Nervous System and Reflexes Quiz

Gray matter contains cell bodies and synapses, while white matter is composed of axons coated in fatty myelin.

The dorsal root allows sensory neurons to enter the spinal cord, containing a swelling known as the dorsal root ganglion that houses cell bodies.

The stimulus (heat) activates receptor cells, sending an impulse via the sensory neuron to the spinal cord's relay neuron, which then activates the motor neuron to withdraw the limb.

<p>A reflex arc should include a stimulus, receptor, sensory neuron, relay neuron, motor neuron, effector, and response.</p> Signup and view all the answers

<p>Reflexes provide fast, automatic responses that protect the body from harmful stimuli.</p> Signup and view all the answers

<p>Nerve nets have shorter neurons that branch in all directions, while mammalian neurons are longer and branch in one direction. Additionally, nerve nets consist of one type of neuron, compared to three types in mammals.</p> Signup and view all the answers

<p>The resting potential of an axon is maintained at -70mV, creating a polarized membrane. This is achieved through the active transport of 3 Na⁺ ions out and 2 K⁺ ions into the axon.</p> Signup and view all the answers

<p>Sodium-potassium pumps actively transport 3 Na⁺ ions out of the axon and 2 K⁺ ions into it, thus establishing the ion concentration gradient necessary for maintaining resting potential.</p> Signup and view all the answers

<p>The outward movement of K⁺ ions makes the inside of the axon negative relative to the outside, which is more positive due to the higher concentration of Na⁺ ions outside the axon.</p> Signup and view all the answers

<p>The axon membrane's high permeability to K⁺ ions allows them to leak out, contributing to the negative charge inside relative to the positive outside.</p> Signup and view all the answers

<p>A stimulus is any detectable change in the internal or external environment of an organism.</p> Signup and view all the answers

<p>Sensory neurons carry nerve impulses from receptor cells in sense organs to the central nervous system (CNS).</p> Signup and view all the answers

<p>The autonomic nervous system controls internal organs unconsciously, while the somatic nervous system manages voluntary muscle movements.</p> Signup and view all the answers

<p>Schwann cells produce the fatty myelin sheath, which acts as an electrical insulator for neurons.</p> Signup and view all the answers

<p>Nodes of Ranvier speed up nerve transmission by enabling depolarization.</p> Signup and view all the answers

<p>The CNS is composed of the brain and spinal cord, processing information and coordinating responses.</p> Signup and view all the answers

<p>A nerve impulse travels from a sensory receptor to a sensory neuron, then to the CNS, followed by a relay neuron, and finally to a motor neuron which reaches the effector.</p> Signup and view all the answers

<p>Relay neurons connect sensory neurons with motor neurons within the CNS and help in processing information.</p> Signup and view all the answers

<p>Na⁺ ions flood into the axon, leading to depolarization that can generate an action potential.</p> Signup and view all the answers

<p>+40mV</p> Signup and view all the answers

<p>K⁺ channels open to allow K⁺ ions to leave the axon, which repolarizes the membrane.</p> Signup and view all the answers

<p>The refractory period prevents the generation of new action potentials until the membrane is repolarized.</p> Signup and view all the answers

<p>Hyperpolarization occurs when the membrane potential becomes more negative than the resting potential due to excessive K⁺ outflow.</p> Signup and view all the answers

<p>Stimulus 2 does not cause enough voltage-gated Na⁺ channels to open, preventing sufficient Na⁺ influx for depolarization.</p> Signup and view all the answers

<p>The sodium-potassium pump helps restore the resting potential by moving Na⁺ out of the axon and K⁺ back in.</p> Signup and view all the answers

<p>During the absolute refractory period, no action potential can be generated, whereas during the relative refractory period, a stronger stimulus can trigger one.</p> Signup and view all the answers

<p>They open channels that allow neurotransmitter release into the synaptic cleft.</p> Signup and view all the answers

<p>Cocaine blocks the dopamine transporter, causing dopamine to remain in the synaptic cleft longer and intensifying stimulation of the postsynaptic neuron.</p> Signup and view all the answers

<p>Cholinesterase hydrolyzes acetylcholine into choline and ethanoic acid to prevent continuous stimulation of the postsynaptic neuron.</p> Signup and view all the answers

<p>The synapse transmits information between neurons and prevents overstimulation.</p> Signup and view all the answers

<p>ATP is required for the regeneration of neurotransmitters and packaging them into synaptic vesicles.</p> Signup and view all the answers

<p>The All or Nothing Law states that if a stimulus exceeds a certain threshold, a full action potential is generated, regardless of further increases in stimulus intensity.</p> Signup and view all the answers

<p>Propagation occurs through localized electrical currents generated by the juxtaposition of positive and negative charges in the axon's membrane.</p> Signup and view all the answers

<p>Increased temperature raises kinetic energy, resulting in faster ion transport and quicker nerve transmission.</p> Signup and view all the answers

<p>A larger axon diameter decreases resistance to ion movement, thereby increasing the speed of transmission.</p> Signup and view all the answers

<p>Myelination insulates the axon with a fatty sheath and allows the action potential to jump between the Nodes of Ranvier, significantly speeding up transmission.</p> Signup and view all the answers

<p>The Nodes of Ranvier are gaps in the myelin sheath where the axon membrane is exposed, allowing depolarization to occur and facilitating rapid transmission.</p> Signup and view all the answers

<p>Myelination is primarily a feature of vertebrates due to the evolutionary advantages offered in terms of speed and efficiency of nerve impulse transmission.</p> Signup and view all the answers

<p>If the stimulus is below the threshold, no action potential is generated, and no nerve impulse is propagated.</p> Signup and view all the answers

<p>Cocaine accelerates neurotransmitter production and blocks the removal of neurotransmitters from the synaptic cleft.</p> Signup and view all the answers

<p>Psychoactive drugs can make post-synaptic receptors more sensitive or less sensitive to neurotransmitters.</p> Signup and view all the answers

<p>Synaptic transmission can be inhibited by closing sodium channels on the post-synaptic membrane.</p> Signup and view all the answers

<p>Cholinesterase breaks down neurotransmitters in the synaptic cleft, preventing excessive stimulation of post-synaptic receptors.</p> Signup and view all the answers

<p>Drugs that mimic neurotransmitters activate post-synaptic receptors, leading to similar physiological effects.</p> Signup and view all the answers