BIOD 331 Module 9 (Endocrine Physiology, Thyroid
Disorders, Adrenal Gland Disorders, Diabetes Mellitus)
9.1: Endocrine Physiology
● Comprised of glands-pituitary, thyroid, parathyroid, adrenal, and organs-pancreas,
gonads
● Produce hormones which regulate bodily functions including metabolism, growth,
sex drive, and sleep regulation
● Endocrine: Hormones are released into circulation to act on a distant target organ
(TSH, ADH)
● Paracrine: Hormones act locally on cells close to where they are released (estrogen,
testosterone)
● Autocrine: Hormones produce a biologic action on the cell that released them
(insulin)
● Hormones can be derived from amines and amino acids, peptides and proteins,
steroids (cholesterol)
● Amines & Amino Acids
○ Dopamine, epinephrine, norepinephrine, thyroid hormone ●
Peptides, Polypeptides, and Proteins
○ Corticotropin releasing hormone (CRH), growth hormone releasing hormone
(GHRH), thyrotropin releasing hormone (TRH), adrenocorticotropic hormone
(ACTH), follicle stimulating (FSH), luteinizing (LH), thyroid stimulating
(TSH), growth hormone (GH), antidiuretic (ADH), oxytocin, prolactin, insulin, glucagon,
somatostatin, calcitonin, parathyroid hormone (PTH) ● Steroids
○ Aldosterone, glucocorticoids, estrogens, testosterone, progesterone,
androstenedione, 1,25-Dihydroxyvitamin D, dihydrotestosterone,
dehydroepiandrosterone
● Hormones travel freely unattached or attached to transport carriers. Peptide and
proteins typically unattached, steroid hormones transported by carrier protein
produced in liver
● Receptors act through an effector system within the cell. Some hormone receptors
are located on the surface of the cell, others are located within the cell. As
hormone binds to receptor, its binding triggers a cellular response. Speed of
process can vary, NTs work in milliseconds, thyroid hormone takes days to achieve
, full effect. Response of target cell depends on number of receptors available and
affinity of receptors for hormone binding. Approx 2000-100,000 hormone receptor
molecules per cell. Receptors may be increased or decreased through upregulation
and downregulation. Hormone secretion varies, some are released w the sleep-wake
cycle (GH, ACTH), some released in cycles (female sex hormones), others are
regulated by a negative feedback system (insulin, ADH)
● Hypothalamus serves as link between nervous and endocrine systems, works w the
pituitary gland to control functions of many other endocrine glands. Regulates
homeostasis, body temp, hunger, behavior, emotion, and pain. Produces releasing
hormones, which stimulates pituitary to release stimulating hormones.
Hypothalamus releases GHRH, somatostatin, dopamine, TRH, CRH, and GnRH
hormones which stimulate the following:
○ GHRH -> GH, TRH -> TSH, CRH -> ACTH, GnRH -> LH & FSH
● Pituitary gland is known as the master gland, stimulates target organs to secrete
their hormones. Hypothalamus secretes TRH which stimulates anterior pituitary to
secrete TSH, which stimulates thyroid gland to release T3 and T4.
○ Anterior: GH, ACTH, TSH, FSH, LH, prolactin
○ Posterior: ADH, oxytocin
● These hormones affect body growth & metabolism, glucocorticoid hormone levels,
thyroid gland function, gonad function, and breast growth and milk production
● Homeostasis requires keeping hormone levels within a specific range that the body
needs for optimal function. Body maintains homeostasis and regulates hormone
production to the appropriate level through a negative feedback mechanism, most
hormones are controlled this way. Ex: ADH, once blood is dilute, hypothalamus
detects the dilute levels and stops releasing ADH. Brain is constantly monitoring
hormone levels to keep levels within their normal range or set-point. Negative
feedback also prevents over-secretion of any hormone.
● Positive feedback enhances or increases the amount of the hormone that is release.
Ex: oxytocin, causes uterus to contract, contractions cause more oxytocin to be
released. Enhances strength of contractions, causing more oxytocin to be released.
