Recent Changes for "Users/LucyFitzGibbon" - Davis Wiki

Users/LucyFitzGibbon

LucyFitzGibbon — 2007-08-02 10:41:42

Differences for Users/LucyFitzGibbon

Deletions are marked with - .	Additions are marked with +.
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- Lucy loves Julien!!!! - - Lucy is a freshman at Yale University (DHS '06). She loves ["Madrigal Choir" Madrigals] and sings all of the time, to the dismay of her neighbors.	+ Lucy is at Yale University (DHS '06). She loves ["Madrigal Choir" Madrigals] and sings all of the time, to the dismay of her neighbors.

Users/LucyFitzGibbon

LucyFitzGibbon — 2007-03-22 15:05:50

Differences for Users/LucyFitzGibbon

Deletions are marked with - .	Additions are marked with +.
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- Lucy is a senior at DHS. She loves ["Madrigal Choir" Madrigals] and sings all of the time, to the dismay of her neighbors.	+ Lucy is a freshman at Yale University (DHS '06). She loves ["Madrigal Choir" Madrigals] and sings all of the time, to the dismay of her neighbors. + Her sister, Elaine, plays the cello. Together with their mother, these formidable Fitz Gibbons make noise everywhere.

Users/LucyFitzGibbon

LucyFitzGibbon — 2006-05-22 14:31:25

Differences for Users/LucyFitzGibbon

Deletions are marked with - .	Additions are marked with +.
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- - Biology Chapter 45: Chemical Signals in Animals, pages 893-910 - - Endocrine system: made up of all of an animal’s hormone-secreting cells - - Endocrine glands: hormone-secreting glands, also known as ductless glands (because they directly secrete the chemicals into the body fluids) - - Neurosecretory cells: specialized nerve cells that secrete hormones - - Some chemicals serve as hormones of both the endocrine and nervous system. Ex.: Epinephrine, the “fight or flight” hormone and neurotransmitter that allows for messages. - - All groups of arthropods have extensive endocrine systems. Ex.: crustaceans molt controlled by the hormone ecdysone; it also favors the development of adult characteristics (like changing from caterpillar to a butterfly). - - In insects, brain hormone (BH) controls the production of ecdysone while juvenile hormone (JH) balances out both BH and ecdysone. - - - Neurotransmitters carry information from one neuron to another or from a neuron to a muscle, gland, or other target. - - Many types of cells produce nitric oxide—highly reactive, potentially toxic. Acts as a neurotransmitter (when secreted by neurons), kills some cancerous cells and bacteria in blood cells (when secreted by white blood cells), makes smooth muscles relax in blood vessels when secreted by endothelial cells to dilate vessel walls. - - Growth factors: peptides and proteins that are local regulators (act between cells on a localized scale) must be present in extracellular matrix environment for most cells to act normally. Research suggests that growth factors can increase synapse strength in the brains of mature animals. - - Prostaglandins (PGs): modified fatty acids; often come from lipids of plasma membrane. Are local regulators (released from most cells into interstitial fluid). They act as a positive feedback mechanism to coordinate body function in the inducement of labor during childbirth. Also, they are local regulators in vertebrate defense mechanisms; they induce fever and inflammation, and intensify the pain sensation. Anti-inflammatory drugs such as aspirin and ibuprofen work because they inhibit enzymes in prostaglandin synthesis. Prostaglandin E causes the smooth muscle cells in walls of blood vessels serving the lungs to relax, dilating the vessels and promoting oxygenation. F makes the muscles contract and this constricts the vessels to reduce blood flow through the longs. The chemicals are antagonistic (counterregulatory). Helps maintain homeostasis. - - Chemical signals work by having a specific shape that the signal’s target cells’ proteins). When this chemical signal binds to the receptor protein, it triggers chemical events within the target cell that change its behavior. Cells are therefore unresponsive to a signal if they do not have the receptor. - - Most chemical signals (neurotransmitters, hormones, and all growth factors) cannot pass through the target cell’s plasma membrane. The receptors are a part of the signal-transduction pathways converting an extracellular signal into a specific intracellular response. Ex.: melanocyte-stimulating hormone (MSH), secreted in frogs by the pituitary gland. This changes the color of frogs but it does nothing if injected directly into the cell. - - Steroid and thyroid hormones as well as some local regulators (like NO) enter target cells and bind with intracellular receptors instead (specialized proteins within the cells). The chemical signal activates the receptor so that it can trigger a response in the target cell. - - - The vertebrate endocrine system!!!! See chart on page 899. - - Tropic hormones: target other endocrine glands - - Hypothalamus: region of lower brain, receives information from nerves throughout body and brain, signals the release of the proper hormones. The cells that release hormones are sets of neurosecretory cells around the pituitary gland. It has two parts, the anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis). The anterior pituitary develops from a fold of the roof of the mouth that grows upward toward the brain, losing its connection to the digestive tract. The endocrine cells here synthesize and secrete hormones directly into the blood. The hypothalamus controls the anterior pituitary through other hormones. Releasing hormones make the anterior pituitary secrete the hormones whereas inhibiting hormones make the anterior pituitary stop secreting the hormone. The hypothalamic hormones have direct access to the gland they