18) Endocrine System Cheat Sheet

Endocrine

Targets a distant cell through the bloodstream

Exocrine

Secretes enzymes into ducts

paracrine

targets nearby cells

autocrine

targets itself

tropic hormones

stimulate other endocrine glands

nontropic hormones

directly stimulate target organs

peptide hormones

bind to surface cell membrane receptor → receptors start cell signaling pathways via secondary messengers

steroids

diffuse through plasma membrane and bind to receptor in cytoplasm → hormone + receptor is transported into nucleus to act transcriptionally

tyrosine derivatives

• thyroid hormones

• catecholamines

thyroid hormones

lipid soluble, bind to receptors in the nucleus, and require protein carrier in blood

catecholamines

water-soluble, bind to receptors on target tissue. and mainly act via secondary messenger cAMP

secondary messengers

small molecules that pass along signals (such as growth factors and protein hormones)

• initiated by ligand-receptor binding

• ligands, receptors, and second messengers all play a role in cell-cell communication

  • amplify signal strength to target molecules in the cytoplasm or nucleus

Pancreas

Essential organ located behind the stomach in the upper abdomen that plays a dual role in digestion and blood sugar regulation

Glucagon

• secreted by alpha cells, released when energy levels are low

• increases glucose levels in blood

• stimulates liver to convert glycogen to glucose (glyconeogenesis)

• stimulates gluconeogenesis

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Insulin

• secreted by Beta cells

• anabolic, released when energy levels are high\

• lowers glucose levels in blood

  • stimulates liver and muscle to store glucose as glycogen

somatostatin

• secreted by Delta cells

• inhibits release of insulin and glucagon

• increases nutrient absorption time by decreasing digestive system flow

Hypothalamus

primary control center linking nervous system to endocrine system via pituitary gland

Key Functions: homeostasis maintenance, autonomic and endocrine regulation, hormone production

Key Hormones: Thyrotropin-Releasing Hormone (TRH); Corticotropin-Releasing Hormone (CRH); Gonadotropin-Releasing Hormone (GnRH); Growth Hormone-Releasing Hormone (GHRH)

Thyrotropin-Release Hormone

Simulates the anterior pituitary to release thyroid-stimulating hormone (TSH), which controls the thyroid gland

Corticotropin-Releasing Hormone (CRH)

triggers the anterior pituitary to release adrenocorticotropic hormone (ACTH), activating the stress and cortisol response.

Gonadotropin-Releasing Hormone (GnRH)

stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to govern reproductive function.

Growth hormone-releasing hormone (GnRH)

Promotes the secretion of growth hormone (GH)

Somatostatin (Growth Hormone-Inhibiting Hormone)

Inhibits the release of both growth hormone and TSH

Dopamine (Prolactin-inhibiting hormone)

inhibits prolactin release from the anterior pituitary

Anterior Pituitary Gland

The front, larger lobe of the pituitary gland

• master gland system

• synthesizes and secretes vital peptide and glycoprotein hormones under direct control of hypothalamus via a portal blood system

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Thyroid Stimulating Hormone (TSH)

Stimulates the thyroid gland to produce thyroid hormones (T3 and T4) regulating the metabolism

Adrenocorticotropic Hormone (ACTH)

Stimulates the Adrenal cortex to release glucocorticoids (ex: cortisol) to manage stress, metabolism, and immune response

Follicle-Stimulating Hormone (FSH)

Regulates reproduction by promoting egg development in the ovaries, and sperm production in testes

Luteinizing hormone (LH)

Triggers ovulation and estrogen/progesterone production in females, and testosterone production in males.

Growth Hormone (GH)

Stimulates cellular growth, tissue regeneration, linear bone growth, and metabolic regulation

• NONTROPIC

Prolactin (PRL)

targets mammary glands to stimulate breast milk production and lactation

• NONTROPIC

Pineal Gland

• secretes melatonin

  • regulates circadium rhythm

thymus

• immune function

• secretes thymosin that stimulate white blood cells to become T-cells

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Testosterone

Increases spermatogenesis, secondary sex characteristics

estrogen

menstrual cycle regulation, secondary sex characteristics

progesterone

menstrual cycle regulation, pregnancy

PTH

Hormone released by Parathyroid glands

• Raises Ca2+ levels in the blood by:

  • stimulating osteoclasts to break down bone

  • increasing kidney reabsorption of calcium

  • increasing calcium uptake from the gut

Thyroid

Small endocrine gland located at front of neck that produces hormones that regulate your body’s energy use and metabolism

Thyroxine and Triidothyronine

increases basal metabolic rate in body

• iodine necessary for synthesis of thyroid hormones and prevents goiters

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Calcitonin

Stimulates osteoblast activity (builds up bone by using calcium in the blood)

Adrenal Glands

two small triangular shaped orans that produce hormones that regulate metabolism, blood pressure, the immune system, and my response to stress

• adrenal medulla (epinephrine + nonepinephrine)

• Adrenal cortex (glucocorticoids)

• Mineralcorticoids (aldosterone)

Adrenal Medulla

Produces Epinephrine and Nonepinephrine

• fight or flight catecholamines

• converts glycogen to glucose (increases blood glucose)

• vasoconstrictor to kidneys and bladder

• vasodilator to skeletal muscle, increased heartbeat

• bronchodilation

• prepares body for intense physical activity

Adrenal Cortex

produces glucocorticoids like cortisol and cortisone

• raises blood glucose levels

• degrades adipose tissue to use as energy

produces mineralcorticoids like aldosterone

• increases reabsorption of Na+ and excretion of K+ in kidneys

• causes passive reabsorption of water in nephron which raises blood pressure

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