Unit 18: Endocrine System Flashcards
What are “target cells”?
Cells with receptors for a specific hormone released by endocrine glands
What are the 3 classes of hormones?
Steroids: synthesized from cholesterol (testosterone, estrogen, Vitamin D, etc)
Hormones derived from amino acids
Peptide and protein hormones: amino acids with peptide bonds (oxytocin, insulin, growth hormone, etc)
What are the 2 types of hormones derived from amino acids?
Thyroxine/T4: thyroid hormone, controls cellular metabolism, growth, and dev.
Epinephrine and norepinephrine: secreted by adrenal medulla as part of fight/flight response & sexual climax
Endocrine glands are glands with no other function (pure endocrine glands—only function is to secrete hormones). Name 4 endocrine glands
Pituitary gland
Thyroid gland
Parathyroid gland
Adrenal glands
Describe the differences between the anterior and posterior pituitary glands
Anterior: epithelial tissue, regulated by hormones from the hypothalamus, secretes its own hormones
Posterior: nervous tissue, attached to hypothalamus, stores and secretes hormones produced by the hypothalamus
What hormones are secreted by the anterior pituitary?
Growth hormone (GH)
Thyroid stimulating hormone (TSH)
Adrenocorticotropic Hormone (ACTH): stimulates steroid secretion
Gonadotropins: reproductive hormones
Prolactin: milk production
What are the 2 types of gonadatropins (reproductive hormones)?
Luteinizing hormone (LH): stimulates ovulation and formation of corpus luteum—stimulates testosterone production by Leydig cells in the testes
Follicle stimulating hormone (FSH): stimulates sustentocytes & follicle cells
What are 2 hormones that the posterior pituitary deals with?
Oxytocin: stimulates uterine contractions and milk ejection during suckling
Antidiuretic hormone (ADH, aka vasopressin): enhances water reabsorption in the kidneys
This is a butterfly-shaped gland on the anterior surface of the superior trachea
Thyroid gland
Explain the difference between the follicles and parafollicular cells in the thyroid gland
Follicles: walls composed of follicles composed of epithelial (follicular) cells the secrete thyroxine (T4)
Parafollicular cells: between follicles, secrete calcitonin to increase Ca++ uptake into bone (lowers blood calcium)
Parathyroid glands secrete parathyroid hormone (PTH), which acts to increase blood calcium levels. Where can parathyroid glands be found?
There are usually 4, which are imbedded in the posterior thyroid
What gland would be used to lower blood calcium, and what gland would raise it?
Thyroid gland: LOWERS Blood Ca++
Parathyroid gland: RAISES Blood Ca++
What glands are located on the superior surface of the kidneys?
Adrenal glands
The adrenal glands are composed of the adrenal cortex (outer) and the adrenal medulla (inner). What type of tissue makes up each of these and what is their basic purpose respectively?
Adrenal cortex: epithelial tissue, secretes only steroids
Adrenal medulla: modified nervous tissue, synthesizes epinephrine(80%) and norepinephrine(20%) to regulate the “fight or flight” response
The adrenal cortex of the adrenal gland is composed of 3 layers which secrete a single class of hormones each:
The *zona glomerulosa, zona fasciculata, *and zona reticularis
What does each of these layers secrete?
-Zona glomerulosa: mainly aldosterone, acts on nephrons, regulating Na balance
-Zona fasciculata: cortisol, regulates body processes during prolonged stress
-Zona reticularis: androgens (sex hormones), converted to testosterone or estrogen in other tissues
