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Reproduction Topic 6.6

In this section of Topic 6 we need to look at reproduction. For those of you who may think this section is difficult, just remember that you are at the current end of a very long line of ancestors who were very successfully reproductively, so it cant be that difficult! In this section we will look at the male and female reproductive organs, the female menstrual cycle, the role of testosterone in males, In Vitro fertilisation and the ethical issues surrounding it.

A very useful resource, a SlideShare by our favourite Indonesian teacher can be found HERE.

An excellent description of the role of hormones in the menstrual cycle can be found here. This link allows you to see both how the normal menstrual cycle works, and how it can be manipulated for contraceptive purposes in the female contraceptive pill.

TOK issue, should women be allowed to take responsibility for their own fertility? In many societies this is a no-brainer, but this is not the case in all societies. This article from the influential Catholic Planet outlines reasons why the Catholic church is against contraception, though interestingly for approximately 11 years the Catholic Church did authorise the use of the contraceptive pill when it first came out!

Nervous Control

Now this  video I did not Show in class but if you get the chance you may wish to look at it .This video shows a person who has an incurable degenerative nerve disease and has chosen to decide the timing and the manner of their own death. This video raises all manner of emotive questions from a moral and ethical perspective, not least should we look at this kind of thing in our lessons? As this occurred in our host country of Switzerland, and as it leads into a discussion of what can go wrong with our neurons and how this impacts our function then I think yes. However please be advised this video is upsetting, and I would understand if you choose not to watch it.

In this section we aim to cover the following curriculum statements: –

6.5.1State that the nervous system consists of the central nervous system (CNS) and peripheral nerves, and is composed of cells called neurons that can carry rapid electrical impulses

6.5.2 Draw and label a diagram of the structure of a motor neuron

6.5.3 State that nerve impulses are conducted from receptors to the CNS by sensory neurons, within the CNS by relay neurons, and from the CNS to effectors by motor neurons.

6.5.4 Define resting potential and action potential (depolarization and repolarization).

6.5.5 Explain how a nerve impulse passes along a non-myelinated Neuron.

6.5.6 Explain the principles of synaptic transmission.

A nice diagram of a Neuron can be found Here. Remember you must be able to draw a labelled diagram of a motor neuron. When looking at the diagram think “STRUCTURE AND FUNCTION”. These links are made in this clip. Details of the sodium potassium pump are here

Want to understand synapses? Follow this . There is a very nice video that summarises the Khan academy video

Defence against infectious disease

So what are Pathogens, why are they dangerous, and how does your body deal with them? All of these questions (and more) can be answered by watching THIS SlideShare from everyone’s favourite Biology teacher Stephen Taylor.

Preventing the ingress of pathogens is obviously very important. While the skin forms an impenetrable barrier it can only protect you if it is intact. Should you suffer structural damage to your skin very quickly a waterproof (and pathogen proof) scab quickly forms. Want to know how this occurs then watch This video. It would be useful to use this information together with pg 283+4 of text book to produce a (stopping) flow chart of the process.

When pathogens get past our first line defences there are other responses. Firstly there is the NON SPECIFIC RESPONSE – Phagocytosis , and there is the production of antibodies. Khan Academy has several excellent video tutorials on this subject, follow THIS link and choose the presentations you wish to see. If you don’t wish to watch the videos then check out the text 164 – 166.

The Endocrine System and Homeostasis

Endocrine system from downloaded 2nd feb 2015

In order for our cells (and hence tissues and hence organs and hence organ systems) to function effectively there are many physiological variables that have to be maintained within certain limits. The maintenance of a constant internal environment is called Homeostasis and that is what we will study here. In the last section where we looked at nervous control we stated that motor neurons stimulate either muscles or glands. The glands concerned are the glands of the endocrine system.  The endocrine system is under nervous control, many homeostatic mechanisms are initiated by the autonomic nervous system. Glands release chemical messengers into the bloodstream (hormones) which travel around the body until they come into contact with target cells where they initiate a response. Hormones often have much wider effects upon the body than nerves.

In the USA as in Europe and many other (mainly increasingly affluent countries) there is an epidemic of an endocrine disease -Diabetes. In the Ted talk below Peter Attia poses the question is our current consensus of obesity being the driving force behind diabetes correct? Watch the video and judge for yourself.

Peter Attia on Diabetes

A really nice overview of the endocrine system can be found Here – remember to learn both the male and female endocrine organs including the hormones they produce and their target Areas.

Blood vessels and blood

Now that we understand the structure and function of the heart we need to look at the next 2 components of the circulatory system, the blood vessels and the blood.

We will start our study of the circulatory system by looking again at the past paper data analysis question on blood pressure. As you can see from the graph the presures in the arteries can be very high – to cope with these pressures arteries have certain adaptations. By the time the blood has passed from arteries to arterioles to capillaries to venules and veins, how do you think the pressure has changed, and how might that be reflected in the structure of veins? To answer that question we will look at This and this Khan academy Videos.  If you want to test your understanding of this Topic check out the 3 quizzes.

Finally we look at the components of blood and what it carries. A nice introductory Video on blood can be found HERE.