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22 Cards in this Set
- Front
- Back
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Main Regulatory Functions of the Endocrine System (8)
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1. Metabolism
2. Blood pH & ion concentration 3. Water balance 4. Blood cell production 5. Heart rate & blood pressure 6. Blood glucose levels 7. Reproduction 8. Uterine contractions & lactation |
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2 Major Regulatory Systems
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1. Nervous system
2. Endocrine system |
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Cell Secretions
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- cells secrete chemicals to communicate with other cells
- cells that secrete same substance are grouped to form a gland - secretions characterized by where they have an effect |
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Autocrine
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- secreted by a cell & have a local effect on same cell type
- don't enter blood stream Ex: platelet activation factor |
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Paracrine
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- secreted by a cell & have a local effect on a different cell type
- don't enter blood stream - Ex: histamine from mast cells |
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Pheromones
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- chemical signal released by an individual that affects a different individual
Ex: cats & dogs release sex pheromones Ex: fish release fear pheromone (secreted when fish is attacked by a predator. Humans: - Females release pheromones during menstrual cycle that influence menstrual cycle of other females. Occurs when females spend a lot of time together. Dominant female sets cycle & all females have same cycle T-shirt Experiment: Men wore shirt without washing. Females rank smell of shirt. DNA MHC complex, more alike DNA was more repulsive smell. Prevents imbreeding |
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How Cells Secrete Substances
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- most substances secreted in vesicles
- secrete in response to stimulation Neurosecretory cells: stimulation generates APs, APs stimulate release of neurotransmitters or neurohormones Neurohormone: hormone secreted by some type of nervous tissue |
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Endocrine Glands
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- ductless
- secrete into blood stream - secrete hormones - hormones secreted in small amounts - hard to identify ~ ductless |
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Exocrine Glands
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- duct
- secrete onto an epithelial surface - secrete fluids (mucous, sweat) - amount of secretion varies - easy to identify |
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Overview of Endocrine System
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Composed of glands that secrete chemical signals called hormones (type of ligand) into the circulatory system
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** 4 Characteristics used to define a hormone **
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1. Hormones are produced in minute amounts by a group of cells
2. Cells secrete hormones into interstitial spaces 3. Hormone enters circulatory system & travels to other areas of body 4. Hormones act on specific tissues called target tissues & alters the activity of target tissue |
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Endocrine system regulates many functions of the body
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- hormones are always present in body
- hormone concentration fluctuates - creates amplitude modulated signal |
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Amplitude Modulated Signal
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- increase or decrease of hormone concentration generates a response
- concentration can fluctuate from minutes, hours, days - target tissue response is directly correlated with hormone concentration |
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Endocrine Vs Nervous regulation
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- In general, endocrine system regulates activity more slowly than NS & for a longer period of time
- NS can produce a response in milliseconds Endocrine system generally requires longer |
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Relationship of Endocrine & Nervous Systems
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- NS secretes some signals called neurohormones that function as hormones
- some nerves innervate endocrine glands & affect their activity - some hormones affect NS & its activity * both systems work in different ways together & apart to regulate body activity |
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General Principles of Hormones (11)
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1. Can change chemical reaction rate in body
2. Can act like enzymes but are NOT enzymes 3. Specificity ~ only act on target tissues 4. Always present, levels fluctuate 5. Always being inactivated by degradation, destruction, or excretion 6. MAY influence activity of other hormones 7. Come in contact with all tissues of the body 8. In general, a hormone DOES NOT affect all cells in body 9. Only act on cells with a receptor for that specific hormone 10. Usually produced in very small amounts 11. Target cell receptors & hormones have high affinity for each other (very attracted to each other) |
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Hormone Structures
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- proteins: growth hormone, prolactin, insulin
- polypeptides: parathyroid hormone, oxytocin, endorphins - amino acids: epinephrine, norepinephrine, thyroid hormones (both T4 & T3), melatonin - lipids: steroids: estrogens, progestins, testosterone. fatty acids: leukotrines - glycoproteins: follice-stimulating hormone, thyroid-stimulating hormone |
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Receptors
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- hormone only bind to cells with a receptor for the hormone
- receptor can be on membrane surface or in cell |
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Lipid Soluble Hormones
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- pass directly through cell membrane
- bind to receptors in cytoplasm or nucleus - have long term effects: hours to days |
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Non-lipid Soluble Hormones (water soluble)
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- do not pass directly through cell membrane
- binds to a receptor on membrane surface - may activate 2* messenger inside cell |
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* Special Note *
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- recently learned some lipid soluble hormones bind to membrane receptors & have short term effects
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Control of Secretion (Regulation)
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- most hormones secreted at fluctuating rates over time
- most regulation is by negative feedback |
