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The Endocrine System The Endocrine System Endocrine cells release hormones into the bloodstream Hormones go throughout the body and affect many tissues and organs at the same time Effects are slow to appear and last a long time even if there is no additional hormone released Hormones control many long term processesi.e. development of embryo, growth, sexual maturation, reproduction Endocrine vs. Exocrine Glands Endocrine Produce hormones Hormones released directly into bloodstream No ducts Exocrine Produce a variety of secretions Release secretion to a surface (internal and external) Have ducts Endocrine System vs Nervous System Both are control systems for the body. How are they different? Endocrine Slow acting Long duration Targets all tissues and cells Nervous Quick acting Short duration Targets specific cells Hormones Control many long term processes Many chemicals act as both hormones and neurotransmitters Adrenal medulla and hypothalamus have both endocrine and nervous functions Most are either peptide hormones (protein based) or steroids (lipid based) Hormones work by changing types, action, amount or properties of enzymes Endocrine Reflexes Simplest functional unit of endocrine system Similar to the reflex arcs in the nervous system Endocrine Reflexes Simplest endocrine reflexes Disturbance in homeostasis endocrine response homeostasis restored More complex require more steps: Disturbance in homeostasis activates the pituitary gland messenger to another gland response restore homeostasis (examples: blood sugar and pancreas) Endocrine Reflexes (continued) Pituitary = “master gland” The most complex endocrine reflexes involve the hypothalamus Disturbance in homeostasis activates the Hypothalamus pituitary targets a specific gland stimulates a response homeostasis is restored Hypothalamus Main connection of nervous and endocrine systems 3 functions: Controls sympathetic output of adrenal medulla Acts as endocrine gland—releases hormones into the posterior pituitary gland Secretes hormones that control activity of the anterior pituitary Releasing hormones Inhibiting hormones Pituitary Gland (Master Gland) Also known as Hypophysis 2 parts—anterior and posterior 9 hormones come from pituitary gland (all peptide) Posterior Pituitary Neurohypophysis 2 Hormones: 1. ADH (antidiuretic hormone /vasopressin)-decreases water loss from the kidneys, constricts peripheral vessels ( increases blood pressure) Diabetes insipidus- posterior pituitary releases too little ADH so too much water is lost. Person is always thirsty. Fluid is not kept in the system. Can lead to severe dehydration and death. Treatment: synthetic ADH Posterior Pituitary 2. Oxytocin (quick childbirth) causes smooth muscles to contract and causes contraction of cells surrounding the secretory cells in mammary glandsoxytocin involved in child birth and breast feeding Anterior Pituitary Adenohypophysis 7 hormones 1. TSH- Thyroid stimulating hormonecauses the release of thyroid hormone Anterior Pituitary 2. ACTH- adrenocorticotropic Hormone- releases steroid hormones from the adrenal glands, especially those for glucose metabolism (glucocorticoids) 3. FSH- Follicle stimulating hormone. In females causes egg development and promotes estrogen release. In males involved in sperm production Anterior Pituitary 4. LH- Lutenizing hormone. In females causes ovulation and promotes secretion of progesterone (preparation for pregnancy) In males-called interstitial cell stimulating hormone (ICTH)-stimulates production of androgens (male hormones) FSH and LH= gonadotroic hormones (gonadotropins)-regulate the gonads Anterior Pituitary 5. Prolactin – involves in the development of mammary glands and milk production. 