Lecture 8 Flashcards
Androgens and mineralocorticoids are secreted from where?
Adrenal medulla: catecholamines are also released from here, as well as epinephrine and norepinephrine..
The medulla is similar in structure to what?
They ganglion.
Consequences of thyroid hormone deficiency.
Physical growth and development problems, brain development is impaired. Cretinism: stunted physical and mental growth.
Thyroid hormones T3 and T4.
T3 is the most powerful form; T4 tends to be converted into T3. Thyroid hormones need iodine.
Goiter.
Lack of iodine causes the thyroid to enlarge. T3 and T4 are low in the case of low iodine intake; the hypothalamus releases TRH and causes the release of TSH in the anterior pituitary (TSH tells the thyroid gland to produce more T3 and T4). Note: in Goiter, T3 and T4 levels are low, but TRH and TSH levels are high.
Grave’s disease.
Most common form of hyperthyroidism. Process: TIH acts as TSH to perpetually stimulate the thyroid gland, though the process is inhabited.
Most peptide or protein hormones are hydrophilic or hydrophobic?
Hydrophilic.
Steroids and hormones are lipophilic or lipophobic?
Lipophobic.
Tropic hormones.
Target other endocrine glands and stimulate the growth and secretion of other hormones. Example: ACTH target the adrenal cortex.
Sex hormones.
They target reproductive tissues.
Anabolic hormones.
They stimulate anabolism (building) in target cells. Example: testosterone stimulates protein synthesis and build-up of cellular tissue. Insulin is also an anabolic hormone: leads to uptake and storage within the cell.
Transportation of hydrophilic hormones.
They are dissolved in the plasma.
Transportation of lipophilic hormones.
Bound reversible to plasma proteins.
Hydrophilic peptide hormone synthesis.
Made on the ribosomes of the ER as preprohormones. They are sent tot he Golgi complex where they are turned into pro hormones and then active hormones. They re released from the endocrine cells by exocytosis.
Which steroid hormone precursor is the only one that can be stored?
Cholesterol.
Steroid hormones synthesis.
All are synthesized from cholesterol. They are lipid soluble, which means they can pass through membranes to enter the cell. They travel to the nucleus, bind to the receptor that has a zinc finger DNA binding domain, and binds at the hormone response element (HRE) to initiate gene transcription.
Examples of steroid hormones.
Cortisol (adrenal), aldosterone (adrenal), estrogen (ovary and testes), progesterone (ovary-CL), and testosterone (testis, Leydig cells).
Non-steroid hormone synthesis.
They are synthesized form amino acids
HCG (human chorionic hormone) is an example of which class of hormones?
Glycoprotein hormone (protein hormone with carbohydrate groups attached).
Non-steroid hormones.
Peptide hormones (example: oxytocin and antidiuretic hormone ADH), amino acid derived (synthesized by modifying a single molecule of tyrosine), amino acid hormones (derived from a single amino acid molecule), and T4 (thyroxin: tyrosine residues and 4 iodine molecules).
Hormones, once they enter the cell, can…
Inactivate enzymes or cause initiation of gene transcription.
Synergism of hormone action.
Hormones act together to have a greater effect on the target cell than the sum of the effects each would have if acting alone.
Permissiveness in hormone action.
A small amount of one hormones permits or enables a second one to have its full effect on a target cell.
Antagonism in hormone action.
One hormone produces the opposite effects of another hormone.
