Nervous System - Quiz

The parasympathetic nervous system generally acts to conserve energy by promoting rest and digestion. It is responsible for activities such as decreasing heart rate, constricting pupils, increasing digestive secretions, and promoting bladder emptying. In contrast, the sympathetic nervous system, which is responsible for the body's fight or flight response, acts to expend energy by increasing heart rate, dilating pupils, decreasing digestive secretions, and promoting bladder retention. Therefore, option D is the correct answer.

Nissl’s granules are present in both non-myelinated and myelinated neurons. These granules are clusters of rough endoplasmic reticulum (ER) and free ribosomes in the cell body of the neuron. They play an important role in protein synthesis, which is essential for the survival and function of the neuron. On the other hand, myelin forming Schwan cells are only present in myelinated neurons, where they wrap around axons to form the myelin sheath. Nodes of Ranvier are only present in myelinated neurons and are the points between two adjacent myelin sheaths where the axon is exposed.

The junction that transmits impulses from one neuron to another is called a synapse. It is formed by the membranes of pre-synaptic and post-synaptic neurons. Synapses are the gaps between two neurons where chemical or electrical signals are transmitted to communicate with each other.

The synaptic cleft is the fluid-filled space that separates the membranes of the pre- and post-synaptic neurons at chemical synapses. The transmission of impulses at these synapses involves the release of neurotransmitters from the pre-synaptic neuron into the synaptic cleft, which then bind to receptors on the post-synaptic neuron to initiate a response. Gap junctions, on the other hand, are found at electrical synapses and allow for direct communication between the cytoplasm of adjacent cells. Synapse is a general term used to describe the junction between two neurons or a neuron and a target cell. Synaptic vesicles are small membranous sacs found in the pre-synaptic neuron that contain neurotransmitters.

Chemical synapses are characterized by the slow transmission of impulse in one direction only. These synapses are commonly found in the neural system and involve the release of neurotransmitters. However, multidirectional impulse transmission is not a feature of chemical synapses.

The cranial meninges are the three layers of protective membranes that surround the brain and spinal cord. The three layers of the cranial meninges are the dura mater, arachnoid, and pia mater. The dura mater is the outermost layer, followed by the arachnoid and then the innermost layer, pia mater. The corpus callosum is not a part of the cranial meninges. It is a bundle of nerve fibers that connects the two hemispheres of the brain and allows for communication between them. Therefore, option D is the correct answer.

The forebrain is the anterior part of the brain and consists of cerebrum, thalamus, and hypothalamus. The cerebellum, located in the posterior part of the brain, is not a part of the forebrain. The cerebrum is responsible for conscious thought, voluntary actions, and processing of sensory information. The thalamus is a relay center for sensory information, and the hypothalamus controls the endocrine system and regulates various physiological processes like temperature, hunger, and thirst.

After a nerve impulse, the membrane potential of the neuron becomes depolarized due to the influx of sodium ions. However, the resting potential must be restored for the neuron to be able to fire another action potential. This is achieved through the movement of potassium ions out of the cell. After the peak of the action potential, the voltage-gated potassium channels open, and potassium ions move out of the cell due to their concentration gradient. This causes the membrane potential to become more negative, eventually reaching the resting potential. The movement of potassium ions outside the membrane also restores the concentration gradient of potassium ions, which is important for maintaining the resting potential.

Neurotransmitters are specialized chemical compounds that are released by the presynaptic neuron in response to an action potential. These neurotransmitters then diffuse across the synaptic cleft and bind to specific receptors on the post-synaptic neuron or effector cell, leading to a change in its membrane potential and the transmission of a nerve impulse. There are many different types of neurotransmitters, including acetylcholine, dopamine, serotonin, and norepinephrine, each of which has a unique role in modulating the activity of the nervous system. In contrast, synaptic knobs are the enlarged axon terminals that contain the vesicles of neurotransmitters, while Schwan cells are glial cells that form the myelin sheath around axons and Nissl's granules are clusters of rough endoplasmic reticulum found in the cell bodies of neurons.

Neurotransmitters are specialized chemical compounds that are released by the presynaptic neuron in response to an action potential. These neurotransmitters then diffuse across the synaptic cleft and bind to specific receptors on the post-synaptic neuron or effector cell, leading to a change in its membrane potential and the transmission of a nerve impulse. There are many different types of neurotransmitters, including acetylcholine, dopamine, serotonin, and norepinephrine, each of which has a unique role in modulating the activity of the nervous system. In contrast, synaptic knobs are the enlarged axon terminals that contain the vesicles of neurotransmitters, while Schwan cells are glial cells that form the myelin sheath around axons and Nissl's granules are clusters of rough endoplasmic reticulum found in the cell bodies of neurons.