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63 Cards in this Set
- Front
- Back
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Hormones |
- are chemical messengers secreted into the blood by specialized cells to a specialized target - under hormonal control: growth and development, metabolism, regulation of the internal environment and reproduction - excrt their effect at a very low concentrations, if they do not meet the range than they are not considered to be hormones |
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Hormones Act on Target Cells |
1) by controlling the rates of enzymatic reaction 2) the controlling the transport of ions or molecules across cell membranes 3) by controlling gene expression and the synthesis of proteins |
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Classic Steps of Identifying Endocrine Gland |
1) Remove the suspected gland - will have deficiency if the gland does produce hormones 2) Replace the hormone - placing back in animal and will see the elimination of hormone deficiency 3) Create a state of hormone excess - implant extra gland in animal to crate hormone excess |
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Secretion |
- the movement of substance for inside a cell to the extracellular fluid or directly into the external environment |
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Ectohormone |
- name for signal molecules that secreteed into the external environment |
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Pheromones |
- are specailized ectohomrones that act on other organisms of the same species to elict a physiological or behaivoral response |
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Candidate Hormones (Factor) |
- molecules that are suspected of being hormones but not fully accepted as such |
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Growth Factors |
- large group of substances that influence cell growth and divison |
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Cellular Mechanism of Action |
- all hormones bind to target cells receptors and indicate biochemical responses |
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Insulin Affects In Particular Cell |
- Muscle and adipse tissue: isuling alters glucose transport protiens and enzymes for flucose metabolsim - Liver: it modulates enzyme activity but has no direct effect on glucose transport proteins - Brain: glucose metabolism is totally independent of insulin |
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Response of homormone depends: |
- primarly one the cell's receptor and signal transduction pathways |
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Hormone Degration |
- hormones are brocken down into inactive metabolites by enzymes foudn in the liver and kidneys - metabolites are then excreted in either the bile or the urine |
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Half life |
- indicated the rate of the breakdown - the amount of time required to reduce the concentration of hormone by one half |
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Hormones Bound to Cell Membranes Termination |
- enzumes present in the plasma can degrade the peptide hormones bound to the cell membrane receptors - the receptor hormone complex is brought into the cell by endocytosis and the hormones is then digested in lysosomes |
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Preprohormones |
- initial peptide that comes of the ribosome is this large inactive protein - contain one or more copies of peptide hormones, a signal sequence that directs the protein into the lumen of rough ER and other peptide sequence that may or may not have biological activity |
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Peptide Hormone Sythesis and Processing |
1) Messenger RNA binds amino acids into a prephoromone. The chain is directed into the ER lumen by signal sequence of the amino acids 2) enzymes in the ER chop off the signal sequence, creating an inactive prohormone 3) the prohormone passes form the ER through the golgi complex 4) secretory vesicles containing enzymes and prohormone bud off the golgi. The enzymes chop of the prohome into one or more active peptides plus additional peptide fragments 5) the secretory vesicles releases it contents by exocytosis into the extracellular space 6) the hormones moves into the circulation for transport to its target cell |
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Secretory Vesicles |
- are stored inside the cytoplasm of the endocrine cell until the cell receives a signal for the secretion - move to the cell membrane and release their contents y calcium dependent exocytosis |
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Peptide Hormones |
- are water soluble and therefore generally dissolves easilly in the extracelullar fluid - half life are quite short in the range of several minutes - must be secreted continuously for long its response to stay sustained |
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Action of Peptide Hormones |
- initiates the cellular response through the signal transduction system - work through the cAMP second messenger system - is rapid because second messenger system modify existing proteins - include opening or closing membrane channels and modulating metabolic enzymes or transport proteins |
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Adrenal Cortex |
- the outer portion of the adrenal glands makes several types of steriod hormones |
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Adrenal Gland |
- atop of each kidney - the gonads produce sex steriods |
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Steriod Hormones |
- cells that secrete have unusually large amounts of smooth enplasmic recticulum - are lipophilic and diffuse easily across the membrane - they are synthesized as they are needed - |
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Sythesis of Steriod Hormones |
1) most hydrophobic steriods are bound to protein carriers. only unbound hormones can diffuse into the target cells 2) steroid hormone receptors are in the cytoplasm or the nucleus. Some receptors also bind to membrane receptors that use second messenger systems to create rapid responses 3) the receptor hormone complex binds to DNA and activates or represses one or more genes 4) activated genes create new mRNA that moves back to the cytoplasm 5) translation produces new proteins for cell processes |
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Transport Proteins and Steriod Hormones |
- carrier steriod complex reamins outside the cell becasue the carrier proteins are lipophobic and cannot diffuse through the membrane - unbound hormone molecule can diffuse into the target cell |
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Nongenomic Responses |
- signal trasnduction pathways that have receptors that allow steriod hormones to have a rapid response |
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Catecholamines |
- derive form tyrosine - modification of a single tyrosine molecule - are neurohormones that bind to cell membrane receptors the way peptide hormones do |
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Thyroid Hormones |
- drived form tyrosine - made from two tyrosine molecules plus iodine atoms - produced by the butterfly shaped thyroid gland in our neck, behave more like steroid glands with intracellular receptors that activate genes |
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Simple Endocrine Reflex |
- endorcrine cell controls directly sense a stimulus and repsonds by secreting its hormone - endocrine cell acts as both sensor and integration center |
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Parathyroid Hormone |
