Dr Gawad - CNS - Mid Moduel Exam Training

The parasympathetic nervous system is characterized by the presence of terminal ganglia near the organs and by short postganglionic fibers. This means that the ganglia, which are clusters of nerve cell bodies, are located close to the target organs. Additionally, the postganglionic fibers, which are the nerve fibers that extend from the ganglia to the organs, are relatively short. This arrangement allows for quick and localized control of organ function by the parasympathetic nervous system.

A lesion of the dorsal column system is most likely to affect fine touch. The dorsal column system is responsible for transmitting sensory information related to fine touch, proprioception, and vibration. If there is a lesion or damage to this system, it can result in a loss or impairment of fine touch sensation. Itch and tickle sensations are not primarily transmitted through the dorsal column system, but rather through other sensory pathways. Pain and temperature sensations are primarily transmitted through different pathways, such as the spinothalamic tract.

The correct answer is "constriction of bronchioles." Parasympathetic function includes the constriction of bronchioles, which helps to regulate airflow in the respiratory system. This narrowing of the bronchioles helps to control the amount of air entering the lungs, allowing for more efficient gas exchange.

Acetylcholine is a neurotransmitter that is released from preganglionic fibers of both the parasympathetic and sympathetic nervous systems. It is also released from preganglionic fibers that supply the adrenal medulla. However, postganglionic sympathetic fibers release norepinephrine, not acetylcholine. Therefore, the correct answer is "all postganglionic sympathetic fibers."

The generator potential is a graded potential that occurs in sensory neurons in response to a stimulus. It is directly proportional to the strength of the stimulus, meaning that it becomes larger in amplitude as the stimulus strength increases. This property allows the generator potential to provide information about the intensity of the stimulus.

The area of flare is due to the release of histamine from the injured area. Histamine is a chemical released by mast cells in response to tissue injury or inflammation. It causes vasodilation and increased permeability of blood vessels, leading to redness and swelling in the surrounding area. This release of histamine is responsible for the characteristic flare response seen in hyperalgesia, where the area around the injured site becomes hypersensitive to pain.

Sensory ataxia is a condition characterized by a loss of coordination and balance due to a lesion in the dorsal column of the spinal cord. The dorsal column is responsible for transmitting sensory information, such as proprioception (awareness of body position) and vibration sense, to the brain. When this column is damaged, it can result in the inability to accurately perceive and interpret sensory information, leading to difficulties in coordinating movements and maintaining balance.

not-available-via-ai

Noradrenaline is released at the end of most postsynaptic sympathetic fibers. This neurotransmitter is involved in the sympathetic nervous system's fight-or-flight response. When released, noradrenaline binds to adrenergic receptors on target cells, activating a physiological response. The release of noradrenaline at the end of these fibers allows for the transmission of signals from the sympathetic nervous system to target tissues and organs, coordinating the body's response to stress or danger.

The gracile pathway is a neural pathway that transmits unconscious kinesthetic sensation. It is characterized by thin slow afferent fibers and runs in the spinal cord medially to the cuneate tract. The transmission of sensory information through the gracile pathway is perceived by the thalamus.

The correct answer is lateral horn cell. The center of the autonomic reflex arc is located in the lateral horn cell. This cell is responsible for receiving and processing signals from sensory neurons and sending out motor signals to control involuntary functions of the body. The lateral horn cell is part of the autonomic nervous system, which regulates activities such as heart rate, digestion, and breathing.

The sympathetic nervous system is characterized by longer postganglionic fibers than preganglionic ones, which allows for a greater distribution of signals. It is also catabolic, meaning it promotes the breakdown of molecules for energy production. Additionally, the sympathetic system produces generalized effects throughout the body, such as increased heart rate and dilated pupils. However, it does have divergence in autonomic ganglia, meaning that preganglionic fibers can synapse with multiple postganglionic neurons, allowing for amplification and distribution of signals.

The convergence projection theory suggests that referred pain occurs when sensory nerves from different areas of the body converge onto the same neurons in the spinal cord. This convergence leads to confusion in the brain, causing the pain to be perceived in a different location than its actual source. This theory explains why pain from internal organs, for example, can be felt in distant areas of the body.

The somatosensory association area is responsible for processing and interpreting sensory information related to touch, temperature, and proprioception. It is located in the parietal lobe, not the temporal and occipital lobes. This area helps to give meaning to sensations, allowing us to recognize objects by touch and understand their significance. It is not specifically associated with fine touch sensation or the perception of pain, which are functions of other areas in the somatosensory cortex.

Erection is mediated by parasympathetic muscarinic receptors. When these receptors are activated, they cause the release of nitric oxide, which leads to relaxation of smooth muscles in the blood vessels of the penis. This relaxation allows for increased blood flow into the penis, resulting in an erection.

Intracranial headache may result from decreased CSF pressure, distension of dura vinous sinuses, and pressure upon tentorium cerecri. However, spasm of scalp muscles is not a clinical cause of intracranial headache.

Severe cutaneous pain is associated with hypotension. This means that when a person experiences intense pain on their skin, it can lead to a decrease in blood pressure. This is because the body's response to severe pain includes the release of certain chemicals that can cause blood vessels to dilate and blood pressure to drop. This physiological response is a protective mechanism that diverts blood flow to vital organs and tissues in order to ensure their survival.

