The endocrine System and Hormones 2.3.1- Chemical Messengers 2.3.2- Hormones Gone Wild

The Basics The Endocrine System is a collection of glands that produce hormones. Endocrine Glands (glands secrete chemical substances) Pituitary gland Thyroid gland Parathyroid gland Adrenal gland Pancreas Ovaries/Testicles Hypothalamus Hormones regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood.

Pituitary Gland (aka- The Master Gland) The pituitary gland regulates growth, puberty, the thyroid, reproductive function, ACTH (in the adrenal gland), and ADH. Without the pituitary gland, the thyroid gland and adrenal gland cannot function properly, which are also responsible for releasing hormones.

Thyroid Gland T4, T3, and calcitonin are the main hormones produced. Regulates breathing, heart rate, nervous system, body weight, muscle strength, menstrual cycles, body temperature, cholesterol, and more! T4, T3, and calcitonin are the main hormones produced. T4 is converted into T3 using energy from ATP, Na ions, K ions in ATPase mediated sodium transport In order for the thyroid to produce hormones, the hypothalamus must release thyrotropin releasing hormone, which signals the pituitary to release thyroid stimulating hormone, which tells the thyroid to release thyroid hormone.

ParaThyroid Gland Provides Electrical energy for the nervous system Regulates calcium Provides Electrical energy for the nervous system Electrical energy for the muscular system Strong skeletal system

Hypothalamus Some hypothalamus hormones that you may have heard of… The hormones from the hypothalamus govern physiologic functions such as temperature regulation, thirst, hunger, sleep, mood, sex drive, and the release of other hormones within the body.  Some hypothalamus hormones that you may have heard of… Human Growth Hormone Oxytocin (aka- the love hormone) Dopamine

Pineal Gland The pineal gland regulates circadian rhythm and seasonal patterns. Melatonin is a derivative of serotonin and regulates sleep patterns. It is produced when the body senses it is bed time (darkness).

adrenal Gland The adrenal glands are small glands located on top of each kidney. They produce hormones that you can't live without, including sex hormones and cortisol. Cortisol helps you respond to stress and has many other important functions.

Pancreas The main function of the pancreas is to produce hormones that help us convert the food we eat into energy

Are there other entities that secrete hormones? Yes! Even your adipose tissue (fat tissue) can release hormones. Some hormones need to be detected by organs/cells and are released to send messages to the brain, rather than the other way around.

Different types of Hormones Peptide Hormones (aka- Protein hormones) are made of… you guessed it… Peptides! You of course remember from PBS that peptides are two or more amino acids joined together, and that amino acids are the monomers of the polymer, protein. Steroid Hormones are made from cholesterol. Steroids are a class of lipids (fats). You of course remember from PBS that cholesterol travels through the blood stream via lipoproteins… like cholesterol, steroid hormones are transported attached to carrier proteins.

Different types of Receptors Cell Surface Receptors, as the name implies, are on the surface of the cell. Hormones that are not fat soluble (like hormones made of proteins) cannot enter the cell membrane, so they signal the cell by binding to receptors on the outside of the cell. Intracellular Receptors, as the name implies, are inside of the cell. Hormones that are fat soluble (like hormones made of lipids) can enter the cell and they will signal the cell by entering the cell membrane and binding to receptors inside the cell. Because these hormones enter cells, they are able to interact with molecules on the interior of the cell, such as DNA. Therefore, they are able to turn on and off genes (or turn on and off transcription). Once hormones (first messenger) bind to the intracellular receptors, they can also cause secondary messengers to signal cell responses.