Endocrine System Hormones

Anterior Pituitary Gland:

• Growth Hormone- determines growth of skeletal muscles (highest levels at night sleep)

  • Regulation:

    • Growth hormone releasing hormone

    • Growth hormone inhibiting hormone (somatostatin)

  • Homeostatic Imbalances:

    • Hyposecretion: dwarfism

    • Hypersecretion: gigantism/acromegaly

• Prolactin- stimulates breast development and milk production (levels rhythmically rise and fall with estrogen levels)

  • Regulation:

    • Prolactin releasing hormone

    • Prolactin inhibiting hormone (dopamine)

  • Homeostatic Imbalances:

    • Hypersecretion: lack of menses, infertility, and breast enlargement in women, impotency in men

• Adrenocorticotropic hormone- stimulates the release of glucocorticoids in response to stress.

  • Regulation:

    • Corticotropin releasing hormone- levels peak in the morning shortly before waking).

• Thyrotropic hormone- stimulates the release of the thyroid hormone

  • Regulation:

    • Thyrotropin releasing hormone

• Follicle Stimulating hormone (gonadotropic)- stimulates follicle development in ovaries (women) and sperm development in testes (men)

  • Regulation:

    • Gonadotropin releasing hormone

  • Homeostatic Imbalance

    • Hyposecretion- sterility in men and women

    • Hypersecretion- no problems in men and women

• Luteinizing hormone (gonadotropic)- assists in maturation of the follicle and ovulation (women) and testosterone production (men) (aka interstitial cell stimulating hormone)

  • Regulation:

    • Gonadotropin releasing hormone

  • Homeostatic Imbalance

    • Hyposecretion- sterility in men and women

    • Hypersecretion- no problems in men and women

Posterior Pituitary Gland

• Oxytocin- stimulates uterine contractions and milk ejections (positive feedback mechanisms)

• ADH (antidiuretic hormone)- inhibits urine production by making the kidneys reabsorb water

  • Homeostatic Imbalance

    • Hyposecretion- diabetes insipidus: huge amounts of urine and intense thirst

    • Hypersecretion- occurs in children with meningitis, causes retention of fluid, brain edema, and weight gain

Thyroid Gland (2)

• Thyroid Hormone- it regulates metabolic rate. (made up of two iodine containing hormones: thyroxine and triiodothyronine)

  • Regulation:

    • TSH (anterior pituitary hormone)

  • Homeostatic Imbalance

    • Hyposecretion:

      • Goiter- enlargement of the thyroid gland caused by iodine deficiency

      • Cretinism- hypothyroidism is in infants leads to cretinism (a form of dwarfism with mental retardation)

      • Myxedema- hypothyroidism in adults leading to physical and mental sluggishness

    • Hypersecretion:

      • Graves’ Disease- autoimmune disorder, hyperthyroidism, the body produces antibodies that mimic TSH leading to the continuous production of TH. Causes high metabolic rate, nervousness/agitation, inability to relax, and anterior bulging of eyes (exophthalmos).

• Calcitonin- inhibits osteoclasts and decreases blood calcium to bring increased calcium into the bones.

Parathyroid Gland (4)

• Parathyroid Hormone- stimulates osteoclasts to break down bone matrix release calcium to the blood increasing blood calcium levels (antagonist of calcitonin), also stimulates kidneys to absorb calcium from urinary filtrate, PTH activates vitamin D

  • Homeostatic Imbalance

    • Hyposecretion- hypoparathyroidism leads to hypocalcemia (low blood calcium levels) making neurons extremely irritable causing uncontrolled muscle spasms

    • Hypersecretion- hyperparathyroidism leads to massive bone destruction

Adrenal Cortex

• Aldosterone- regulates sodium and potassium in the blood (mineralocorticoid)

  • Regulation:

    • renin-angiotensin mechanism

    • increased potassium stimulates aldosterone

    • ACTH

    • atrial natriuretic peptide inhibits aldosterone

  • Homeostatic Imbalance

    • Hyposecretion- Addison’s disease (hyposecretion of mineralocorticoids AND glucocorticoids), leads to bronze skin tone, weight loss, electrolyte imbalance, and hypoglycemia

    • Hypersecretion- hyperaldosteronism leading to high blood pressure (excessive amounts of water and sodium are left in the body), large amounts of potassium are lost leading to disruption of heart and nervous system activities

• Glucocorticoids (ex. cortisol)- increases blood sugar, decrease edema, and inhibit prostaglandins- they are given as treatment for patients with rheumatoid arthritis

  • Homeostatic Imbalance

    • Hyposecretion- Addison’s disease (hyposecretion of mineralocorticoids AND glucocorticoids), leads to bronze skin tone, weight loss, electrolyte imbalance, and hypoglycemia

    • Hypersecretion- Cushing’s’ Syndrome, leads to high blood pressure, hyperglycemia, fat accumulation on the back, and severe depression of the immune system

• Gonadocorticoids- mainly androgens but some estrogens as well (levels rise from ages 7-13)

  • Homeostatic Imbalance

    • Hypersecretion- Masculinization: development of beard and masculine pattern of body hair and distribution (in women and men)

Adrenal Medulla

• Epinephrine (80%)- stimulates heart, dilates bronchioles,

• Norepinephrine (20%)- peripheral vasoconstriction, increases blood pressure

They are catecholamines that are released into the blood by the chromaffin cells when the sympathetic nervous system is activated during the fight-or-flight response.

• Homeostatic Imbalance

  • Hypersecretion- rapidly beating heart, high blood pressure, high blood glucose, irritability. (may be caused by chromaffin cell tumor called pheochromocytoma)

Pancreas

• Insulin- decreases glucose levels (released by beta cells)

  • Homeostatic Imbalance

    • Hyposecretion- diabetes mellitus

      • Type 1: absence of deficiency of insulin

      • Type 2: body is unable to respond to insulin because of insulin resistance

• Glucagon- increases glucose levels (released by alpha cells)

• Somatostatin- inhibits the release of insulin and glucagon (released by delta cells)

Pineal Gland

Melatonin- derived from serotonin and makes us sleepy (peak levels are at night)

Thymus

Thymopoietin, thymulin, and thymosin which program T-lymphocytes. (they are paracrine hormones)