11.1 - Endocrine and Hepatic Disequilibrium Flashcards
Functions of Hormonal Regulation
1) Maintenance of Homeostasis
2) Supports growth and development
3) Regulates Metabolism
4) Coordinates male and reproductive systems
Hormones are released in patterns
Diurnal - daily
Pulsatile - intermittently
Cyclic - in cycles
What regulates hormone release?
- changes in the bodys environment
- most hormonal regulation is controlled by negative feedback systems
- hormones bind to specific target receptors
- hormones are released by endocrine glands
Negative feedback (output inhibits its own activity)
ex. body temp rises, hypothalamus is triggered to vasodilate and cause sweating. Result: temp returns to normal
Hormone Effects
Direct: directly impact target cells
Permissive: 1 hormone enhances action of another
Water VS. Lipid Soluble Hormones
Lipid-Soluble (small, hydrophobic)
- Need HELP to circulate in blood: require carrier protein
- cross plasma membrane and bind to INTRAcellular receptors
- have longer lasting effects
- ex. steroids
Water-Soluble (small, hydrophilic)
- circulate freely (dont need help)
- act quickly, but have short lasting effects
- bind to the receptors on surface of target cells
Up Regulation Vs. Down Regulation
Up -Regulation
- cell increases # of receptors on its surface
- occurs when hormone levels are low to to promote more uptake of hormone
Down-Regulation
- cell decreases its # of hormone receptors = ↓ sensitivity
- occurs when there is excess amount of hormone to prevent overstimulation of cell
Mechanism of Action: Lipid Soluble
1) Cross plasma membrane
2) bind to intracellular receptors
3) directly influence gene expression and protein synthesis
- effects are slower but longer-lasting
Mechanism of Action: Water Soluble
Signal Transduction/Cascade
1) water-soluble peptide binds to cell surface receptor
2) receptor activates intracellular signalling molecules (Ca)
- the 2nd messengers amplify the signal within the cell
- effects are faster
Function of Hypothalamic Pituitary Axis
- controls hormone release from pituitary gland
- master of endocrine function
Anterior VS. Posterior Gland
Anterior
- secretes TROPIC hormones (regulate endocrine glands)
- pars distalis, tuberalis, and intermedia
Posterior
- STORES and releases hormones (made im hypothalamus)
- pars nervosa, pituitary stalk
Examples of Tropic Hormones
1) ACTH
2) LH
3) FSH
4) TSH
5) MSH (melanocyte stimulating hormone)
Function of Anterior Pituitary
1) Hormones travel from bloodstream to target organ to through hypophyseal portal system
- HP portal system: network of blood vessels connecting hypothalamus to anterior pituitary
2) Blood travels to portal veins directly to anterior pituitary
3) In anterior pituitary, hormones trigger or inhibit the release of tropic hormones
- tropic hormones enter bloodstream and travel to organs
Hypophesal Portal System - needed for rapid communication bw hypothalamus and anterior pituitary; allows body to respond quickly to changes
Hormones Released by Pituitary Hormones
1) Antidiuretic Hormone (ADH)
- promotes water reabsorption
- blood vessel constriction
2) Oxytocin
- facilitates orgasm
- causes uterine contractions
- contracts smooth muscle in breasts: for milk ejection
Function of Pineal Gland
- located near centre of brain
- secretes melatonin
Melatonin
- regulates sleep-wake cycle and circadian rhythm
- influences onset pf puberty
- regulates immune system
Thyroid and Parathyroid
Thyroid
- located beside trachea
- made up of colloid and parafollicular cells (secrete Calcitonin; aid in Ca regulation)
Parathyroid
- secretes parathyroid hormone; aids in Ca balance
Thyroid Hormone
Regulates
- growth
- metabolism
- heat production
- oxygen consumption
- secreted in response to thyroid stimulating hormone (TSH)
- binds to proteins in the blood
- composed of T4 and T3; most is T4 and it gets converted to T3 in tissues
How the Parathyroid Regulates Ca
- PTH increases serum Ca levels (Ca in blood)
- Vitamin D is a cofactor for PTH; it helps reabsorb Ca
-PTH promotes bone breakdown to release Ca into blood
Function of Calcitonin
- lowers serum Ca levels
- inhibits reabsorption of Ca
Function of Pancreas
- has 2 functions: hormonal (endocrine) and digestive (exocrine)
- contains islets of langerhans
1) Alpha cells - secrete glucagon: ↑ blood sugar
2) beta cells - secrete insulin: ↓ blood sugar and amylin (regulates glucose)
3) Delta cells - secrete somatostatin (inhibits hormones) and gastrin (stimulates digestion)
4) F cells: secrete pancreatic polypeptide (regulates pancreatic secretions)
Function of Insulin and Amylin
BOTH LOWER Blood sugar
Insulin
- increases glucose uptake; means glucose is moving out of blood and into cells ( to lower blood sugar)
- secretes in response to high blood sugar
Amylin
- secreted WITH insulin
- delays nutrient uptake
- suppresses glucagon uptake: by suppressing glucagon, it reduced release of glucose (which lowers blood sugar)
Function of other Pancreatic Hormones
Glucagon (raises blood sugar) - secreted when blood sugar is low
Somatostatin - regulates alpha/beta cell activity
Ghrelin - stimulates hunger/appetite
Pancreatic Polypeptide - regulates pancreatic secretions
Adrenal Glands
- sit on top of the kidney
Consists of
1) Adrenal Cortex
- produces hormones (cortisol, aldosterone)
2) Arenal Medulla
- produces catecholamines (norepinephrine epinephrine)
Glucocorticoids
- stimulates by ACTH
- regulate metabolism
- CORTISOL: most potent glucocorticoids
Function of Aldosterone
- secreted by adrenal cortex
- stimulates by RAAS pathway
- increases Na retention to help maintain BP and fluid balance
Adrenal Androgens and Estrogens
Adrenal Androgens
- produce weak androgens that get converted into stronger androgens (testosterone) in peripheral tissues
Adrenal Estrogens
- secrete small amounts of estrogen
- play a role in estrogenic function (fat distribution in females)
Adrenal Medulla and Catecholamines
- adrenal medulla secretes catecholamines: epinephrine and norepinephrine
- involves in the fight or flight response
Effects of Epinephrine and Norepinephrine
-increase HR
- increase blood sugar
- cause vasoconstriction
- dilate bronchioles
- convert glycogen to glucose to increase glucose
Hows does endocrine system relate to Aging
- as we age, glands undergo atrophy: decreases secretion and clearance of hormones
