Neuroscience Quiz: Neuron Functions and Anatomy

Neuron Structure and Function

• Neurons are composed of a cell body, dendrites, and an axon.
• Dendrites receive incoming signals.
• Axons transmit signals away from the cell body.
• Axons are connected to the cell body by the axon hillock.
• Axon collaterals are branches that sometimes occur along the axon's length.
• Neurotransmitters are stored and released from axon terminals and axon varicosities.
• Axonal transport moves proteins and organelles along the axon.
• Anterograde and retrograde axonal transport are forms of fast transport.
• Clusters of nerve cell bodies in the PNS are called ganglia.

Glial Cells

• Glial cells maintain homeostasis in the brain and help neurons during development and repair.
• They provide structural and metabolic support.
• Glial cells communicate primarily via chemical signals.
• Myelin is formed by Schwann cells and oligodendrocytes.
• Microglia act as scavengers and are involved in some neurological disorders. (e.g., Lou Gehrig's disease)
• Ependymal cells are CNS glial cells potentially relevant in neural degenerative disorders.

Resting Membrane Potential and Action Potentials

• The resting membrane potential arises from an uneven distribution of ions across the cell membrane and differences in membrane permeability to Na+ and K+.
• Potassium concentration is higher inside the cell than outside.
• Ion channel inactivation is the closing of a channel even when the stimulus continues.
• The total number of neurotransmitter released is directly related to the number of action potentials.
• Action potential overshoot occurs when the inside of the cell becomes more positive than the outside.
• Activation gate opens during depolarization.
• The absolute refractory period ensures one-way travel and prevents summation of action potentials.
• Increasing the stimulus strength leads to a more frequent rate of action potentials.

Action Potential Generation and Conduction

• Voltage-gated channels are found in dendrites, axons, and the cell body.
• The sodium-potassium exchange pump requires ATP.
• When voltage-gated Na+ channels open, sodium enters the neuron and depolarizes it.
• When voltage-gated K+ channels open, potassium exits the neuron.
• In a resting nerve cell, if chemically gated Cl- channels open, chloride ions enter the cell.
• Ion concentrations are significantly affected after numerous action potentials.
• Increasing axon diameter and membrane resistance to ion leakage enhances action potential conduction speeds.
• Some toxins and anesthetics work by binding to and inactivating sodium channels.

Synaptic Transmission

• Chemical synapses include axon terminals, presynaptic cells, a synaptic cleft, and a postsynaptic cell.

• Calcium triggers acetylcholine release in the synaptic cleft.

• Increasing action potential frequency increases neurotransmitter release.

• GABA and glycine are common inhibitory neurotransmitters in the CNS, acting by opening chloride channels.

• Excitatory neurotransmitters usually open sodium channels.

• Trigger zones are sites of information integration.

• Ion channels open, ions enter or exit, and second messengers may be activated when a stimulus alters cell membrane receptors.

• Neurotransmitters are released into the synaptic cleft.

• Calcium is crucial for the exocytosis of neurotransmitters at the synapse.

• Postsynaptic cells respond to neurotransmitters in various ways, including opening ion channels, activating second messengers, and regulating protein synthesis.

• Glutamate is involved in learning and memory.

• Inhibitory postsynaptic potentials (IPSPs) lead to hyperpolarizations.

• Graded potentials arriving simultaneously can summate, creating excitatory or inhibitory effects.

• Presynaptic facilitation increases the likelihood of a pathway being used.

• Spatial summation is the arrival of multiple graded potentials at one location simultaneously.

• Dendrites receive signals, analogous to a satellite dish receiving signals in a TV system.

• Hyperkalemia causes neurons to be hyperexcitable due to resting potentials being closer to the threshold, resulting in a quicker response to smaller stimuli.

Nervous System Organization

• The central nervous system (CNS) consists of the brain and spinal cord.
• The peripheral nervous system (PNS) includes afferent and efferent axons.
• The autonomic nervous system controls exocrine glands, smooth muscles, and cardiac muscles.
• The autonomic nervous system is divided into sympathetic and parasympathetic divisions.
• The enteric nervous system controls digestion.

Nervous System Components

• The nervous system is made of neurons and glial cells.
• Neuron cell bodies generally comprise 10% of the cell volume.
• Interneurons are found in the brain.
• Nerves carry information between the CNS and peripheral effectors.

Nervous System Function

• A sequence leading to a response involves: sensory input, afferent neuron, integrating center, efferent neuron, and effector.
• Substances like caffeine, nicotine, and alcohol affect synaptic activity.

Test your knowledge on the key functions and anatomy of neurons with this quiz. Explore questions on the types of neurons, roles of glial cells, and the mechanisms behind action potentials. Perfect for anyone studying neuroscience or psychology!