Frumulag og virkni taugakerfisfrumna

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Questions and Answers

Hvað gerist þegar Na+ göngin opnast um leið og boðspennuþröskuldi er náð?

Na+ jónir streymir inn í frumuna. (correct)

K+ jónir hreyfast inn í frumuna.

Himnuspennan eykst jafnt og þétt.

Himnuspennan fer undir -70 mV.

Hvenær opnast K+ göngin í frumusímanum?

Við hámark himnuspennunnar.

Þegar himnuspennan fellur undir -70 mV.

Um leið og Na+ göngin lokast. (correct)

Strax eftir afskautun frumusímans.

Hvað gerist við himnuspennuna eftir að K+ jónir flæða út úr frumunni?

Hún leiðir til hærri himnuspennu.

Hún fer undir -70 mV um tíma. (correct)

Hún breytist strax í +40 mV.

Hún breytist ekki að neinu leyti.

Hvað lýsir best lögmálinu um „Allt eða ekkert“ í tengslum við boðspennu?

Boðspenna heldur áfram af sama krafti þegar hún hefur byrjað. Signup and view all the answers

Hvers vegna virðist boðspennan 'hoppa' í mýldum símum?

Vegna stökkleiðni við mýlisskorið. Signup and view all the answers

Hvað er hvíldarspenna taugafrumu almennt að verulegu leyti?

-70 mV Signup and view all the answers

Hver er aðalhlutverkið fyrir hreyfitaugafrumur?

Að stjórna samdrátt vöðva Signup and view all the answers

Hvað gerist við afskautun taugafrumu?

Himnuspenna minnkar Signup and view all the answers

Hvers vegna eru Natríumjónir (Na+) mikilvægar fyrir boðspennu?

Þær breyta himnuspennunni með því að hleypa inn í frumuna Signup and view all the answers

Hvað er boðspenna?

Skammvinn rafboð sem leiða til rafleiðni Signup and view all the answers

Hver er megin munurinn á katjónum og anjónum?

Katjónir hafa jákvæða hleðslu, en anjónir neikvæða Signup and view all the answers

Hvað er jónagöng?

Sérhæfðar próteinsameindir sem hleypa jónum í gegnum frumuhimnuna Signup and view all the answers

Hvað stjórnar himnuspennu almennt?

Óvirkir kraftar og jónasamsetning innan og utan frumunnar Signup and view all the answers

Hver er hlutverk rafstöðuþrýstings?

Að laða jónir að andstæðri hleðslu Signup and view all the answers

Hver er efni sem mýelínslíður er aðallega samsett úr?

Fitu Signup and view all the answers

Study Notes

Nervous System Cell Structure and Function

Nervous system cells are called neurons
Neurons communicate with each other via electrical signals
Neurons have specific parts impacting communication

Neuron Parts and Structure

Dendrites: Receive signals from other neurons
Cell body (soma): Contains nucleus and other organelles
Axon: Carries signals away from the cell body
Myelin sheath: Insulates the axon, speeding signal transmission
Nodes of Ranvier: Gaps in the myelin sheath
Synaptic terminals (axon terminals): Release neurotransmitters to other neurons
Synapse: The junction between neurons where neurotransmitters are passed

Communication Within a Neuron

Action Potential: A rapid change in the electrical potential across the neuron membrane.
Resting Potential: The electrical potential across the neuron membrane when it's not transmitting a signal. Typically around -70mV.
Depolarization: The inside of the neuron becomes less negative, a shift towards zero, which leads to the action potential
Repolarization: The inside returns to resting potential, becoming more negative
Hyperpolarization: The inside of the neuron becomes more negative than the resting potential, a temporary dip in the potential below resting state.
Threshold of excitation: The specific level of depolarization needed to trigger an action potential
Ion channels: Protein channels that allow ions to pass through the membrane (ex: Na+, K+, Cl-) impacting polarization
Sodium-Potassium pumps: Maintain the resting potential by moving Na+ out of the cell and K+ into the cell

Types of Neuron Communication

Sensory neurons: Relay information from sensory receptors to the central nervous system.
Motor neurons: Carry signals from the central nervous system to muscles or glands.
Interneurons: Connect sensory and motor neurons within the central nervous system.

Reflex Arc & Withdrawal Reflex

Reflex arc: A simple neural pathway that mediates a rapid, automatic response to a stimulus.
Withdrawal reflex: A simple reflex in response to a painful stimulus to pull away the body part.

Conduction of Action Potential

All-or-none law: An action potential either occurs or it doesn't. Strength does not differ.
Rate Law: The level of stimulation will affect the frequency of action potentials
Conduction/Propagation: Movement of the action potential along the neuron.
Saltatory Conduction: Rapid signal transmission, specific to myelinated axons. Action potential jumps between Nodes of Ranvier, speeding up the propagation process

Summary of Action Potential

The action potential is initiated when reaching a threshold of stimulation.
The action potential has specific steps (depolarization, repolarization, hyperpolarization).
Sodium ions flow into the axon which triggers an action potential.
Following Sodium's influx, Potassium channels open to return back to normal potential.

Electrochemical Gradient

Diffusion: Movement of ions from high to low concentration
Electrostatic pressure: Opposite charges attract, same charges repel

Factors influencing membrane potential

Sodium, potassium, and chloride ions are primary contributors

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Description

Í þessari spurningarlistu skoðum við uppbyggingu og virkni taugafruma. Við einblínir á mikilvægar hlutar neuronanna, svo sem dendritar, frumubol og axon. Þú munt einnig læra um hvernig excitatory og inhibitory boðstraumar mynda samskipti milli frumna.