The Endocrine System Flashcards
The Endocrine System
Organ system that controls the body using chemical messengers called hormones
Major Processes Regulated By the Endocrine System
- Reproduction (estrogen (in females)), testosterone (in males))
- Growth + Development (growth hormone, thyroid hormone)
- Mobilization of Body Defenses (thymic hormone)
- Electrolyte + Water Balance (ADH, ANP, Aldosterone)5. Regulation of Cellular Metabolism + Energy Balance (insulin, glucagon)
Major Endocrine Glands
- Pineal Gland
- Hypothalamus
- Pituitary Gland
- Thyroid Gland
- Parathyroid Gland
- Thymus Gland
- Adrenal Gland
- Pancreas
- Ovary
- Testes
Other Hormone Producing Structures and what they produce
- Adipose Cells: produces Leptin
- Mucosa of Digestive System: produces Gastrin, Secretin
- Kidneys: produces Erythropoietin (make RBCs)
- Heart: produces atrial natriuretic peptide (ANP)
- Skin: produces Vitamin D
- Placenta: produces hCG (indicates pregnancy), Progesterone + Estrogen (keep pregnancy going), Prostaglandins (helps push baby out)
Other Hormone Producing Structures
- Adipose Cells
- Mucosa of Digestive System
- Kidneys
- Heart
- Skin
- Placenta
Circulating Hormones
carried by blood, act on distant target cells
- Endocrine Glands:
- are ductless
- secrete into interstitial fluid (IF)
Local Hormones
do not circulate in blood
- Paracrines- local hormones acting as neighboring cells
- Autocrines- local hormones acting on own cells
Chemical Classes of Hormones
- Lipid- Soluble= steroids + thyroid hormone
2. Water- Soluble= amines, peptides/proteins, and eicosanoids
Chemical Classes of Hormones: Water- Soluble Hormones
Can dissolve in water
- Amines- modified amino acid (epinephrine, norepinephrine)
- Peptide- less than 50 amino acids (ANP)
- Protein- (Insulin, Growth Hormone)
- both chain of amino acids - Eicosanoids- modified fatty acid (arachidonic acid)
- most act as local hormones
Chemical Classes of Hormones: Lipid- Soluble Hormones
Can dissolve in lipids (fats)
- Steroids- estrogen, testosterone
- modified from cholesterol - Thyroid Hormone- contain iodine’s
Mechanisms of Hormone Action
- Lipid-soluble hormones use Direct Gene Activation
2. Water-soluble hormones use Second Messenger Activation
Direct Gene Activation by Lipid-soluble hormones
- Hormone diffuses through plasma membrane
- Binds to intracellular receptor
- Transcription of specific gene
- New protein is made by cell (translation)
Second Messenger Activation by Water-soluble hormones
- Hormone (1st messenger) binds to receptor on cell surface
- This causes a 2nd messenger to be made inside the cell
- 2nd messenger activates protein kinase
- Protein kinase activates a protein
An example of a 2nd messenger is
cyclic AMP (cAMP)
What causes Endocrine Glands to secrete hormones?
- Humoral Stimulus
- Neural Stimulus
- Hormonal Stimulus
What causes Endocrine Glands to secrete hormones?
Humoral Stimulus
gland responds to change in chemical composition of blood
ex: increase Ca+2 –> thyroid gland releases calcitonin –> decreases Ca+2
ex: decrease Ca+2 –> thyroid gland release parathyroid –> increase Ca+2
What causes Endocrine Glands to secrete hormones?
Neural Stimulus
gland responds to Nervous System
ex: sympathetic division (fight or flight) –> adrenal medulla will release epinephrine + norepinephrine
What causes Endocrine Glands to secrete hormones?
Hormonal Stimulus
gland responds to a hormone
(1st endocrine gland stimulates hormone secretion from 2nd endocrine gland)
ex: adrenal cortex is hormonally stimulated by one of the pituitary hormones
Hypothalamus makes what kind of hormones?
Water-soluble
Pituitary Gland makes what kind of hormones?
Water-soluble
tract
branch of axons
What is the Hypophysis?
the Pituitary Gland
Neurohypophysis
posterior pituitary and infundibulum
-the hypothalamic-hypophyseal tract is the neural connection between hypothalamus and posterior pituitary
Hypothalamic- hypophyseal tract
the neural connection between hypothalamus and posterior pituitary
The hypothalamus makes 2 hormones that are sent by the hypothalamic- hypophyseal tract to the neurohypophysis
- ADH- kidneys excrete concentrated urine
- Oxytocin- labor contractions, milk ejection
- Then these 2 hormones are secreted into the blood from the neurohypophysis (posterior pituitary)
Releasing hormones (RH)
stimulate hormone secretion from anterior pituitary
Inhibiting hormone (IH)
inhibits hormone secretion from anterior pituitary
The pituitary gland responds to inhibiting hormones (IH) by?
stopping or slowing down its hormone secretion
- GHIH= inhibits both GH (growth hormone) and TSH (thyroid stimulating hormone) secretion
- PIH= inhibits prolactin secretion
TRH (thyroid releasing hormone)
increases TSH (thyroid stimulating hormone) release
CRH
increases ACTH (adrenocorticotropic hormone) release
GnRH
increases FSH (follicle stimulating hormone) + LH (luteinizing hormone) release
PRH (prolactin releasing hormone)
increase prolactin release
PIH (prolactin inhibiting hormone)
decrease prolactin release
GHRH (growth hormone releasing hormone)
increase GH (growth hormone)
GHIH (growth hormone inhibiting hormone)
decrease GH (growth hormone) + TSH (thyroid stimulating hormone) release
