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26 Cards in this Set
- Front
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Hormone
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A chemical messenger secreted into interstitial fluid and then diffused into blood vessels. From there it travels via blood to site of action, & binds to target cells. It's purpose is regulation and it is slower acting that Nervous Regulation. |
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Target cells
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Cells that receive hormones and respond
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Neurosecretory cells
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They form the chemical relationship between the nervous system and the endocrine system. One example is ADH |
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Endocrine glands
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Ductless organs such as the thyroid where endocrine cells are grouped. They secrete hormones directly into the surrounding fluid. By contrast, exocrine glands like salivary glands have ducts which carry secreted substances onto body surfaces or into body cavities. |
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Tropic hormones
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A hormone that acts on another endocrine gland. It causes the release of another endocrine hormone Tropic hormones regulate the function of other endocrine cells or glands. |
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Peptide hormones
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Hormones whose molecules are made up of peptides. They are water-soluble and insoluble in lipids. |
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Steroid hormones
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Lipids that contain four fused carbon rings. All are derived from the steroid cholesterol. They are lipid-soluble and can pass through cell membranes easily. Receptors for lipid-soluble hormones typically reside in the cytoplasm or nucleus. |
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Catecholamine
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A class of amine hormones synthesized from the amino acid tyrosine. Two hormones of the adrenal medulla, norepinephrine (noradrenaline) and epinephrine (adrenaline), are catecholamines. |
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Transcription factors
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A protein that binds to specific DNA sequences within the nucleus, thereby altering transcription of particular genes by interacting with a specific DNA-binding protein or response element in the DNA. Steroid hormones (lipid-soluble) can bind to receptors in the nucleus that activate transcription of genes for particular proteins. |
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Signal transduction pathways
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The series of changes in cellular proteins that converts extracellular chemical signal into a specific intercellular response. For peptide hormones (water-soluble, but not lipid/membrane-soluble), receptors in the plasma membrane can receive the hormone (extra-cellular signal) thereby triggering an intercellular response. This can be the activation of an enzyme, a change in the uptake or secretion of specific molecules, or a rearrangement of the cytoskeleton. In addition, some cell-surface receptors cause proteins in the cytoplasm to move into the nucleus and alter transcription of specific genes. |
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Hypothalamus
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A region of the brain that links the nervous and endocrine system. It plays a key role in homeostatic regulation. It receives information from nerves from all parts of the body and other areas of the brain, then initiates an appropriate endocrine response depending on the body's internal environment. It works by producing inhibiting hormones and releasing hormones, and by producing hormones which are then stored in the pituitary gland. |
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Anterior pituitary
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An endocrine gland that that synthesizes and secretes hormones in response to signals from the hypothalamus. Many anterior hormones act as tropic hormones.
It produces either inhibiting hormones that cause the pituitary to stop secreting, or releasing hormones that act to cause secretion of hormones. |
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Posterior pituitary
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An extension of the hypothalamus, growing downward. It stores and secretes two hormones: 1. Oxytocin, which acts on muscles in uterus and causes increasing contractions. It also causes mammary glands to eject milk in nursing. 2. ADH - antidiuretic hormone, which regulates the osmolarity of the blood by increasing the permeability of the nephron to water. |
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Pineal gland
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Produces melatonin, the sleep hormone. It has nervous connections to eyes, It plays a role in regulating biological clock and biological rhythms. It secretes at night, so more melatonin is produced in the winter |
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Thyroid gland
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An organ consisting of two lobes on the ventral surface of the trachea. It produces Calcitonin if blood Ca^2+ rises above a set point, which lowers blood calcium, and stimulates calcium decomposition in bone (for bone remodeling). Calcitonin also decreases calcium uptake in the nephron, so more Ca^+2 is excreted. The thyroid also produces Triiodothryonine (T3, more active than T4), and thyroxine (T4) which stimulate and maintain metabolic processes. They increase the rate of oxygen consumption and cellular metabolism, and play a role in homeostasis (BP, heart rate, digestive and reproductive function) and vertebrate development and maturation. |
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Parathyroid gland
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Four glands which make PTH = parathyroid hormone, which is release when blood Ca^2+ falls below a set point. It causes bone to mineralize, thereby RAISING blood calcium rather than decreasing it like Calcitonin does. It also raises Ca^2+ levels by effecting the kidneys. It stimulates the reabsorption of Ca^2+ and coverts Vitamin D to Calcitriol, which functions as a hormone. Calcitriol stimulates calcium reuptake in the digestive tract. Tetany, the convulsive contractions of muscles due to lack of PTH (parathyroid hormone) can be fatal. |
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Pancreas
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Releases insulin and glucagon to maintain blood glucose level. They are both protein hormones. Insulin lowers blood glucose level and encourages the liver and blood to store glucose, while glucagon pushes the liver to release glucose. |
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Glucagon
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When there exists an absence of glucose in the blood (e.g., after skipping a meal), alpha cells of the pancreas stimulate the release glucagon into the blood. This pushes the liver to break down its stored glycogen and release glucose into the blood. When blood glucose rises to a set point, the stimulus for glucagon release diminishes. |
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Insulin
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When blood glucose is too high (e.g., after eating a carbohydrate-rich meal), beta cells of the pancreas release insulin into the blood. This stimulates body cells and the liver to take up more glucose, with the liver storing it as glycogen. When blood glucose declines to a set point, the stimulus for insulin release also diminishes. |
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Adrenal medulla
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The central portion of the kidneys (the "renal organs"). It has close ties with the nervous system because its secretory cells are derived from neural tissue during embryonic development. It releases catecholamines norepinephrine and epinephrine in response to stress. It has different cells types, functions, and embryonic origins than the adrenal cortex. |
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Epinephrine
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Adrenaline. It causes the breakdown of glycogen in the liver, providing the fuel you need to move quickly. It has a greater effect on heart rate and metabolic rate than norepinephrine. |
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Norepinephrine
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Noradrenaline. Like epinephrine, it increases the rate of glycogen breakdown in response to stress -- whether extreme pleasure or life-threatening danger. Also causes release of fatty acids from fat cells. Goal is to provide more chemical energy. It plays a greater role in regulating blood pressure than epinephrine. |
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Adrenal cortex
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Outer part of the kidney. Responds to adrenocorticotropic hormone (ACTH) from the Anterior pituitary. ACTH causes the adrenal cortex to make and secrete corticosterioids, a family of steroids. There are two main types of corticosteroids which are released by the adrenal cortex: glucocorticoids and mineralocorticoids. (Also sex hormones are third type of corticosteroids, with low levels in adrenal cortex). |
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Glucocorticoids
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Steroids which have a primary effect upon glucose metabolism. They promote the synthesis of glucose from noncarbohydrate sources, such as proteins, making more glucose available as fuel. |
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Mineralocorticoids
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Steroids which have a major effect on mineral metabolism. THey act principally in maintaining salt and water balance. For example, the mineralocorticoid aldosterone functions in ion and water homeostasis of the blood. |
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Pituitary gland
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It illustrates the close relationship between the nervous and endocrine systems. |
