How a Cell's Shape Affects Its Function | Sciencing
What is the relationship between the structure and the function of a parts of the brain, otherwise similar cells may behave with near total. Nerve cells are classified based on the type of the message they transmits Association nerve cell- The nerve cell, which connects to our sensory and motor. To investigate the relationship between the structure and function of neurons in the neurons by performing whole-cell recordings in a brain slice preparation.
Nerve Cells Nerve cells, or neurons, carry electrical messages to and from the brain and spinal cord, helping the body respond to various stimuli, regulate mechanisms, and absorb and store information. To most efficiently transmit these electrical messages, neurons have a long, thin structure, allowing for very quick and accurate communication and responses. Length is beneficial to the structure of a neuron because electrical messages within a neuron travel more quickly than the chemical messages between neurons.
Thus, a few longer neurons means faster transmission of signals than a chain of many shorter neurons.
A single muscle cell is elongated in shape, containing within it many myofibrils. These are thin strands made of the proteins actin and myosin that perform muscle contraction. Nuclei and other organelles that are normally within a cell lay at the perimeter of muscle cells, making space for the ordered patterns of the proteins.
Sperm Cells Sperm cells in males are the only human cell with flagella, or whiplike cell extensions. This is because of their need to "swim" long distances to reach an egg for fertilization.
Also due to their need to travel, the body of a sperm cell is very light, carrying not much more than the chromosomes containing the DNA for a potential zygote. The Purkinje cell has a very complex "tree" of dendrites with many branches, to the point that it resembles a branching bush or shrub.
Purkinje cells have a highly complex dendritic tree that allows them to receive — and integrate — an enormous number of synaptic inputs, as shown above. Other types of neurons in the cerebellum can also be recognized by their distinctive shapes. See a diagram of other cerebellum cell types A classic drawing of a section slice of brain tissue, showing that the different types of neural cells found in the cerebellum have different shapes. For example, some have many branching dendrites, while others have fewer dendrites or dendrites that are less branched.
There is also variation in the length and branching of the axons of the different cell types. Similarly, neurons can vary greatly in length.
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While many neurons are tiny, the axons of the motor neurons that extend from the spinal cord to innervate your toes can be a meter long or longer, in basketball players like Michael Jordan, LeBron James, or Yao Ming! Another example of diversity in form comes from sensory neurons: A single myelinated process leaves the cell body and splits in two, sending one branch to the spinal cord to communicate information and the second to sensory receptors in the periphery to receive information.
See a diagram of a sensory neuron Note: This diagram does not show myelination. However, if it did, the myelin sheath would cover the single process leaving the neuron, as well as the two processes that it splits to form. Simple diagram of a sensory neuron, showing that it has just one process that leaves the cell body, which subsequently splits in two, forming one process that has dendrite-like structures and another that has axon terminal-like structures.
Individual neurons connect to other neurons to stimulate or inhibit their activity, forming circuits that can process incoming information and carry out a response. Neuronal circuits can be very simple, and composed of only a few neurons, or they can involve more complex neuronal networks. The knee-jerk reflex The simplest neuronal circuits are those that underlie muscle stretch responses, such as the knee-jerk reflex that occurs when someone hits the tendon below your knee the patellar tendon with a hammer.
Tapping on that tendon stretches the quadriceps muscle of the thigh, stimulating the sensory neurons that innervate it to fire. Axons from these sensory neurons extend to the spinal cord, where they connect to the motor neurons that establish connections with innervate the quadriceps. The sensory neurons send an excitatory signal to the motor neurons, causing them to fire too. The motor neurons, in turn, stimulate the quadriceps to contract, straightening the knee.
In the knee-jerk reflex, the sensory neurons from a particular muscle connect directly to the motor neurons that innervate that same muscle, causing it to contract after it has been stretched.
Simplified diagram of neural circuits involved in the knee-jerk reflex.
