Questions and Answers
What is the primary function of the endocrine system?
What type of hormone is adrenocorticotropic hormone (ACTH)?
What is the function of oxytocin?
Which gland is responsible for regulating certain metabolic processes and other activities of the autonomic nervous system?
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What is the function of parathyroid hormone?
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What type of feedback involves a response that is the reverse of the change detected?
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What is the primary function of the adenohypophysis?
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What is the function of glucocorticoids?
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What is the function of antidiuretic hormone (ADH)?
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What is the primary function of the thyroid gland?
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Study Notes
Endocrine System
- Encompasses a group of tissues that release hormones into circulation for travel to and action on distant targets.
- Endocrine tissue is typically a ductless gland that releases its hormones into capillaries that permeate the tissue.
Hormones
- Control or regulate a multitude of biologic processes in virtually all tissues.
- Three major classes of hormones:
- Protein/Polypeptide Hormones: act on their target cells by binding to receptors located on the cell surface.
- Examples: adrenocorticotropic hormone (ACTH) from the pituitary, insulin from the pancreas, and parathyroid hormone (PTH).
- Steroid Hormones: derivatives of cholesterol, including products of the adrenal cortex, ovaries, and testes, as well as vitamin D.
- Synthesized from cholesterol by enzymatic reactions and stored intracellularly in the tissue of origin.
- Modified Amino Acid Hormones: made by chemical modification of amino acids, mainly tyrosine.
- Protein/Polypeptide Hormones: act on their target cells by binding to receptors located on the cell surface.
Organs
Hypothalamus
- Links the nervous system to the endocrine system via the pituitary gland.
- Regulates certain metabolic processes and activities of the autonomic nervous system.
Pituitary Gland
- Under adenohypophysis:
- Inhibiting hormone (IH) restrains pituitary hormone.
- Releasing hormone (RH) stimulates pituitary hormone.
- Under neurohypophysis:
- Oxytocin stimulates urine contraction, milk let-down for the uterus and mammary gland.
- Antidiuretic hormone (ADH) releases vasopressin, conserves water, reduces urine volume in kidneys, and constricts vessels to raise blood pressure in arterioles.
Adrenal Gland
- Under adrenal cortex:
- Glucocorticoids are essential for normal response to stress, play important roles in protein and carbohydrate metabolism in multiple organs, including the liver.
- Mineralocorticoids (aldosterone) conserve Na, eliminate K in the kidney.
- Under adrenal medulla:
- Epinephrine and Norepinephrine augment the sympathetic response to stress by actions on several organs.
Thyroid
- Thyroid follicular cells produce thyroid hormone.
Parathyroid
- Parathyroid hormone promotes an increase in plasma calcium and a reduction in plasma phosphate in bones and kidneys.
Processes
Feedbacks
- Negative Feedback: involves a response that is the reverse of the change detected, reducing the change.
- Positive Feedback: involves a response that reinforces the change detected, amplifying the change.
- Steps of feedback:
- Detect change in body homeostasis.
- Produce change in variable.
- Detected by receptor (sensor).
- Information sent along afferent/internal pathway to control center.
- Information sent along efferent/external pathway to effector.
- Response of effector feeds back to influence magnitude of stimulus, returning variable to homeostasis.
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Description
Learn about the endocrine system, a group of tissues that release hormones to regulate various biological processes in the body.