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73 Cards in this Set
- Front
- Back
The endocrine system
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Second controlling system of the body "slow acting" control system, uses chemical messengers that are released into the blood
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Endocrine system hormones control what processes?
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Reproduction, Growth and development, mobilization of body defenses, maintenance of much of homeostasis, regulation of metabolism
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How hormones work
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1. Hormones are produced by specialized cells
2. Cells secrete hormones into extracellular fluids 3. Blood transfers hormones to target sites 4. These hormones regulate the activity of other cells |
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Hormone chemical classifications
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Amino acids, Steroids, Prostaglandins
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Amino acid classifications
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Proteins, peptides, amines
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Proteins
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Multiple chains of amino acids
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Peptides
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Single chain of amino acids
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Amines
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Modified single or double amino acids
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Steroids
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Made from cholesterol, include many different hormones including testosterone and estrogen
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Prostaglandins
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Made from highly active lipids, have local effects on reproductive function, blood pressure, etc..
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Mechanisms of Hormone action
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Hormones affect only certain tissues or organs,Target cells must have specific protein receptors, Hormone-binding alters cellular activity
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Effects caused by hormones
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1. Changes in plasma membrane permeability or electrical state
2. Synthesis of proteins, such as enzymes 3. Activation or inactivation of enzymes 4. Stimulation of mitosis 5. Promotion of secretory activity |
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Two mechanisms in which hormones act
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Direct gene activation, and second-messenger system
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Process of direct gene activation
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1. Steroid hormone moving through the blood enters interstitial fluid
2. Passes through the plasma membrane 3. Steroid binds to a receptor in the nucleus 4. Creates hormone-receptor complex which attatches to DNA 5. Initiates transcription (making mRNA) 6. mRNA transported out of the nucleus 7. Ribosomes use mRNA to create proteins 8. Proteins go to almost everything |
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Process of second messenger system
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1. Blood in the interstitial fluid bind to its receptor in plasma membrane
2. Receptor activates enzymes in the plasma membrane 3. Enzymes are then activated that create the second messenger 4. Cyclic AMP is the second messenger (inside cells) (hormone was first messenger) 5. Second messenger creates many cellular effects |
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How hormone release is controlled
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Mainly controlled by negative feedback, A stimulus or low hormone levels in the blood triggers the release of more hormone, Hormone release stops once an appropriate level in the blood is reached
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Hormonal stimulation of Endocrine glands
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Hormones are main stimuli
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Neural stimulation of endocrine glands
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Nerve impulses (action potentials) stimulate hormone release, most are under the control of the sympathetic nervous system
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Hierarchy of hormone release
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Hypothalamus--> Hormones--> Pituitary--> Hormones--> Endocrine glands
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Humoral stimulation of endocrine glands
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Changing blood levels of certain ions stimulate hormone release, relates to homeostasis of ions and molecules
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Humoral
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indicates various body fluids such as blood and bile
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Major endocrine organs
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Pituitary gland
Thyroid gland Parathyroid glands Adrenal glands Pineal gland Thymus gland Pancreas Gonads (Ovaries and Testes) Hypothalamus |
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Pituitary gland location
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Hangs by a stalk from the hypothalamus in the brain, rests in the “sella turcica” a saddle shaped bone,
Protected by the sphenoid bone |
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Lobes of the pituitary gland
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Anterior pituitary and posterior pituitary
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Anterior pituitary gland
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Glandular tissue, true endocrine gland
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Posterior pituitary gland
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Nervous tissue, extension of the hypothalamus (neurons)
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Hormones of the anterior pituitary gland
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Growth hormone, Prolactin, Thyroid-stimulating hormone (thyrotropic hormone) TSH,
Adrenocorticotropic hormone ACTH, Two gonadotropic hormones |
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Characteristics of all anterior pituitary hormones
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Proteins (or peptides), Act through second-messenger systems, Regulated by hormonal stimuli, mostly negative feedback
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Growth hormone (GH) disorders
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Pituitary dwarfism results from hyposecretion of GH during childhood
Gigantism results from hypersecretion of GH during childhood Acromegaly results from hypersecretion of GH during adulthood |
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Hormones produced by hypothalamus
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Oxytocin and Antidiuretic hormone, released by cells in the posterior pituitary
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Posterior pituitary
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neural tissue, extension of the hypothalamus, almost completely composed of axon terminals
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Pituitary–Hypothalamus Relationship
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Hormonal release is regulated by releasing and inhibiting hormones produced by the hypothalamus,These hormones are transported to neurosecretory cells of the posterior pituitary
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Thyroid gland location
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Found at the base of the throat
Consists of two lobes and a connecting isthmus |
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Thyroid gland function
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Produces two hormones:
Thyroid hormone and Calcitonin |
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Thyroid hormones
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Major metabolic hormone, T3 & T4, small hormones made from two tyrosine amino acids with iodine atoms attached, t3= 3 iodines, t4= 4 iodines
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Thyroid gland is stimulated by what?
