The Endocrine System

Endocrine Introduction The Endocrine System works with the Nervous System to maintain homeostasis. The Endocrine System consists of special organs called glands which secrete chemicals called hormones into the bloodstream The blood carries these chemicals to all parts of the body. When these chemicals reach the intended organ, they initiate a chemical reaction.

Endocrine Introduction Hormones do not ‘seek’out particular organs, but rather organs await the arrival of the hormone. Cells that react to a particular hormone have specific receptors for that particular hormone. The receptors combine with the hormone in a ‘lock-and-key’ fashion.

Endocrine Introduction Some of the regulatory functions of the endocrine system include: 1.Heart rate 2.Blood pressure 3.Immune system response to infection 4.Reproduction 5.Emotional state - mood 6.Overall growth & development

Major Components of the Endocrine System

Glands Glands: organs which are specialized to produce chemical substances needed by the body. –exocrine glands - glands produce chemicals which travel to target organ through channels or ducts. i.e. sweat glands, tear glands, salivary glands, mammary glands and secrete substances such as sweat, saliva, tears, milk, or digestive enzymes –endocrine glands - chemicals produced by glands are released into the bloodstream and make their way all around the body. – -“ductless” system; glands secrete hormones directly into the bloodstream usually for maintaining longer term processes.

Hormones Hormones: chemical signals that are sent to many parts of the body; examples are adrenaline and noradrenaline from the neurons of the adrenal glands Referred to as ‘chemical messengers’ These chemicals travel throughout the body via the blood stream and regulate overall metabolism, maintenance of homeostasis, reproduction and vital body functions. –Hormones are only able to produce their effect in the specific target organ. -hormone production increases or decreases in response to changing metabolic needs of the body (fluid balance, infection, injury, stress, etc.)

Target organ: organ that contains receptors for a particular hormone Intro: m3T3U

Types of Hormones (1) Steroid Hormones – Secreted in the blood quickly by the endocrine organs that produce them. – They are Fat soluble, and pass through the membrane of a target cell and the nuclear envelop. – Inside the target cell steroid hormones attach to a protein receptor molecule in the cytoplasm. – The hormone-receptor complex binds to a specific part of the cell’s DNA, activating a gene. This gene produces an enzyme which causes the desired changes.

Types of Hormones Non-steroid hormones Also called: first messenges ex. Adrenaline, thyoxine, glucagons, etc. Water soluble Do not enter the cell. They bind to receptors on the surface of target cell and cause ATP(adenosine triphosphate) to change into cAMP (cyclic AMP) or second messenger. This cAMP activates an entire series of enzyme reactions in the cell, which results in the desired changes.

HormoneSolubility in Cell Membrane Location of Receptors End Result SteroidSolubleWithin cellGene produces a Protien NonsteroidInsolubleSurface of cellcAMP causes chain reactions

Hormones Antagonistic Hormones –Hormones that work against each other or have the opposite effects. Insulin and glucagon Tropic Hormones –Hormones that regulate the hormone production of many other glands. Thyroid Stimulating hormone (TGH)

Hormone Problems/Disorders Hyposecretion- an under secretion of a hormone within the body Hypersecretion- an over secretion of a hormone within the body.

Gland Man esource.html

Pituitary gland called the “master gland” –It controls the function of other endocrine glands actually two glands: anterior and posterior Anterior: Largest portion. Located towards the front of the head. –Produces 6 different hormones: Human growth hormone, Adrenocorticotropic Hormone (ACTH), Prolactin, Thyroid Stimulating hormone (TSH), Follicle Stimulating hormone (FSH) and Lutenizing hormone (LH) Posterior: Smaller of the two glands. Located on the back. It stores hormones, but does not make any. –Secreats 2 hormones : Oxytocin and Antidiuretis Hormone

Glands of the Endocrine System Hypothalamus controls the endocrine hormone system (as well as the autonomic nervous system). It monitors the blood and send out hormones from glands when needed. The hypothalamus plays a key role in the body’s response to stress. It produces 2 hormones (both stored and secreted from the posterior pituitary gland) –1. ADH (anti-diuretic hormone): controls water levels –2. oxytocin: triggers muscle contractions in childbirth and promotes lactation interacts constantly with the pituitary gland

Thyroid Gland Located in the throat Butterfly, or bowtie Regulates metabolism and growth Produces Thyroxine and Calcitonin –Help increase metabolism rate and oxygen consumption.

Parathyroid Located on the surface of thyroid gland Regulates calcium levels Produces Parathyroid Hormone –Causes bones to release calcium into blood stream. –Causes kidneys to reabsorbed calcium from blood, therefore increasing the amount of calcium in the body.

Pancreas (Islets of Langerhans) Located near small intestine. Helps regulate blood glucose levels. Contain specialized endocrine cells called Islets of Langerhans Which are made up of Alpha and Beta cells. Secretes Insulin and Glucagons.

Pineal Gland Located deep in the brain Regulates circadian rhythm Produces Melatonin –Causes a feeling of “sleepiness” and aids with sleep

Thymus Gland Located between the lobes of the lung in the upper chest. Helps regulate the immune system Produces thymosin –Casuses the production and maturation of lymphocytes into T-cells (help fight infection)

Adrenal Gland Located on top of kidneys Regulates body’s metabolism Two layers: -Outside: Adrenal Cortex - Inside: Adrenal Medulla »Both are controlled by the Hypothalamus. Three Major Hormones: –Aldosterone: regulates blood pressure and salt levels in blood –Cortisol: Reduces inflammation and causes glucose to be made by the liver –Sex Hormone: Males- hormone called “Androgens” Females: hormone called “Estrogens”

Gonads: Ovaries and Testes Reproduction Ovaries- found in females Produce: Estrogen-controls secondary sex characteristics in females and prepares the uterus for pregnancy. -Progesterone-Maintains uterus during pregnancy. Testes- found in males Produces testosterone »Controls secondary sex characteristics in males (traits that distinguish the two sexes of a species, but that are not directly part of the reproductive system)

Next class hormones melatonin thyroxine adrenaline somatotropin (HGH – human growth hormone) insulin glucagon