Endrocine System
Define diabetes mellitus.
Diabetes mellitus is a condition characterized by elevated blood glucose levels resulting from inadequate insulin production or diminished sensitivity to insulin by cells.
Identify and describe the two types of diabetes mellitus..
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).
Explain the action of renin in the bloodstream.
Upon its release into bloodstream, renin functions as an enzyme that activates the renin-angiotensin system, which ultimately causes blood pressure to rise.
Identify the two regions of n adrenal gland, and cite the hormones secreted by each.
the two regions of an adrenal gland are the cortex and medulla. The cortex secretes mineralocrticiods, primarily aldosterone; glucorticoids, mainly cortisol (or hydrocortisone) and corticosterone; and androgens. The medulla secretes epinephrine and norepinephrine.
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. The 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 a specific hormone.
Define regulatory hormone.
A regulatory hormone is a special hormone, secreted by the hypothalamus, that controls endocrine cells in the anterior lobe of the pituitary gland.
What condition is characterized by increased body weight due to Na+ and water retention and low blood K+ concentration?
Aldosteronism is characterized by increased body weight due to Na+ and water retention and a low blood K+ concentration.
Why does a person with diabetes mellitus urinate frequently?
An individual with type 1 or type 2 diabetes has such high blood glucose levels that the kidneys cannot reabsorb all the glucose; some glucose is lost in the urine. Because the urine contains high concentrations of glucose, less water can be reclaimed by osmosis, so the volume of urine production increases, and the individual needs to urinate more often.
What thyroid hormone aids in the regulation of calcium?
Calcitonin aids in calcium regulation.
Decreased blood calcium levels would result in increased secretion of which hormone?
Decreased blood calcium levels would result in increased secretion of parathyroid hormone (PTH).
What effects would elevated circulating levels of glucocorticoids have on the pituitary secretion of ACTH?
Elevated circulating levels of glucocorticoids inhibit the release of CRH by the hypothalamus. The lack of CRH reduces the secretion of ACTH from the pituitary gland, so ACTH levels would decrease. This is an example of negative feedback.
What effects would elevated cortisol levels have on blood glucose levels?
Elevated cortisol levels would result in elevated blood glucose levels, because cortisol reduces the use of glucose by cells while increasing both available glucose (by promoting the breakdown of glycogen) and the conversion of amino acids to carbohydrates.
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.
Which type of hormone diffuses across the plasma membrane and binds to receptors in the cytoplasm?
Hormones that diffuse across the plasma membrane and bind to receptors in the cytoplasm are steroid hormones.
In a dehydrated person, how would the amount of ADH released by the posterior pituitary change?
In a dehydrated individual, the amount of ADH released by the posterior pituitary increases in response to increased blood osmotic pressure resulting from a rise in solute concentration.
List three functions of melatonin.
In humans, melatonin may affect the timing of sexual maturation, protect against damage by free radicals, and set circadian rhythms.
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 would in turn reduce the amount of glycogen stored in the liver.
Increased amounts of light would inhibit the production of which hormone?
Melatonin secretion is influenced by light-dark cycles. Increased amounts of light would inhabit the production (and release) of melatonin from the pineal gland, which receives neural input concerning the presence of light of darkness from visual pathway collaterals.
Why do signs and symptoms of decreased thyroxine concentrations not appear until about a week after a thyroidectomy?
Most of the body's reserves of thyroid hormone. thyroxine, are bound to transport protiens in the bloodstream called thyroid-binding globulins. Because these compounds represent such a large reservoir of thyroxine, it takes several days after removal of the thyroid gland for blood levels of thyroxine to decline.
The secretion of which hormone lowers blood glucose concentrations?
The secretion of insulin lowers blood glucose concentrations.
Name the organs of the endocrine system.
Organs of the endocrine system are the hypothalamus, pituitary gland, thyroid gland, adrenal glands, pancreas, pineal gland, and parathyroid glands. Organs of other systems that have endocrine functions are the heart, thymus, digestive tract, kidneys, and gonads.
Explain how parathyroid hormone raises the blood calcium levels.
Parathyroid hormone (PTH) raises blood calcium levels by reducing 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.
If a blood sample contained elevated levels of somatomedins, which pituitary hormone would you expect to be elevated?
Somatomedins mediate the actions of growth hormone. Elevated levels of growth hormones typically accompany elevated levels of somatomedins.
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. 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 GAS.
Identify three common causes of hormone hyposercretion.
The common causes of hormone hyposercretion are metabolic factors, physical damage, and congenital disorders.
Define endocrine system.
The endocrine system includes organs whose primary function is the productions of hormones or paracrine factors, which are chemical secretions that are transported via the extracellular fluid or blood system to target cells in other sites within the body.
Name a peptide secreted by the heart and a hormone released by the kidneys.
The heart secretes natriuretic peptide, 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 (T4), T3, and calcitonin.
Describe the structural classification of hormones.
The structural classes of hormones are (1) amino acid derivatives (thyroid hormones, catecholamines and tryptohanderivatives); (2) peptide hormones (glycoproteins or short polypeptide chains), which are chains of amino acids that are synthesized as prophormones; and (3) lipid derivatives which contain carbon rings and side chains that are built from fatty acids or cholesterol.
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 respnds 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(1) oxytocin (OXT), which targets the mammary glands, and (2) anit-diuretic hormone (ADH), which targets the kidneys.
List the hypothalamic releasing hormones.
The hypothalamic releasing hormones are corticotropin-releasing hormone (CRH), thryotrophin-releasing hormone (TRH), growth hormone releasing hormone (GH-RH), prolactin-releasing hormone (PRF), and gonadotrophin releasing hormone (GnRH).
Describe the locations of the parathyroid glands.
The parathyroid glands are embedded in the posterior surfaces of the lateral lobes of the thyroid glands.
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 resistance phase.
The resistance phase is characterized by long-term metabolic adjustments, including mobilization of remaining energy reserves, conservation of glucose, elevation of blood glucose concentrations, and conservation of salts and water coupled with the loss of K+ and H+.
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 and oxytocin, (2) secretion of regulatory hormones that control activities 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 fasciculate, and zona reticularis.
Name the two lobes of the pituitary gland.
The two lobes of the pituitary gland are the anterior lobe and posterior lobe.
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).