- an exmaples of ahormones that operates via the simple endocrine reflex - is secreted by four small parathyroid glands that lie behind the thyroid gland - parathyroid endocrine cells monitor the plasma Ca 2+ concentration on the cell membranes - if Ca 2+ is low, inhibition cease and the parathyroid cells secrete parathyroid hormone - PTH travels through the blood and acts on bone, kidney, and intestine to increase concentration of Ca 2+ - increase in Ca 2+ is a negative feedback signal that turns off the reflex |
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Nuerohormones |
- are chemical signals released into the blood by neurons - three major groups: catecholamines, hypothalamic, hypothalamic |
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Pituitary Gland |
- lima bean sized strucutre that extends downward from the brain connected to it by a thin stalk and cradled in a proective pocket of bone - |
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Anterior Pituitary Gland |
- trkue endocrine gland of epithelial origin drived from embryonic tissue that formed the roof of the mouth - hormones are adenohypophyseal secretions |
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Posterior Pituitary Gland |
- extension of the nueral tissue of the brains - it secretes neurohormones made in the hypothalamus a region of the brain that controls many homeostatic functions |
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Posterior Pituitary Hormones |
- storage and release of oxytocin and vasopressin - each made in a separate cell type and the synthesis and processing follow the standard pattern for peptide hormone - once packaged in secretory vesicles the vesicle is transported to the posterior pituitary through long extensions of axons - stored in axons terminals until they are waiting for their release |
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Posteiror Pituitary Secretion Process |
1) nuerohormone is made and packed in cell body of nueron 2) vesicles are transported down the cell 3) vesicles contains neurohormones are stored in the posterior pituitary 4) neurohormones are released in the blood |
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Vasopressin |
- acts on the kidneys to regulate water balance in the body |
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Oxytocin |
- controls the ejection of milk during breast feeding and contractions of the uterus during labor - a few neurons release it as a neurotransmitter or neuromodulator onto neurons in other parts of the brain |
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Tropic Hormone |
- a hormone that contols the secretion of another hormone - usually have suffixes that end in -troponin |
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Anterior Pituitary |
- secretes six homrones: prolactin, thryoidtroponin, adrnocortiocotropin, growth homrone, follicle stimulating hormone, and luerinizing hormone |
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Nuerohormones |
- signals that regulate the secretin of the anterior pituitary hormones come form the brain - secreted from the hypothalamus |
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Hypothalamic Phyophyseal Portal System |
- system in which hypthatlaus hromes travel form the hypothalamus to the pituiary gland through blood vessels |
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Portal Sytem |
- specailized region of the circulation consiting of two sets of capillaries connected in series by a set of larger blood vessles - hormones secreted here are given the advantage that a much smaller amount of hormone ban be secreted to elicit a given level of response |
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Anterior Pituitary |
- master gland of the body because controls many vital functions - controls metabolism, growth, and reproduction |
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Prolactin |
- controls the milk production in the female breast - regulation of the immune system |
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Growth Hormone |
- affects metabolism of many tissues in additon to stimulating hormes whose secretion is controlled by both releasing hormones and inhbiting hormones |
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Follicle Stimulating Hormone and Luteinizing Hormone |
- known collectively: gonadotropins - known for their effects on ovaries but both hormones are trophic on testes as well |
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Thyroid Stimulating Hormone |
- cotnrols hormone sythesis and secretion in the thyroid gland |
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Adrenocortiocotropic Hormone |
- acts on certain cells of the adrenal cortex to control the sythesis and relase of steriod hormone cortisol |
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Long Loop Negative Feedback |
- last hormone in a pathway feeds back to suppress secretion of its tropic hormones |
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Short Loop Negative Feedback |
- pituitary hormones feed vack to decrease hromone secreation by the hypothalamus |
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Synergism |
- two or more hormones interact at their targets so that the combination yeilds a result that is greated |
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Permissiveness |
- one hormone cannot fully exert its effects unless a second homrne is present - |
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Antagonism |
- tow molecules that work against each other, diminishing the effectiveness of the other - compete for the same cell receptor |
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Hypersecretion |
- if a hormone is present in excessive amounts the normal effects of a hormone are exagerated - may result from the exogenous hormones or agonist - |
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Atrophy |
- the loss of cell mass - if cells of endocrine gland atrophy because of exogenous hormone administration they may be very slow or totally unable to regain function |
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Hyposecretion |
- symptoms of homorne defiency occur when to little hormone is secreted - most common cause of hypersecretion is atrophy of gland due to some disease process - absence of negative feedback loop causes trophic hormones levels to rise as the trophic hormones attempt to make the defective gland increase its hormone output |
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Down Regulation |
- caused when hormone secretion is abnormally high for an extended period of time |
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Hyperinsulinemia |
- is an example of down regulation - in this disorder, sustained high level of insulin in the blood cause target cells to remove insulin receptors from the cell membrane |
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Testicular Ferminizing Syndrome |
- androgen receptors are nonfunctional in the male fetus becasue of a genetic mutation - as a result androgens produced by the developing fetus are unable to influence development of genitalia |
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Gentic Alterations in Signal Tranductions |
- can lead to symptoms of hormone excess or defiency |
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Primary Pathology |
- if a deficiency arises in the last endocrine gland in a reflex |
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Secondary Pathology |
- if the dysfunction arises in of the tisseus producing tropic hormones |
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Evoltionary Conservation |
- hormone function is also demonstrated by the fact that some hormones from other organisms have biological activity when administered to humans |
