The Endocrine System

The Endocrine System Body has two systems for control Electrical Nervous system Chemical Endocrine system Chemical compounds released into the blood stream Hypothalamus: Area of the brain that turns electrical signals into chemical signals Changes in homeostasis turn on the pituitary gland Pituitary gland releases hormones into the blood stream

Types of Glands Gland organ that secrets chemicals Exocrine glands release chemicals from the body or into the digestion system (Pancreas) Endocrine glands release chemicals directly into the blood (Pituitary) Prostaglandins released by any cell for local communication

Types of Hormones Two types of hormones: Steroids - lipid-soluble; easily diffuses into cells through the plasma membrane - inside the cell steroids react receptors that activate mRNA synthesis Examples: Cholesterol signals production of bile; Vitamin D Testosterone signals males to develop male characteristics during puberty

Types of Hormones Two types of hormones: Examples: 2) Amino Acid Hormones - bind to specific receptors on the plasma membrane - Receptor on target cell will then activate an enzyme, open an ion channel in the membrane, or start some chain reaction Examples: Serotonin regulates mood, appetite, and sleep Insulin regulates blood sugar level

Hormones And Target Cells Hormones are designed to attach to a specific binding sites (receptors) on a specific type of cell (target cell) They can have one or multiple binding sites Regulated by Negative Feedback Inhibition Chain reaction from binding to receptor releases signal that stops the release of the hormone

Blood Sugar Regulation Glucose is major source of energy (cellular respiration) Regulated by two opposing hormones and negative feedback inhibition Glucagon promotes breakdown of glycogen to release glucose; happens when hungry or during exercise Insulin lowers glucose levels after eating Diabetes cannot regulate glucose because defective or missing insulin

Water Levels in the Blood Blood consists of blood cells, white blood cells and plasma (water and various other molecules) Plasma thickness is highly regulated by Antidiuretic Hormone (ADH) After losing water through exercise or by taking in diuretics (alcohol, coffee, sugar drinks), ADH is released due to low H2O levels in the blood Kidneys react to ADH and start absorbing as much water as possible Signal also informs us we need water (thirsty)

Additional Endocrine Glands Adrenal Glands: Located onto top of the kidneys; made of two parts Outer portion releases steroids Ex: Glucocorticoids and Aldosterone which raise blood sugar and blood pressure Inner portion releases Amino acids hormones Ex: Epinephrine and Norepinephrine which raise heart rate, blood pressure, and respiration Why releases all these hormones at once?

Additional Endocrine Glands Fight or Flight Response (Adrenaline Rush) Instinct when in conflict to fight the enemy or run for safety Results in raised heart rate, reaction time, blood pressures, respiration rate Sometimes you may empty waste to be as light as possible

Thyroid/Parathyroid Gland Thyroid releases hormones to regulate growth, metabolism, and development Examples: Thyroxin- regulates energy use in the body Calcitonin- regulates calcium levels Parathyroid releases hormones to regulate mineral intake and use Parathyroid Hormone (PTH)- regulates calcium, phosphate, and magnesium levels

Review Neo and Batman get into a fight. Batman punches Neo in his shoulder. The pressure from Batman’s fist pass into the skin, muscle tissue and bones in Neo’s body. Pressure sensors are fired and an electrical signal is sent. 1) Where does the signal go? 2) What endocrine gland is activated because of the signal? The pituitary gland releases endorphins (pain numbing hormones) which enter the blood stream 3) Where in Neo’s body do they go? 4) How do the endorphins react to the muscles cells? The Hypothalamus Pituitary Gland Muscle cells in the shoulder Bind to receptors on the plasma membrane

Review As the fight continues, Batman is throwing many punches at Neo. Neo is quickly learning to dodge them so not to take any damage. Neo’s reflexes are increasing and he is moving faster 5) What has happened to Neo? 6) What gland has caused this to happen? 7) What hormones are causing this increase in speed? 8) What physical changes has Neo’s body gone through because of the hormones? He is in “Fight or Flight Mode” Adrenal Gland Glucocorticoids, aldosterone, epinephrine, norepinephrine Increase heart rate, breathing, blood pressure, etc…

Review After a series of fast punches from Neo, Batman gives up and runs away. Neo starts to relax after a few minutes. His breathing is normal and his heart slows down. However, his glucose levels are still high. The glucocorticoid is still active. 9) What type of hormone is glucocorticoid? 10) What hormone must be released to lower Neo’s blood sugar level? 11) What type of system is this called? Steroid Insulin Negative Feedback Inhibition

Review Now the fight is over Neo feels hungry. His shoulder bone has taken damage in the fight. 12) What gland will slow Neo’s metabolism until he gets food? 13) What element is needed to fix the bone and where can Neo get is from? 14) What hormone will increase the absorption of Ca+ from Neo’s lunch? What gland will produce this? 15) What hormone will increase the Ca+ in the blood so repairs can start? Thyroid gland Calcium PTH from the Parathyroid gland Calcitonin