Lecture 10, 30 Sept 2003Chapter 9
Vertebrate PhysiologyECOL 437
University of ArizonaFall 2003
instr: Kevin Boninet.a.: Bret Pasch
Vertebrate Physiology 437
1. Cellular and GlandularSecretions, Hormones (CH9)
2. Announcementsxx
3. Exams in Lab
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Remove and Replace Experiments
Exam I, ECOL437 2003
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mean 70.09091max 96min 35.5s.d. 18.19955
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The Doings for this upcoming Friday, Sept 26, will be presented by Doug Keen(UA, PSIO) who is presently a post-doc in Dr. Andy Fuglevand's lab. Thetitle and abstract for his Doings follows."The Neural and Muscular Control of the Human Extensor Digitorum Muscle."Many of the extrinsic hand muscles responsible for flexion and extension ofthe fingers are single bellied muscles that give rise distally to multipletendons. Current thinking is that these multi-tendoned muscles may be comprised offunctional compartments that each produce force selectively on a singledigit and thereby provide independent control of each finger. We examined thishypothesis at the level of the single motor unit.
To whet your appetite, future Doings are as follows:Oct 3 - Kati Gothard (UA, Depts of Psio and Neurology) " Neural andautonomic responses to facial expressions in the Rhesus monkey."Oct 10- Rescheduled MotorBytes - Bob Lansing (UA, Psychology, ProfEmeritus ) Discussion of "Pride and the Daily Marathon" - Movementwithout proprioception: the remarkable story of a person who achievedskilled motor control after having lost it through disease"
See you Friday 4-5 pm in 601 Gould-Simpson Bldg.
-----------------------------------Cindy Rankin, Ph.D.Dept of Physiologyphone: (520) 621-3104email: [email protected]: BioSci West 274Mail: 101 Gittings Bldg.University of ArizonaTucson, AZ 85721-0093
Chap 9. Endocrine System – Glands and Hormones
Secretions with consequences
All cells secrete, butSpecialized secretory cells grouped into glands
Secrete same specialized substance (e.g., hormone)
Nervous System neurotransmitter acts near and fast
Other secretions, such as hormones, may act moredistantly and over a longer time period
Helpful list of abbreviations on page 357.
Four categories of cellular secretions:
Autocrine – affect the secreting cell directlyParacrine – affect neighboring cells
e.g., histamine and inflammation
Endocrine – release into bloodstreamExocrine – release onto epithelial surface
e.g., sweat onto skin, bile into digestive system
Pheromone – exocrine secretion to signal otherindividuals
Neuroendocrine – secretion from axon terminal intoblood stream
Glandular Secretion
Secretory Granules/Vesicles –similar to synaptic vesicles butusually larger
Exocytosis – common releasemechanism
Regulation via Calcium –remember that free cytosoliccalcium concentration iscorrelated with exocytosis(including of NT, hormones,etc.)
9-2 Randall et al. 2002
Storage before Secretion
Large molecules easily stored because can’t leave readily
Small molecules often stored bound to accessory proteins
Some molecules actively/continuosly taken into vesicles
Steroid hormones (lipid soluble) tend to leak out soon
Hydrophobic steroid and thyroid hormonesmove in blood bound to carrier proteins
Glandular SecretionResponse to stimulus
HormoneNeurotransmitterAction Potentialetc. (e.g., osmolarity and ADH)
1
Delivery Vesicle formation
EndoplasmicReticulum
Golgi
Transfervesicle
Apicalmembrane
Basolateralmembrane
Secretoryvesicle
Secretion
2 3
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Endocrine - release into bloodstream - secretions called hormones
Exocrine - release onto epithelial surface - via duct onto epithelial surface
Glands…
-often in sol’n called primary fluid (salt, water, etc.)
-incl. saliva, bile salts, pheromones, salt glands
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Hormones:
- synthesized by specific tissues - carried in bloodstream to site of action - cause change in activity of target tissue
Endocrine Glands
-Hormone action often amplified by second messenger cascade
-Hormones often released in very low concentrations
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Hormone Types
Amines – small (e.g., epi, norepi, thyroid)
Eicosenoids from arachodonic acid (prostaglandins etc.)
