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Endocrine glands are derived from what kind of tissue?
Epithelial tissue
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List and describe the two types of endocrine organs.
- Primary endocrine organs: primary function is the secretion of hormones.
- Secondary endocrine organs: secretion of hormones is secondary to some other function.
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What unique structure functions as an endocrine gland in pregnant females?
The placenta
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The pituitary lobe is divided into two structurally and functionally distinct sections called what?
- Anterior lobe (Adenohypophysis)
- Posterior lobe (Neurohypophysis)
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Describe the linkage of the hypothalamus to the posterior pituitary.
The posterior lobe contains neural tissue consisting of the endings of neurons originating in the hypothalamus.
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What are the two peptide hormones released by the posterior lobe of the pituitary gland?
- Antidiuretic hormone (ADH) (Vasopressin)
- Oxytocin
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Where is ADH synthesized?
paraventricular nucleus
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Where is oxytocin synthesized?
supraoptic nucleus
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Describe the process by which hormones are released from the neurohypophysis.
The hormones are released from the neural ends into the blood via exocytosis when the neurons receive a signal.
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What is the function of Vasopressin?
Regulation of water reabsorption by the kidneys.
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What is the function of Oxytocin?
Stimulates uterine contractions and milk letdown in the breasts.
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What type of hormones are released by the Adenohypophysis and what is there function?
Tropic hormones, which regulate the secretion of other hormones.
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What is the general signaling pathway of tropic hormones?
- 1. Hypothalamus releases a tropic hormone that effects the release of another tropic hormone from the anterior pituitary.
- 2. Tropic hormone effects the release of a third hormone from another endocrine gland.
- 3. Third hormone exerts effects on target cells throughout the body.
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What connects the hypothalamus and the anterior lobe?
Hypothalamic-pituitary portal system
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What is the Hypothalamic-pituitary portal system?
Specialized arrangement of blood vessels in which two capillary beds are located in series.
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After the hypothalamus secrets tropic hormones into a capillary bed, tropic hormones travel down the_____ to the pituitary gland via a _____, from which they enter a secondary capillary bed.
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List all the tropic hormones.
- Prolactin releasing hormone (PRH)
- Prolactin inhibiting hormone (PIH) (Dopamine)
- Thyrotropin releasing hormone (TRH)
- Corticotropin releasing hormone (CRH)
- Growth hormone releasing hormone (GHRH)
- Growth hormone inhibiting hormone (GHIH)
- Gonadotropin releasing hormone (GnRH)
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What does prolactin releasing hormone stimulate?
The release of prolactin from the anterior pituitary, which stimulates mammary gland development and milk secretion in females.
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What does prolactin inhibiting hormone do?
Inhibits the release of prolactin.
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What does Thyrotropin releasing hormone stimulate?
The release of thyroid stimulating hormone (TSH) from the anterior pituitary, which stimulates the secretion of thyroid hormones by the thyroid gland.
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What does Corticotropin releasing hormone stimulate?
The release of adrenocorticotropic hormone (ACTH) by the anterior pituitary, which stimulates the secretion of other hormones by the adrenal cortex.
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What does Growth hormone releasing hormone stimulate?
The secretion of growth hormone (GH) by the anterior pituitary, which regulates the growth and energy metabolism by also functions as a tropic hormone by stimulating the secretion of Insulin-like growth factors (IGFs) by the liver.
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What does Growth hormone inhibiting hormone do?
Inhibits the secretion of growth hormone by the anterior pituitary.
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What does Gonadotropin releasing hormone (GnRH) stimulate?
The release of both Follicle stimulating hormone (FSH) and Luteinizing hormone (LH). LH stimulates ovulation in females and stimulates the secretion of sex hormones by the gonads in both sexes. FSH promotes the development of egg cells in females and sperm cells in males, stimulates the release of inhibin in both sexes.
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How are the pathways of the hypothalamic and adenohypophysis regulated?
Negative feed back loops.
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Describe a short loop negative feed back.
The inhibition of a hypothalamic tropic hormone by the anterior pituitary tropic hormones.
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Describe a long loop negative feedback.
A hormone whose secretion is stimulated by the tropic hormone generally feeds back to the hypothalamus to inhibit the secretion of the tropic hormone, thereby limiting its own secretion.
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