Anatomy: Ch 16
What thyroid hormone aids in calcium regulation?
calcitonin
Describe the resistance phase
characterized by long term metabolic adjustments, including mobilization of remaining energy reserves, conservation of glucose, increased blood glucose concentrations, and conservation of slats and water coupled with the loss of K+ and H+
Identify three common causes of hormone hyposecretion
metabolic factors, physical damage, and congenital disorders
What are the chemical means of cellular communication in the nervous and endocrine system?
the nervous system communicates with neurotransmitters, whereas the endocrine system communicates with hormones
What effects would increased circulating levels of glucocorticoids have on the pituitary secretion of ACTH?
inhibit the release of CRH by the hypothalamus. The lack of CRH decreases the secretion of ACTH from the pituitary gland, so ACTH levels would decrease
What kind of effect do hormones have if they produce different but complementary effects?
integrative effects
Define endocrine system
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 of the thyroid gland
thyroxine (T4), triiodothyronine (T3), and calcitonin
List three functions of melatonin
timing of sexual maturation, protect against free radical damage, and maintain circadian rhythms
Define synergistic effect
when two hormones have an additive effect so that the net result is greater than the effect each would produce alone
List the three zones of the adrenal cortex
zona glomerulosa, zona fasciculata, and zona reticularis
Explain the action of renin in the blood stream
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
Define regulatory hormone
a hormone secreted by the hypothalamus that controls endocrine cells in the anterior lobe of the pituitary gland
Define hormone receptor
a protein molecule, located either on the plasma membrane or inside the cell, that binds to a specific hormone
List the three phases of the stress response
alarm, resistance, exhaustion
Identify the types of cells in the pancreatic islets and the hormones produced by each
alpha cells ( glucagon), beta cells (insulin), delta cells (GH- IH), and F cells (pancreatic polypeptide, or PP)
Describe the structural classification of hormones
amino acid derivatives (thyroid hormones, catecholamines, and tryptophan derivatives); peptide hormones (glycoproteins or short polypeptide chains), which are chains of amino acids that are synthesized as prohormones; and lipid derivatives (eicosanoids and steroid hormones), which contain carbon rings and side chains that are built from fatty acids or cholesterol
In a dehydrated person, how would the amount of ADH released by the posterior lobe of the pituitary change?
amount of ADH released increases in response to increased blood osmotic pressure resulting from an increase in solute concentration
Define diabetes mellitus
an endocrine disorder characterized by elevated blood glucose levels resulting from inadequate insulin production or diminished cell sensitivity to insulin
Which of the four hormonal effects are involved in a negative feedback response?
antagonistic effects
Name the two lobes of the pituitary gland
anterior lobe and posterior lobe
What effect would increased cortisol levels have on 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
Differentiate between a first messenger and a second messenger
First messenger: hormone whose binding to a protein receptor in the plasma membrane gives rise to a second messenger in the cytoplasm Second messenger: changes the rate of various metabolic reactions by acting as an enzyme activator, an enzyme inhibitor, or a cofactor
Identify several hormones necessary for normal growth and development
GH, thyroid hormones, insulin, PTH, calcitriol, and reproductive hormones
List they hypothalamic releasing hormones
corticotropin releasing hormone (CRH), thyrotroponin releasing hormone (TRH), growth hormone- releasing hormone (GH- RH), prolactin releasing factor (PRF), and gonadotropin releasing hormone (GnRH)
Explain how parathyroid hormone increases blood calcium levels
decreases calcium deposition in bones, by increasing reabsorption of calcium from the blood by the kidneys, and by increasing the production of calcitrol by the kidneys
Identify some clinical problems associated with diabetes mellitus
diabetic retinopathy, blockages in heart circulation and increased risk for heart attack, diabetic neuropathy, and decreased blood flow to the distal portions of the limbs
During which phase of the general adaptation syndrome is there a collapse of vital systems?
exhaustion phase of the stress response
Define the prefixes hyper- and hypo- in the context of endocrine disorders
hyper: excessive hormone production hypo: inadequate hormone production
Name the organs of the endocrine system
hypothalamus, pituitary gland, thyroid gland, adrenal glands, pancreas (pancreatic islets), pineal gland, and parathyroid glands
Describe the locations of the parathyroid glands
embedded in the posterior surfaces of the lateral lobes of the thyroid gland
The secretion of which hormone lowers blood glucose concentrations?
insulin
Identify the nine pituitary hormones and their target tissues
(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 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, (7) melanocyte-stimulating hormone (MSH) which targets melanocytes in the skin, (8) oxytocin (OXT) which targets the uterus and mammary glands, (9) antidiuretic hormone (ADH) which targets the kidneys
Which type of hormone diffuses across the plasma membrane and binds to receptors in the cytoplasm?
steroid hormones
What is the effect of increased glucagon levels on the amount of glycogen stored in the liver?
stimulate the conversion of glycogen to glucose in the liver, which in turn decreases the amount of glycogen stored in the liver
Identify the three mechanisms by which the hypothalamus integrates neural and endocrine function
ADH and OXT, secretion of regulatory hormones the control activity of the anterior lobe of the pituitary gland, and neural (sympathetic) control over the endocrine cells of the adrenal medullae
What condition is characterized by increased body weight due to Na+ and water retention and a low blood K+ concentration?
Aldosteronism
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 (T4) , 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
Decreased blood calcium levels would result in an increased secretion of which hormone?
PTH
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
The release of which pituitary hormone would lead to an increased level of somatomedins in the blood?
Somatomedin mediate the action of growth hormone (GH). Increased levels of GH typically accompany increased 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 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
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 two regions of an adrenal gland, and cite the hormones secreted by each
The two regions are the cortex and the medulla. The cortex secretes mineralocorticoids, primarily aldosterone; glucocorticoids, mainly cortisol (or hydrocortisone) and corticosterone; and androgens. The medulla secretes epinephrine and norepinephrine.
Identify and describe the two types of diabetes mellitus
Type 1: characterized by inadequate insulin production by the pancreatic beta cells Type 2: characterized by insulin resistance (failure of the body to use insulin properly)
Identify the hormone secreting cells of the pineal gland
pinealocytes
What is the common goal of the nervous and endocrine systems?
preserve homeostasis by coordinating and regulating the activities of other cells, tissues, organs, and other organ systems