Summary
Summary Module 5.1.1: Homeostasis and neuronal communication
- Institution
- OCR
OCR A Level Biology A Key concepts from homeostatic processes to neurones and action potentials.
[Show more]
Seller
Follow
Content preview
HOMEOSTATIS NEURONAL COMMUNICATIONCommunication Neurone structure
- Respond to internal + external environ, coordinate - Cell body – nucleus, cytoplasm, mito for neurot
- Cell signalling – molecule released, specific shape, - Dendrons – impulses towards, divide into dendrites
receptor on target cell complimentary shape - Axon – elongated nerve fibre, impulses away
Feedback Sensory – from receptor to relay/motor/brain
- Homeostasis = fluctuations over narrow range Relay – between neurones, short axon/dendron
- Sensory receptors monitor + detect internal changes Motor – from neurone to effector (muscle/glad)
- Effectors (muscle/gland) respond + change condition
Negative = detect by sensory, effectors restore optimum
Common E.g. blood sugar, temp, water balance
Positive = deviation from normal conditions amplified
Eg blood clotting, childbirth contractions
Thermoregulation
Maintain constant core body temp (optim enzyme)
> Exothermic chemical reactions
> Latent heat of vaporisation (evaporation cools) Myelinated neurone
> Radiation (between air, water, ground) - Myelin sheath = multiple membrane layers
> Convection (current), conduction (molec collision) - Schwan cells grow round axon many times
- Insulting layer = faster electrical impulse speed
Ectotherms - Nodes of Ranvier = impulse jumps between
- Use surroundings to heat, not control own temp
- Invertebrate animals, fish, amphibians, reptiles Sensory receptors
- Dark colours absorb ↑ radiation (cold climates) Specific to stimulus type, act as transducer
1) Mechanoreceptor = pressure in skin
Behavioural responses 2) Chemoreceptor = chemicals in nose
1) Bask in the sun, ↑SA = ↑ metabolic reactions 3) Thermoreceptor = heat in tongue
2) Conduction by pressing body against ground 4) Photoreceptor = light in eyes
3) Exothermic metabolic reactions, contractions
4) Shade, cool ground, low SA, prevent denaturing Pacinian corpuscle
- Pressure sensor in skin
Endotherms - Constant pressure = stop
- Metabolic processes to warm, mammals and birds responding as sodium ion
- Actively maintain stable core temp, -ve feedback channels remain open, no AP
- Anatomical adaptions - change SA:V, insulating fat
- Peripheral temp receptors in skin 1) Resting potential = Na channels closed
- Effectors in skin, muscles, vessels, liver 2) Pressure deforms rings + push against nerves
- Hypothalamus in brain = blood temp deep in body 3) Stretch mediated sodium channels, Na+ diffuse in
Heat loss curve = ↑ blood temp, impulses autonomic 4) Depolarised from Na+ forms generator potential
motor neurones to effectors + lower core temp 5) AP down neurone to CNS
Become too warm Generating impulses
1) Vasodilation – arterioles near surface dilate, ↑ Resting potential = polarised, pd -70mV (outside +ve)
radiation, conduction if against cool surfaces 1) Sodium/potassium pump (3Na out, 2K in)
2) Sweating – evaporates + blood below 2) Closed Na+ channels, open K+ channels (out)
3) Hair – erector pili muscles relax + lie flat 3) Large organic anions on inside of cell
Becoming too cold
1) Vasoconstriction – surface arterioles constrict,
2) Decrease sweating – still evaporation from lungs
3) Raise body hair – erector pili contract = insulates
4) Shivering – involuntary relax/contract muscles,
metabolic heat from exothermic reactions warms
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller katieg1500. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £5.00. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
52510 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now