the endocrine system (part 2) Flashcards
Review the anatomy of the hypothalamus and pituitary gland. What is the difference in tissue type between the anterior and posterior pituitary gland?
The hypothalamus is connected to the pituitary gland (hypophysis) via a stalk called the infundibulum
The pituitary gland secretes at least 8 major hormones and has 2 major lobes
Posterior Pituitary Lobe: composed of neural tissue that secretes neurohormones
Neurohypophysis: posterior lobe of the pituitary + infundibulum
Anterior Pituitary: composed of glandular tissue; called the adenohypophysis
What is the hypophyseal portal system? Why is it important? What is the hypothalamic-hypophyseal tract? Why is it important?
The anterior lobe of the pituitary gland is made of glandular tissue - derived from an out-pocketing of oral mucosa
The anterior lobe is vascularly connected to the hypothalamus via the hypophyseal portal system:
Primary Capillary Plexus
Hypophyseal Portal Veins
Secondary Capillary Plexus
The hypothalamus regulates hormone secretion by secreting releasing and inhibiting hormones to the anterior pituitary gland
The hypothalamic-hypophyseal tract maintains neural connection to the hypothalamus
What does it mean to be a tropic hormone?
All but 2 are tropic hormones (tropins) – they regulate the secretion of other hormones
Complete your hormone chart for the following hormones: oxytocin, antidiuretic (ADH), growth hormone (GH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin.
What hormone(s) stimulate the release of GH? What hormone inhibits its release?
Growth Hormone-Releasing Hormone (GHRH) stimulates GH release
Growth Hormone-Inhibiting Hormone (GHIH) inhibits GH release (also called somatostatin)
What hormone stimulates the release of TSH? How is the release of TSH inhibited?
TSH stimulates normal development and secretory activity of the thyroid gland
Release of TSH is triggered by secretion of thyrotropin-releasing hormone (TRH) from the hypothalamus
TSH is inhibited by rising blood levels of thyroid hormones acting on both the pituitary and the hypothalamus; also inhibited by GHIH
What hormone stimulates the release of ACTH? How is the release of ACTH inhibited?
Also called corticotropin. Secreted by corticotropic cells.
ACTH stimulates the adrenal cortex to release corticosteroids
Triggered by hypothalamic corticotropin-releasing hormone (CRH) in a daily rhythm – highest levels are in the morning
What hormone stimulates the release of FSH and LH? How is the release of FSH and LH inhibited?
Follicle-Stimulating Hormone (FSH) + Luteinizing Hormone (LH) are secreted by the gonadotropic cells of the anterior pituitary
FSH stimulates the production of gametes (egg or sperm)
In females, levels of prolactin tend to rise/fall in rhythm with ____________.
estrogen
Complete your hormone chart for the following hormones: thyroid hormone (TH), calcitonin, parathyroid hormone (PTH), aldosterone, atrial natriuretic peptide (ANP), cortisol, epinephrine, norepinephrine, melatonin, glucagon, insulin, estrogen, testosterone, human chorionic gonadotropin (hCG), gastrin, ghrelin, and erythropoietin (EPO).
Where is the thyroid gland located? What are the 2 forms of thyroid hormone that it secretes? What is the difference between the 2 forms of thyroid hormone?
The thyroid is a butterfly-shaped gland in the anterior neck. It is located on the trachea, just inferior to the larynx.
Found in 2 forms:
Thyroxine (T4): major form; consists of 2 tyrosine molecules with 4 bound iodine atoms
Triiodothyronine (T3): form of TH that has 2 tyrosine molecules with 3 bound iodine atoms
T3 must be converted to T4 at the tissue level
Where is the parathyroid gland?
The parathyroid gland is 4 to 8 tiny, yellow-brown glands embedded in the posterior aspect of the thyroid
Where are the adrenal glands located? What are the anatomical differences between the adrenal cortex and adrenal medulla? What class of hormones is secreted by the adrenal cortex? What class of hormones is secreted by the adrenal medulla?
Adrenal Cortex: 3 layers of glandular tissue – synthesize and secrete several different hormones
Adrenal Medulla: nervous tissue – part of the sympathetic nervous system
…
Define Cushing’s Disease and Addison’s Disease.
What cells of the pancreas secrete glucagon? Insulin? What is secreted by the pancreas’ acinar cells?
Glucagon
Triggered by decreased blood glucose levels, rising amino acid levels, or the sympathetic nervous system
Targets the liver to raise blood glucose levels by:
Breaking down glycogen to glucose (glycogenolysis)
Synthesizing glucose from lactic acid and other noncarbohydrates (gluconeogenesis)
Releasing glucose into the blood
Insulin
Secreted when blood glucose levels increase
Synthesized as proinsulin then modified
Insulin lowers blood glucose levels by:
Enhancing membrane transport of glucose into fat and muscle cells
Inhibiting the breakdown of glycogen to glucose
Inhibiting the conversion of amino acids or fats to glucose
