The nurse observes bilateral 3+ pitting edema on a client diagnosed with severe malnutrition. Which explanation is the best explanation for the edema?

Choice A reason: Compression of white matter in the brain and spinal cord is not the best explanation because it is a condition that affects the transmission of nerve impulses, not the perception of sensory stimuli. White matter is the part of the nervous system that consists of myelinated axons, which are the extensions of nerve cells that carry electrical signals from one cell to another. Compression of white matter can be caused by various factors, such as tumors, trauma, or inflammation, and can result in symptoms such as weakness, numbness, or paralysis.

Choice B reason: Decreased levels of gamma-aminobutyric acid (GABA) in the brain stem is not the best explanation because it is a condition that affects the regulation of muscle tone, not the perception of sensory stimuli. GABA is a neurotransmitter, which is a chemical messenger that transmits signals between nerve cells. GABA is an inhibitory neurotransmitter, which means that it reduces the activity of the nerve cells that it binds to. GABA is mainly found in the brain stem, which is the part of the brain that connects the spinal cord to the cerebrum and cerebellum, and controls vital functions such as breathing, heart rate, and blood pressure. Decreased levels of GABA in the brain stem can cause symptoms such as spasticity, rigidity, or tremors.

Choice C reason: Decreased levels of neurotransmitters in the pons and medulla is not the best explanation because it is a condition that affects the coordination of movements, not the perception of sensory stimuli. Neurotransmitters are chemical messengers that transmit signals between nerve cells. The pons and the medulla are parts of the brain stem that are involved in the control of voluntary and involuntary movements, such as chewing, swallowing, coughing, sneezing, and blinking. Decreased levels of neurotransmitters in the pons and the medulla can cause symptoms such as ataxia, dysarthria, dysphagia, or nystagmus.

Choice D reason: Edema and necrosis of the parietal lobe neurons is the best explanation because it is a condition that affects the processing of sensory stimuli, such as touch, pain, temperature, and position. The parietal lobe is the part of the cerebrum that is responsible for integrating and interpreting sensory information from different parts of the body. The parietal lobe is divided into two hemispheres, each corresponding to the opposite side of the body. A left-sided intracerebral hemorrhage is a condition where a blood vessel in the left parietal lobe ruptures, causing bleeding and swelling in the brain tissue. This can damage the neurons, which are the nerve cells that communicate with each other and form the basis of the nervous system. Edema and necrosis of the parietal lobe neurons can cause symptoms such as loss of sensation, neglect, or agnosia on the right side of the body.

Choice A reason: Infected macrophages and lymphocytes surround the Mycobacterium tuberculosis bacteria and form a tuberculous granuloma is the best explanation for the primary immune response to tuberculosis infection. A granuloma is a collection of immune cells that wall off the bacteria and prevent their spread. It is a protective mechanism that limits the infection and preserves the lung function.

Choice B reason: Tumor necrosis factor is released by T lymphocytes and lyses the Mycobacterium tuberculosis bacteria in the alveoli is not a correct explanation for the primary immune response to tuberculosis infection. Tumor necrosis factor is a cytokine that activates macrophages and induces inflammation, but it does not directly kill the bacteria. It may also have harmful effects by causing tissue damage and weight loss.

Choice C reason: Natural killer cells and neutrophils form a thick purulent debris, which becomes a caseous necrosis is not a correct explanation for the primary immune response to tuberculosis infection. Natural killer cells and neutrophils are part of the innate immune system, which is not very effective against intracellular bacteria like Mycobacterium tuberculosis. Caseous necrosis is a type of tissue death that results from the liquefaction of the granuloma. It is a sign of progressive disease, not primary infection.

Choice D reason: The inflammatory response of cytokines activates the complement system and causes permanent lung tissue damage is not a correct explanation for the primary immune response to tuberculosis infection. The inflammatory response of cytokines and the complement system are part of the innate immune system, which is not very effective against intracellular bacteria like Mycobacterium tuberculosis. Permanent lung tissue damage is a complication of chronic or reactivated tuberculosis, not primary infection.