Lecture 1 - Hormones Flashcards
Define hormone
A substance in the body that transmits a signal to produce an effect or alteration at the cellular level
What are the major glands of the endocrine system?
Hypothalamus, pituitary, thyroid, parathyroids, adrenals, pineal body
What are the major organs of the endocrine system?
ovaries, testes, pancreas, kidneys
Define endocrine
hormone released into bloodstream to contact distant cell
Define paracrine
hormone released to contact a neighboring cell
Define autocrine
hormone released onto itself
What are peptide and protein hormones?
Products of translation
Are peptide and protein hormones hydrophobic or hydrophilic?
Hydrophilic
Are peptide and protein hormones carrier proteins?
No
How are peptide and protein hormones released?
The cell stores them in secretory granules and releases them in “bursts” when stimulated = allows cells to secrete a large amount of hormone over a short period of time
OR
Cell synthesizes them and releases them immediately in secretory vesicles
What are neurophysins?
Carrier proteins for vasopressin and oxytocin
Neurophysin I - oxytocin
Neurophysin II - vasopressin
What type of hormone is vasopressin?
Anti-diuretic hormone
What is oxytocin known as and when is it released?
“Love hormone”, released during childbirth and breastfeeding
Who does Type 1 diabetes affect and what causes it?
Juveniles, pancreatic cells destroyed = no insulin production
Who does Type 2 diabetes affect and what causes it?
Adults, body does not produce enough insulin and/or does not utilize insulin efficiently = insulin resistance
What is the main reason why Type 2 diabetes is more prevalent than Type 1?
Obesity
How is Type 1 diabetes treated?
Insulin injections
How is Type 2 diabetes treated?
Diet and exercise; Drugs targeting organs involved in glucose metabolism; chronic cases- insulin injections
Are amino acid-derived hormones hydrophobic or hydrophilic?
Both
How are amino acid-derived hormones released?
Depends on hormone
Are amino acid-derived hormones carrier proteins?
Yes
What type of hormones are norepinephrine and epinephrine?
Amino acid-derived hormones
Which amino acid is norepinephrine (no adrenaline) synthesized from? Where is it synthesized?
Phenylalanine, adrenal medulla
Which amino acid is epinephrine (adrenaline) synthesized from? Where is it synthesized?
Tyrosine, adrenal medulla
Cortisol initiates the synthesis of ______?
PNMT (Phenylethanolamine N-methyltransferase)
Which enzyme converts norepinephrine to epinephrine?
PNMT (Phenylethanolamine N-methyltransferase)
Define catecholamines
hydrophilic hormones/neurotransmitters that respond to stress, which in turn, accelerates heartbeats, increases blood pressure, and increases blood flow
Are catecholamines hydrophobic or hydrophilic?
Hydrophobic
Is the thyroid hormone hydrophobic or hydrophilic?
Hydrophobic
Where does thyroid hormone synthesis occur?
Follicular space of thyroid gland
What are the steps of thyroid hormone synthesis?
1) Thyroglobulin contains about 100-120 Tyrosine residues
2) Uptake of Iodide (I-)
3) Oxidation to Iodine (I)
4) Iodination of thyroglobulin (on tyrosine residues)
5) Formation of MIT (monoiodotyrosine) (T1) and DIT (diiodotyrosine) (T2)
6) Polymeric molecules T3 (triiodothyronine) and T4 (thyroxine; tetraiodothyronine)
7) Secretion
T3 is the _____ _____ hormone.
final active
T4 is the _____ hormone.
storage
Is reverse T3 active or inactive?
inactive
What is hyperthyroidism also called?
Graves’ disease
What causes hyperthyroidism?
1) Thyroid stimulating immunoglobulin bind to TSH and stimulates thyroid gland
2) Stimuation causes thyroid gland to grow and increases T3 production
3) Negative feedback to TSH
How is hyperthyroidism diagnosed?
Low TSH, high T3 and T4
What are the symptoms of Graves’ disease (hyperthyroidism)?
nodules on thyroid (goiter), restlessness, anxiety, sweating, bulging eyes
How is Graves’ disease (hyperthyroidism) treated?
Anti-thyroid drug Tapazole, thyroid removal
What is chronic lymphocytic thyroiditis also known as?
Hashimoto’s disease
What is Hashimoto’s disease?
An autoimmune condition that causes hypothyroidism (not making enough thyroid hormone)
How is hyperthyroidism diagnosed?
Low TSH, high T3 and T4
How is Hashimoto’s disease diagnosed?
High titers of antibodies to thyroglobulin, thyroid peroxidase and TSH receptor
What are the symptoms of Hashimoto’s disease?
Weight gain, dry skin, low heart rate, depression
Who does Hashimoto’s diease affect?
Women
Almost 95% cases are seen in women between ages 30-50 years
How is Hashimoto’s disease treated?
