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115 Cards in this Set
- Front
- Back
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What communication system regulates homeostasis by detecting deviations from the balanced state and then sending messages in the form of nerve impulses to organs to counteract the stress? Quick changes
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Nervous System
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What communication system regulates homeostasis by secreting hormones into the bloodstream? Slow changes
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Endocrine System
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Direct cell-cell communicating junction (signaling mechanism)
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Gap junctions
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Cell secretes chemical mediator and has receptors on itself for that substance (signaling mechanism)
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Autocrine
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Chemical mediator released affects neighboring cells (signaling mechanism)
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Paracrine
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Cells produce a chemical mediator which affects cells at a long distance. Uses both vascular systems to get the mediator from one location in the body to another. (signaling mechanism)
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Endocrine
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Neurotransmitter is sent from a neuron to a synapse where a specific cell is affected. Indirect cell-cell communicating junction. (signaling mechanism)
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Neurotransmission
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Neuron releases a chemical mediator not into a synapse but into one or both of the vascular systems. Mediator then gets out and affects a cell at some distance. (signaling mechanism)
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Neuroendocrine
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A chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, muscle fiber, or other structure.
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Neurotransmitter
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A regulatory substance produced in an organism and transported in tissue fluids to stimulate specific cells or tissues into action.
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Hormone
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What communication system regulates homeostasis by detecting deviations from the balanced state and then sending messages in the form of nerve impulses to organs to counteract the stress? Quick changes
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Nervous System
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What communication system regulates homeostasis by secreting hormones into the bloodstream? Slow changes
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Endocrine System
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Direct cell-cell communicating junction (signaling mechanism)
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Gap junctions
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Cell secretes chemical mediator and has receptors on itself for that substance (signaling mechanism)
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Autocrine
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Chemical mediator released affects neighboring cells (signaling mechanism)
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Paracrine
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Cells produce a chemical mediator which affects cells at a long distance. Uses both vascular systems to get the mediator from one location in the body to another. (signaling mechanism)
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Endocrine
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Neurotransmitter is sent from a neuron to a synapse where a specific cell is affected. Indirect cell-cell communicating junction. (signaling mechanism)
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Neurotransmission
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Neuron releases a chemical mediator not into a synapse but into one or both of the vascular systems. Mediator then gets out and affects a cell at some distance. (signaling mechanism)
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Neuroendocrine
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A chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, muscle fiber, or other structure.
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Neurotransmitter
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A regulatory substance produced in an organism and transported in tissue fluids to stimulate specific cells or tissues into action.
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Hormone
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What communication system regulates homeostasis by detecting deviations from the balanced state and then sending messages in the form of nerve impulses to organs to counteract the stress? Quick changes
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Nervous System
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What communication system regulates homeostasis by secreting hormones into the bloodstream? Slow changes
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Endocrine System
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Direct cell-cell communicating junction (signaling mechanism)
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Gap junctions
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Cell secretes chemical mediator and has receptors on itself for that substance (signaling mechanism)
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Autocrine
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Chemical mediator released affects neighboring cells (signaling mechanism)
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Paracrine
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Cells produce a chemical mediator which affects cells at a long distance. Uses both vascular systems to get the mediator from one location in the body to another. (signaling mechanism)
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Endocrine
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Neurotransmitter is sent from a neuron to a synapse where a specific cell is affected. Indirect cell-cell communicating junction. (signaling mechanism)
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Neurotransmission
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Neuron releases a chemical mediator not into a synapse but into one or both of the vascular systems. Mediator then gets out and affects a cell at some distance. (signaling mechanism)
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Neuroendocrine
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A chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, muscle fiber, or other structure.
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Neurotransmitter
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A regulatory substance produced in an organism and transported in tissue fluids to stimulate specific cells or tissues into action.
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Hormone
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Ductless, very vascular, produce hormones, capsule of dense irregular ct, bound via reticular fibers
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endocrine glands
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How do steroid-secreting glands store their hormones?
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As the hormone precursor, cholesterol
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What are the 3 basic components of a feedback system?
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control center, receptor and effector
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What feedback system tends to maintain conditions that require frequent monitoring and adjustment within physiological limits?
