Flashcards in Intro to endocrine Deck (22):
What is the endocrine system?
Produces chemical messengers (hormones) that influence growth, development, and metabolic activities. Two major categories of glands– exocrine and endocrine
What are hormones?
Chemical messengers that are released in one tissue and transported by bloodstream to reach target cells in their tissues
What are exocrine glands?
Produce secretions which are released to the outside; the sweat, salivary, mammary, and digestive gland systems
What are endocrine glands?
Hormones are secreted directly into the blood and are carried throughout the body where they influence the appropriate receptor sites
What are mixed glands?
Some glands have non-endocrine regions that have functions other than hormone secretion. For example, the pancreas has a major exocrine portion that secretes digestive enzymes and an endocrine portion that secretes hormones
Describe the hypothalamus
Regulates activities of nervous and endocrine systems in three ways: releases hormones ADH and OXYTOCIN, secretes REGULATORY HORMONES, and control endocrine cells in the adrenal medulla
Describe the pituitary gland
aka hypophysis. Small oval gland seated in the sella turcica of the sphenoid bone. Consists of two lobes: Anterior – ADENOHYPOPHYSIS (made up of glandular cells). Posterior – NEUROHYPOPHYSIS (cells are non-secretory, resemble neuroglial tissue
What are the hormones of adenohypophysis?
TSH, ACTH, FSH, LH, PRL, Growth hormone, MSH
Describe the pineal gland
Lies in the roof of the thalamus (third ventricle), under the posterior end of the corpus callosum. It contains neurons, glial cells and secretory cells that synthesize the hormone MELATONIN
Describe the thyroid gland
Lies anterior to the trachea and just below the thyroid cartilage, which forms most of the anterior surface of the larynx. Produces the hormones triiodothyronine (T3), thyroxine(T4), and calcitonin
Describe the parathryoid glands
two pairs embedded in the posterior surface of the thyroid gland. CHIEF CELLS produces parathyroid hormone (PARATHORMONE ). Fxn of oxyphil cells is unknown
What is the fxn of the parathormone?
stimulates osteoclasts, inhibits osteoblasts, increases intestinal absorption, and reduces urinary excretion of calcium ions
Describe the thymus
Embedded in the mediastinum, usually posterior to the sternum. The CORTEX secretes the thymic hormones (thymosins= T Cells). The MEDULLA has the thymic corpuscles (Hassall´s corpuscles) surrounded by lymphocytes
Describe the adrenal glands
Lie along the superior borders of the kidneys. Pyramid-shaped glands. ADRENAL CORTEX
produces adrenocortical steroids or CORTICOSTEROIDS. ADRENAL MEDULLA produces EPINEPHRINE and NOREPINEPHRINE
What are the zones of the adrenal cortex?
Zona glomerulasa – outermost layer. Secretes aldosterone. Zona fasciculata – middle layer, produces glucocorticoids (cortisol, corticosterone and cortisone). zona reticularis – inner layer, produces androgens
Describe the pancreas
Endocrine cells are found within the pancreatic islets (ISLETS OF LANGERHANS): alpha cells secrete glucagon and beta cells secrete insulin
Describe the gonads
testes: the INTERSTITIAL CELLS secrete ANDROGENS, notably TESTOSTERONE. ovaries: follicles produce estrogens and corpus luteum that produces progesterone.
What factors affect the response of a target cell to a hormone?
number of receptors present (up-regulation/down regulation) or the affinity of these receptors for hormones
What are the two groups of hormones derived from tyrosine?
thyroid hormones and catecholamines (epi and norepi)
What are the adipokines?
adiponectin, resistin, leptin, TNFa, IL6 (produced by adipose tissue as endocrine organ)
What are the five cell types of the anterior pituitary gland?
Thyrotrophs: produce thyrotropin, also called TSH. Corticotrophs: produce corticotrophin, also called ACTH. Gonadotrophs: produce the gonadotropins—LH and FSH. Somatotrophs: produce GH. Lactotrophs: produce prolactin