control because the hormones go into capillaries and then they go to short blood vessels to travel to the anterior pituitary. The posterior pituitary is an extension of the brain. It develops from a part of the hypothalamus that grows down toward the mouth fold making the anterior pituitary, but it stays attached. The posterior pituitary releases oxytocin and antidiuretic hormone (ADH), both made by the hypothalamus. Oxytocin induces contraction of the uterine muscles during childbirth and causes the mammary glands to eject milk when nursing. ADH increases water retention of the kidneys and decreases urine volume. There are nerve cells functioning as osmoreceptors in the hypothalamus which release ADH from their tips; when ADH reaches the kidneys, it binds to receptors on the surface of the cells lining the collecting ducts so that they are more water permeable. When water exists the ducts, it enters nearby capillaries to help prevent an increase in blood osmolarity above the set point. The osmoreceptors also stimulate thirst so that, in drinking water, blood osmolarity returns to the set point. - The anterior pituitary has many hormones. Four are tropic: thyroid stimulating hormone (TSH), that regulates the release of thyroid hormones; adrenocorticotropic hormone (ACTH), that controls the adrenal cortex; and follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which control reproduction. The anterior pituitary also produces growth hormone (GH), prolactin (PRL), melanocyte-stimulating hormone (MSH), and the endorphins. GH affects many different target tissues with tropic and direct effects. GH can stimulate bone and cartilage growth because it also signals the liver to make insulinlike growth factors (IGF), which circulate in blood plasma to directly stimulate bone and cartilage growth. Without GH, skeletal growth stops. If GH is injected, growth will be partially restored. There are several human growth disorders related to abnormalities of GH production. Too much during development may result in gigantism while during adulthood, it can cause acromegaly (abnormal growth of bones in the hands, head, and feet). Deficient GH in childhood can turn into pituitary dwarfism. Treatment with extra GH is effective; however, it must be obtained from cadavers and the supply is usually inadequate (most other animals’ GH is ineffective). The development of technology to produce GH by bacteria with genes for human GH spliced in has been successful. Both children with hypopituitary dwarfism and athletes (legally or illegally) take GH. - - Prolactin (PRL) is incredibly similar to GH (they may be encoded in genes evolving from the same ancestral gene). PRL stimulates mammary gland growth and milk synthesis in mammals; regulates fat metabolism and reproduction in birds; delays metamorphosis in amphibians and serves as a larval growth hormone; and regulates salt and water balances in freshwater fish. The diversity of uses suggests that prolactin is an ancient hormone with multiple functions that arose throughout the evolution of the vertebrate classes. - Follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid-stimulating hormone (TSH) are all very similar, chemically. FSH and LH are called gonadotropins because they stimulate male and female gonad activities (gonads and ovaries). TSH stimulates the production of hormones by the thyroid gland. - - The rest of the hormones from the anterior pituitary come from one parent molecule, the pro-opiomelanocortin. It is a big protein that the pituitary cells cut into several shorter pieces. Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to produce and secrete steroid hormones. Melanocyte-stimulating hormone regulates pigment-containing cells in some vertebrates; in mammals, it is probably a feedback mechanism that targets neurons in the hypothalamus. Endorphins are produced from pro-opiomelanocortin and also by some neurons in the brain. They are called the body’s natural opiates because they inhibit pain perception. - - Pineal gland: it is near the center of the mammalian brain. It secretes melatonin, a modified amino acid. It may contain light-sensitive cells or nervous connections from the eyes. Thus, it affects skin pigmentation in some vertebrates. It is secreted at night so in winter when the days are short, more melatonin is secreted. It is a link between the biological clock and daily or seasonal activities like reproduction. The main target cells of melatonin are in the suprachiasmatic nucleus (SCN), decreasing neuron activity. - - Thyroid gland: two lobes on the ventral surface of the trachea in humans and other mammals (or on either side of the pharynx in most other vertebrates). It produces triodothyronine (T3) or thyroxine (T4). T3 is the most active of the two in mammals. In frogs, it controls metamorphosis from tadpole into the adult form. The inherited thyroid deficiency (cretinism) causes dramatically retarded skeletal growth and poor mental development. The effects can be reduced with thyroid hormone treatment early in life. In adult mammals, the thyroid hormones help maintain blood pressure, heart rate, muscle tone, digestion, and reproductive functions. They can increase the rate of oxygen consumption and cellular metabolism. Hyperthyroidism has symptoms such as high body temperature, profuse sweating, weight loss, irritability, and high blood pressure. Hypothyroidism can cause cretinism in infants, weight gain, lethargy, and intolerance to cold. Goiter is caused by a deficiency of iodine in the diet. The thyroid gland also secretes calcitonin in mammals. - - There are four parathyroid glands that are on the surface of the thyroid and function in the homeostasis of calcium ions by secreting parathyroid hormone (PTH) to raise blood levels of calcium. They are antagonistic with calcitonin. PTH stimulates Ca2+ reabsorption in