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Negative feedback loops
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If the response reverses the original stimulus, what is the feedback system?
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Negative feedback system
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If the response enhances or intensifies the original stimulus, what is the feedback system?
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Positive feedback system
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What feedback system tends to involve conditions that do not occur often and do not require continual fine tuning?
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Positive feedback system
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Blood clotting, labor contractions during childbirth and immune responses that provide defense against pathogens are examples of conditions regulated by what feedback system?
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Positive feedback system
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Blood pressure, body temperature and blood glucose level are examples of conditions regulated by what feedback system?
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Negative feedback system
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What kind of solubility in water do steroid hormones and thyroid hormones have?
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They are small and hydrophobic
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What hormones are hydrophilic signaling molecules?
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Most other hormones and all neurotransmitters
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Aldosterone, cortisol, estrogen, progesterone, and testosterone are examples of what kind of hormones?
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Steroids
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What are examples of hormones that are derivatives of tyrosine?
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Epinephrine and norepinephrine (catecholamines), T3 and T4
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What are two eicosanoids that are produced by all cells except red blood cells?
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Prostaglandins and leukotrienes
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Hormones that bind to cell-surface receptors located in the plasma membrane
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Protein hormones
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Upon what does the responsiveness of a target cell to a hormone depend?
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hormones concentration, number of receptors, and influences exerted by other hormones
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What is the effect when two hormones acting together is greater than effect of each working alone?
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synergistic effect
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Actions of some hormones on target cells require a simultaneous or recent exposure to a second hormone. The second hormone is said to have...
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permissive effect
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When one hormone opposes the actions of another hormone?
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antagonistic effect
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What are the ten endocrine organs?
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Pituitary gland, thyroid gland, pineal gland, parathyroid gland, thymus, adrenal cortex, adrenal medulla, pancreatic islets of Langerhans, theca interna cells and corpus luteum of ovary, interstitial cells of testis
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What are the two parts of the infundibulum?
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Infundibular stem and median eminance
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What are the three parts of the adenohypophysis?
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Pars distalis, pars intermedia, pars tuberalis
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What is the embryonic origin of the posterior lobe of the pituitary gland?
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Nervous tissue (neural ectoderm)
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Which part of the pituitary gland is absent in adults?
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Pars intermedia
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What is the name of the bony fossa in the sphenoid bone in which lies the majority of the pituitary gland?
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stella turcica
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The parenchymal cell type in the pars distalis that responds poorly to stains
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chromophobes
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The parenchymal cell type in the parts distalis that has strong staining affinities
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chromophils
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This part makes us three fourths of the pituitary gland
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Pars distalis
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What are the hormone-secreting cells of the adenohypophysis?
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Chromophils
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What hormones do the acidophils produce?
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growth hormone and prolactin
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What hormones do the basophils produce?
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FSH, TSH, LH and ACTH
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What hormone stimulates gonadotrophs to release FSH and LH?
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GnRH
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What hormone stimulates corticotrophs to release ACTH?
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CRH
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What hormone stimulates thyrotrophs to release TSH?
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TRH
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What hormone stimulates somatotrophs to release GH?
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GHRH
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What hormone inhibits growth hormone release from somatotrophs?
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GHIH (somatostatin)
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What hormone inhibits prolactin release from mammotrophs?
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PIH (dopamine)
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What are the releasing hormones?
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GnRH, CRH, TRH and GHRH
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What are the inhibiting hormones?
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GHIH and PIH
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What hormone is increased by suckling and then stimulates milk ejection by mammary glands?
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Oxytocin
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What hormone increases with increased blood osmolarity and stimulates water resorption by the renal medullary collecting ducts?
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Arginine vasopressin (AVP) or antidiuretic hormone (ADH)
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What hormone is synthesized primarily by cells of the paraventricular nucleus?
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Oxytocin
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What hormone is synthesized mainly by cells of the supraoptic nucleus?
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AVP or ADH
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What are the three major digestive hormones?
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Gastrin, secretin and cholecystokinin
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What hormone promotes secretion of gastric juice, increases gastric motility and promotes growth of gastric mucosa?
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Gastrin
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What hormone stimulates secretion of pancreatic juice and bile that are rich in HC03?