Positive feedback loop is stopped once the baby is born, and uterus no longer needs
to contract, stopping production of oxytocin
● Hypothalamus
○ Hormones: Release & inhibit hormones CRH, TRH, GHRH, GnRH.
Somatostatin, dopamine
○
, ○ Controls release of pituitary hormones, inhibits GH and TSH, inhibits
prolactin, FSH, LH
● Anterior pituitary
Hormones: GH, ACTH, TSH, FSH, LH
○ Stimulates growth of bone and muscle, promotes protein/fat metabolism.
Stimulates synthesis/secretion of adrenal cortical hormones. Stimulates
thyroid hormone. Stimulates ovarian follicle, ovulation/sperm production.
Corpus luteum, oocyte release, estrogen/progesterone/testosterone ●
Posterior pituitary
○ Hormones: ADH, oxytocin
○ Increase water reabsorption by kidney, uterine contractions, milk ejection
● Adrenal cortex
○ Hormones: Mineralocorticosteroids, mainly aldosterone. Glucocorticoids,
mainly cortisol. Adrenal androgens (DHEA & androstenedione)
○ Increase Na absorption, K loss by kidney. Regulates metabolism of nutrients,
regulates blood glucose levels, affects growth, anti-inflammatory action, decrease
effects of stress. Converted to testosterone and DHT, minimal androgenic activity ●
Adrenal medulla
○ Hormones: epinephrine/norepinephrine
○ NTs for the SNS ●
Thyroid (follicular cells)
○ Hormones: thyroid hormones, T3, T4
○ Increases metabolic rate, protein & bone turnover, fetal/infant
growth/development ● Parathyroid glands
○ PTH
○ Regulates serum calcium ●
Pancreatic islet cells
○ Insulin, glucagon, somatostatin
○ Decrease blood glucose by facilitating glucose to muscles, liver, adipose
tissue. Increase blood glucose by stimulating glycogenolysis and glyconeogenesis.
Delays intestinal absorption of glucose ● Kidney
○ 1,25-Dihydroxyvitamin D
○ Stimulates Ca absorption from intestine ●
Ovaries
○ Estrogen, progesterone
○
Disorders, Adrenal Gland Disorders, Diabetes Mellitus)
9.1: Endocrine Physiology
● Comprised of glands-pituitary, thyroid, parathyroid, adrenal, and organs-pancreas,
gonads
● Produce hormones which regulate bodily functions including metabolism, growth,
sex drive, and sleep regulation
● Endocrine: Hormones are released into circulation to act on a distant target organ
(TSH, ADH)
● Paracrine: Hormones act locally on cells close to where they are released (estrogen,
testosterone)
● Autocrine: Hormones produce a biologic action on the cell that released them
(insulin)
● Hormones can be derived from amines and amino acids, peptides and proteins,
steroids (cholesterol)
● Amines & Amino Acids
○ Dopamine, epinephrine, norepinephrine, thyroid hormone ●
Peptides, Polypeptides, and Proteins
○ Corticotropin releasing hormone (CRH), growth hormone releasing hormone
(GHRH), thyrotropin releasing hormone (TRH), adrenocorticotropic hormone
(ACTH), follicle stimulating (FSH), luteinizing (LH), thyroid stimulating
(TSH), growth hormone (GH), antidiuretic (ADH), oxytocin, prolactin, insulin, glucagon,
somatostatin, calcitonin, parathyroid hormone (PTH) ● Steroids
○ Aldosterone, glucocorticoids, estrogens, testosterone, progesterone,
androstenedione, 1,25-Dihydroxyvitamin D, dihydrotestosterone,
dehydroepiandrosterone
● Hormones travel freely unattached or attached to transport carriers. Peptide and
proteins typically unattached, steroid hormones transported by carrier protein
produced in liver
● Receptors act through an effector system within the cell. Some hormone receptors
are located on the surface of the cell, others are located within the cell. As
hormone binds to receptor, its binding triggers a cellular response. Speed of
process can vary, NTs work in milliseconds, thyroid hormone takes days to achieve
, full effect. Response of target cell depends on number of receptors available and
affinity of receptors for hormone binding. Approx 2000-100,000 hormone receptor
molecules per cell. Receptors may be increased or decreased through upregulation
and downregulation. Hormone secretion varies, some are released w the sleep-wake
cycle (GH, ACTH), some released in cycles (female sex hormones), others are
regulated by a negative feedback system (insulin, ADH)
● Hypothalamus serves as link between nervous and endocrine systems, works w the
pituitary gland to control functions of many other endocrine glands. Regulates
homeostasis, body temp, hunger, behavior, emotion, and pain. Produces releasing
hormones, which stimulates pituitary to release stimulating hormones.