the kidneys and induce osteoclasts (specialized bone cells) to decompose the matrix of the bone to release CA2+ to the blood. Calcitonin does the opposite. Vitamin D (made in the skin) is essential for PTH function. PTH makes blood calcium levels drop dramatically and can cause convulsive contractions of the skeletal muscles (tetany). It can be fatal. - - The pancreas’ cells called the islets of Langerhans secrete insulin and glucagon. The hormones are secreted directly into the circulatory system. Each islet has alpha cells which secrete glucagon and beta cells which secrete insulin. They regulate blood glucose. Glucose is a major fuel for cellular respiration and source of carbon skeletons for the synthesis of organic compounds. In humans, blood glucose is about 90 mg/100 mL. When glucose exceeds this level, insulin is released and lowers the glucose level by stimulating cells to take up glucose (except in the brain, which does not need insulin to take up glucose), by slowing glycogen breakdown in the liver, and by inhibiting the conversion of amino and fatty acids to sugar. The liver, skeletal muscles, and adipose tissues store fuel molecules (the liver and muscles as glycogen and adipose as fats). The liver is sensitive to glucagon so when excess glucose is cleared from the blood, glucagon signals the liver to increase glycogen hydrolysis, conversion of amino and fatty acids to glucose, and the slow release of glucose into circulation. - - Example: diabetes mellitus. Extremely high blood glucose (kidneys excrete glucose, prompting excessive drinking to flush out sugar), cells cannot use carbohydrates as fuel and must use fat as a substrate for cellular respiration. This can lead to ketoacidosis (acidic metabolites accumulate in the blood and lower blood pH). Type I is an autoimmune disorder which destroys the person’s islet cells. Patients are dependent upon insulin injections. Type II is characterized by reduced target cell responsiveness, usually after the age of 40. It is hereditary and patients can usually manage their blood glucose with exercise and dietary control. - - Adrenal glands: adjacent to the kidneys. In mammals, they are made of two glands, the adrenal cortex and adrenal medulla. Nonmammalian vertebrates have different arrangements of these tissues. The secretory cells are derived from cells of the neural crest. The adrenal medulla makes epinephrine (or adrenaline) and norepinephrine (noradrenaline). They are members of the catecholamines that are made from the amino acid tyrosine. They are secreted in response to positive or negative stress. They increase the basal metabolic rate. Epiephrine and norepinephrine increase the rate of glycogen breakdown in the liver and skeletal muscles to release glucose into the blood by the liver cells. They stimulate the release of fatty acids from fat cells to be used as energy. They increase the rate and stroke volume of the heartbeat and dilate the bronchioles in the lungs to increase the rate of oxygen delivery to the body. Catecholamines cause smooth muscles of some vessels to contract and others to relax to shunt blood away from the skin, digestive organs, and kidneys and increase blood supply to the heart, brain, and skeletal muscles. When under stress, nerve cells release the neurotransmitter acetylcholine in the adrenal medulla to stimulate the release of epinephrine. Epinephrine is important to control heart and metabolic rates whereas norepinephrine, controlled separately, sustains blood pressure. The adrenal cortex responds to stress signals from the endocrine system, rather than the nervous system. The hypothalamus secretes a releasing hormone which stimulates the anterior pituitary to release the tropic hormone ACTH, which in turn stimulates adrenal cortex cells to synthesize corticosteroids. Elevated corticosteroid levels suppress ACTH secretion. - The corticosteroids isolated from the adrenal cortex include glucocorticoids (cortisol) and mineralocorticoids (aldosterone). The former promote the synthesis of glucose from noncarbohydrate sources (like proteins) to make more glucose available as food. The glucocorticoids target skeletal muscle and transports the proteins to the liver and kidney for conversion into glucose. When high doses of glucocorticoids are administered, they suppress the inflammatory reaction at infection sites; thus, cortisone was considered a miracle drug capable of curing inflammatory diseases like arthritis. Unfortunately, the immunosuppressive effects of corticosteroids makes them dangerous for long-term use. - Mineralcorticoids help to maintain the body’s salt and water balance. Aldosterone acts as an antidiuretic, stimulating kidney cells to reabsorb sodium ions and water from filtrate to raise blood pressure and volume (as a response to blood loss, for example). Aldosterone, the posterior pituitary’s ADH, and heart’s atrial natiuretic factor (ANF) make up a regulatory complex with feedback loops to help maintain ion and water homeostasis in the blood. - It seems that glucocorticoids and mineralocorticoids help to maintain homeostasis when the body is under an extended period of stress. - Sex hormones such as androgens, estrogens, and progesterone are also corticosteroids. All three types of hormones are found in males in females, but their differing levels help define sex characteristics. The testes make mostly androgens (such as testosterone) to help develop and maintain the male reproductive system both as an embryo to determine sex and also at puberty to develop male secondary sex characteristics. Estrogens (such as estradiol) act like androgens, but in females. Progestins (such as progesterone) prepare and maintin the uterus. The anterior pituitary gland’s gonadotropins FSH and LH and the hypothalamus’ GnRH control the synthesis of these hormones. - - - - - - - - - - - - - - -

