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Questions and Answers
What is the result of hypersecretion of growth hormone during adulthood?
Which anterior pituitary hormone stimulates milk production following childbirth?
Which hormone regulates the endocrine activity of the adrenal cortex?
What is the primary function of thyroid-stimulating hormone?
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What condition can result from an iodine deficiency affecting the thyroid gland?
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Which hormone is responsible for triggering ovulation in females?
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Which hormone stimulates sperm development in males?
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What characterizes all anterior pituitary hormones?
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What condition is caused by hyposecretion of thyroxine during childhood?
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What is a result of hypothyroidism in adults?
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Which hormone is responsible for increasing blood calcium levels?
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Which of the following is NOT a result of Graves’ disease?
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What role does calcitonin play in the body?
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Which of the following hormones is produced by the parafollicular cells of the thyroid?
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What mechanism do glucocorticoids serve in the body?
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What is a common effect of hyperthyroidism?
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What is the consequence of hyposecretion of growth hormone (GH) during childhood?
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Which hormones are produced by the anterior pituitary and affect nonendocrine targets?
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How does antidiuretic hormone (ADH) affect blood pressure?
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Which condition results from insufficient secretion of ADH?
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Gonadotropic hormones from the anterior pituitary are primarily responsible for regulating which aspect of the body?
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What hormone is responsible for stimulating contractions during labor and milk ejection during breastfeeding?
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An increase in thyroid hormone secretion can lead to which condition?
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What is the master hormone-producing gland often referred to as?
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Which hormone promotes the growth of skeletal muscles and long bones?
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What type of glands release hormones directly into the blood or lymph without ducts?
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Study Notes
Anterior Pituitary Hormones
-
Growth hormone (GH):
- Stimulates growth of skeletal muscles and long bones.
- Plays a major role in determining final body size.
- Causes amino acids to be built into proteins.
- Promotes breakdown of fats for energy.
- Hyposecretion during childhood leads to pituitary dwarfism.
- Hypersecretion during childhood leads to gigantism.
- Hypersecretion during adulthood leads to acromegaly.
-
Prolactin (PRL):
- Stimulates and maintains milk production following childbirth.
- Function in males unknown.
-
Adrenocorticotropic hormone (ACTH):
- Regulates endocrine activity of the adrenal cortex.
-
Thyrotropic hormone (TH) (also called thyroid-stimulating hormone (TSH))
- Influences the growth and activity of the thyroid gland.
-
Follicle-stimulating hormone (FSH):
- Stimulates follicle development in ovaries.
- Stimulates sperm development in testes.
-
Luteinizing hormone (LH):
- Triggers ovulation of an egg in females.
- Stimulates testosterone production in males.
Thyroid Gland
- Located at the base of the throat.
- Composed of two lobes and a connecting isthmus.
- Produces two hormones:
-
Thyroid hormone:
- A major metabolic hormone.
- Controls the rate of glucose oxidation to supply body heat and chemical energy.
- Needed for tissue growth and development.
- Composed of two active iodine-containing hormones:
- Thyroxine (T4): secreted by thyroid follicles.
- Triiodothyronine (T3): conversion of T4 at target tissues.
-
Calcitonin:
- Decreases blood calcium levels by causing calcium deposition on bone.
- Antagonistic to parathyroid hormone.
- Produced by parafollicular cells found between the follicles.
- Important in protecting the body against hypercalcemia.
-
Thyroid hormone:
Thyroid Hormone Disorders
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Goiters:
- Thyroid gland enlarges due to iodine deficiency.
- Iodized salt helps prevent goiters.
-
Cretinism:
- Caused by hyposecretion of thyroxine during childhood.
- Results in dwarfism during childhood.
-
Myxedema:
- Caused by hypothyroidism in adults.
- Results in physical and mental sluggishness.
-
Graves’ disease:
- Caused by hyperthyroidism.
- Results in increased metabolism, heat intolerance, rapid heartbeat, weight loss, and exophthalmos (protruding eyes).
