Biology - Chapter 11.7: Endocrine System Flashcards
Three Types of Hormones
1) Peptide hormones
2) Steroid hormones
3) Amino-acid derived hormone
Peptide Hormone Synthesis
- rough ER
- made of amino acids connected by peptide bonds
Peptide Hormone Action
- Indirect stimulation
- Bind to cell surface receptors
- via secondary messengers or ligand-gated ion channels
GPCRs
- G-protein coupled receptors
- cell surface receptors that initiate a secondary messenger response
- dissociates into subunits after activation (alpha beta gamma)
RTKs
- Receptor tyrosine kinases
- cell surface receptors that dimerizes and initiates a second messenger response after binding to peptide hormone
- intracellular domains of RTKs cross-phosphorylate and initiate second messenger signaling within the cell
Second messenger system allows for…
… quick and immediate physiological changes
Steroid Hormone Synthesis
- smooth ER
- made up of fused 4-ring structure
Steroid Hormone Examples
- All hormones produced by adrenal cortex (glucocorticoids, mineralocorticoids, androgenic steroids)
- All hormones produced by reproductive organs
Steroid Hormone Action
- carried through blood-stream via protein carrier
- freely crosses cell membrane
- binds to receptors in cytoplasm or nucleus to form molecule-receptor complex
- these complexes bind to DNA and influence gene transcription (direct stimulation)
Amino-acid derived hormones
can have properties that are similar to both peptide hormones and steroid hormones
Amino-acid derived hormones synthesis
- rough ER and cytosol
- mainly derived from tyrosine
Amino-acid derived hormones examples
- All hormones produced in adrenal medulla (epinephrine, norepinephrine)
- T3 and T4
Posterior pituitary hormones
1) ADH: decreases urination by increasing water retention
2) Oxytocin: uterine contractions, lactation
Anterior pituitary hormones
1) GnRH (gonadotropin-releasing): causes release of LH and FSH
2) TRH (thyrotropin-releasing): causes release of TSH
3) CRH (corticotropin-releasing): causes release of ACTH
4) GRH: causes release of GH (growth hormone)
Hypothalamic-inhibiting hormones
-Released by hypothalamus to inhibit release of other hormones by anterior pituitary
Tropic hormones
-Target other endocrine glands for further hormone release
FSH
- tropic hormone released by anterior pituitary
- follice growth and sperm maturation
LH
- tropic hormone released by anterior pituitary
- ovulation, corpus luteum formation and testosterone production
ACTH
- tropic hormone released by anterior pituitary
- release of glucocorticoids from the adrenal gland to fight stress
TSH
- tropic hormone released by anterior pituitary
- stimulates T3 and T4 production by the thyroid gland to increase metabolism
Direct hormones
-targets organs directly for effects
Prolactin
- direct hormone released by anterior pituitary
- stimulates mammary gland development and increases milk production
Growth Hormone
- direct hormone released by anterior pituitary
- BIG BONES BOI
Pineal gland
- releases melatonin
- regulates circadian rhythm
3 Main Thyroid Hormones
1) Triiodothyronine (T3)
2) Thyroxine (T4)
3) Calcitonin
T3
- Triiodothyronine
- released in response to TSH
- increases metabolism in body
- has a negative feedback effect on TSH secretion
T4
- Thyroxine
- increases metabolism in body
- less potent than T3 but is more stable in blood
Calcitonin
- thyroid hormone
- decreases blood calcium
- stimulates osteoblasts
- inhibits osteoclasts
Hypothyroidism
- under-secretion of T3 and T4
- reduced levels of metabolism
- over-secretion of TRH, enlarging thyroid gland
Hyperthyroidism
- over-secretion of T3 and T4
- increased levels of metabolism in the body
- hyperactive thyroid gland
PTH
-parathyroid hormone
-increases blood calcium
-stimulates osteoclasts
-
Pancreas Exocrine Tissue
-Secretes digestive enzymes through pancreattic duct into small intestine
Islets of Langerhans
- Endocrine pancreas glands
- secretes:
1) glucagon
2) insulin
3) somatostatin
Alpha cells
-secrete glucagon in response to low blood glucose which stimulate liver and fat tissue to release glucose storages
Beta cells
- secrete insulin in response to high blood glucose levels
- insulin lowers glucose levels by stimulating the liver, muscles, and fat tissue to store glucose
Insulin
lowers glucose levels by stimulating the liver, muscles, and fat tissue to store glucose
Delta cells
-secretes somatostatin, which inhibits growth hormone
Somatostatin
- inhibits growth hormone
- inhibits secretion of glucagon and insulin
Adrenal cortex
- stimulated by secretion of ACTH from anterior pituitary
- releases steroid hormones
- produces glucocorticoids (cortisol), mineralocorticoids (aldosterone)
- small amounts of sex hormones
Glucocorticoids
- cortisol
- raise blood glucagon levels for immediate fuel during periods of long-term stress
- lowers immune response
Mineraloccorticoids
- aldosterone
- increase blood volume and blood pressure by raising reabsorption of Na+
Ovaries
-Progesterone and Estrogen
Testes
-testosterone
LH
Females: ovulation
Males: testosterone production
FSH
Females: follicle growth in ovaries (increased progesterone and estrogen)
Males: stimulates sperm maturation