Users/LucyFitzGibbon

LucyFitzGibbon — 2006-05-22 13:50:02

Differences for Users/LucyFitzGibbon

Deletions are marked with - .	Additions are marked with +.
Line 8:	Line 8:
	+ + Biology Chapter 45: Chemical Signals in Animals, pages 893-910 + + Endocrine system: made up of all of an animal’s hormone-secreting cells + + Endocrine glands: hormone-secreting glands, also known as ductless glands (because they directly secrete the chemicals into the body fluids) + + Neurosecretory cells: specialized nerve cells that secrete hormones + + Some chemicals serve as hormones of both the endocrine and nervous system. Ex.: Epinephrine, the “fight or flight” hormone and neurotransmitter that allows for messages. + + All groups of arthropods have extensive endocrine systems. Ex.: crustaceans molt controlled by the hormone ecdysone; it also favors the development of adult characteristics (like changing from caterpillar to a butterfly). + + In insects, brain hormone (BH) controls the production of ecdysone while juvenile hormone (JH) balances out both BH and ecdysone. + + + Neurotransmitters carry information from one neuron to another or from a neuron to a muscle, gland, or other target. + + Many types of cells produce nitric oxide—highly reactive, potentially toxic. Acts as a neurotransmitter (when secreted by neurons), kills some cancerous cells and bacteria in blood cells (when secreted by white blood cells), makes smooth muscles relax in blood vessels when secreted by endothelial cells to dilate vessel walls. + + Growth factors: peptides and proteins that are local regulators (act between cells on a localized scale) must be present in extracellular matrix environment for most cells to act normally. Research suggests that growth factors can increase synapse strength in the brains of mature animals. + + Prostaglandins (PGs): modified fatty acids; often come from lipids of plasma membrane. Are local regulators (released from most cells into interstitial fluid). They act as a positive feedback mechanism to coordinate body function in the inducement of labor during childbirth. Also, they are local regulators in vertebrate defense mechanisms; they induce fever and inflammation, and intensify the pain sensation. Anti-inflammatory drugs such as aspirin and ibuprofen work because they inhibit enzymes in prostaglandin synthesis. Prostaglandin E causes the smooth muscle cells in walls of blood vessels serving the lungs to relax, dilating the vessels and promoting oxygenation. F makes the muscles contract and this constricts the vessels to reduce blood flow through the longs. The chemicals are antagonistic (counterregulatory). Helps maintain homeostasis. + + Chemical signals work by having a specific shape that the signal’s target cells’ proteins). When this chemical signal binds to the receptor protein, it triggers chemical events within the target cell that change its behavior. Cells are therefore unresponsive to a signal if they do not have the receptor. + + Most chemical signals (neurotransmitters, hormones, and all growth factors) cannot pass through the target cell’s plasma membrane. The receptors are a part of the signal-transduction pathways converting an extracellular signal into a specific intracellular response. Ex.: melanocyte-stimulating hormone (MSH), secreted in frogs by the pituitary gland. This changes the color of frogs but it does nothing if injected directly into the cell. + + Steroid and thyroid hormones as well as some local regulators (like NO) enter target cells and bind with intracellular receptors instead (specialized proteins within the cells). The chemical signal activates the receptor so that it can trigger a response in the target cell. + + + The vertebrate endocrine system!!!! See chart on page 899. + + Tropic hormones: target other endocrine glands + + Hypothalamus: region of lower brain, receives information from nerves throughout body and brain, signals the release of the proper hormones. The cells that release hormones are sets of neurosecretory cells around the pituitary gland. It has two parts, the anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis). The anterior pituitary develops from a fold of the roof of the mouth that grows upward toward the brain, losing its connection to the digestive tract. The endocrine cells here synthesize and secrete hormones directly