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Secretin
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What hormone stimulates secretion of pancreatic juice rich in digestive enzymes, causes ejection of bile from the gallbladder and opening of the sphincter of Oddi, and induces satiety?
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Cholecystokinin
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What are the two main cell types in the thyroid gland?
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Follicular cells and parafollicular cells
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Do these cause an increase or decrease in TSH release: low environmental temp, puberty, pregnancy?
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Increased TSH
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Do these cause an increase or decrease in TSH release: emotional stress, systemic stress (heat, trauma, hemorrhage)?
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Decreased TSH
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From what amino acid is thyroglobulin derived?
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Tyrosine
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Which thyroid hormone is more active?
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T3
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Which thyroid hormone is predominantly produced?
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T4
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Are T3 and T4 bound or loose when traveling in the blood?
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They are bound to proteins in the plasma.
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Where in the thyroid gland are excess secretions reserved?
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Colloid (mostly in form of thyroglobulin)
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What peptide hormone do the parafollicular cells of the thyroid gland secrete in response to high levels of blood calcium?
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Calcitonin
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What hormone inhibits osteoclastic activity, thereby inhibiting bone resorption, leading to lowered blood calcium?
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Calcitonin
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What are the two major parenchymal cell types in the parathryoid glands?
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Chief cells and oxyphil cells
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What is the embryonic origin of the inferior parathyroid glands?
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Third pharyngeal pouches (which descend with the thymus)
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What is the embryonic origin of the superior parathyroid glands?
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Fourth pharyngeal pouches
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What peptide hormone is secreted by chief cells?
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Parathyroid hormone (PTH)
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How does PTH increase blood calcium in bone?
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By increasing bone resorption
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How does PTH increase blood calcium in kidneys?
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By increasing phosphate excretion and calcium reabsorption, and causing activation if a vitamin D precursor
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How does PTH increase blood calcium in the intestines?
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By increasing absorption of calcium by the intestinal mucosa
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What is the embryonic origin of the adrenal cortex?
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Mesoderm
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What are the three classes of steroid hormone secreted by the adrenal cortex?
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Mineralocorticoids, glucocorticoids and androgens (all synthesized from cholesterol)
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Which two layers of the adrenal cortex produce glucocorticoids?
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Zona fasciculata and zona reticularis
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What are weakly masculinizing hormones produced in the zona reticularis of the adrenal cortex?
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Androgens
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What is the predominant layer of the adrenal cortex?
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Zona fasciculata
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What hormone from the anterior pituitary stimulates secretion of glucocorticoids in the adrenal cortex?
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ACTH
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What is the embryonic origin of the adrenal medulla?
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Neural crest
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What are the two major cell types of the adrenal medulla?
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Chromaffin cells and ganglion cells
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What is the innervation of the chromaffin cells of the adrenal medulla?
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They are innervated by preganglionic sympathetic fibers
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Which hormone is characteristically produced in clear granules within the chromaffin cells of the adrenal medulla?
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Epinephrine
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What are the two hormones produced in the chromaffin cells of the adrenal medulla?
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Epinephrine and norepinephrine
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Cortical steroids are required to stimulate the activity of what enzyme in the adrenal medulla?
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PNMT (phenylethanolamine-N-methyltransferase)
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What can occur with overuse of the neuroendocrine response to restore homeostasis?
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Erosion of lean body mass and tissue injury; immunosuppressive effects
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What are the major stress hormones that are invariably elevated during stress?
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Norepinephrine and epinephrine (catecholamines) and the corticosteroids
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What is the role of the fetal zone of the adrenal cortex?
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To synthesize estrogen precursors, which are converted in the placenta to estrogen
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What are the four main types of cells in the pancreatic islets of Langerhans?
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Beta cells, alpha cells, delta cells and F cells
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What is the function of beta cells?
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Produce insulin in response to high blood glucose
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What is the function of alpha cells?
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Produce glucagon in response to low blood glucose
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What is the function of delta cells?
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Inhibit alpha and beta cells via paracrine action
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What gland's secretions are influenced by the light and dark periods of the day?
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Pineal gland - melatonin and seratonin from pinealocytes
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Are all endocrine glands vascularized?
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Yes
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