Nervous System Histology

What is structure #1?

Answer explanation

This is a multipolar neuron cell body. Multipolar neuron cell bodies are the part of the neuron that contains the nucleus and most of the cellular organelles. These neurons have multiple processes extending from the cell body: one axon and several dendrites. The cell body plays a crucial role in maintaining the neuron's metabolic functions and integrating incoming signals from the dendrites before transmitting the signal down the axon. Multipolar neurons are the most common type of neuron in the central nervous system and are involved in motor and sensory functions.

Name structure(s) #1.

Answer explanation

The structure is a neuroglia nucleus. The neuroglia nucleus refers to the nucleus found within neuroglial cells, also known as glial cells. These cells support, protect, and nourish neurons in the nervous system. The nucleus of a neuroglial cell contains the cell's genetic material and is responsible for regulating its functions, including cell growth, repair, and communication with other cells. Unlike neurons, neuroglial cells can divide and replicate, and their nuclei play a vital role in these processes. Different types of neuroglial cells include astrocytes, oligodendrocytes, microglia, and ependymal cells, each with specific functions in the nervous system.

Name structure(s) #1.

Answer explanation

The structure is a nerve process. A nerve process refers to an extension from the cell body of a neuron. There are two main types of nerve processes: dendrites and axons. Dendrites are short, branched extensions that receive signals from other neurons and transmit them toward the cell body. Axons, on the other hand, are typically longer processes that carry signals away from the cell body to other neurons, muscles, or glands. These processes are essential for the communication and transmission of electrical impulses throughout the nervous system.

Name structure(s) #1.

Answer explanation

The myelin sheath gap, also known as the Node of Ranvier, is a small, unmyelinated segment between adjacent sections of the myelin sheath along a nerve fiber. The myelin sheath is a fatty layer that insulates the axon of a neuron, allowing for faster transmission of electrical impulses. At the Nodes of Ranvier, the axon membrane is exposed, and ion channels are concentrated. These gaps are crucial for the process of saltatory conduction, where the electrical impulse "jumps" from one node to the next, significantly speeding up signal transmission along the axon.

Name structure(s) #2.

Answer explanation

A myelinated axon is an axon covered with a myelin sheath, a fatty, insulating layer produced by glial cells (Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system). The myelin sheath surrounds the axon in segments, with small gaps known as Nodes of Ranvier between the segments. This structure allows for rapid transmission of electrical impulses along the axon through a process called saltatory conduction, where the impulse jumps from one Node of Ranvier to the next. Myelinated axons are essential for the efficient and quick transmission of signals in the nervous system, enabling rapid communication between neurons and other cells.

Name structure(s) #1.

Answer explanation

The myelin sheath gap, also known as the Node of Ranvier, is a small, unmyelinated segment between adjacent sections of the myelin sheath along a nerve fiber. The myelin sheath is a fatty layer that insulates the axon of a neuron, allowing for faster transmission of electrical impulses. At the Nodes of Ranvier, the axon membrane is exposed, and ion channels are concentrated. These gaps are crucial for the process of saltatory conduction, where the electrical impulse "jumps" from one node to the next, significantly speeding up signal transmission along the axon.

Name structure(s) #1.

Answer explanation

The posterior gray horn, also known as the dorsal horn, is a region of the spinal cord's gray matter. It contains the cell bodies of sensory neurons that receive incoming sensory information from the body. This information includes touch, pressure, pain, and temperature sensations. The sensory neurons in the posterior gray horn process and relay this information to higher levels of the central nervous system, including the brain, where it is interpreted. The posterior gray horn plays a crucial role in the processing of sensory input and is essential for the body's response to environmental stimuli.

Name structure(s) #2.

Answer explanation

The lateral gray horn is a region of the spinal cord's gray matter located primarily in the thoracic and upper lumbar segments. It contains the cell bodies of autonomic motor neurons that are involved in the regulation of involuntary functions, such as heart rate, digestion, and blood vessel constriction. These neurons send their axons out of the spinal cord to synapse with autonomic ganglia, which then send signals to various organs and tissues. The lateral gray horn is specifically associated with the sympathetic division of the autonomic nervous system, playing a key role in the body's fight-or-flight response.

Name structure(s) #3.

Answer explanation

The anterior gray horn, also known as the ventral horn, is a region of the spinal cord's gray matter that contains the cell bodies of motor neurons. These motor neurons are responsible for transmitting signals from the spinal cord to skeletal muscles, initiating voluntary movements. The axons of these motor neurons exit the spinal cord through the ventral roots and directly innervate muscles, causing them to contract. The anterior gray horn is crucial for motor control, enabling movement and coordination throughout the body.

Name structure(s) #4.

Answer explanation

The posterior median sulcus is a shallow groove located on the dorsal (back) surface of the spinal cord. It runs along the midline and divides the spinal cord's posterior (dorsal) side into left and right halves. The posterior median sulcus marks the separation between the two dorsal columns, which contain ascending sensory nerve tracts that carry information such as touch, pressure, and proprioception to the brain. This sulcus is an important anatomical landmark that helps distinguish the organization of the spinal cord's white matter and the location of sensory pathways.