into the blood. The hypothalamus controls the anterior pituitary through other hormones. Releasing hormones make the anterior pituitary secrete the hormones whereas inhibiting hormones make the anterior pituitary stop secreting the hormone. The hypothalamic hormones have direct access to the gland they control because the hormones go into capillaries and then they go to short blood vessels to travel to the anterior pituitary. The posterior pituitary is an extension of the brain. It develops from a part of the hypothalamus that grows down toward the mouth fold making the anterior pituitary, but it stays attached. The posterior pituitary releases oxytocin and antidiuretic hormone (ADH), both made by the hypothalamus. Oxytocin induces contraction of the uterine muscles during childbirth and causes the mammary glands to eject milk when nursing. ADH increases water retention of the kidneys and decreases urine volume. There are nerve cells functioning as osmoreceptors in the hypothalamus which release ADH from their tips; when ADH reaches the kidneys, it binds to receptors on the surface of the cells lining the collecting ducts so that they are more water permeable. When water exists the ducts, it enters nearby capillaries to help prevent an increase in blood osmolarity above the set point. The osmoreceptors also stimulate thirst so that, in drinking water, blood osmolarity returns to the set point. + The anterior pituitary has many hormones. Four are tropic: thyroid stimulating hormone (TSH), that regulates the release of thyroid hormones; adrenocorticotropic hormone (ACTH), that controls the adrenal cortex; and follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which control reproduction. The anterior pituitary also produces growth hormone (GH), prolactin (PRL), melanocyte-stimulating hormone (MSH), and the endorphins. GH affects many different target tissues with tropic and direct effects. GH can stimulate bone and cartilage growth because it also signals the liver to make insulinlike growth factors (IGF), which circulate in blood plasma to directly stimulate bone and cartilage growth. Without GH, skeletal growth stops. If GH is injected, growth will be partially restored. There are several human growth disorders related to abnormalities of GH production. Too much during development may result in gigantism while during adulthood, it can cause acromegaly (abnormal growth of bones in the hands, head, and feet). Deficient GH in childhood can turn into pituitary dwarfism. Treatment with extra GH is effective; however, it must be obtained from cadavers and the supply is usually inadequate (most other animals’ GH is ineffective). The development of technology to produce GH by bacteria with genes for human GH spliced in has been successful. Both children with hypopituitary dwarfism and athletes (legally or illegally) take GH. + + Prolactin (PRL) is incredibly similar to GH (they may be encoded in genes evolving from the same ancestral gene). PRL stimulates mammary gland growth and milk synthesis in mammals; regulates fat metabolism and reproduction in birds; delays metamorphosis in amphibians and serves as a larval growth hormone; and regulates salt and water balances in freshwater fish. The diversity of uses suggests that prolactin is an ancient hormone with multiple functions that arose throughout the evolution of the vertebrate classes. + Follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid-stimulating hormone (TSH) are all very similar, chemically. FSH and LH are called gonadotropins because they stimulate male and female gonad activities (gonads and ovaries). TSH stimulates the production of hormones by the thyroid gland. + + The rest of the hormones from the anterior pituitary come from one parent molecule, the pro-opiomelanocortin. It is a big protein that the pituitary cells cut into several shorter pieces. Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to produce and secrete steroid hormones. Melanocyte-stimulating hormone regulates pigment-containing cells in some vertebrates; in mammals, it is probably a feedback mechanism that targets neurons in the hypothalamus. Endorphins are produced from pro-opiomelanocortin and also by some neurons in the brain. They are called the body’s natural opiates because they inhibit pain perception. + + Pineal gland: it is near the center of the mammalian brain. It secretes melatonin, a modified amino acid. It may contain light-sensitive cells or nervous connections from the eyes. Thus, it affects skin pigmentation in some vertebrates. It is secreted at night so in winter when the days are short, more melatonin is secreted. It is a link between the biological clock and daily or seasonal activities like reproduction. The main target cells of melatonin are in the suprachiasmatic nucleus (SCN), decreasing neuron activity. + + Thyroid gland: two lobes on the ventral surface of the trachea in humans and other mammals (or on either side of the pharynx in most other vertebrates). It produces triodothyronine (T3) or thyroxine (T4). T3 is the most active of the two in mammals. In frogs, it controls metamorphosis from tadpole into the adult form. The inherited thyroid deficiency (cretinism) causes dramatically retarded skeletal growth and poor mental development. The effects can be reduced with thyroid hormone treatment early in life. In adult mammals, the thyroid hormones help maintain blood pressure, heart rate, muscle tone, digestion, and reproductive functions. They can increase the rate of oxygen consumption and cellular metabolism. Hyperthyroidism has symptoms such as high body temperature, profuse sweating, weight loss, irritability, and high blood pressure. Hypothyroidism can cause cretinism in infants, weight gain, lethargy, and intolerance to cold. Goiter is caused by a deficiency of iodine in the diet. The thyroid gland also secretes calcitonin in mammals. + + There are four parathyroid glands that are on the surface of the thyroid and function in the homeostasis of calcium ions by secreting parathyroid hormone (PTH) to raise blood levels of calcium. They are antagonistic with calcitonin. PTH stimulates Ca2+ reabsorption in the kidneys and induce osteoclasts (specialized bone cells) to decompose the matrix of the bone to release CA2+ to the blood. Calcitonin does the opposite. Vitamin D (made in the skin) is essential for PTH function. PTH makes blood calcium levels drop dramatically and can cause convulsive contractions of the skeletal muscles (tetany). It can be fatal. + + The pancreas’ cells called the islets of Langerhans secrete insulin and glucagon. The hormones are secreted directly into the circulatory system. Each islet has alpha cells which secrete glucagon and beta cells which secrete insulin. They regulate blood glucose. Glucose is a major fuel for cellular respiration and source of carbon skeletons for the synthesis of organic compounds. In humans, blood glucose is about 90 mg/100 mL. When glucose exceeds this level, insulin is released and lowers the glucose level by stimulating cells to take up glucose (except in the brain, which does not need insulin to take up glucose), by slowing glycogen breakdown in the liver, and by inhibiting the conversion of amino and fatty acids to sugar. The liver, skeletal muscles, and adipose tissues store fuel molecules (the liver and muscles as glycogen and adipose as fats). The liver is sensitive to glucagon so when excess glucose is cleared from the blood, glucagon signals the liver to increase glycogen hydrolysis, conversion of amino and fatty acids to glucose, and the slow release of glucose into circulation. + + Example: diabetes mellitus. Extremely high blood glucose (kidneys excrete glucose, prompting excessive drinking to flush out sugar), cells cannot use carbohydrates as fuel and must use fat as a substrate for cellular respiration. This can lead to ketoacidosis (acidic metabolites accumulate in the blood and lower blood pH). Type I is an autoimmune disorder which destroys the person’s islet cells. Patients are dependent upon insulin injections. Type II is characterized by reduced target cell responsiveness, usually after the age of 40. It is hereditary and patients can usually manage their blood glucose with exercise and dietary control. + + Adrenal glands: adjacent to the kidneys. In mammals, they are made of two glands, the adrenal cortex and adrenal medulla. Nonmammalian vertebrates have different arrangements of these tissues. The secretory cells are derived from cells of the neural crest. The adrenal medulla makes epinephrine (or adrenaline) and norepinephrine (noradrenaline). They are members of the catecholamines that are made from the amino