Steroid Hormones from cholesterol (e.g., testosterone, estrogen)
Peptide Hormones – common,large, complex(e.g., insulin)
(autocoids = otherslike histamine andserotonin) 9-11 Randall et al. 2002
Feedback...
NoFeedback
NegativeFeedback
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Neuroendocrine Systems
Neurosecretory cellssecrete neurohormones
Axon terminates intoneurohemal organ
Neurohormones often [effect]other glands/hormones
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Major Players:
Pituitary (9 hormones)1. Anterior (~nonneuronal)
2. Posterior (~neuronal control)
Neuroendocrine System
Hypothalamus - (~7 neurohormones) - mostly peptides
(Portal Vessels)
9-15 Randall et al. 2002
Example:Neuroendocrine System
Hypothalamus-corticotropin-releasing hormone
In response to cold,fright, pain etc…
Portal vessel
Anterior Pituitary-Adrenocorticotropin (ACTH)
Adrenal Cortex(corticosterone;stress hormones)
Blood Stream
Response (lizard example)
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Neuroendocrine System
Tropic hormones = act on other
endocrine tissues(e.g., adrenal cortex,
thyroid, gonads)NegativeFeedback
Anterior Pituitary
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Neuroendocrine System
Posterior Pituitary
Oxytocin – uterinecontractions, milk ejection
Antidiuretic Hormone (ADH)- water retention in kidney
Both are peptide hormones
Both are similar and highlyconserved
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Neuroendocrine System
Posterior Pituitary
Similar, highly conserved peptide hormones
ADH
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Hormone ACTION! (receptors etc.)
1. Lipid Soluble
2. Lipid Insoluble
- Steroid and Thyroid Hormones (~long-lived)
- Bind Cytoplasmic Receptors, then to Nucleus- Directly affect transcription (therefore long-term)
- Through Membrane
- Bind cell-surface receptors- Often one or more 2nd messengers- Amplification- Rapid, short-duration responses
Hormone ACTION!(receptors etc.)
1. Lipid Soluble
2. Lipid Insoluble
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Possible 2nd messengers:
Hormone ACTION! (receptors etc.)
2. Lipid Insoluble Hormones and Intracellular Signaling
1. cAMP, cGMP (cyclic nucleotide monophosphates)
2. IP3, DAG (diacylglycerol; inositol phospholipids)
3. Ca2+ ions
General Model of Hormone Bindingand Intracellular Signaling:
A few receptors with direct catalytic activity, but mostvia 2nd messengers :
1. cAMP (cyclic nucleotide monophosphates)
GTP/GDP GTP/GDPcAMP
Protein kinase A
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Glycogenolysis Example:
cAMP, cGMP
-Epi (muscle)
(glycogen-> glucose)
-Glucagon (liver)
Goal is to increaseblood [glucose]
Protein kinase A
AMPLIFICATIO
N -->
1 cAMP
~opposite effectsCalcium once again cAMP at low [Ca]
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2. IP3, DAG (diacylglycerol; inositol phospholipids) as 2nd msngr
GTP/GDP
Ca2+ = 3rd
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- Intracellular stores (ER)3. Ca2+ ions
- Influx from extracellular fluid
1- binds and activates Troponin Cin skeletal muscle
2- binds and activatesCalmodulin also
cAMP
cGMP
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2nd Messenger Networks
Convergence(several pathsto same result)
Divergence(multiple different effects)
Allows forregulation and
control atmany levels
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Hormone Effects
Catecholamines(from medulla)
Glucocorticoids
inside
outside
Adrenal Gland
(from cortex)
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Catecholamines(adrenal medulla)- Epi, Norepi
Fight/flight, exertion
Secretion regulatedby sympatheticpreganglionic
cholinergic neurons
Catecholamine receptorsare Alpha and Betaadrenoreceptors
Alpha – smooth musclecontraction
Beta1 – cardiac muscle stimulantBeta2 – broncho/vaso dilation
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Glucocorticoids(from adrenal cortex)
Released in response toACTH (Adrenocorticotropin)from Anterior Pituitary
Steroid hormones(lipid soluble) derivedfrom cholesterol
• Reproductive• Kidney Function
(mineralocorticoids)• Glucocorticoids
(mobilize a.a.s andglucose, etc.) Includes ‘Stress Hormones’
Cortisol, cortisone,corticosterone
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