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When the patellar tendon is tapped, the quadriceps muscle on the front of the thigh is stretched, activating a sensory neuron that wraps around a muscle cell. The sensory neuron's axon extends all the way into the spinal cord, where it synapses on two targets: Motor neuron innervating the quadriceps muscle.
The sensory neuron activates the motor neuron, causing the quadriceps muscle to contract. The sensory neuron activates the interneuron.
However, this interneuron is itself inhibitory, and the target it inhibits is a motor neuron traveling to the hamstring muscle on the back of the thigh. Thus, the activation of the sensory neuron serves to inhibit contraction in the hamstring muscle.
The hamstring muscle thus relaxes, facilitating contraction of the quadriceps muscle which is antagonized by the hamstring muscle. It wouldn't make sense for the sensory neurons of the quadriceps to activate the motor neurons of the hamstring, because that would make the hamstring contract, making it harder for the quadriceps to contract.
Instead, the sensory neurons of the quadriceps connect to the motor neurons of the hamstring indirectly, through an inhibitory interneuron. Activation of the interneuron causes inhibition of the motor neurons that innervate the hamstring, making the hamstring muscle relax. The sensory neurons of the quadriceps don't just participate in this reflex circuit. Instead, they also send messages to the brain, letting you know that someone tapped your tendon with a hammer and perhaps causing a response.
Glial cells At the beginning of this article, we said that the nervous system was made up of two types of cells, neurons and glia, with the neurons acting as the basic functional unit of the nervous system and the glia playing a supporting role. Just as the supporting actors are essential to the success of a movie, the glia are essential to nervous system function. Indeed, there are many more glial cells in the brain than there are neurons.
There are four main types of glial cells in the adult vertebrate nervous system. Three of these, astrocytes, oligodendrocytes, and microglia, are found only in the central nervous system CNS. The fourth, the Schwann cells, are found only in the peripheral nervous system PNS.
Types of glia and their functions Astrocytes are the most numerous type of glial cell. In fact, they are the most numerous cells in the brain! Astrocytes come in different types and have a variety of functions.
They help regulate blood flow in the brain, maintain the composition of the fluid that surrounds neurons, and regulate communication between neurons at the synapse. During development, astrocytes help neurons find their way to their destinations and contribute to the formation of the blood-brain barrier, which helps isolate the brain from potentially toxic substances in the blood.
Microglia are related to the macrophages of the immune system and act as scavengers to remove dead cells and other debris. Both of these types of glial cells produce myelin, the insulating substance that forms a sheath around the axons of many neurons.
Myelin dramatically increases the speed with which an action potential travels down the axon, and it plays a crucial role in nervous system function. Glia of the central nervous system. Astrocytes extend their "feet" projections onto the cell bodies of neurons, while oligodendrocytes form the myelin sheaths around the axons of neurons. Microglial cells hang around in the interstices, scavenging dead cells and debris.
Overview of neuron structure and function
Ependymal cells line the ventricles of the brain and have projections on the non-ventricle side of the ependymal layer that link up with the "feet" of the astrocytes. Glia of the peripheral nervous system. The cell body of a sensory neuron in a ganglion is covered with a layer of satellite glial cells. Schwann cells myelinate the single process extending from the cell body, as well as the two processes produced by the splitting of that single process one of which will have axon terminals at its end, and the other of which will have dendrites at its end.
Satellite glial cells cover the cell bodies of neurons in PNS ganglia. Satellite glial cells are thought to support the function of the neurons and might act as a protective barrier, but their role is still not well-understood. Ependymal cells, which line the ventricles of the brain and the central canal of the spinal cord, have hairlike cilia that beat to promote circulation of the cerebrospinal fluid found inside the ventricles and spinal canal.
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The organization of the nervous system. Nervous systems consist of circuits of neurons and supporting cells. In Campbell biology 10th ed. Neuron structure and organization reflect function in information transfer. Neurons and nervous systems. The science of biology 9th ed. The spinal cord transmits and processes information.
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