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64 Cards in this Set
- Front
- Back
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What is direct communication vis gap junctions?
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a. cells function as a group
b. the group of cells must be interconnected for exchange of ions c. an example is cardiac muscle |
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What is paracrine communication?
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a. "local communication"
b. chemicals released, but in relatively low concentrations, so only reach neighboring cells c. an example is testosterone secreted from the testes stimulates spermatogenesis |
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What is endocrine communication?
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a. chemical messengers that are released from one tissue and transported in the bloodstream to alter the activities of distant tissues
b. hormones can only be "interpreted" by cells with the proper receptor c. blood vessels are the conduits to deliver hormones d. if hormones are bound to transport proteins, increases 1/2 life e. leptin secreted by adipose to decrease food intake |
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What is synaptic communication?
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a. quick communication over long distances
b. generally short-lived response, an exception being adrenal EPI + NE into bloodstream is neural and endocrine together c. an example is the vagus nerve decreases heart rate |
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A cell must have ______ to have a respone
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a receptor for a specific hormone
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_____ is the 1st messenger
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Hormone
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the 1st messenger activates a cascade of ____
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2nd messengers
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Amplification
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mafnification of the original signal (hormone binding receptor)
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____ are bound to receptors in cell membrane
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G-proteins
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Down-regulation
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High levels of circulating hormone leads to a decrease in the # of receptors
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Up-regulation
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Low levels of circulating hormone leads to an increase in the # of receptors
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Intracellular Messengers
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a. Only lipid soluble
b. Bind to cytoplasm or nuclear receptor c. can then enter the nucleus to act as a transcription factor or inhibit transcription |
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Endocrine Reflexes
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1. Humoral (changes in the composition of the extracellular fluid)
2. Hormonal (the arrival or removal of a specific hormone) 3. Neural (the arrival of neurotransmitters at neuroglandular junctions) |
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Hypophyseal Portal System
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allows the hypothalamus to secrete hormones and the anterior pituitary and posterior pituitary to recieve hormones
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Anterior and Posterior Pituitary are a.k.a ____ & _____
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Adenohypophysis and Neurohypophysis
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At the adenohypophysis ____ releases _____ at the ____ (swelling near the attachment at the infundibulum)
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the hypothalamus regulatory factors/hormones
median eminence |
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Fenestrated capillaires are ____
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permeable
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Portal vessels
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Link 2 capillary beds, factors brought to adenohypophysis
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Where axons from the hypothalamus run to posterior lobe and release hormones onto capillaries (directly into blood stream)
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Neurohypophysis
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Hormones of the Adenophypophysis
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HT Regulatory Hormones
Thyroid Stimulating Hormone (TSH) Prolactin |
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HT Regulatory Hormones
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Releasing hormone (stimulates synthesis and secretion of a hormone at the adenohypophysis)
Inhibiting hormone ( prevents synthesis) Controlled by negative feedback |
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TSH
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Triggers release of thyroid hormones at thyroid gland
As blood level rises, tryptotropin-releasing hormone is decreased from the hypothalamus |
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Prolactin
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Stimulates mammary gland development during pregnancy, stimulates milk production
As levels rise, prolactin-inhibiting hormone is released from they hypothalamus |
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Hormones of the Neurohypophysis
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Antidiuretic hormone (ADH)
Oxytocin |
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ADH
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a.k.a arginine vasopressin
Released from supraoptic neurons from the HT Osmoreceptors sense a rise in solute concentrations Stimulated by a drop in blood pressure Reduces H20 loss at kidneys |
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Oxytocin
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Released from paraventricular nucleus of HT
Stimulates smooth muscle concentration in the uterus Stimulates ejection of milk from mammary glands |
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Location of the pancreas
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Lies between the inferior border of the stomach and the proximal small intestine
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"Islets of Langerhans"
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Clusters of endocrine cells
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Alpha Cells
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Produce glucagon; released when blood glucose falls
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Beta Cells
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Produce insulin; released when blood glucose rises
