Neuron Structure and Function Quiz

A: The cell body contains the nucleus and organelles (mitochondria, endoplasmic reticulum, ribosomes, Golgi apparatus) responsible for cell function.

Dendrites are short, branched extensions that carry impulses toward the cell body.

The axon is a long, single extension that carries impulses away from the cell body and ends in branches called axon terminals.

The myelin sheath is a fatty layer covering most axons, acting as an insulator, protecting the axon, and speeding up impulse transmission.

In the peripheral nervous system, Schwann cells form the myelin sheath and neurilemma (outermost coil), which aids in nerve fiber repair. In the central nervous system, oligodendrocytes produce the myelin sheath, with myelinated areas called white matter and unmyelinated areas called grey matter.

A: Synapses are junctions where the axon terminal of one neuron connects to the dendrite or cell body of another, separated by a small gap. Neurotransmitters are chemicals that carry impulses across this gap, enabling neuron-to-neuron communication. A similar synapse, called a neuromuscular junction, occurs between an axon and a muscle cell.

<p>A: Sensory (afferent) neurons transmit signals from receptors (sense organs, skin) to the central nervous system. Motor (efferent) neurons send signals from the central nervous system to muscles and glands. Interneurons, found in the central nervous system, link sensory and motor neurons, allowing integration and response coordination.</p> Signup and view all the answers

<p>A: Multipolar neurons have one axon and multiple dendrites, are most common, and include motor and most interneurons.</p> <p>Bipolar neurons have one axon and one dendrite, found in sensory organs (eye, ear, nose). Unipolar neurons have a single extension (axon) and are not found in vertebrates. Pseudounipolar neurons have one axon that splits into two branches, common in sensory neurons leading to the spinal cord.</p> Signup and view all the answers

<p>A: Nerve fibres are the axons and dendrites of neurons. Outside the brain and spinal cord, nerve fibres are bundled together with connective tissue to form a nerve, which includes multiple fibre bundles joining together for transmission and protection.</p> Signup and view all the answers

<p>A: The myelin sheath acts as an insulator, protects the axon, and speeds up nerve impulses. In the peripheral nervous system, it’s formed by Schwann cells (with neurilemma aiding repair). In the central nervous system, it’s formed by oligodendrocytes, creating white matter (myelinated) and grey matter (unmyelinated regions).</p> Signup and view all the answers

<p>A: White matter consists of myelinated nerve fibers, which appear white due to the fatty myelin. Grey matter consists of cell bodies and unmyelinated fibers, giving it a grey appearance. White matter facilitates rapid signal transmission, while grey matter primarily manages processing and integration in the brain and spinal cord.</p> Signup and view all the answers

<p>A: At synapses, neurotransmitters carry impulses across the small gap between neurons, enabling signal transmission without direct contact. A similar process occurs at neuromuscular junctions, where neurotransmitters transmit signals from neurons to muscle cells, triggering muscle contraction.</p> Signup and view all the answers

<p>They serve as connectors or links between sensory neurons and motor neurons</p> <p>this design allows them to form numerous connections with other neurons. A multipolar structure, with one axon and multiple dendrites extending from the cell body, provides interneurons with several points for receiving and sending signals. This is especially important for their role in the central nervous system, where they serve as critical links between sensory and motor neurons and are responsible for processing and integrating information.</p> Signup and view all the answers