Hypothalamus releases GHRH, somatostatin, dopamine, TRH, CRH, and GnRH
hormones which stimulate the following:
○ GHRH -> GH, TRH -> TSH, CRH -> ACTH, GnRH -> LH & FSH
● Pituitary gland is known as the master gland, stimulates target organs to secrete
their hormones. Hypothalamus secretes TRH which stimulates anterior pituitary to
secrete TSH, which stimulates thyroid gland to release T3 and T4.
○ Anterior: GH, ACTH, TSH, FSH, LH, prolactin
○ Posterior: ADH, oxytocin
● These hormones affect body growth & metabolism, glucocorticoid hormone levels,
thyroid gland function, gonad function, and breast growth and milk production
● Homeostasis requires keeping hormone levels within a specific range that the body
needs for optimal function. Body maintains homeostasis and regulates hormone
production to the appropriate level through a negative feedback mechanism, most
hormones are controlled this way. Ex: ADH, once blood is dilute, hypothalamus
detects the dilute levels and stops releasing ADH. Brain is constantly monitoring
hormone levels to keep levels within their normal range or set-point. Negative
feedback also prevents over-secretion of any hormone.
● Positive feedback enhances or increases the amount of the hormone that is release.
Ex: oxytocin, causes uterus to contract, contractions cause more oxytocin to be
released. Enhances strength of contractions, causing more oxytocin to be released.
Positive feedback loop is stopped once the baby is born, and uterus no longer needs
to contract, stopping production of oxytocin
● Hypothalamus
○ Hormones: Release & inhibit hormones CRH, TRH, GHRH, GnRH.
Somatostatin, dopamine
○
, ○ Controls release of pituitary hormones, inhibits GH and TSH, inhibits
prolactin, FSH, LH
● Anterior pituitary
Hormones: GH, ACTH, TSH, FSH, LH
○ Stimulates growth of bone and muscle, promotes protein/fat metabolism.
Stimulates synthesis/secretion of adrenal cortical hormones. Stimulates
thyroid hormone. Stimulates ovarian follicle, ovulation/sperm production.
Corpus luteum, oocyte release, estrogen/progesterone/testosterone ●
Posterior pituitary
○ Hormones: ADH, oxytocin
○ Increase water reabsorption by kidney, uterine contractions, milk ejection
● Adrenal cortex
○ Hormones: Mineralocorticosteroids, mainly aldosterone. Glucocorticoids,
mainly cortisol. Adrenal androgens (DHEA & androstenedione)
○ Increase Na absorption, K loss by kidney. Regulates metabolism of nutrients,
regulates blood glucose levels, affects growth, anti-inflammatory action, decrease
effects of stress. Converted to testosterone and DHT, minimal androgenic activity ●
Adrenal medulla
○ Hormones: epinephrine/norepinephrine
○ NTs for the SNS ●
Thyroid (follicular cells)
○ Hormones: thyroid hormones, T3, T4
○ Increases metabolic rate, protein & bone turnover, fetal/infant
growth/development ● Parathyroid glands
○ PTH
○ Regulates serum calcium ●
Pancreatic islet cells
○ Insulin, glucagon, somatostatin
○ Decrease blood glucose by facilitating glucose to muscles, liver, adipose
tissue. Increase blood glucose by stimulating glycogenolysis and glyconeogenesis.
Delays intestinal absorption of glucose ● Kidney
○ 1,25-Dihydroxyvitamin D
○ Stimulates Ca absorption from intestine ●
Ovaries
○ Estrogen, progesterone
○
