vertebrate physiology ecol 437 university of arizona fall...

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

9-10 Randall et al. 2002

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.)


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


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


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



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

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Neuroendocrine Systems

Neurosecretory cellssecrete neurohormones

Axon terminates intoneurohemal organ

Neurohormones often [effect]other glands/hormones



Major Players:

Pituitary (9 hormones)1. Anterior (~nonneuronal)

2. Posterior (~neuronal control)

Neuroendocrine System

Hypothalamus - (~7 neurohormones) - mostly peptides

(Portal Vessels)


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)



Tropic hormones = act on other

endocrine tissues(e.g., adrenal cortex,

thyroid, gonads)NegativeFeedback

Anterior Pituitary


Randall et al. 2002


Posterior Pituitary

Oxytocin – uterinecontractions, milk ejection

Antidiuretic Hormone (ADH)- water retention in kidney

Both are peptide hormones

Both are similar and highlyconserved



Posterior Pituitary

Similar, highly conserved peptide hormones

ADH

Randall et al. 2002

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


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


Randall et al. 2002

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]


2. IP3, DAG (diacylglycerol; inositol phospholipids) as 2nd msngr

GTP/GDP

Ca2+ = 3rd


- 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



2nd Messenger Networks

Convergence(several pathsto same result)

Divergence(multiple different effects)

Allows forregulation and

control atmany levels


Hormone Effects

Catecholamines(from medulla)

Glucocorticoids

inside

outside

Adrenal Gland

(from cortex)


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


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


vertebrate physiology ecol 437 university of arizona fall...

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