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33 Cards in this Set
- Front
- Back
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What are two of the primary communicating and coordinating systems in the body?
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The endocrine system and the nervous system
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How does the endocrine system communicate with the body?
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Through chemical substances known as hormones
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What role does the endocrine system play in the body?
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Reproduction, growth and development, and regulation of energy
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What is the endocrine system composed of?
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Glands or glandular tissues
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What is the purpose of the glands or glandular tissues in the endocrine system?
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They produce, store, and secrete hormones that travel through the blood to specific target cells
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Name the endocrine glands
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Hypothalamus
Pituitary Thyroid Parathyroids Adrenals Pancreas Ovaries Testes Pineal |
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Define hormone
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A chemical substance synthesized and secreted by a specific organ or tissue
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What are common characteristics of most hormones?
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Secretion in small amounts at variable but predictable rates
Circulate in blood Bind to cell receptors in cell membrane or in cell itself |
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What are the chemical structure of hormones?
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Either:
lipid-soluble (steroid and thyroid) or water-soluble (protein-based) |
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What mechanisms stimulate or inhibit hormone synthesis and secretion?
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Simple Feedback
Complex feedback Nervous System Control Rhythms |
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What are two types of simple feedback?
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Negative Feedback
Positive Feedback |
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What is the most common type of feedback system?
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Negative Feedback
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What is the mechanism of Negative Feedback?
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The gland responds by increase or decreasing the secretion of a hormone based on feedback from various factors, causing the change to be reversed
ex. Insulin secretion in response to blood glucose level ex. PTH secretion in response to low blood levels of calcium |
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What is the mechanism of Positive Feedback
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The gland responds by increase or decreasing the secretion of a hormone based on feedback from various factors, causing an increase in the target organ action beyond normal
ex. Oxytocin release during childbirth |
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What is the mechanism of Complex Feedback?
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Communication via hormones among several glands to turn on or off target organ hormone secretion
ex. TRH secreted by the hypothalamus stimulates the synthesis and secretion of TSH from the anterior pituitary |
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What is the mechanism of the Nervous System Control?
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Stimuli causes the nervous system to modulate hormone release. Neural involvment is intiated by the CNS and implemented by the SNS
ex. CNS sense stress, SNS secretes catecholamines |
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Where do rhythms of secretions originate?
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In brain structures
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Name two rhythms involved in hormone secretion
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Circadian
Ultradian |
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What are characteristics of Circadian Rhythm?
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Hormone levels fluctuates predictably during a 24-hour period. They may be related to sleep-wake or dark-light cycles
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What are characteristics of Ultradian Rhythm?
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Rhythm is longer than 24 hours
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What is the pituitary gland also called?
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The hypophysis
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Where is the pituitary gland located
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In the sella turcica under the hypothalamus
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What are the two parts of the pituitary gland?
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Adenohypophysis (Anterior Lobes)
Neurohypophysis (Posterior Lobes) |
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What percentage by weight of the gland does the Adenohypophysis account for?
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80%
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Name the hormones that the anterior lobe secretes
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Tropic Hormones
ex. TSH, ACTH, FSH, LH Growth Hormone Prolactin |
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What are tropic hormones?
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Hormones that control the secretion of hormones by other glands
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What is the function of growth hormones?
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Stimulates liver to produce insulin like growth hormones causing growth of bone and soft tissue
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Name the hormones that the posterior lobe secretes
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Antidiuretic Hormone (ADH)
Oxytocin |
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Where are Antidiuretic Hormones (ADH) and Oxytocins produced?
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The hypothalamus
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What are Antidiuretic Hormones (ADH)?
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A potent vasoconstrictor that regulates fluid volume by stimulating reabsorption of water in the renal tubules
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What are Oxytocins?
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Hormones that stimulates the ejection of milk into mammary ducts and contraction of uterine smooth muscle
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What inhibits Oxytocins secretion?
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Endorphins and Alcohol
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What is the "Master Gland"
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The pituitary gland, but since most of the functions of the pituitary gland rely on an interrelationship with the hypothalamus, some may say the hypothalamus is the master gland
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