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Normal blood glucose
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70-110 mg/dl
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Insulin
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Released by beta cells
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Insulin dependant
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Most cells in the body have insulin receptors
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Insulin independant
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Cells w/o insulin receptors such as brain, kidneys, lining of digestive tract, rbc
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At target cells,
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increase in glucose uptake via and increase # of glucose transporters
Increase glucose utilization and increase ATP production Stimulates glycogen formation Increased amino acid absorption and protein synthesis Trigylceride formation in adipose tissue |
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Location of the Thyroid Gland
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Curves around the anterior trachea, 2 lobes connected by isthmus
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C-cells
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Lie between follicle cells and their basement membrane
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Calcitonin
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Produced by c-cells
results in a decrease in the Ca concentration of the blood, activated/released by increased circulation of Ca levels a. inhibition of oseoclasts b. stimulation of Ca excretion at the kidneys Important at childbirth, starvation, and pregnancy |
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Follicle cavity holds:
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dissolved proteins such as thyroglobulin
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Follicle cells surround
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follicle cavity and produce thyroglobulin
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Iodide
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is absorbed from the digestive tract, transported through the bloodstream, and taken up by the follicle cells
is incorporated into thyroglobulin at the follicle cavity |
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90& released by follicles cells are ___, then converted to ___
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T4, T3
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Iodine is transported into follicle cells via
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TSH sensitive carrier
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Goiter
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enlargement of the thyroid gland , results from constant TSH stimulation, which increases thyroglobulin, increasing the size of the follicles
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Parathyroid gland location
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embedded in the posterior thyroid, 4 glands total
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Chief cells:
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produce PT hormone
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Oxyphils
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function is unknown
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Parathyroid glands function
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chief cells monitor circulating Ca levels
i. Ca blood levels fall, PTH is released ii. Stimulates oseoclasts and release of Ca from bone iii. inhibits osteoblasts iv. increases reabsorption of Ca at kidneys v. Stimulates calcitrol production; absorption of Ca and PO4 at digestive tract |
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Adrenal glands location
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superior to kidneys
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Adrenal cortex
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superficial, outer layer of the adrenal glands
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3 zones
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Zone glomerulosa: outermost region of cortex, produces mineral corticoids (aldosterone)
Zone fasciculata: produces glucocorticoids (cortisol) Zone reticularis: innerlayer of adrenal gland; produces androgens |
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Adrenal medulla
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Inner layer of adrenal gland; produces epi and n. epi
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Role of Aldosterone
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Returns Na+ at kidneys, sweat glands, salivary glands, pancreas, and prevents Na+ loss in urine, sweat, saliva, and digestive secretions
Stimulated by drop in blood Na+ levels, blood volume, blood pressure, or hyperkalemia |
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Hyperaldosteronism
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Increase in blood pressure, hypokalemia, greater stimulation required
Flaccid paralysis, hyporelfexia, constipation |
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Hypoaldosteronism
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Not enough aldosterone produced
H20 and salt loss Leads to decrease in blood volume, and blood pressure, hyperkalemia, cardiac arrhythmias |
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Cortisol
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Increase glucose synthesis, glycogen formation, increase fat degradation
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Addison's disease
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Insufficient ACTH or glucocorticoids
Decrease in blood glucose and blood pressure with stress |
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Cushings disease
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Over production of glucocorticoids
Glucose metabolism suppressed Lipid reserves mobilized Proteins broken down Adipose distribution changes (around face and back of neck) |
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Epinephrine is __% of secretions from medulla
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80
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Norepinephrine is __% of secretions from medulla
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20
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Alpha-1
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Vasoconstriction, vc of veins, decrease in GI mobility
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Beta-1
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Increase in heart rate
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Beta-2
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Dilation of respiratory passages
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Beta-3
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Increase in lipolysis
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