine concentrations not appear until about a week after a thyroidectomy (surgical removal of the thyroid gland)?
Most of the body's reserves of the thyroid hormone, thyroxine (T 4 ), are bound to transport proteins in the bloodstream called thyroid-binding globulins. Because these compounds represent such a large reserve of thyroxine, it takes several days after removal of the thyroid gland for blood levels of thyroxine to decrease.
Name the organs of the endocrine system.
Organs of the endocrine system are the hypothalamus, pituitary gland, thyroid gland, adrenal glands, pancreas (pancreatic islets), pineal gland, and parathyroid glands. Organs of other systems that have endocrine functions are the heart, thymus, digestive tract, kidneys, and gonads.
How does paracrine communication differ from endocrine communication?
Paracrine communication is by the release of paracrine factors into the extracellular fluid, and is limited to a local area. Endocrine communication is by the release of hormones into the bloodstream, and it can target cells beyond the local area.
Explain how parathyroid hormone increases blood calcium levels.
Parathyroid hormone (PTH) increases blood calcium levels by decreasing calcium deposition in bones, by increasing reabsorption of calcium from the blood by the kidneys, and by increasing the production of calcitriol by the kidneys.
The release of which pituitary hormone would lead to an increased level of somatomedins in the blood?
Somatomedins mediate the action of growth hormone (GH). Increased levels of GH typically accompany increased levels of somatomedins.
Identify some clinical problems associated with diabetes mellitus.
Some clinical problems associated with diabetes mellitus are diabetic retinopathy, blockages in heart circulation and increased risk for heart attack, diabetic nephropathy, diabetic neuropathy, and decreased blood flow to the distal portions of the limbs.
Which type of hormone diffuses across the plasma membrane and binds to receptors in the cytoplasm?
Steroid hormones diffuse across the plasma membrane and bind to receptors in the cytoplasm.
Name and describe the characteristics and functions of the blood vessels that link the hypothalamus with the anterior lobe of the pituitary gland.
The blood vessels of the hypophyseal portal system link the hypothalamus and anterior lobe of the pituitary gland. Unusually permeable fenestrated capillary beds in each structure are connected by portal vessels. This arrangement ensures that hypothalamic regulatory hormones reach the "downstream" endocrine cells of the anterior lobe directly, before mixing with, and being diluted by, the general circulation.
During which phase of the general adaptation syndrome is there a collapse of vital systems?
The collapse of vital systems occurs during the exhaustion phase of the stress response (general adaptation syndrome).
What is the common goal of the nervous and endocrine systems?
The common goal of both the nervous and endocrine systems is to preserve homeostasis by coordinating and regulating the activities of other cells, tissues, organs, and organ systems.
Define endocrine system.
The endocrine system is one of several body systems that includes organs whose primary function is the production of hormones or paracrine factors, which are chemical secretions that are transported by the extracellular fluid or bloodstream to target cells in other sites within the body.
Name the hormones secreted by the heart and a hormone released by the kidneys.
The heart secretes natriuretic peptides, and the kidneys release erythropoietin.
Identify the hormone-secreting cells of the pineal gland.
The hormone-secreting cells of the pineal gland are pinealocytes.
Name the hormones of the thyroid gland.
The hormones of the thyroid gland are thyroxine (T 4 ), triiodothyronine (T 3 ), and calcitonin.
Identify the nine pituitary hormones and their target tissues.
The hormones produced and released by the anterior lobe of the pituitary gland are (1) thyroid-stimulating hormone (TSH), which targets the thyroid gland; (2) adrenocorticotropic hormone (ACTH), which targets the adrenal cortex; (3) follicle-stimulating hormone (FSH) and (4) luteinizing hormone (LH), which target the testes in males and the ovaries in females; (5) growth hormone (GH), which targets liver cells (which respond by synthesizing somatomedins); (6) prolactin (PRL), which targets mammary glands in females; and (7) melanocyte-stimulating hormone (MSH), which targets melanocytes in the skin. Hormones released by the posterior lobe of the pituitary gland are (8) oxytocin (OXT), which targets the uterus and mammary glands; and (9) antidiuretic hormone (ADH), which targets the kidneys.
List the hypothalamic releasing hormones.
The hypothalamic releasing hormones are corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH), growth hormone- releasing hormone (GH-RH), prolactin-releasing factor (PRF), and gonadotropin-releasing hormone (GnRH).
What are the chemical means of cellular communication in the nervous and endocrine systems?
The nervous system communicates with neurotransmitters, whereas the endocrine system communicates with hormones.
Describe the locations of the parathyroid glands.
The parathyroid glands are embedded in the posterior surfaces of the lateral lobes of the thyroid gland.
Define the prefixes hyper- and hypo- in the context of endocrine disorders.
The prefix hyper- refers to excessive hormone production, whereas hypo- refers to inadequate hormone production.
Describe the structural classification of hormones.
The structural classes of hormones are (1) amino acid derivatives (thyroid hormones, catecholamines, and tryptophan derivatives); (2) peptide hormones (glycoproteins or short polypeptide chains), which are chains of amino acids that are synthesized as prohormones; and (3) lipid derivatives (eicosanoids and steroid hormones), which contain carbon rings and side chains that are built from fatty acids or cholesterol.
Identify the three mechanisms by which the hypothalamus integrates neural and endocrine function.
The three mechanisms of hypothalamic integration of neural and endocrine function are (1) secretion of antidiuretic hormone (ADH) and oxytocin (OXT), (2) secretion of regulatory hormones that control activity of the anterior lobe of the pituitary gland, and (3) neural (sympathetic) control over the endocrine cells of the adrenal medullae.
List the three phases of the stress response.
The three phases of the stress response are the alarm phase, the resistance phase, and the exhaustion phase.
List the three zones of the adrenal cortex.
The three zones of the adrenal cortex are the zona glomerulosa, zona fasciculata, and zona reticularis.
Name the two lobes of the pituitary gland.
The two lobes of the pituitary gland are the anterior lobe and the posterior lobe.
Identify the two regions of an adrenal gland, and cite the hormones secreted by each.
The two regions of an adrenal gland are the cortex and medulla. The cortex secretes mineralocorticoids, primarily aldosterone; glucocorticoids, mainly cortisol (or hydrocortisone) and corticosterone; and androgens. The medulla secretes epinephrine and norepinephrine.
Identify the types of cells in the pancreatic islets and the hormones produced by each.
The types of cells in the pancreatic islets (and their hormones) are alpha cells (glucagon), beta cells (insulin), delta cells (GH-IH), and F cells (pancreatic polypeptide, or PP).
Identify three common causes of hormone hyposecretion.
Three common causes of hormone hyposecretion are metabolic factors, physical damage, and congenital disorders.
Explain the action of renin in the bloodstream.
When renin is released into the bloodstream, it functions as an enzyme that activates the renin-angiotensin-aldosterone system, which ultimately causes blood pressure to increase.
Identify and describe the two types of diabetes mellitus.
he two types of diabetes mellitus are Type 1, characterized by inadequate insulin production by the pancreatic beta cells, and Type 2, characterized by insulin resistance (failure of the body to use insulin properly).