Endocrine Glands Flashcards
Recognize common features of endocrine glands and identifying characteristics of cells producing protein/peptide or steroid hormones.
Endocrine glands produce hormones. Most endocrine glands consist of epithelial tissue. Some are derived from neural crest cells or neurons.
Endocrine hormones:
• Act long-‐distance.
• Distributed by circulation.
• Released into capillaries (no ducts are present but the glands are highly vascular & are in close contact with capillaries).
• Some hormones may act on adjacent cells (paracrine)
Many capillaries (sinusoids) in endocrine glands have irregular shape and are fenestrated.
Typical features of cells secreting protein or polypeptide hormones:
• Abundant RER.
• Prominent Golgi.
• Hormones are often stored in secretory granules.
prefix “adeno-‐”, meaning “glandular”. Examples: adenoma/ adenocarcinoma (tumor of glandular origin); adenectomy.
Mnemonic: B-FLAT =
the Basophilic cells of the anterior pituitary secrete: FSH, LH, ACTH, TSH
Mnemonic: GPA =
Growth hormone and Prolactin are secreted by the Acidophilic cells of the anterior pituitary
Mnemonic: salt, sugar, sex hormones
the order of the products of the adrenal cortex: mineralocorticoids (glomerulosa), glucocorticoids (fasiculata), androgens (reticularis)
Mnemonic: FLAT PEG
Hormones secreted by the anterior pituitary gland
FSH (regulation of ovarian follicle development)
LH (spermatogenesis, estrogen and androgen secretion)
ACTH (stimulation of adrenal cortex hormone secretion)
TSH (regulation of thyroid hormone secretion)
Prolactin (stimulation of milk secretion)
Endorphins (endogenous opiates)
GH (growth of long bones)
Compare embryonic origin and major cell types of the anterior and posterior pituitary.
Anterior pituitary is derived from the oral ectoderm = epithelial tissue
Posterior pituitary is derived from the neuroectoderm = neural tissue
How is the activity of the anterior hypophysis regulated by the hypothalamus?
Hypothalamus produces releasing and inhibitory hormones that regulate functions of the adenohypophysis (Anterior pituitary).
What are the characteristic features of steroid-producing cells?
- Central nucleus.
- Lipid droplets in the cytoplasm.
- Abundant smooth ER for cholesterol synthesis.
- Spherical mitochondria with characteristic tubular or vesicular cristae.
Give examples of hormones produced by the adipose tissue.
- Leptin – regulates appetite and metabolism. Leptin tells your brain that you have enough energy stored in your fat cells.
- Adiponectin – regulates fatty acid and glucose metabolism and modulates sensitivity to insulin.
• Steroid hormones (androgens and estrogens).
What is an endocrine gland?
An Endocrine gland secretes its essential product without the use of a duct directly into the bloodstream or else by diffusion into its surrounding tissue (paracrine signaling) where it often affects only target cells near the release site.
What are the hormones made by the hypophysis?
pituitary gland = hypophysis
Anterior pituitary is derived from the oral ectoderm: PLAT PEG
Posterior pituitary is derived from the neuroectoderm: Vasopressin (ADH) & Oxytocin
Vasopressin (ADH): Its two primary functions are to retain water in the body and to constrict blood vessels. Increases water reabsorption in kidney collecting ducts. ADH is synthesized in the hypothalamus. Vasopressin regulates the body’s retention of water by acting to increase water reabsorption in the collecting ducts of the kidney nephron.
Oxytocin: Stimulation of uterine contraction during childbirth and contraction of myoepithelial cells of mammary glands during nursing. Oxytocin is synthesized in the hypothalamus.
What are the hormones made by the thyroid?
Follicular cells produce Thyroid hormones (T3 and T4) regulate basal metabolic rate, body growth and development, heat production.
Parafollicular cells or C cells produce calcitonin that inhibits bone resorption and promotes calcification of bone (opposite of the PTH).
What are the hormones made by the parathyroid?
Chief cells produce parathyroid hormone (PTH), a polypeptide hormone that increases blood calcium level by regulating osteoclast activity, kidney excretion of calcium, vitamin D synthesis, and intestinal absorption of calcium.
PTH increases blood calcium level by:
• Promoting osteoclast activity to increase bone resorption.
• Regulating calcium absorption by the kidneys and the intestine.
• Increasing vitamin D synthesis to enhance calcium absorption.
What are the hormones made by the endocrine/ exocrine pancreas?
Pancreas is an endocrine gland producing several important hormones, including insulin, glucagon, somatostatin, and pancreatic polypeptide which circulate in the blood.
The pancreas as an exocrine gland secretes pancreatic fluid that contains digestive enzymes that pass to the small intestine. These enzymes help to further break down the carbohydrates, proteins and lipids (fats) in the chyme. Bicarbonate ions are made by the Centroacinar cells & digestive enzymes are made by Basophilic cells.
What are some differences between the anterior and posterior pituitary?
Anterior lobe is purple & posterior is pink
What are some differences between the three cortical zones and the medulla of the adrenal glands?
Adrenal cortex produces steroid hormones while medulla secretes catecholamines.
Adrenal cortex (lighter):
• Epithelial origin.
• 3 concentric zones (zona glomerulosa, zona fasciculata, zona reticularis). Mnemonic = girlfriend or GFR
• Cells have typical features associated with steroid synthesis (central nucleus, lipid droplets, abundant smooth ER).
Adrenal medulla (darker):
• Neuronal origin.
• Electron-‐dense secretory granules that react with chromium or silver salts (hence the name chromaffin or argentaffin).
• Produces catecholamines (epinephrine and norepinephrine = fight flight).
What are some differences between the four cell types in the islets of Langerhans?
Glucagon (alpha cells):
• Raises blood glucose level.
Insulin (beta cells):
• Lowers blood glucose level.
Somatostatin (delta cells):
• Inhibits secretion of many other hormones.
• Has both endocrine (long-‐distance) and paracrine (local) effects.
Pancreatic polypeptide (F or PP cells): • Affects digestive processes and food intake.
True/ false: there are hydrophilic & hydrophobic hormones?
True
Name the primary secretions of the zona glomerulosa, zona fasiculata, & zona reticulata.
Mnemonic: salt, sugar, sex hormones
zona glomerulosa = Mineralocorticoids, primarily aldosterone. Mineralocorticoids regulate salt balance & they themselves are regulated by angiotensin 2.
zona fasiculata = Glucocorticoids, primarily cortisol regulate glucose metabolism. Some androgen secretion.
zona reticulata = Glucocorticoids, DHEA, and androgens. Dehydroepiandrosterone is a metabolic intermediate in the biosynthesis of the androgen and estrogen sex steroids. Glucocorticoids & DHEA are regulated by ACTH. So a tumor of anterior pituitary produces more ACTH & enlarges cortex & excision of anterior pituitary produces atrophy of cortex.
Describe Cushing’s syndrome
Cushing’s Syndrome: excessive cortisol causes a combination of symptoms including weight gain, central obesity, hyperglycemia, easy bruising etc.
ACTH is often produced in response to biological stress which releases cortisol.
Cushing’s disease refers to a pituitary-dependent cause of Cushing’s syndrome: a tumor (adenoma) in the pituitary gland produces large amounts of ACTH, causing the adrenal glands to produce elevated levels of cortisol.
Possible causes:
adrenal tumor
excess ACTH secretion by the pituitary gland due to tumor
ectopic ACTH secretion (another location)
