The Endocrine System By Carl Antiado, Marco Habana, Cameron Loewen, and Nikki Ooka
Standards 2.C.2 : Organisms respond to changes in their external environments. 4.A.4: Organisms exhibit complex properties due to interactions between their constituent parts.
Hormones Hormones are chemical signals that are excreted by the endocrine glands. All hormone secreting glands in collection are called the endocrine system. Target cells are the cells that have receptors for a specific type of hormone Hormones have distinct effects, cells aren t going to be affected without a receptor. Because of this a hormone can affect a variety of different sites or a singular site. Hormones take a few seconds to be sent into the bloodstream but the effects can last minutes or hours depending on how long the hormone can remain in the blood. The stimulus responsible for triggering an endocrine response can either be an organic molecule or ion or a response from the nervous system(neuroendocrine signaling) The two type of hormones are either lipid or water soluble, and this determines how the signal is received(inside cell or outside cell.) Water soluble hormones work by binding to the receptor protein of a target cell which causes it to use a signal transduction pathway to either use a relay molecule to change something in the cytoplasm or the genetic code. Water soluble hormones are all made of amino acids, the three forms it comes in are amine, peptide, and protein. Lipid soluble hormones work by passing through the membrane and binding to receptors on the inside. The hormone and receptor will form a complex and become the signal and will enter the nucleus to either turn on or off transcription for the production of a protein.
Feedback Negative feedback-control circuit or loops that reduces or dampens the stimulus. Keeps physiological systems within a normal limit. Positive feedback-response reinforces the stimulus, leading to more of the response. Needed in driving something to its completion. Signal transduction is what dictates the cell response
The Endocrine System Endocrine system-one of the two major systems for coordinating and controlling responses to stimuli. This is done through signals being carried through the bloodstream. The signaling molecules are called hormones (Greek:Horman, to excite). Endocrine cells are often grouped in ductless organs(product is secreted directly into bloodstream) called endocrine glands. The endocrine system s main focus in the body is to coordinate and monitor gradual changes that affect the whole body. Such functions would be growth, development, reproduction, metabolic processes, and digestion. The parts of the endocrine system are the hypothalamus, pituitary gland, thyroid gland, parathyroid gland, adrenal glands, pancreas, and the gonads. Endocrine is comprised of the prefix-endo, meaning in or inner, and the suffix-crine, meaning excretions.
Hypothalamus The hypothalamus is the main control of the endocrine system, it uses nerves to know about the internal and external conditions and sends nervous or endocrine signals appropriately. It also is directly connected with the pituitary glands and uses it to excrete hormones. The hypothalamus is responsible for neuroendocrine signaling which can cause a hormone cascade. This is where the nervous system conveys stimulus to the hypothalamus. In response, the hypothalamus secretes a factor that regulates the release of a specific anterior pituitary hormone. This hormone in turn stimulates an endocrine organ to secrete yet another hormone, which then has a specific target.
Pituitary Glands There are two lobes of the pituitary gland the anterior and posterior 1. the posterior is directly connected to the hypothalamus and stores its hormones 2. the anterior is controlled by hormones secreted into it by short blood vessels from the hypothalamus. Growth hormone is secreted by the anterior pituitary gland and has direct influence on how much a person can grow. Diseases related to this hormone are gigantism and dwarfism. Some of the more important hormones released by the pituitary glands are Thyroid Stimulating hormone, follicle stimulating hormone, and endorphins. Which respectively control the thyroid, the menstrual cycle, and pain regulation.
Thyroid and Parathyroid *The thyroid gland is located under the voice box *Secretes hormones that are necessary for development and maturity, focuses on nerve and bone cells *Triiodotyronine (T3), Thyroxin (T4) *Calcitonin, which decreases the calcium in the blood *The parathyroid are four disc in the Wings of the Thyroid *Produces Parathyroid Hormone (PTH) which releases calcium from our bones to the blood *Antagonistic to the Thyroid
The Thymus Gland *Necessary in supporting the immune system *Developmental center for the T-cells *Produces Thymosin which stimulates T-cell growth. *The Thymus shrinks and is replaced by fatty tissue proceeding puberty
The Pancreas The pancreas, in between the kidneys, is responsible for the balance of sugar in the bloodstream with its two hormones glucagon and insulin. Insulin will be made by the beta cells in the pancreas and released whenever blood sugar levels are too high, the insulin then binds to the receptors on cells allowing a signal transduction that allows a gateway to open that lets sugar enter the cell. In opposition, Glucagon will be made by the alpha cells in the pancreas and will be released whenever blood sugar levels are too high. This will also bind on a receptor and have a signal transduction that will break down glycogen and release glucose into the blood.
Adrenal Glands There are two adrenal glands both on each kidney and are composed of the adrenal medulla and the adrenal cortex. 1. The adrenal medulla is responsible for short term responses to stress with epinephrine and norepinephrine that cause alertness and energy bursts. 2. The adrenal cortex has a longer approach to stress that causes the synthesis of glucose from proteins and fats and in some cases can repress certain defense systems.
Gonads Gonads, they are responsible for development, growth, and sexual reproduction. Both male and females have three types of sex hormones, 1. Progestins 2. Estrogen 3. Androgens Females have a high ratio of estrogen to androgen, which gives them womanly features, while males have a high ratio of androgen to estrogen which gives them facial hair, deeper voices, and larger bones.