BioSciences

https://www.youtube.com/watch?v=kkGeOWYOFoAhttps://vimeo.com/9953368

BioSciences

Copyright Notice

Figures and images indicated by KLES are taken from the subject textbook R B Knox, P Y Ladiges, B K Evans and R Saint, Biology, An Australian Focus 4th Ed, McGraw-Hill, 2009, with permission of the publisher. Diagrams and images without that designation are © Geoff Shaw, or are from public domain sources as indicated.

BioSciences

Nerves and Hormonal Regulation

Professor Geoff Shaw

School of BioSciencesg.shaw@unimelb.edu.au

Ref: KLES 4th Ed: Chapter 27, esp pp 637-643,

Ch 28, esp pp 661-6635th Ed: Chapter 28, esp pp 680-688,

Ch 29, 706-709Resources on LMS

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Internal communication

• Nerves

• Hormones

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Nerves• fast point-to-point

signalling• action potential• synapses and

neurotransmitters

KLES5 fig 29.1a

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Nerves and action potentials

• trans-membrane – ion channels (passive – diffusion)– ion pumps (active)

http://ed.ted.com/lessons/how-do-nerves-work

K+

Na+

K+

K+ Na+

Na+

VV

Resting -70 mV (inside vs outside)

-+

Na / K pump maintains concentration gradient of ions membrane potential

• Na+ / K+ ion pump• voltage gated channels

K+

Na+

K+

K+ Na+

Na+

V V

Depolarised (+ 40 mV)

-+

V

small depolarisation transient opening of voltage dependent Na+ channels influx of Na+ surge of depolarisation.

depolarised?

K+

Na+

K+

K+Na+

Na+

V V

Repolarised (- 70 mV)

-+ V

large depolarisation transient opening of voltage dependent K+ channels eflux of K+ membrane repolarisation K+ channel closes voltage gated channels refractory – cannot respond for short period

V

Na+

depolarisation propagates to adjacent Na+ channels

K+

Na+

K+

K+ Na+

Na+

VV

Resting -70 mV

-+

Voltage gated channels closed Na / K pump restores resting concentration gradient of ions membrane potential restored to normal ready to respond to another signal…

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Nerves

• Model of propagation.

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Nerves

• synapses– junctions

neurons

muscle• neurotransmitter

– released when AP reaches synapse

– triggers AP in next cell

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Hormones and the Endocrine System

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hormones• Chemical messengers• released from endocrine glands into

blood• Receptors on target organs

– specific

A Receptor

hormones

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Hormone action

KLES5-fig 28.2

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Chemical messengers

• endocrine– circulate in blood to distant target

• paracrine– released to act on adjacent cells

• autocrine– action on cell releasing the chemical

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Endocrine system

http://en.wikipedia.org/wiki/File:Endocrine_central_nervous_en.svg

Don’t try to memorise these next few wikipedia figures –

the key point is the endocrine system is complex and affects all body systems

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BioScienceshttp://en.wikipedia.org/wiki/File:Endocrine_reproductive_system_en.svg

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http://en.wikipedia.org/wiki/File:Calcium_regulation.png

http://en.wikipedia.org/wiki/File:Endocrine_caclcium_en.svg

BioScienceshttp://en.wikipedia.org/wiki/File:Endocrine_miscelaneous_en.svg

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Homeostasis: blood glucose

Food

glucose+O2 CO2+H2O

absorptionstorage

transport

glucose + glucose +… glycogen

glycogen glucose +…

release

metabolism

metabolismstorage

absorptiongycogenolysis

transport

transport

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Homeostasis: blood glucose

4.5 mmol/L

eat

ch

oco

late

rapid absorption

glucose metabolised…

eat

ch

oco

late

rapid absorption

If no “feedback” regulation…. (…diabetes…)

time

blo

od

glu

co

se

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Insulin and glucagon• peptide hormones • made by islet cells in pancreas

glucoseglucose

glucose

glucose

glucoseglucose

glucoseglucose

glucoseglucose

glucose

GLYCOGENLiver cells

bloodINSULIN

GLUCAGON

Islet of Langherhans(endocrine)

http://en.wikipedia.org/wiki/Islets_of_Langerhans

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Homeostasis: blood glucose

4.5 mmol/L

eat

ch

oco

late

ba

r

eat

ch

oco

late

ba

r

With “feedback” regulation…. (normal)

time

blo

od

glu

co

se high glucoseinsulininsulinglucose stored

in glycogen

low glucoseglucagonglucagonglucose released from glycogen

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Multiple regulatory mechanism…• endocrine:

– insulin– glucagon– adrenaline– cortisol, …

• behavioural– hunger eating – satiety fasting– activities

• burn off sugar• lethargy, to conserve sugar

• etc etc etc…

Hypothalamus and pituitary

sphenoid bone

posteriorpituitary

hypothalamo-pituitaryportal vessels

anteriorpituitary

hypothalamus

neuro-secretory nerves

http://commons.wikimedia.org/wiki/File:Vertebrate-brain-regions.png

neurosecretions released in the hypothalamic capillary bed are carried by the portal vessels to the pituitary capillary bed

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STEROIDS

PEPTIDES

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liver

Growth Hormone in adults

GH

hypothalamus

pituitary

brain

+-Somatostatin

GHRH

fat cells(adipose tissue)

IGF1(Insulin-like Growth Factor 1)

-

muscle+

lots of othertissues

GH

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Birth, an example of a non-homeostatic processes

contractionsstretch cervix

Pituitarygland

uterinecontractions

oxytocin release

neural reflex

Ferguson Reflex

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What do I expect you to learn from this lecture?• internal regulation and coordination via nerves and

hormones• mechanism of nerve conduction• chemical messengers – endocrine, paracrine and autocrine• hormone action via specific receptors• hypothalamo-pituitary axis• examples of endocrine pathways

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• chase up the drugs/hormones/peptides from ACC into sport Among the products offered for sale are CJC-1295, GHRP-6 and Hexarelin - all identified by the ACC and ASADA as being among the principal peptides "misused in both professional sports and the broader population".

• demonstration nerve – row of students polarised raised arm == voltage etc… add in synaptic comm etc…

• hormones and blood pressure ACE inhibitors & snake venom… http://www.fasebj.org/content/18/3/421.1.full http://www.sciencedirect.com/science/article/pii/S0262407912611713