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TSH (thyroid stimulating hormone), releases more thyroid hormones and gets bigger
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Goiter
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A thyroid gland disorder, swollen thyroid gland, the thyroid trys to make up for a lack of dietary iodine, throid gland swells in result
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T4
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Thyroid hormone, 99% of hormone produced by the thyroid, T4 turns into T3 at target tissues for a stronger effect
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Effect of T3 and T4
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Regulate (increase) metabolic rate, also important in development (of children). Necessary for reproductive function
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Follicular cells
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produce thyroid hormones (stored in follicles as colloid)
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Parafollicular cells
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produce calcitonin
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Cretinism
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Caused by hyposecretion of thyroxine, Results in dwarfism during childhood
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Myxedema
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Caused by hypothyroidism in adults
Results in physical and mental slugishness |
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Graves’ disease
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Caused by hyperthyroidism
Results in increased metabolism, heat intolerance, rapid heartbeat, weight loss, and exophthalmos |
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Parathyroid glands
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Tiny masses on the posterior of the thyroid, Secrete parathyroid hormone (PTH)
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Adrenal glands
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Sit on top of the kidneys, has two regions, the adrenal cortex and the adrenal medulla
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Adrenal cortex
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Outside of medulla, stimulated by ACTH, Has three layers
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Adrenal medulla
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inner neural tissue region
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Three layers of adrenal cortex
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Zona glomerulosa (produces mineralocortocoids), Zona fascicula (produces glucocorticoids), Zona Reticularis (produces sex hormones)
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Hormones of the adrenal cortex
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Mineralocorticoids, Glucocorticoids, sex hormones
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Production of mineralocortocoids
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Production stimulated by renin and aldosterone, Production inhibited by atrial natriuretic peptide (ANP)
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Mechanism of action (aldosterone)
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Low blood pressure:
1. Causes release of renin from the kidneys 2. Which causes angiotensin to be turned into angiotension II 3. Which causes release of aldosterone 4. Effects of aldosterone: Blood sodium levels increase, H2O in blood increases 5. Water retained in blood causes blood pressure to increase |
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Zona reticularis
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Sex hormone production, important for female sex drive, involved in first hormones in adolesence
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Addison’s disease
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Results from hyposecretion of all adrenal cortex hormones
Bronze skin tone, muscles are weak, burnout, susceptibility to infection |
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Hyperaldosteronism
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May result from an ACTH-releasing tumor
Excess water and sodium are retained leading to high blood pressure and edema |
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Cushing’s syndrome
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Results from a tumor in the middle cortical area of the adrenal cortex
“Moon face,” “buffalo hump” on the upper back, high blood pressure, hyperglycemia, weakening of bones, depression |
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Masculinization
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Results from hypersecretion of sex hormones,
Beard and male distribution of hair growth |
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Hormones of the Adrenal Medulla
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Epinephrine (adrenaline)
Norepinephrine (noradrenaline) |
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Purpose of hormones in the adrenal medulla
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These hormones prepare the body to deal with short-term stress (“fight or flight”) by
Increasing heart rate, blood pressure, blood glucose levels Dilating small passageways of lungs |
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Adrenal medulla
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Actually an extension of the nervous system
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Adrenal medulla composition
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composed of axon terminals of nerves in the sympathetic nervous system
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Pancreatic islets
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Produce the hormones insulin and glucagon
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Alpha cells
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Secrete glucagon, works with insulin to maintain blood glucose homeostasis
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Beta cells
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Secrete insulin, works with glucagon to maintain blood glucose homeostasis
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Glucagon
Glucose--> Whats the difference? Glycogen |
Glucagon- hormone
Glucose- Sugar Glycogen- Storage molecule |
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Pineal Gland location
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Found on the third ventricle of the brain
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Pineal gland function
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Secretes melatonin, establishes sleep/wake cycle, coordinates fertility
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Thymus gland location
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Located posterior to the sternum, largest in infants and children
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Thymus gland function
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Produces thymosin, this is where white blood cells congregate
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Gonads
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Ovaries and testes
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Ovaries
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produce eggs, produce estrogen and progesterone
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Testes
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Produce sperm, produce androgens
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Function of placenta
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Produces hormones that maintain the pregnancy
Some hormones play a part in the delivery of the baby Produces human chorionic gonadotropin (hCG) in addition to estrogen, progesterone, and other hormones |