Sensory and Motor Neuron Functions

Task 1:

Question 1:

a) The function of sensory neuron in the nervous system is to convert external stimulus received by the organism from the external environment into internal electrical impulses (Pinho-Ribeiro et al. 2017).

The motor neurons which are present on the spinal cord and is connected with the glands, organs and muscles of the organism has the function to relay electrical impulses to the smooth muscles from the spinal cord so that all the muscles are properly controlled (Agarwal et al. 2018).

b) The external stimulus acts to initiate the action potential in the nerves. The depolarisation is the phase which is caused as a result of rapid rise in the potential of membrane leading to open the sodium channels creating influx of sodium ions. At the peak of the depolarization, the action potential is reached and after it the repolarisation occurs where sodium channel is deactivated and the efflux of potassium ions is seen. The hyperpolarisation is due to the impact of the closing of the potassium channels which later leads to the resting phase (Deemyad et al. 2018).

Question 2:

The synapse is the gap existing between the axon of one neuron and the dendrite of another neuron and through the help of neurotransmitters the signal from one neuron relayed to another. The presence of increased amount of calcium ions coordinates the passage of the nerve signals through neurotransmitters from one neuron to another (Plomp et al. 2018).

Question 3:

Question 4:

Task 2:

Question 1:

One of the examples of negative feedback system in the body is control of blood sugar level. In this process, when there is the rise in the blood glucose level then signals are transmitted to the liver to release insulin in the blood so that the body cells take up glucose and the liver store the extra glucose from the blood into the form of glycogen leading to lower the blood sugar. In contrast, when the blood glucose level falls the alpha cells in the liver are stimulated to release glucagon which also acts to breakdown glycogen stored in the liver to be converted to glucose leading to raise the blood sugar level (Ho, 2019). The other example is change in body temperature that is when the temperature of the body is lower it leads the individuals to feel shivering to bring back the temperature but when the body temperature rises it indicates the body to produce sweat to lower the body temperature to normal. In this process, when the body temperature is raised, vasodilation occurs so that the blood is transferred to the skin surface and most of the heat is released to cool the body temperature (Morrison and Nakamura, 2019).

Question 2:

One of the examples of positive feedback in the body is when blood vessels are damaged leading to ooze out blood the blood platelets initiate to cling to the affected site and produce chemicals which helps to attract more platelets so that blood clot occurs to avoid further blood loss (Khalil et al. 2018). The other example is suckling of the nipples of the mother’s breast leads secretion of milk for the baby. In this process, the suckling impact leads the body to release oxytocin that causes milk to be let down into the breast of the mother (Clement et al. 2016).

Task 3:

Question 1:

Question 2:

Question 3:

a) The mechanism of ultrafiltration includes blood entry into the glomerulus to be filtered with the action of afferent and efferent arterioles. The afferent and efferent arterioles change the pressure in the blood flow which leads the impurities present in the blood to be released and filtered out (Fischbach et al. 2017).

b) The selective reabsorption initially includes sodium to be transported out of the wall of the proximal convoluted tubule (PCT) through co-transport created by the sodium-potassium pump. The glomerulus filtrate enters the PCT so that 60-70% of the water is reabsorbed in the body and the remaining nutrients and solutes are reabsorbed through the blood in the loop of Henle as well as the collecting duct (Shen et al. 2017).

Question 4:

The Anti-diuretic hormone (ADH) binds with the receptor on the cells present on the collecting ducts and acts to promote water to be reabsorbed into the circulation. The channels in the collecting duct transport the solute-free water back in the blood through the tubular cells leading to lower osmolarity in the plasma and increase urine osmolality. The ADH acts on the Distal Convoluted Tubule (DCT) as well as the collecting ducts to allow reabsorption of water by bringing the water channels towards the surface of the membrane when there is low amount of water in the body. However, the increased water presence in the body indicates the ADH to be inhibited leading the collecting ducts and DCT to become impermeable causing diuresis (Kanbay et al. 2019).

References

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