Endogenous bodily clocks are influenced by external (exogenous zeitgebers) factors. One of these lies in the suprachiasmatic nuclei (SN), which is a small group of cells found in the hypothalamus. It receives information by the retina. Information about light and dark synchronises our biological rhythms with the 24-hour cycle of the outside world. If the SN is damaged, or the connection between it and the retina severed, circadian rhythms disappear completely, and the rhythmic behaviours would become random over the day.
Describe and evaluate research into circadian rhythms, with reference to endogenous pacemakers and exogenous zeitgebers (25 marks) Circadian rhythm: those that last around 24 hours. The two main examples of circadian rhythms include the sleep- wake cycle and the body temperature cycle. The circadian rhythm of the sleep wake cycle is controlled by endogenous pacemakers, which are essentially internal biology ‘clocks’ and also by external environmental cues, called exogenous zeitgebers e.g. light. (AO1) Research into circadian rhythms Siffre (1972): investigated the effect of the removal of the exogenous zeitgebers (light) on the circadian rhythm of the sleep wake cycle.
In mammals, the main endogenous pacemaker is a tiny cluster of nerve cells called the suprachiasmatic nucleus (SCN), which lies in the hypothalamus. It is located just above the place where the optic nerves from each eye cross-over. The SCN obtains information about light from the eye via the optic nerve. If our endogenous clock is running slow, morning light automatically shifts the clock ahead, putting the rhythm in tune with the world. The SCN sends signals to the pineal gland, located next to the optic nerve, directing the gland to increase production of the hormone melatonin at night.
Discuss the role of endogenous pacemakers in the control of one or more biological rhythms Endogenous pacemakers and exogenous zeitgebers can manipulate the various bodily rhythms, and have particular affects on the sleep / week cycle in the circadian rhythm. Endogenous pacemakers are separate and distinct internal rhythms that affect the bodily rhythms; similarly, exogenous zeitgebers are outside influences, and sometimes outside rhythms that also affect how the bodily rhythms work. The suprachiasmatic nucleus is located above the optical chiasm. Light enters into the retina and is transferred through the optical nerve to the suprachiasmatic nucleus, which stimulates the release of hormones such as cortisol and melatonin in the pineal gland, thus maintaining our sleep-wake cycle. Circadian rhythms occur over a 24-hour cycle.
(b) (4 marks) (i) Outline one or more explanations for sleep disorders (eg insomnia, sleep walking, narcolepsy). (5 marks) (ii) Evaluate one or more explanations for sleep disorders. (16 marks) PERCEPTION Total for this question: 25 marks 2 Discuss the nature-nurture debate in relation to explanations of perceptual development. (25 marks) RELATIONSHIPS Total for this question: 25 marks 3 ‘To put it at its most basic, women want resources and men want to spread their genes.’ Discuss the evolutionary approach to explaining parental investment in humans (eg sex differences, parent-offspring conflict). (25 marks) AGGRESSION
THE ROLE OF THE ENDOGENOUS PACEMAKER IN THE CONTROL OF THE CIRCADIAN RHYTHM. The body’s biological rhythms are controlled by an interaction between endogenous pacemakers (internal clocks) and exogenous zitegebers (external clock or cues). Animals and plants have evolved endogenous pacemakers to help maintain their natural rhythm with the environment, however there are fluctuations in the Earths cycle such as longer days in summer hence exogenous zitegebers help our body to take into account different fluctuations in our environment. Both the endogenous pacemaker and the exogenous zitegibers control our circadian rhythm which last for about a day, one example of this is our sleep wake cycle. Studies done by Micheal Siffre where he spent prolonged time in underground caves without exogenous zitegibers like sunlight, noise, clocks, etc have supported the existence of endogenous pacemakers in our sleep wake cycle as his results showed that his sleep wake rhythm settled to an average 24 hour cycle.
In Japan, the Japanese beetle has many enemies in Japan that are not in the United States, these enemies helped keep the numbers limited in Japan. In Japan, they have wasp larva that is a huge predator of the beetle larvae, but this is not in America. Without predators, there is nothing from keeping the population of the Japanese beetle from exploding, which it has over the last couple of decades.
Thesis Statement: If I am not responsible then I will not succeed, I am to be held accountable for my own actions because to be successful I must be in control and I can’t be forced to do what I don’t want Informal Outline: Introductory Paragraph: The definition of responsibility is the state or fact of having a duty to deal with something. However, that definition may differ slightly to oneself. To me responsibility is not just having a duty, but to have a purpose. Without personal responsibility one has no purpose. Body Paragraph #1: I am to be held accountable for my own actions.
Interval timing refers to the ability of a person to fit their behaviour to reliable changes in their environment. Assess the evidence for and against the position that interval timing relies on a single biological clock or pacemaker. Make clear whether you support this position or not and detail the rationale on which your support is based. Introduction The issue of interval timing has received considerable attention and come under much debate within the Psychological field, whereby researchers have formulated an array of different theories and ideas to accomplish the most suitable and fitting paradigm for the explanation of this phenomena. The concept of time has been delved into and explored by many, in an attempt to address and unravel the mysteries of interval timing which relates to a person’s ability to fit their behaviour to reliable changes in their environment.
It is definitely remarkable that countless “terminal” illnesses were treated because of researches involving animal testing. People escaped death from diseases such as tuberculosis, cholera, and so on within a short period of time. Millions have been saved and the credit goes to animal testing. The general public holds negative opinion towards animal research even if they realise the benefits of it. Many develop this attitude because of the photos of rats and dogs in terrible status which are all over the Internet.