Endocrine System
Karina Quinones P6

Major Endocrine Glands and Organs

Pancreas: triangular gland located behind stomach

Pineal Gland: small gland hanging from third ventricle that secretes melatonin and regulates sleep-wake cycles, puberty, and body temp, targets the brain

Gonads and Placenta: ovaries produce estrogen and progesterone, testes produce testosterone, placenta secretes estrogens, progesterone, and human gonadotropin (targets testes and ovaries)

Adrenal Gland: paired pyramid shaped organs on top of kidneys, separated into two glands

Steroids vs. Non-Steroids

Diseases Associated with the Endocrine System

Grave's Disease: Hypersecretion of TH (thyroid hormones), abnormal antibodies mimic TSH, stimulating TH release. Symptoms: nervousness, weight loss, sweating, Exophthalmos (eyes protruding)

Myxedema: Hyposecretion of TH due to a lack of iodine, Symptoms: low metabolic rate, thick/dry skin, puffy eyes, constipation, chills, lethargy, Goiter (enlarged thyroid)

Hyposecretion of Growth Hormone

Congenital Hypothyroidism: poor development of thyroid gland, may be asymptomatic or present with weak cry, poor feeding, constipation

Hypersecretion of Growth Hormone

Cushing's Disease: Hypersecretion of ACTH in pituitary gland and stimulates adrenal glands; depression of bone formation, inhibits inflammation, disrupts certain functions; caused by a tumor on the pituitary, or overuse of corticosteroids, Symptoms: moon face or buffalo hump,

Diabetes Insipidus: An ADH deficiency because of damage to the hypothalamus or the posterior pituitary

Acromegaly (in adults): overgrowth of hands, feet, and face

Gigantism (in children): causing to reach great heights

( in adults): causes no problems

Pituitary Dwarfism (in children): may only reach 4 feet

Addison's Disease: Hyposecretion of ACTH and damage to the adrenal cortex, deficits in glucocorticoids and mineralocorticoids, Symptoms: weight loss, dehydration, hypotension,

Diabetes Mellitus: Hyposecretion of Insulin (Type 1 Diabetes); 3 Cardinal Signs

Polydipsia: excessive thirst

Polyphagia: excessive eating

Polyuria: huge urine output

Lipidemia: high levels of fatty acid in blood because sugars cannot be used and fatty acid metabolism may result in ketones

Ketonuria: ketone bodies in urine

Ketonacidoses: ketones build up in blood (when untreated can cause hyperphea, disrupted heart activity, depression of nervous system)

Hypoglycemia: Hyperinsulinism, low blood glucose levels, Symptoms: anxiety, nervousness, unconciousness

Non-Steroid Hormones: Amino acid based hormones are polar and cant pass through target cells, bind to cell membrane receptors on the outside of the cells

Steroid Hormones: Are not stored in cells, and rate of release depends on the rate of synthesis, are nonpolar and can bind to intracellular receptors, lipid soluble

epinephrine, norepinephrine, melatonin, thyroxin, oxytocin, insulin, antidiuretic hormone, glucagon, thyroid hormones, parathyroid hormones

cortisol, testosterone, aldosterone, mineralocorticoids, glucocorticoids, gonadocorticoids, progesterone, estrogen, androgen

Negative and Positive Feedback:

Positive Feedback: continues to increase hormones effect on target organs in order to produce a desired effect, the hormone continues to be released

Negative Feedback: controls blood levels of hormones, increased hormone effect on a target organ will trigger negative feedback and inhibit any further hormone release. It is triggered by endocrine gland stimuli and nervous system modulation

Neural Stimuli: nerve fibers stimulate hormone release

Hormonal Stimuli: hormones stimulate other endocrine organs

Humoral Stimuli: changes in blood levels of ions and nutrients

Nervous System Modulation: can make adjustments to hormone levels when needed, can modify stimulation or inhibition of endocrine glands, the nervous system overrides endocrine

Gastrointestinal tract: stimulates liver and pancreas, gastrin stimulates release of HCI

Parathyroid Gland: in posterior aspect of thyroid, secretes parathyroid hormone which plays role in Calcium homeostasis, targets skeleton, kidneys, and intestines

Heart: atrial natriuretic peptide decreases blood sodium concentration, blood pressure, and blood volume

Thyroid Gland: butterfly shaped in anterior portion of the neck

Skeleton: osteoblasts secrete osteocalcin, restricts fat storage, improves glucose handling

Pituitary Gland

Kidneys: erythropoietin signals produce red blood cells

Anterior Pituitary Hormones

Posterior Pituitary Hormones

Oxytocin and ADH are positive feedback mechanaisms

Antidiuretic Hormone (ADH): monitors solute concentrations (targets kidney tubules and triggered by pain, low bp, drugs)

Ocytocin: stimulant of uterine contractions, and triggers milk ejection (targets mammary gland)

Adrenocorticotropic Hormone (ACTH): stimulates adrenal cortex to release corticosteroids (targets adrenal cortex)

Gonadotropins

Thyroid Stimulating Hormone (TSH): stimulates normal development and secretory activity of thyroid (targets thyroid gland)

Prolactin (PRL): stimulates milk production (targets mammary gland)

Growth Hormone (GH): direct actions on metabolism and indirect growth-promoting actions (targets liver and adipose tissue)

Luteinizing Hormone (LH): promotes production of gonadal hormones (targets ovaries or testes), triggers ovulation

Follicle-Stimulating Hormone (FSH): stimulates production of gametes (egg or sperm)

Calcitonin: produced by parafollicular cells and regulates calcium levels in the blood (targets bone); antagonist to PTH

Thyroid Hormones: increase metabolic rate, regulate tissue growth, maintains blood pressure ( targets tissues)

T3 (triiodothyronine): maintain muscle control, brain and heart functions

T4 (thyroxine): affect every cell in body

Major Functions of the Endocrine System

  • influence metabolic activities through hormones
  • allow for reproduction growth and development
  • maintenance of electrolytes, water, and nutrient balance of blood
  • regulation of cellular metabolism
  • energy balance
  • mobilization of body defenses
  • regulate short and long term activities - stimulate glands

Adrenal Medulla: nervous tissue that is apart of sympathetic nervous system

Adrenal Cortex : three layers of glandular tissue that synthesize and secrete different hormones

Glucocorticoids: regulates blood glucose levels, influences the metabolism of most cells. Types are cortisol, cortisone, corticosterone targets the liver, adipose tissue, brain and lung

Gonadocorticoids (adrenal sex hormone): contributes to onset of puberty, sex drive in women, is testosterone in men and estrogen in women, targets testes or ovaries

Mineralocorticoids: regulate electrolyte concentrations and sodium levels. Aldosterone is the most potent type. targets kidneys

Norepinephrine: influence on peripheral vasoconstriction and blood pressure

Epinephrine: stimulator of metabolic activities

Insulin: decreases blood sugar levels (targets liver)

Glucagon: increases blood sugar levels (targets liver)

Thymus: thymulin involved in normal development of T lymphocytes in immune response

Adipose Tissue: leptin is insulin antagonist, stimulates increased energy and appetite control

Hypothalamus is connected to the pituitary via the infundibulum, it secretes releasing and inhibiting hormones to the anterior pituitary to regulate hormone secretion