Parathyroid Glands
- Tiny masses on the posterior side of the thyroid gland.
- Secrete parathyroid hormone (PTH).
- Stimulates osteoclasts (bone-resorbing cells) to remove calcium from bone.
- Hypercalcemic hormone (increases blood calcium levels).
- Stimulates the kidneys and intestine to absorb more calcium.
- Plays a key role in regulating calcium homeostasis.
Adrenal Glands
- Sit on top of the kidneys.
- Have two regions:
-
Adrenal cortex: outer glandular region with three layers that produce corticosteroids:
- Mineralocorticoids: secreted by the outermost layer.
- Glucocorticoids: secreted by the middle layer.
- Sex hormones: secreted by the innermost layer.
- Adrenal medulla: inner nervous tissue that secretes epinephrine and norepinephrine.
-
Adrenal cortex: outer glandular region with three layers that produce corticosteroids:
Stimuli of Endocrine Glands
-
Hormonal Stimuli:
- The most common stimulus.
- Endocrine organs are activated by other hormones.
- Example: Anterior pituitary hormones travel to target glands, like the thyroid gland, to trigger the release of a specific hormone, like thyroid hormone.
-
Humoral Stimuli:
- Changes in blood chemistry directly stimulate hormone release.
- Example: Low blood calcium levels cause the parathyroid glands to release PTH, which then raises calcium levels.
-
Neural Stimuli:
- Nerve impulses stimulate hormone release.
- Most are under the control of the sympathetic nervous system.
- Example: The release of norepinephrine and epinephrine by the adrenal medulla in response to stress.
Major Endocrine Organs
-
Pituitary gland:
- The size of a pea.
- Hangs by a stalk from the hypothalamus in the brain.
- Protected by the sphenoid bone.
- Has two functional lobes:
- Anterior pituitary: glandular tissue.
- Posterior pituitary: nervous tissue.
- Often called the "master endocrine gland."
- Thyroid gland:
- Parathyroid glands:
- Adrenal glands:
- Pineal gland:
- Thymus gland:
- Pancreas:
- Gonads (ovaries and testes):
- Hypothalamus:
Posterior Pituitary and Hypothalamic Hormones
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Oxytocin:
- Stimulates contractions of the uterus during labor, sexual relations, and breastfeeding.
- Causes milk ejection (let-down reflex) in a breastfeeding woman.
-
Antidiuretic hormone (ADH):
- Inhibits urine production (diuresis) by promoting water reabsorption by the kidneys.
- In large amounts, causes vasoconstriction of arterioles, leading to increased blood pressure (why ADH is known as vasopressin).
- Alcohol inhibits ADH secretion.
- Diabetes insipidus results from ADH hyposecretion.
Posterior Pituitary and Hypothalamic Hormones
-
Oxytocin:
- Stimulates contractions of the uterus during labor, sexual relations, and breastfeeding.
- Causes milk ejection (let-down reflex) in a breastfeeding woman.
-
Antidiuretic hormone (ADH):
- Inhibits urine production (diuresis) by promoting water reabsorption by the kidneys.
- In large amounts, causes vasoconstriction of arterioles, leading to increased blood pressure (why ADH is known as vasopressin).
- Alcohol inhibits ADH secretion.
- Diabetes insipidus results from ADH hyposecretion.
Hypothalamus and Anterior Pituitary
- The Hypothalamus makes releasing and inhibiting hormones.
- These hormones are released into the portal circulation, which connects the hypothalamus to the anterior pituitary.
- The hypothalamus also makes two hormones: oxytocin and antidiuretic hormone.
- Carried to the posterior pituitary for storage via neurosecretory cells.
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Description
This quiz explores the various hormones produced by the anterior pituitary gland, including growth hormone, prolactin, adrenocorticotropic hormone, and others. It covers their functions, effects on the body, and the consequences of their imbalances. Perfect for students studying human physiology and endocrinology.
