A&P Endocrine System - Ana Christensen PDF

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Ana Christensen...

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Anatomy and Physiology 1/22 Communication ●

maintenance of homeostasis

Intercellular communication ● ● ●

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target ○ receptor (protein) messenger molecule direct communication ○ gap junctions ○ cytoplasm paracrines ○ exocytosis ○ extracellular fluid/interstitial fluid ○ (cells communicating side by side) synaptic communication ○ exocytosis ○ neurotransmitter ○ (fastest way of communication) endocrine ○ exocytosis ○ circulatory system ○ (slower than synaptic) ○ hormone

Endocrine System ● ● ●

glands and specialized groups of cells ○ endocrine vs exocrine hormones effects ○ stimulate protein synthesis ○ increase/decrease rate of protein synthesis ○ alter the activity of existing protein

Hormones ● ●

a chemical substance that has an action on a particular cell type ○ target may be far away from source bond to a receptor at the target cell ○ number of receptors may vary with time ■ up-regulation ■ more sensitive ■ down-regulation

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less sensitive

Chemical classification ●

amino acid derivatives ○ tyrosine (most common used as an amino acid message molecule) ■ thyroid hormones ■ catecholamines: epinephrine, norepinephrine, dopamine ○ tryptophan ■ melatonin ○ peptides ■ glycoproteins: TSH, LH, FSH ■ short polypeptides: ADH, growth hormone ○ lipid derivatives ■ eicosanoids: prostaglandins (inflammations) and leukotrienes (allergies) ■ steroid hormones: estrogen, testosterone, corticosteroids

Receptor location ●

cell surface ○ water soluble ■ catecholamines, peptides, eicosanoids ○ use G proteins and second messengers ■ cAMP, cGMP, Ca^+2 ○ set a cascade of reactions in motion ■ amplification ■ turn on/off enzymes already present ○ intracellular ■ lipid soluble or transporter ■ cytosol or nucleus ■ alters gene expression ■ turns transcription on or off

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Response of target depends on ○ presence or absence of receptors ■ number of receptors ○ amount of hormone ○ influences of other hormones ■ permissive ■ synergistic ■ antagonistic

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Secretion regulated by ○ neural stimuli ○ chemical changes in body fluids

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hormonal effects negative feedback

Hypothalamus ● ● ● ●

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located in the brain, just below thalamus controls autonomic nervous system regulates homeostasis ○ temperature, thirst, hunger, sexual behavior, fear, anger secrete regulatory hormones

produces 9 hormones ○ 7 affect release of anterior pituitary hormones ○ 2 are stored in and released by the posterior pituitary

Pituitary gland ● ●

connected to hypothalamus by infundibulum composed of 2 parts ○ anterior pituitary ■ hypophyseal portal system ○ posterior pituitary

Anterior pituitary ●

secretes 7 hormons ○ prolactin (PRL) milk production in mammary glands ○ melanocyte stimulating hormone (MSH) ○ human growth hormone ■ gigantism, dwarfism, acromegaly...