6. GH- Growth Hormone- also known as human growth hormone. Especially targets skeletal muscle and cartilage cells. Pituitary Dwarfism-too little GH production Giantism- too much GH before puberty Anterior Pituitary 7. MSH-Melanocyte Stimulating Hormoneincreases production of skin pigment ACTH GH TSH prolactin LH FFSH MSH –skin Pineal Gland Parathyroid Glands are not shown—found on the back of the Thyroid Pituitary Gland Anterior Pituitary Posterior Pituitary Thyroid Gland Thymus Adrenal Gland Pancreas Ovary Testes Thyroid Gland On the trachea (windpipe) under the thyroid cartilage Shaped like a butterfly Thyroid follicles release hormones into the bloodstream Thyroid Hormones Thyroxine (T4)-causes gradual, long term increase in metablolism. Accounts for 90% of thyroid secretions Triiodothyronine (T3) causes a strong, immediate increase in cellular metabolism short lasting Thyroid Hormones Thyroid hormone functions: cellular metabolism and temperature, O2 and energy use heart rate and blood pressure Stimulate formation of RBCs Stimulate activity of other endocrine tissues Accelerate turnover of minerals in bones Maintain respiratory sensitivity to changes in O2 and CO2 levels Allows us to adapt to cold temperatures by metabolism and O2 consumption Thyroid Disorders Hypothyroidismhormones production of thyroid Infants- leads to inadequate skeletal and nervous development, metabolic rate up to 40% below normal Later childhood-retards growth, delays puberty Adults- lethargic, can’t adjust to the cold Signs/Symptoms- dry skin, hair loss, slow reflexes, low body temp., intellectual slowness Treatment: synthetic thyroid hormones Thyroid Disorders Hyperthyroidism-too much thyroid hormone Metabolic rate, perspiration, BP, and irregular heart beat, skin becomes flushed Restless, excitable, mood shifts Very little reserve energy and fatigues easily Thyroid Disorders Goiter- enlarged thyroid gland Caused by increase of thyroid follicle size from low amounts of iodine in diet. Salt has added iodine Graves Disease-excess thyroid activity leading to goiter, leading to symptoms of hyperthyroidism Bulging eyes More common in women- has genetic base Treatment: anti-thyroid drugs, removal or destruction of part of the thyroid(surgically or radioactive iodine) Parathyroid Glands 4 tiny glands—2 on each side of posterior thyroid Hormone = parathormone Regulates calcium concentration in blood and other body fluids (increases Calcium concentration) Thymus Located in thoracic cavity behind sternum Gets larger until puberty, then atrophies Hormone—thymosin—important for normal immune system (T Cells) Adrenal Glands Cap on top of each kidney Each adrenal gland surrounded by a capsule 2 parts: Adrenal Cortex Adrenal Medulla Adrenal Cortex Outer part Stores lipids Produces many steroid hormones— adrenocorticosteroids or corticosteroids Necessary for life 3 zones produce different types: Androgens, glucocorticoids (incl. cortisone and cortisol), mineralocorticoids Adrenal Cortex (continued) 1. Androgens—male hormones 2. Glucocorticoids—affect glucose metabolism reduce inflammation throughout the body. Example: Cortisol is a naturally occurring GC that is made by your adrenal glands, and works to regulate inflammation and other processes in your body. Cushing’s Disease-overproduction of glucocorticoids leads to exaggerated response to stress, energy reserves moved around. Body fat changes-(moon face), muscles break down Adrenal Cortex (continued) 3.Mineralocorticoids-effect electrolyte composition of body fluids Hormone=aldosterone Addison’s Disease-inadequate secretion of both glucocorticoids and mineralocorticoid Signs/symptoms: hypoglycemia, weakness, can’t mobilize energy reserves, can’t tolerate stress, can cause sharp and fatal fall in blood pressure, increased skin pigmentation Adrenal Cortex (continued) Androgenital Syndrome-tumors that cause overproduction of androgens Women develop male secondary sex characteristics(hair patterns, muscle development, fat distribution Men it is called gynecomastia (gyne=women,mast=breast). Development of female secondary sexual characteristics Adrenal Medulla Inner part of adrenal glands 2 hormones—epinephrine (adrenalin) and norepinephrine (noradrenalin) Epinephrine 75-80% of adrenal medulla secretions Increase cardiac activity, BP, glycogen breakdown, increases blood glucose. Causes adipose tissue to release lipids. Norepinephrine Causes blood vessels to constrict and heart rate to increase Steroid Abuse Used to increase muscle size and strength Results: heart disease and heart attacks liver disease