The sense of joint movement is not an unconscious kinesthetic sensation because it is a conscious perception of the position and movement of our joints. Unlike muscle tone, muscle contraction, and muscle length, which are all unconscious sensations, the sense of joint movement requires conscious awareness and perception.

Neurotransmitters are chemical messengers that transmit signals between neurons. They are produced and stored in presynaptic neurons and bind to special receptors on the postsynaptic membrane to transmit the signal. However, neurotransmitters are not released into the blood in response to a stimulus. Instead, they are released into the synapse, the small gap between neurons, to transmit signals across the neural network.

The answer is correct because the coding of sensory information indeed involves the discrimination of modality, locality, and intensity of the sensation. Modality refers to the type of sensation, such as touch, temperature, or pain. Locality refers to the specific area or location where the sensation is felt. Intensity refers to the strength or magnitude of the sensation. These three factors are essential in encoding sensory information and allowing us to perceive and interpret different sensations accurately.

The gate theory in the spinal cord involves the inhibition of pain signals by tactile stimulation of a skin surface. This means that when the gate is closed, both the pain and touch pathways cannot send signals to the thalamus, resulting in a decrease in pain perception. This theory suggests that by stimulating the skin with touch or pressure, it can help alleviate or reduce the sensation of pain.

The correct answer is "It is a form of partial depolarization." Receptor potential refers to the graded electrical potential that occurs in sensory receptors in response to a stimulus. It is a form of partial depolarization because it does not always reach the threshold for action potential generation. Instead, the magnitude of the receptor potential is directly proportional to the intensity of the stimulus, allowing for the encoding of different stimulus strengths.

Generalized sympathetic activity is characterized by several physiological responses, including contraction of the radial muscle of the iris, increased secretion of catecholamines, and lipolysis in adipose tissue. However, relaxation of sphincteric smooth muscle in the alimentary tract is not a characteristic of sympathetic activity. Instead, sympathetic activity typically leads to the contraction of smooth muscle in the alimentary tract, which can reduce digestion and slow down the movement of food through the digestive system.

Cholinergic nicotinic receptors mediate the secretion of epinephrine by the adrenal medulla. These receptors are activated by acetylcholine, which leads to the release of epinephrine. Epinephrine is a hormone that plays a crucial role in the body's response to stress and helps regulate various physiological processes. Therefore, activation of cholinergic nicotinic receptors is essential for the secretion of epinephrine by the adrenal medulla.

Referred pain refers to the phenomenon where pain is felt in a different area of the body than the actual source of the pain. It is not always accompanied by cutaneous pain, meaning pain on the skin or superficial tissues. Referred pain can occur without any cutaneous pain, and this statement contradicts that fact.

The ventral spinothalamic tract is the ascending pathway in which the second order neurons decussate within the spinal cord. This means that the sensory information from one side of the body crosses over to the opposite side of the spinal cord before ascending to the brain. The other pathways listed (fasciculus cuneate, dorsal spinocerebellar tract, and fasciculus gracilis) do not involve decussation within the spinal cord.

Stimulation of the medial part of the right primary somatosensory area will result in a sensation referred to the left foot. This is because the primary somatosensory area is responsible for processing sensory information from different parts of the body. The right primary somatosensory area specifically receives input from the left side of the body, meaning that stimulation in this area will result in a sensation on the opposite side of the body. Therefore, stimulating the medial part of the right primary somatosensory area will result in a sensation in the left foot.

Stimulation of the vagus nerve causes mucous secretion from the bronchial mucosal cells. The vagus nerve is responsible for the parasympathetic innervation of the lungs and bronchial tubes. When the vagus nerve is stimulated, it activates the bronchial mucosal cells to secrete mucus. This helps to lubricate the airways and protect them from irritants, pathogens, and foreign particles. The increased mucous secretion can also aid in the clearance of mucus and improve respiratory function.

Cardiac pain is conducted through sympathetic nerve fibers. This means that the pain signals from the heart are transmitted through the sympathetic nervous system, which is responsible for the body's fight-or-flight response. This pathway allows for the rapid transmission of pain signals, leading to the characteristic sharp and intense pain experienced during a cardiac event. The other statements provided in the question are incorrect and do not accurately describe visceral pain.

Body representation in somatosensory area II is not sharply localized. Unlike somatosensory area I, which has a precise representation of the body, somatosensory area II has a more diffuse and less precise representation. This means that the body parts are not as clearly defined in somatosensory area II as they are in somatosensory area I.

The ventral spinothalamic tract is responsible for transmitting pain and temperature sensations. It consists of type A-delta and type C fibers, not just type C fibers. The crossing of the tract to the midline mainly occurs in the first-order neuron, not the second-order neuron. It transmits crude touch, but its main function is to transmit pain and temperature sensations. The main center of this tract is the brainstem, specifically the medulla and the pons, not the thalamus.

According to the spinal cord gate theory of pain, the correct statement is that stimulation of the sensory C fiber afferent of the lateral spinothalamic tract will inhibit the tonically active inhibitory interneuron. This theory suggests that the transmission of pain signals can be modulated by the activity of inhibitory interneurons in the spinal cord. Stimulation of the C fibers, which are associated with pain transmission, can inhibit these inhibitory interneurons, allowing pain signals to be transmitted to the brain. Therefore, this statement aligns with the principles of the spinal cord gate theory of pain.