Endocrine (Hormone) System Flashcards
Role of Endocrine System
to maintain homeostasis (along with the nervous system)
Homeostasis
process by which a constant internal environment is maintained despite changes in the external environment
Endocrine vs Nervous System
Nervous system: quick system, adjusting rapidly to changes
Endocrine: slower system, long term control over homeostasis
Hormones
Chemicals produced in one part of the body by the endocrine system to affect distant cells.
- act as regulators (speed up/slow down certain processes)
- cells have receptors for certain hormones only
Non- Target Hormones
Affect many cells throughout the body
ex. insulin causes many cells to absorb glucose
Target Hormones
Affect specific cells/tissues only
ex. gastrin affects the stomach only
Tropic Hormones
Activate other endocrine glands to release other hormones.
ex. TSH from the pituitary activates the thyroid gland to release thyroxine
Non- Tropic Hormones
Stimulate other tissues that are not endocrine.
ex. Epinephrine affects the heart, blood vessels, diaphragm, air-ways, etc.
Steroid Hormones
-Made from cholesterol
-Fat soluble
-longer lasting effects
Act from inside the cell by diffusing into the specific cell and can be taken orally by patients (will not be digested by stomach)
ex. thyroxine, testosterone,
Protein Hormones
-Composed of proteins, peptides, or amino acid derivatives
-Water soluble
-aka “non-steroidal hormones”
Act from outside the cell, binding to receptor sites which activate enzymes to carry out specific functions
-CANNOT be taken orally
ex. ADH, hGh
Regulation of Hormones
Hormones are regulated through NEGATIVE feedback mechanisms.
Hypothalamus
Maintains homeostasis.
- controls the pituitary gland via nerves and hormones
- produces releasing hormones (factors)
- produces ADH and oxytocin
Posterior Pituitary
DOES NOT MAKE HORMONES
- made of nervous tissue
- stores and releases hormones made by the hypothalamus (ADH and oxytocin)
- hypothalamus sends these hormones by neurosecretory cells
Anterior Pituitary
MAKES ITS OWN HORMONES
- made of glandular tissue
- makes and stores hormones
- releases hormones via releasing hormones from the hypothalamus
- hormones: TSH, ACTH, PRL, hGH, FSH, LH
ADH (hormone)
Antidiuretic Hormone= Vasopressin
- stimulates water reabsorption in kidneys
- produced by hypothalamus, released by pos. pituitary
Oxytocin (hormone)
Stimulates uterine contraction and milk “let down” reflex
-produced by hypothalamus, released by pos. pituitary
hGH (hormone)
Human Growth Hormone
- stimulates growth in bones and muscles
- associated with diet, stress levels, and amount of sleep
- produced by ant. pituitary
TSH (hormone)
Thyroid Stimulating Hormone
- Stimulates thyroid gland to release thyroxine to increase metabolism.
- produced by ant. pituitary
ACTH (hormone)
Adrenalcorticotrophic Hormone
-stimulates adrenal cortex to release aldosterone and cortisol
Prolactin
- Stimulates the production of breast milk after childbirth
- Produced by ant. pituitary
GnRH
Gonadotropin Releasing Hormone
- stimulates ant. pituitary to release FSH and LH
- produced by hypothalamus, released by pos. pituitary
FSH
Follicle Stimulating Hormone
- stimulates ovaries/testes to produce eggs and sperm
- also stimulates production of estrogen
LH (or ICSH in males)
Luteinizing Hormone
- Females: stimulates ovulation and production of corpus luteum which produces progesterone and some estrogen
- Males: stimulates interstitial cells to produce testerone
Blood Sugar
The pancreas and adrenal gland affect blood sugar levels.
Pancreas
Called “dual purpose gland” because it produces hormones and digestive enzymes.
-Islets of Langerhans: special hormone producing cells in the pancreas
Hormones: Somatostatin, Insulin and Glucagon
Somatostatin (hormone)
Controls rate at which blood absorbs nutrients.
Glucagon (hormone)
Produced by ALPHA cells
- increases blood glucose levels by stimulating liver to break down glycogen into glucose
- released when blood sugar levels are too low
- released by pancreas
Insulin (hormone)
Produced by BETA cells
- decreases blood gluclose levels by increasing uptake of glucose by cells
- released by pancreas
Adrenal Glands
Found on top of kidneys
Outer= cortex
Inner= medulla
-Prepares the body for stress
Adrenal Medulla
Releases epinephrine (adrenaline) and norepinephrine (noradrenaline) -involved in short-term stress
Epinephrine/Norepinephrine (hormone)
Released by adrenal medulla
- involved in “fight or flight” response
- controlled by sympathetic NS
- increases heart rate, breathing rate, blood flow, blood sugar levels, redirects blood flow to brain and muscles
Adrenal Cortex
Function in the body’s long-term stress response.
Releases glucocorticoids and mineralcorticoids.
Glucocorticoids - Cortisol (hormone)
Increases level of amino acids in blood which are converted into glucose to be used as energy, left over amino acids are available for protein synthesis.
-Released by Adrenal Cortex
Mineralcorticoids - Aldosterone (hormone)
Increases absorption of sodium in kidneys which leads to increased absorption of water.
-responds when blood pressure is low
Released by Adrenal cortex
Metabolism
3 glands that affect metabolism:
- Thyroid
- Parathyroid
- Anterior Pituitary
T3 and T4 (hormone)
Thyroxine and Triiodothyronine
- iodine containing hormones
- controls rate that glucose is burned in the body
- increase metabolism, heat production and regulates growth
released by thyroid gland
Calcitonin (hormone)
Causes calcium levels to decrease by causing calcium to be deposited into bones.
-triggered when calcium levels are too high
Released by thyroid gland
PTH (hormone)
Parathyroid Hormone
- Stimulated by low levels of calcium
- Increases calcium levels in blood by moving calcium from bone into the blood