stroke atrophy of testes and decreased sperm count decreased production of testosterone immune system depression “roid rages” acne hair loss Pancreas Lumpy, pink organ near the connection between the stomach and small intestine Both exocrine and endocrine functions Pancreas (continued) Exocrine function Produces digestive enzymes Endocrine function Pancreatic islets (islets of Langerhans) produce glucagon (alpha cells) and insulin (beta cells) which work together to regulate blood glucose Hypoglycemia-low blood glucose Diabetes Mellitus Hyperglycemia = high blood glucose Leads to glycosuria and polyuria 2 types of Diabetes mellitus Type 1 Diabetes = Insulin Dependent Diabetes Mellitus (IDDM). Pancreas does not produce enough insulin Fatal without insulin therapy and dietary control Treatment: insulin injections plus diet and exercise Diabetes Mellitus (continued) Type 2—Non Insulin Dependent Diabetes Mellitus (NIDDM)—pancreas produces insulin, but peripheral tissues do not respond appropriately Treatment: weight loss, diet, oral medications Three times as common as IDDM Diabetes Mellitus (continued) Complications Diabetic retinopathy- changes to blood vessels in the retina Diabetic nephropathy- kidney disease Diabetic neuropathy- disturbance to blood supply to neural Degenerative problems with cardiac circulation leading to heart attacks Peripheral vascular changes leading to decreased blood flow to the feet that can lead to sores and amputation Testes Male Cells in testes produce androgens (testosterone is most important) which are responsible for: Functional sperm Secondary sex characteristics and associated behaviors Protein synthesis Muscle growth Ovaries Female: Ovarian follicles = place eggs (ova) develop FSH causes follicles to produce estrogens which are responsible for: Maturation of ova Growth of uterine lining Female secondary sex characteristics Ovaries (continued) LH causes ovulation Corpus Luteum = follicle after ovulation Causes release mix of estrogens and progesterone Progesterone: Moves fertilized egg along fallopian tubes Prepares uterus for implantation Prepares mammary glands for lactation In pregnancy—placenta works as endocrine gland Pineal Gland Location = roof of thalamus Hormone = melatonin—inhibits melanin production Melatonin production increases at night and decreases in daylight Involved in the establishment of circadian rhythms Seasonal Affective Disorder (SAD) Pineal Gland (cont.) Seasonal Affective Disorder (SAD) Happens in December through March when daylight hours are fewer and melatonin production increases More common in northern latitudes Causes depression, lethargy, decreased concentration, over eating, over sleeping, may be responsible for increased suicides Stress Stress = any threat to homeostasis General Adaptation Syndrome (GAS)— body’s response to stress regardless of source 3 phases: Alarm phase Resistance phase Exhaustion phase General Adaptation Syndrome (GAS) 3 Phases 1. Alarm phase- fast response directed by sympathetic division of ANS. Energy reserves mobilized (glucose) to get the body ready. Epinephrine is main hormone- fight or flight 2. Resistance phase- Long term adjustments. Happens if stress lasts longer than a few hours (severe illness, severe anxiety, starvation, etc) Glucocorticoids are primary hormones although others are also involved. Lipid and protein reserves mobilized; glucose levels increase, stable glucose conserved for neural tissue General Adaptation Syndrome (GAS) 3. Exhaustion phase- collapse of vital systems. Eventually homeostatic regulation breaks down. Nerve and muscle cells malfunction. Causes: exhaustion of lipid reserves, can’t produce glucocorticoids. Vital organs are damaged. Death will happen without immediate steps taken to correct the problem Hormones and Behavior Sex hormones at puberty Hormones can effect ability to learn, memory, intellect, emotional state Decrease of sex hormones at menopause and male climacteric More aggressive, assertive Mood swings Mood swings “Roid Rages” Hormones and Aging Few changes to hormones with aging except for reproductive hormones (decrease) Tissues may become less responsive to hormones with age.