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Questions and Answers
What is the primary function of the anterior pituitary gland?
What is the primary function of the anterior pituitary gland?
- Regulate blood pressure
- Control the majority of endocrine glands (correct)
- Produce insulin
- Store calcium
Which hormone is secreted by somatotropes?
Which hormone is secreted by somatotropes?
- Thyroid stimulating hormone (TSH)
- Growth hormone (correct)
- Prolactin
- Adrenocorticotrophic hormone (ACTH)
What type of feedback mechanism is most common in the endocrine system?
What type of feedback mechanism is most common in the endocrine system?
- Ultra short loop feedback
- Positive feedback
- Negative feedback (correct)
- Short loop feedback
Which hormone's levels would be decreased in response to high levels of growth hormone?
Which hormone's levels would be decreased in response to high levels of growth hormone?
What is the role of prolactin inhibitory hormone (PIH)?
What is the role of prolactin inhibitory hormone (PIH)?
Which hormone is secreted by the gonadotropes?
Which hormone is secreted by the gonadotropes?
Which type of feedback encourages the endocrine gland to increase hormone secretion?
Which type of feedback encourages the endocrine gland to increase hormone secretion?
What is the function of Thyrotropine Releasing Hormone (TRH)?
What is the function of Thyrotropine Releasing Hormone (TRH)?
What effect does growth hormone (GH) have on carbohydrate metabolism?
What effect does growth hormone (GH) have on carbohydrate metabolism?
Which factor is NOT known to increase growth hormone secretion?
Which factor is NOT known to increase growth hormone secretion?
What characterizes pituitary dwarfism due to GH deficiency?
What characterizes pituitary dwarfism due to GH deficiency?
What hormone inhibits the production of growth hormone from the anterior pituitary?
What hormone inhibits the production of growth hormone from the anterior pituitary?
What is the result of excess GH secretion after epiphyseal closure?
What is the result of excess GH secretion after epiphyseal closure?
What condition is characterized by a deficiency of all anterior pituitary hormones?
What condition is characterized by a deficiency of all anterior pituitary hormones?
Which change is NOT associated with premature senility due to panhypopituitarism?
Which change is NOT associated with premature senility due to panhypopituitarism?
Which action does GH NOT typically perform in terms of mineral retention?
Which action does GH NOT typically perform in terms of mineral retention?
What is the primary action of Growth Hormone (GH) on the skeleton?
What is the primary action of Growth Hormone (GH) on the skeleton?
What effect does cortisol have in the context of long loop feedback?
What effect does cortisol have in the context of long loop feedback?
Which of the following statements about somatomedins is correct?
Which of the following statements about somatomedins is correct?
What is a significant factor that can decrease the levels of somatomedins?
What is a significant factor that can decrease the levels of somatomedins?
What action does Growth Hormone have on protein metabolism?
What action does Growth Hormone have on protein metabolism?
Which of the following describes the effect of estrogen in feedback mechanisms?
Which of the following describes the effect of estrogen in feedback mechanisms?
Which of the following factors is NOT associated with an increased level of Growth Hormone?
Which of the following factors is NOT associated with an increased level of Growth Hormone?
What is the average level of Growth Hormone in adults over a 24-hour period?
What is the average level of Growth Hormone in adults over a 24-hour period?
What effect does high levels of prolactin have on the secretion of prolactin?
What effect does high levels of prolactin have on the secretion of prolactin?
What is a common effect of hyperprolactinemia in females?
What is a common effect of hyperprolactinemia in females?
Which hormone is released by the posterior pituitary?
Which hormone is released by the posterior pituitary?
What is the primary action of ADH in renal physiology?
What is the primary action of ADH in renal physiology?
What is the effect of dopamine antagonists on prolactin secretion?
What is the effect of dopamine antagonists on prolactin secretion?
What role does vasopressin play in the vascular system?
What role does vasopressin play in the vascular system?
How does stress affect prolactin levels?
How does stress affect prolactin levels?
Which type of receptor is NOT associated with ADH?
Which type of receptor is NOT associated with ADH?
What is the primary function of oxytocin during lactation?
