Chapter 16 Part A Flashcards
(69 cards)
What is the primary function of the endocrine system?
To coordinate and integrate activity of body cells via hormones.
What is endocrinology?
The study of hormones and endocrine organs.
What are the main functions controlled by the endocrine system?
- Reproduction
- Growth and development
- Maintenance of electrolyte, water, and nutrient balance of blood
- Regulation of cellular metabolism and energy balance
- Mobilization of body defenses
What is the difference between exocrine and endocrine glands?
Exocrine glands produce nonhormonal substances and have ducts; endocrine glands produce hormones and lack ducts.
Name some major endocrine glands.
- Pituitary gland
- Thyroid gland
- Parathyroid glands
- Adrenal glands
- Pineal gland
What role does the hypothalamus play in the endocrine system?
It is considered a neuroendocrine organ.
What are the two main classes of hormones?
- Amino acid–based hormones
- Steroids
What are autocrines and paracrines?
- Autocrines: Chemicals that exert effects on the same cells that secrete them
- Paracrines: Locally acting chemicals that affect cells other than those that secrete them
What is the role of target cells in hormone action?
Target cells are tissues with receptors for a specific hormone that are affected by the hormone.
How do water-soluble hormones act on target cells?
They act on plasma membrane receptors and use G protein second messengers.
How do lipid-soluble hormones act on target cells?
They act on intracellular receptors that directly activate genes.
What is the cyclic AMP (cAMP) signaling mechanism?
A hormone binds to a receptor, activating a G protein that activates adenylate cyclase, converting ATP to cAMP, which then activates protein kinases.
What is the role of calcium ions in hormone signaling?
Calcium ions act as a second messenger that alters enzyme activity and channels.
True or False: Calcium ions can bind to regulatory proteins to amplify cellular response.
True.
What initiates the release of hormones in the endocrine system?
Hormone release is triggered by endocrine gland stimuli, nervous system modulation, and negative feedback systems.
What is the function of humoral stimuli in hormone release?
Changing blood levels of ions and nutrients directly stimulate secretion of hormones.
Fill in the blank: The three types of endocrine gland stimuli are _______ stimuli, _______ stimuli, and _______ stimuli.
humoral, neural, hormonal.
What is a humoral stimulus?
Hormone release caused by altered levels of certain critical ions or nutrients.
Example: Declining blood Ca2+ concentration stimulates parathyroid glands to secrete PTH.
What triggers the secretion of parathyroid hormone (PTH)?
Low concentration of Ca2+ in capillary blood.
What is a neural stimulus?
Hormone release caused by neural input.
How do sympathetic nervous system fibers affect hormone release?
They stimulate adrenal medulla to secrete catecholamines.
What is a hormonal stimulus?
Hormone release caused by another hormone (a tropic hormone).
What role do hypothalamic hormones play in the endocrine system?
They stimulate the release of most anterior pituitary hormones.
What is the feedback loop involving hypothalamic, pituitary, and target endocrine organs?
Hypothalamic hormones stimulate anterior pituitary hormones, which in turn stimulate target organs to secrete hormones.