Exam 2 Ch.7 Introduction to Endocrinology PDF

Exam 2 Ch.7 Introduction to Endocrinology The Endocrine System communicates via Chemical Release. Types of chemical releases: Paracrine: chemicals that target nearby cells. Autocrine: chemicals that targets itself Neurocrine: chemicals released by neurons (nerve cells).These chemicals can be release...

Exam 2 Ch.7 Introduction to Endocrinology The Endocrine System communicates via Chemical Release. Types of chemical releases: Paracrine: chemicals that target nearby cells. Autocrine: chemicals that targets itself Neurocrine: chemicals released by neurons (nerve cells).These chemicals can be released to another neuron, cell of another organ, or blood Exocrine: chemicals released into body surface Endocrine system is going to be the release of chemicals into blood. Chemicals that are released by the Endocrine systems are called hormones. Hormones are responsible for many bodily functions including: 1) Metabolism 2) Homeostasis: Regulation of internal environment (temperature, water balance, ions) 3) Reproduction, growth, development, sexual drive. Classify Hormones: Steroid Hormones Peptide Hormones Amine Hormones Steroid Hormones Steroid Hormones are Hydrophobic. They will easily cross the plasma membrane and bind to intracellular receptors. Made From: Cholesterol Steroid Hormones have a Long half life Carried around in blood by protein carriers Steroids generally will activate transcription/translation process to make proteins (DNA to RNA to protein...... protein synthesis) Steroid Hormones are released by the following organs: Organ Hormone release Adrenal Cortex: Cortisol and Aldosterone Ovaries: Estrogen Placenta: Progesterone Testes: Testosterone “Mechanism of Action for Steroid Hormones” Peptide Hormones (Protein Hormones) Most hormones in the endocrine system are peptide hormones These hormones range in size (few amino acids to few hundred amino acids) If a hormone is not an amine or steroid hormone, then it is a peptide hormones Short half life Hydrophilic molecules (need to bind to cell surface receptor on plasma membrane) Released widely by cells in body General function is to activate second messengers Peptide Hormones come from Prohormones Prohormones are the inactivated forms of peptide hormones. Cleavage needs to occur to have the activated peptide hormones ready for usage. Peptide Hormones bind to GPCR or Tyrosine Kinase Receptors Example of Peptide Hormones : 1. Insulin 2. Parathyroid hormones Amine Hormones Derived from single amino acids Example of Amine Hormones : MELATONIN Melatonin is derived from Tryptophan Melatonin is released by PINEAL GLAND. This hormone is secreted at night as we sleep (helps the brain in controlling your biological clock). There are 2 classes of Amino Hormones that are derived from Tyrosine. 1.-Catecholamines Examples: 1) Dopamine 2) Norepinephrine 3) Epinephrine 2.-Thyroid Hormones (have Iodine) Learning Objective 2: Describe the posterior pituitary gland pathway. ➔ The pituitary is actually 2 glands with different embryological origins. Both glands sit inferior to the Hypothalamus ➔ It sits in a protected pocket of bone, connected to the brain by a thing stalk ➔ Structure of Pituitary Gland: Infundibulum: is the stalk that connects the pituitary to the brain. Posterior Pituitary : extension of the neural tissue Anterior Pituitary: is a true endocrine gland of epithelial origin 1. Posterior pituitary gland pathway Is an extension of the brain that secretes neurohormones made in the Hypothalamus. Oxytocin and Vasopressin (ADH) (the 2 neurohormones released by the Posterior Pituitary Gland) Oxytocin and Vasopressin (the two neurohormones released by the Posterior Pituitary Gland) Vasopressin (ADH) 💦💦💦💦 Peptide hormone also called antidiuretic hormone (ADH) Acts on kidneys to regulate water balance in the body (maintain blood osmolarity levels) ADH release increases when there are high blood osmolarity levels (hypertonicity) Describe the negative feedback loop controlling blood osmolarity levels Oxytocin 💕💕💕💕 Peptide hormone Acts on mammary glands (ejection of milk during breastfeeding) Acts on uterus (uterine contraction during labor and delivery) Also known as the “love hormone” when released within the brain 💞 Describe the positive feedback loop of labor/delivery Nursing/Milk Delivery Learning Objective 3: Describe the anterior pituitary gland pathway. Anterior Pituitary Gland: Secretes 6 classic hormones Neurohormones from the Hypothalamus control release of anterior pituitary hormones. The hypothalamic hormones reach the anterior pituitary through a specialized region of the circulation called PORTAL SYSTEM Examples of trophic Neurohormones: 1. 2. 3. 4. 5. Dopamine→→→→→→→→→→ TRH→→→→→→→→→→→→→ CRH→→→→→→→→→→→→→ Somatostatin and GHRH→→ GnRH These neurohormones go to the portal system that is in the anterior pituitary. These neurohormones CONTROL hormones release in anterior pituitary. Hormones released by endocrine cells in anterior pituitary: Hormone Target organ 1. Prolactin→ Mammary Gland 2. TSH→ Thyroid Gland →T3 & T4 3. ACTH→ Adrenal Cortex →Cortisol 4. GH→ Liver →IGFs 5. FSH & LH→ Gonads(Ovary, testis) Progesterone, Estrogen and Androgen