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Direct Communication:
- exchange of ions and molecules between adjacent cells across gap junctions
- occurs between 2 cells of same type
- highly specialized and rare
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Paracrine Communication
- uses chemical signals to transfer info from cell to cell within single tissue
- most common form of intercellular communication
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Endocrine communication
- endocrine cells release chemicals(hormones) into bloodstream
- alters metabolic activities of many tissues and organs simultaneously
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Endocrine system
- regulates long term processes: growth, developement, reproduction
- uses chemical (hormone) messengers to relay info between cells
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Synaptic communication
- occurs across synaptic cleft
- chemical mediator is a neurotransmitter
- (muscle contraction)
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Target cells
specific cells that possess receptros needed to bind and read hormonal messages
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Hormones
- stimulate synthesis of enzymes/structural proteins
- increase/decrease rate of synthesis
- turn existing enzyme/membrane channel on or off
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Two classes of Hypothalamic Regulatory Hormones
- Releasing hormones
- Inhibiting hormones
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Releasing Hormones
stimulate synthesis and secretion of one/more hormones at anterior lobe
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Inhibiting hormones
prevent synthesis and secretion of hormones from anterior lobe
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Anterior Lobe
- aka Adenohypophysis
- divided into 3 regions: pars distalis, intermedia, tuberalis
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Thyroid Stimulating Hormone
secretion of thyroid hormones
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Adrenocorticotropic hormone
secretion of glucocorticoids (cortisol, corticosterone)
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Follicle Stimulating Hormone
- secretion of estrogen, follicle developement
- stimulation of sperm maturation
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Luteinizing Hormone
- ovulation, formatio of corpus luteum
- secretion of progesterone
- secretion of testosterone
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Prolactin
mammary glands for production of milk
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Growth hormone
growth, protein synthesis, lipid mobilization and catabolism
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Melanocyte-Stimulating hormone
increased melanin synthesis in epidermis
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Antidiuretic Hormone
reabsorption of water, elevation of blood volum and pressure
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Oxytocin
- labor contractions, milk ejection
- contraction of ductus deferens and prostate gland
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Relationship between anterior pituitary and hypothalamus
- 1. When stimulated, hypothalamic neruons secrete releasing/inhibiting hormones into primary capillary plexus
- 2. hypothalamic hormones travel through portal veins to anterior pituitary either stimulating/inhibitng hormones
- 3. Anterior pituitary hormones secreted into secondary capillary plexus
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Relationship between posterior pituitary and hypothalamus:
- 1. Hypothalamic neurons synthesize oxytocin and ADH
- 2. Oxytocin and ADH are transported along hypothalamic-hypophyseal tract to posterio pituitary
- 3. Oxytocin and ADH are stored in axon terminals
- 4. Oxytocin and ADH release into blood when hypothalamic neurons fire
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Effects of Thyroid Hormones:
- 1. Elevates rates of oxygen consumption and energy consumption in children
- 2. increased heart rate and force of contraction, rise in BP
- 3. increased sensitivity to sympathetic stimulation
- 4. maintenance of normal sensitivity of respiratory center to changes in oxygen and CO2 concentrations
- 5. Stimulation of red blood cell formation and thus enhanced oxygen delivery
- 6. Stimulation of activity in other endocrine tissues
- 7. Accelerated turnover of minerals in bone
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Follicular/Epithelium
increases energy, oxygen consumption, growth, development
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C cells
decreases Calcium concentrations in body fluids
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Parathyroid (Chief) cells
increases Calcium concentrations in body fluids
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Zona Glomerulosa
- Mineralcorticoids
- Aldosterone: regulate electrolyte concentration in extracellular lfuids particularly of Sodium and Potassium
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Zona Fasciculata
- Glucocorticoids
- cotisol: influence energy metabolism of most body cells and help us resist stressors , adapt to food intake by keeping glucose levels constant
- inhibits activites of white blood cells: anti-infammatory effect
- *Inhibitory: Corticotopin releasing hormone and ACTH
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Zona Reticularis
- network of endocrine cells
- Produces androgens
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Suprarenal Medulla produces _____ and ______ and what are the % of the secretions?
- epinephrine: 75-80%
- norepinephrine: 20-25%
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Cushions Syndrome
- Too much cortisol
- buffalo hump, round face
- tendency to bruise and poor wound healing
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Kidneys Hormonal Effects
- Stimulates red blood cell production
- " calcium and phosphate absorption
- Calcium release from bone
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Heart Hormonal Effects
- increase water and salt loss at kidneys
- decrease thirst
- suppress secretion of ADH and aldosterone
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Thymus
coordinate and regulate immune response
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Adipose Hormonal Effects
suppression of appetite; permissive effects on GnRH and gonadotropin synthesis
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Steroid Hormones
- Adrenal Cortex layes
- Estrogen
- Progesterone
- Calcitrol from Kidney
- Calciferol from skin
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Steroid Hormones attach to segment of ____ which undergoes transciption and ____ results in new protein being made.
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Humoral Control
- cells of gland monitor blood levels and secrete hormone in response to decrease
- ex: parathyroid-Calcium levels
- pancreas-Glucose
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Neural Control
- hormones release by nerve stimulation
- ex: adrenal Medulla-epinephrine
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Hormone Stimuli
- most hormones release hormones in response to other hormones attaching to target cells on their glands
- ex: anterior pituitary: releasin and inhibin from hypothalamus
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