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write an essay of 1500 words, excluding references, on the following: To operate effectively, the mammalian circadian system must be entrained to the 24h daily cycle. The most effective entrainment...

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write an essay of 1500 words, excluding references, on the following:
To operate effectively, the mammalian circadian system must be entrained to the 24h daily cycle. The most effective entrainment signal for mammals is light. A circadian light-sensitive input pathway to the central clock in the suprachiasmatic nuclei has evolved that is separate from the image-forming visual pathway. However, recent experimental data have shown that these two separate pathways do interact to modulate their functions.
1. Briefly review the literature showing that the mammalian circadian photoreceptor system and the image-forming visual system interact (50%).
2. Briefly describe an experiment (aims and hypotheses/ protocol/ methods) where you would test this interaction (in humans or animals). You should justify your experimental design and the measures that will be analysed (50%).



The above is the whole topic of the assignment. There are a few files are the lecture notes. Please that a read, and have some information and ideas from the lecture notes, as well as other sources.Also, there's a file called "Coursework" the the content of the assignment that should be included in it.Please have a look and read them. Thank you very much.
Answered Same DayMar 06, 2020

Solution

Soumi answered on Mar 12 2020
57 Votes
MAMMALIAN CIRCADIAN SYSTEM
Table of Contents
Introduction    3
1. Literature Review Indicating Interaction between Mammalian Circadian Photoreceptor System and the Image-Forming Visual System    3
Mammalian Circadian Photoreceptor System    3
Image-Forming Visual System    4
Interaction between them    4
2. Experiment to Test this Interaction    5
Aim    5
Hypotheses    6
Methods    6
Justification for Chosen Experimental Design    6
Data Analysis Method    6
Protocol    6
Conclusion    7
References    8
Introduction
Mammalian circadian system positions the human body according to the biological clock that makes the body conduct its activities at all pre-determined timings. The impact of the light into our eyes have been linked with the activation of photoreceptors that help the body to start its activities, while with the advent of darkness, the body clock finishes a day’s round. This paper reviews the prevailing literature on the interaction between mammalian circadian photoreceptor system and image-forming visual system, which has been tested in a further experiment. This interaction will be easy to assess the circadian rhythm of the body.
1. Literature Review Indicating Interaction between Mammalian Circadian Photoreceptor System and the Image-Forming Visual System
Mammalian Circadian Photoreceptor System
The mammalian circadian photoreceptor system virtues the biological phenomenon of oscillating the body into a rhythm, by entrailing it with the mechanical 24 hours’ clock. As mentioned by Walmsley et al. (2015), this rhythm is caused by an internal operative clock that makes them do things on a fixed time. The reason for this is that the suprachiasmatic nuclei (SCN) contained in the hypothalamus that controls the complex signalling cascade and synchronizes local clock in the
ain as well as throughout the body. As supported by Tosini et al. (2016), many extensive biological approaches were taken to identify a substantial number of clock genes collectively comprising the biochemical signalling cascade that drives circadian oscillations.
However, as argued by Pagano et al. (2017), this clock component is not constant across all kingdoms of species; nevertheless, their mechanism of activity across every biological organism is almost same. Moreover, it is also to be noted that the functioning of the biological clock is also not essentially conscious. They might observe the control of the clock only out of involuntary functioning of the body and this indeed, helps the mammalian body to respond to the changes that occur in the external environment. As affirmed by Lucas et al. (2014), circadian system in mammals are subject to photoreceptivity and photosensitivity, which is why the body responds to the diurnal changes that are initiated with the advent of light onto the pupil and advent of darkness at night. However, as contradicted by Brown (2016), these responses are necessarily light dependent in mammals, unlike being dependent on the duration of darkness as in the cases of the plants. Below is a visualisation of the pathway for the circadian system in mammals:
Figure 1: The Mammalian Circadian Photoreceptor System Pathway
(Source: Bena
och, 2008, p.595)
Image-Forming Visual System
The image formation by the mammalian eyes is a function of the central nervous system (CNS) that enables the organisms to see objects and perceive them. As mentioned by Ksendzovsky et al. (2017), the light that enters the eyes, through the pupil, gets deviated due to the biconvex lenses, to reach the retina. The retina is the area, where the photoreceptor cells are present— for both dark vision and light vision. As noted by Gonzalez Fleitas et al. (2015), one of the photoreceptors, rods are for dark, black and white vision, which is due to the pigment contained within it, known as the rhodopsin. While, on the other hand, as stated by Palmer et al. (2017), coloured vision in the
ight light is enabled by the cones, which...
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