What is the primary function of oxytocin during lactation?
Which factor would most likely result in an increase in ADH secretion?
Which factor would most likely result in an increase in ADH secretion?
What effect does stress have on ADH levels?
What effect does stress have on ADH levels?
What is a key symptom of diabetes insipidus?
What is a key symptom of diabetes insipidus?
How does oxytocin aid during labor?
How does oxytocin aid during labor?
What is the effect of hot weather on ADH secretion?
What is the effect of hot weather on ADH secretion?
Which of the following describes a mechanism for increased ADH secretion?
Which of the following describes a mechanism for increased ADH secretion?
What effect does morphine have on ADH secretion?
What effect does morphine have on ADH secretion?
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Study Notes
Pituitary Gland Overview
- Small gland measuring 1 cm in diameter, located in the sella turcica.
- Connected to the hypothalamus via the pituitary stalk.
- Divided into anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis).
Anterior Pituitary (Adenohypophysis) Functions
- Acts as the master gland for most endocrine functions.
- Regulates thyroid glands, adrenal cortex, and gonads.
Hormones Secreted by Anterior Pituitary
- Growth Hormone (GH) - secreted by somatotropes (acidophils).
- Prolactin (PRL) - secreted by mammotropes (acidophils).
- Thyroid Stimulating Hormone (TSH) - secreted by thyrotropes (basophils).
- Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) - secreted by gonadotropes (basophils).
- Adrenocorticotropic Hormone (ACTH) - secreted by corticotropes (basophils).
Regulation of Anterior Pituitary
- Controlled by hypothalamic releasing and inhibiting factors.
- Releasing factors: TRH, FRH, LHRH, CRH, GH releasing hormone (GRH).
- Inhibitory factors: Somatostatin (GH inhibitory hormone), Prolactin inhibitory hormone (PIH).
Feedback Mechanisms
- Negative feedback: Hormonal levels in blood regulate secretion levels; high levels lead to decreased secretion.
- Short, long, and ultra short loops describe feedback mechanisms influencing different glands.
- Positive feedback: Less common, such as increased estrogen leading to more LH secretion.
Growth Hormone (GH)
- Polypeptide hormone with an average secretion of 5-8 ng/24 hours in children and 2-4 ng in adults.
- Functions: Stimulates cell growth (hypertrophy) and division (hyperplasia); increases mineral retention; promotes protein synthesis.
Somatomedins
- Polypeptides secreted mainly by the liver, mediating GH effects.
- Insulin-like Growth Factor I (IGF-I) and Insulin-like Growth Factor II (IGF-II) are key somatomedins.
- Factors decreasing somatomedins include protein deficiency and untreated diabetes.
Disorders of Anterior Pituitary
- Deficiency Conditions:
- Pituitary dwarfism: Characterized by arrested skeletal growth.
- Pituitary infantilism: Deficiency of GH and gonadotropins causing hypogonadism.
- Panhypopituitarism: Loss of all hormone functions leading to premature aging signs.
- Excess Conditions:
- Gigantism: Excess GH before epiphysis closure.
- Acromegaly: Excess GH after epiphysis closure.
Posterior Pituitary Overview
- Secretes Vasopressin (ADH) and Oxytocin.
- Hormones are synthesized in the hypothalamus and stored in the pituitary.
Antidiuretic Hormone (ADH) Function
- Regulates water reabsorption in kidneys via V2 receptors.
- Increases blood pressure through vasoconstriction in large doses via V1 receptors.
- Release is stimulated by increased plasma osmolarity and hypovolemia.
Diabetes Insipidus
- Caused by ADH deficiency leading to polyuria and polydipsia.
- Nephrogenic diabetes insipidus results from a lack of kidney response to ADH.
Oxytocin Functions
- Important for milk ejection during breastfeeding and uterine contractions during labor.
- Involves neurohormonal reflexes triggered by suckling and cervical dilation during labor.
Control of Oxytocin and ADH
- Oxytocin levels rise during suckling and labor due to reflex triggers.
- ADH levels are influenced by osmolarity, blood volume status, stress, and certain drugs.
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