acid tyrosine. They are secreted in response to positive or negative stress. They increase the basal metabolic rate. Epiephrine and norepinephrine increase the rate of glycogen breakdown in the liver and skeletal muscles to release glucose into the blood by the liver cells. They stimulate the release of fatty acids from fat cells to be used as energy. They increase the rate and stroke volume of the heartbeat and dilate the bronchioles in the lungs to increase the rate of oxygen delivery to the body. Catecholamines cause smooth muscles of some vessels to contract and others to relax to shunt blood away from the skin, digestive organs, and kidneys and increase blood supply to the heart, brain, and skeletal muscles. When under stress, nerve cells release the neurotransmitter acetylcholine in the adrenal medulla to stimulate the release of epinephrine. Epinephrine is important to control heart and metabolic rates whereas norepinephrine, controlled separately, sustains blood pressure. The adrenal cortex responds to stress signals from the endocrine system, rather than the nervous system. The hypothalamus secretes a releasing hormone which stimulates the anterior pituitary to release the tropic hormone ACTH, which in turn stimulates adrenal cortex cells to synthesize corticosteroids. Elevated corticosteroid levels suppress ACTH secretion. + The corticosteroids isolated from the adrenal cortex include glucocorticoids (cortisol) and mineralocorticoids (aldosterone). The former promote the synthesis of glucose from noncarbohydrate sources (like proteins) to make more glucose available as food. The glucocorticoids target skeletal muscle and transports the proteins to the liver and kidney for conversion into glucose. When high doses of glucocorticoids are administered, they suppress the inflammatory reaction at infection sites; thus, cortisone was considered a miracle drug capable of curing inflammatory diseases like arthritis. Unfortunately, the immunosuppressive effects of corticosteroids makes them dangerous for long-term use. + Mineralcorticoids help to maintain the body’s salt and water balance. Aldosterone acts as an antidiuretic, stimulating kidney cells to reabsorb sodium ions and water from filtrate to raise blood pressure and volume (as a response to blood loss, for example). Aldosterone, the posterior pituitary’s ADH, and heart’s atrial natiuretic factor (ANF) make up a regulatory complex with feedback loops to help maintain ion and water homeostasis in the blood. + It seems that glucocorticoids and mineralocorticoids help to maintain homeostasis when the body is under an extended period of stress. + Sex hormones such as androgens, estrogens, and progesterone are also corticosteroids. All three types of hormones are found in males in females, but their differing levels help define sex characteristics. The testes make mostly androgens (such as testosterone) to help develop and maintain the male reproductive system both as an embryo to determine sex and also at puberty to develop male secondary sex characteristics. Estrogens (such as estradiol) act like androgens, but in females. Progestins (such as progesterone) prepare and maintin the uterus. The anterior pituitary gland’s gonadotropins FSH and LH and the hypothalamus’ GnRH control the synthesis of these hormones. + + + + + + + + + + + + + + +

Users/LucyFitzGibbon

LucyFitzGibbon — 2006-05-14 22:42:16

Differences for Users/LucyFitzGibbon

Deletions are marked with - .	Additions are marked with +.
Line 7:	Line 7:
- Lucy is a senior at DHS. She loves ["Madrigal Choir" Madrigals.] and sings all of the time, to the dismay of her neighbors.	+ Lucy is a senior at DHS. She loves ["Madrigal Choir" Madrigals] and sings all of the time, to the dismay of her neighbors.

Users/LucyFitzGibbon

LucyFitzGibbon — 2006-05-14 22:42:05

Differences for Users/LucyFitzGibbon

Deletions are marked with - .	Additions are marked with +.
Line 4:	Line 4:
	+ + Lucy loves Julien!!!! + + Lucy is a senior at DHS. She loves ["Madrigal Choir" Madrigals.] and sings all of the time, to the dismay of her neighbors.

Users/LucyFitzGibbon

JulienBiewerElstob — 2006-02-16 21:26:12

Differences for Users/LucyFitzGibbon

Deletions are marked with - .	Additions are marked with +.
Line 1:	Line 1:
	+ Lucy = Love + + Come visit her at ["Madrigal Choir" Tenor Sectionals.]