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Hormones
chemical signals produced by endocrine glands and released into blood
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Functions
maintain homeostasis, and regulate energy use, metabolism, and growth
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Protein Hormones
short peptide sequences. water soluble, can't pass through cell membrane. Bonds to receptor on surface of target cell. Triggers signal transduction pathway.
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Protein Hormone Mechanism
signal from hormone amplified and sent through cell.
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Steroid Hormones
made from cholesterol. Insoluble in water. Targets cell by diffusion through cell membrane, binds to receptor in cytoplasm or nucleus. Turns genes on or off
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Feedback Mechanism
Hypothalamus releases hormone that acts on pituitary gland, which releases 2nd hormone that stimulates other endocrine glands to release hormones. Final hormone targets certain tissues and inhibits pituitary from releasing more.
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Pituitary Gland
base of hypothalamus. 2 parts.
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Posterior Pituitary Gland
extension of hypothalamus. Same hormones as hypothalamus ( ADH and Oxytocin )
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Anterior Pituitary Gland
separate from hypothalamus. makes its own set of hormones that the hypothalamus can stimulate or inhibit
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Growth Hormone
Stimulates Growth (hypertrophy, increases cells size and volume). Stimulates Cell Reproduction (increased mitosis).. Stimulates Cell Metabolism (increase protein synthesis and glycogen and fat breakdown)
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Growth Hormone Cont.
secreted in bursts during sleep. Production declines with age.
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Dwarfism
deficiency in child's GH secretion during development
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Gigantism
overproduction of GH during development. Poor blood flow. Tumor formed by pituitary.
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Acromegaly
increased GH as an adult. Bone thickens.
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Location
Base of neck
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Main Hormone
Thyroxine (T4) ..looses iodine atom- T3
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Functions
increases protein synthesis, glucose metabolism, and oxygen consumption. Regulates growth and tissue differentiation.
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Stimulus
Decrease in metabolic rate detected by hypothalamus
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Effect
Hypothalamus releases thyroid releasing hormone.... Anterior Pituitary Gland releases thyroid stimulating hormone.... Thyroid releases T4, which acts on body cells
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Result
increase in metabolic rate
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Hyperthyroidism
overactive thyroid, doesn't always mean extra T4.
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Weight loss, increased heat release, swollen neck
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Grave's Disease - antibody targets TSH receptors stimulates TSH secretion. Bugged eyes.
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stimulus signals hypothalamus
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hypothalamus produces hormones that act directly on target cells w/o stimulating endocrine glands
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hormones released by hypothalamus are neurohormones
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they travel along nerve cells and through blood stream until they reach the pituitary gland
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Pancreas
secretes antagonistic hormones insulin and glucagon to main glucose levels
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Islet of Langerhans - ( Alpha Cells - Glucagon ) ( Beta Cells - Insulin )
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Insulin
stimulated by high blood glucose levels. Insulin released and taken by glucose in blood. Liver converts glucose to glycogen for storage
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Glucagon
stimulated by low blood glucose levels. Glucagon released by pancreas to breakdown glycogen.
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Diabetes Mellitus
type 1 and type 2. Frequent urination
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hyperglycaemia, excessive hunger, kidneys excrete glucose - sweet urine, persistent thirst
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Type I
Insulin Deficiency. Born With. Immune system attacks insulin producing cells
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*Type II
Insulin Resistance. Based on life style.
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Diabetes Mellitus
type 1 and type 2. Frequent urination
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hyperglycaemia, excessive hunger, kidneys excrete glucose - sweet urine, persistent thirst
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Type I
Insulin Deficiency. Born With. Immune system attacks insulin producing cells
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*Type II
Insulin Resistance. Based on life style.
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