Thyroid hormone pills
What are steroid hormones?
cholesterol-derived hormones with many functions dependent upon the derivation
Are steroid hormones hydrophobic or hydrophilic?
Hydrophobic
What are the 5 types of steroid hormones?
Mineralocorticoids, glucocorticoids, androgens, estrogens, progestogens
How are steroid hormones released?
Immediately secreted, not stored
Are steroid hormones carrier proteins?
Yes
What is the most prominent mineralocorticoid?
Aldosterone
Which glucocorticoids is the major representative in most mammals?
Cortisol
Testosterone belongs to which class of steroid hormones?
Androgens
Estradiol and estrone belong to which class of steroid hormones?
Estrogen
Progesterone belongs to which class of steroid hormones?
Progesterones
What is the function of aldosterone?
Acts in the kidneys to aid in conservation of sodium, secretion of potassium, water retention, and stabilizes blood pressure
What is the function of cortisol?
Metabolic - increases insulin resistance and gluconeogenesis, lipolysis
Immunosuppressive - inhibits leukotrienes and prostaglandins, blocks histamine release from mast cells, blocks IL-2 production
Maintains blood pressure
How are steroid hormones transported in the blood?
Transported in the blood by albumin, sex hormone-binding globulin (SHBG), and corticosteroid-binding globulin (CBG)
What causes congenital adrenal hyperplasia?
ACTH (adrenocorticotropic hormone) continues to stimulate steroid production due to a lack of feedback inhibition from cortisol
What are the symptoms of congenital adrenal hyperplasia?
Excessive loss of salt, ambiguous genitalia in infants
What causes Cushing’s disease?
High cortisol levels
What are the symptoms of Cushing’s disease?
Growth retardation, hump on shoulder and weight gain
How is Cushing’s disease treated?
Medications that control excessive production of cortisol in the adrenal gland
Ex: ketoconazole(Nizoral), mitotane (Lysodren), metyrapone(Metopirone)
What does a hormone bind to after it is secreted by an endocrine tissue? What happens after it binds?
Binds to a specific plasma protein carrier. The complex spreads to distant tissues.
Which carrier proteins exist for all classes of endocrine hormones?
Plasma carrier proteins
What is the carrier protein for peptide hormones? What does it do?
IGF, prevents hormone destruction by plasma proteases
What do carriers for small, hydrophilic amino acid-derived hormones do?
Prevent their filtration through the renal glomerulus, greatly prolonging their circulating half-life.
What do carriers for steroid and thyroid hormones do?
Allow these very hydrophobic substances to be present in the plasma at concentrations several hundred-fold greater than their solubility in water would permit.
What are the steps for hormone clearance?
Inactivation, Degradation, Excretion, Metabolic rate of clearance
What happens during the inactivation step of hormone clearance?
Hormones can be inactivated in the liver through hydroxylation or oxidation and/or glucuronidation, sulfation, or reduction with glutathione reactions and excreted via the kidneys
What happens during the degradation step of hormone clearance?
Hormones can be degraded at their target cell through internalization of the hormone-receptor complex followed by lysosomal degradation of the hormone.
What happens during the excretion step of hormone clearance?
A small fraction of total hormone production is excreted intact in the urine and feces
What is the metabolic rate of clearance?
Measurement of a hormone as the volume of plasma cleared of the hormone per unit of time. (TA Lecture 1 slide 27)
All of the following are examples of hydrophobic hormones except:
A) Cortisol
B) Thyroid hormone
C) Vasopressin
D) Aldosterone
C) Vasopressin
Which of the following is the correct order of hormonal release?
A) Releasing hormone, tropic hormone, ultimate hormone
B) Tropic hormone, ultimate hormone, releasing hormone,
C) Tropic hormone, releasing hormone, ultimate hormone
D) Releasing hormone, ultimate hormone, tropic hormone
A) Releasing hormone, tropic hormone, ultimate hormone
High T3 and T4 production with low TSG levels characterize which disease?
A) Cushing’s disease
B) Hashimoto’s disease
C) Grave’s disease
D) Hypothyroidism
C) Grave’s disease
All of the following are modes of contact-independent intercellular signaling except:
A) Paracrine
B) Juxtacrine
C) Synapse
D) Autocrine
B) Juxtacrine
Which of the following statements is incorrect regarding tyrosine kinase activity?
A) The receptor exhibits intrinsic kinase activity to phosphorylate itself
B) The more phosphorylated the protein and/or receptor, the more active it is
C) In insulin, it activates a cascade of downstream phosphorylation
D) When adding GDP to Ras, the Ras protein becomes activated
D) When adding GDP to Ras, the Ras protein becomes activated
Steroid hormones can have receptors located:
A) Within the nucleus
B) On the cell surface
C) Extracellularly
D) Directly on DNA
A) Within the nucleus
