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Hormones
chemical signals secreted by cells of the endocrine system
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Endocrine cells
cells that secrete chemical signals
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Target cells
cells that have receptors
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Paracrine signals
1.affect only target cells near site of release
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autocrine signals
affect the cells that released the signal
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Endocrine glands
secretory organs composed of aggregations of endocrine cells which secrete signals into the extracellular fluid
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Exocrine glands
Have ducts that carry their signals to the outside of the body
Ex.Sweat gland, liver, salivary gland
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Neurotransmitters
chemical signals by which neurons communicate with other cells
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neurohormones
neurotransmitters that diffuse into the blood
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Pheromones
chemical signals released into the environment
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Schreckstoff
- 1.Alarm pheromone of fish
- -if injured, releases it and other fish run away
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Hormones are in three chemical groups:
- 1. Peptides or proteins
- -water-soluble,
- -ransported in blood with receptors on cell surfaces
- 2.Steroid hormones
- -synthesized from cholesterol
- -lipid-soluble
- -must be bound to carrier proteins to be carried in blood
- -Testosterone, estrogen
- 3.Amine hormones
- -derivative of tyrosine
- -Norepinephrine,T3
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Hormone receptors can be ______or ________
Hormone receptors can be membrane-bound or intracellular.
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where are the recpetors for Lipid soluble hormones?
inside the cell
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where are receptors for water-soluble hormones?
on the outside becausethey cannot readily pass cell membrane
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Binding domain
projects outside plasma membrane
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Transmembrane domain
anchors receptor
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Cytoplasmic domain
extends into cytoplasm, initiates target cell response
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The hypothalamus sends secretions tothe anterior pituitary via________
the portal blood vessels.
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Hormones from the hypothalamus control
the anterior pituitary
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downregulation
continous high level hormone decreases number of recpetors
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Upregulation
when hormone secretion is suppressed, receptors increase
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Negative feedback of target organ
target organ hormone levels inhibits release of tropic hormones
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Positive feedback of delivery
- 1.stretching of uterus
- 2. Increase Oxytocin release
- 3. which causes more stretching of uterus, until delivery
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Type 2 diabets
- 1. Produces too much insulin
- 2.Insulin receptors are permanently shut off by negative feedback
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Temperature regulation: too cold
- 1.Activation of TRH
- 2.Anterior pituitary stimulated
- 3.TSH secreted and travels in blood
- 4.Thyroid stimulated and produces T3 of T4
- 5. Increases metabolic rate and temp increases
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Temperature regulation: over 37C
- 1.Hypothalamus monitos temperature
- -TRH secretion inhibited
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Thyroid Gland
- 1.Largest endocrine gland
- 2.High rate of blood flow
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Hypothyroidism
- 1. Thyroxine deficiency
- 2. result of low circulating thyroxine
- 3.Iodine deficiency
- 4.Thyroglobulin is not converted efficiently to T3 or T4
- 5.too much thyroglobulin
- -antibody actives TSH receptors and this increases thyroxine
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How is Thyroxine(T4) produced?
- 1.Anterior pituitary secretes thyroid-stimuating hormone (TSH)
- 2. This activates the follicles to produce thyroglobulin
- 3.Thyroglobulin combines with iodine, the it is produced
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Cortisol
- 1.Stress response
- 2.Increases blood glucose levels by inhibiting glucose uptake into muscle and fat cells
- 3.Blocks immune system reactions
- 4.Increases cardiac muscle contractions
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Cortisol negative feedback
- 1.When blood concentrations rise above a certain theshold,
- 2. cortisol inhibits CRH secretion from the hypothalamus,
- 3.which turns off ACTH secretion,
- 4.which leads to a turning off of cortisol secretion from the adrenal.
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