The Endocrine System Miss Richardson SBI4U
The Endocrine System The nervous system uses specific molecules (hormones) as signals to control the vertebrate body Advantages of chemical messengers: Chemical messengers can spread to all the tissues via the blood Hormones have a specific shape that will only work on organs, tissues that are a match.
Hormones Released from endocrine glands as steroid or protein Can be transported or stored to the target cell Induce long-lasting effects
Endocrine Glands Over 200 hormones have been identified and are secreted from tissues and organs known as endocrine glands Endocrine glands are ductless regions that produce hormones Endocrine glands (exclusive): Pituitary Pineal Thyroid Parathyroid Adrenal Other tissues and organs contribute: Hypothalamus Thymus Pancreas Testes Ovaries
Endocrine Glands
Sending Molecular Signals CNS controls hypothalamus, which regulates release of hormones from pituitary Hormones can act on nearby cells or be transported through blood until they reach a cell with matching receptor (target cell) Target cell carries the receptor protein which will bind to hormone, changing its shape Cellular activity is triggered
Steroid Hormones Located in cytoplasm of target cell Lipid soluble and can pass through cell membrane Once inside cell, binds to receptor protein forming receptor-hormone complex Complex binds to DNA and changes gene activity by inhibiting or promoting transcription
Protein/Peptide hormones Water soluble Don’t enter target cell Hormone receptors located within cell membrane Protein hormone binds to receptor which triggers events within cytoplasm through secondary messengers Secondary messengers amplify original signal
Pituitary Gland Located in the brain, linked to hypothalamus 2 regions: Anterior – controlled by hypothalamus Growth hormone, THS, adrenocorticotropic hormone, gonadotropic hormone, prolactin Posterior – controlled by nerves Antidiuretic hormone, oxytocin
Hypothalamus Region of the middle of the base of the brain, responsible for regulation of many functions Body temperature Hunger Moods Sleep Sex drive Thirst
Thyroid Gland Consists of two lobes, located in neck below larynx Produces thyroxine (T4) which increases metabolic rate Also produces triiodothyronine (T3) and calcitronin Responsible for regulation of metabolism
Thyroid Gland - calcitronin Calcitronin regulates calcium levels in blood Essential for healthy teeth and bone development
Parathyroid Gland On surface of thyroid gland Release parathyroid hormone in response to low calcium levels