The endocrine system releases?
Slow acting hormone into the blood and fast acting neurotransmitters
Hormones in the endocrine system are?
Slower - more circulating all over the place
Neurotransmitters in the nervous system are?
Exact site to create the response
Once in the blood, the hormones
travel to..
specific organs and tissues of the body where they bind to the specific protein receptor cells
What hormones do follicular cells of the thyroid produce, and what stimulates their release?
Thyroxine (T4) and Triiodothyronine (T3), stimulated by TSH.
What are the main functions of thyroid hormones (T3 & T4)?
Increase basal metabolic rate, maintain body temperature, stimulate protein synthesis, increase use of glucose and fatty acids for ATP, upregulate β-receptors, and promote growth with hGH and insulin.
What hormone do parafollicular cells produce, and what is its function?
Calcitonin, which lowers blood calcium by stimulating osteoblasts and inhibiting osteoclasts.
Where are the parathyroid glands located?
On the posterior surface of each lobe of the thyroid (two per lobe, four total).
What is the main hormone secreted by the parathyroid glands?
Parathyroid hormone (PTH).
What are the functions of PTH?
Increases osteoclast activity, increases calcium and magnesium reabsorption in kidneys, and promotes calcitriol formation to increase GI absorption of calcium and magnesium.
What are the two main regions of the adrenal glands?
Outer cortex and inner medulla.
What are the three types of hormones secreted by the adrenal cortex?
Mineralocorticoids (aldosterone), glucocorticoids (cortisol), and weak androgens (DHEA).
What does Aldosterone do?
major mineralocorticoid secreted which helps regulate sodium and potassium homeostasis
What are the major functions of cortisol?
Protein breakdown, gluconeogenesis, lipolysis, resistance to stress, anti-inflammatory effects, and immune suppression.
What role does DHEA play in males vs. females?
Major source of estrogen and libido in females; negligible effect in males after puberty due to high testosterone.
What does the adrenal medulla secrete and when?
Epinephrine and norepinephrine during the fight-or-flight response (sympathetic stimulation).
Why is the pancreas both exocrine and endocrine?
Exocrine cells produce digestive enzymes (via ducts), endocrine islets (Langerhans) secrete hormones into blood.
Steps of Hormone Secretion
Hypothalamus - Relaeses Stimulating hormones - Acts on Anterior Pituitary Gland - Stimulates the release of hormones - Acts on target endocrine organ - Releases acting hormone
How does the body increase blood glucose levels (step-by-step)?
Low blood glucose → pancreas releases glucagon → liver breaks down glycogen (glycogenolysis) and makes new glucose (gluconeogenesis) → epinephrine boosts glycogen breakdown and blocks insulin → cortisol and growth hormone maintain glucose by reducing uptake → result = blood glucose levels rise.
How do you Decrease blood glucose levels?
High blood glucose → pancreas releases insulin → insulin promotes glucose uptake by cells (especially muscle and fat) → stimulates glycogen formation in liver and muscle (glycogenesis) → increases fat and protein synthesis → inhibits gluconeogenesis and glycogen breakdown → result = blood glucose levels fall.
What hormones do alpha and beta cells of the islets secrete?
Alpha (A) cells: glucagon (raises blood glucose).
Beta (B) cells: insulin (lowers blood glucose).
What hormone does the pineal gland secrete, and what is its function?
Melatonin, regulates circadian rhythm (sleep-wake cycle).
What condition is linked to overproduction of melatonin?
Seasonal Affective Disorder (SAD).
What is the main function of the thymus?
Produces hormones that promote T-cell maturation for the immune system.
