Control System in Biology

Regulators are the organisms that can regulate their own internal environment. They are present over a wide range of environment and habitats. The non-regulator organisms tend to confine to environments which are more stable such oceans or lakes, examples of non-regulators are algae and cnidarians. The mechanisms of regulations found in living organisms have many features in common with the mechanisms of regulations used in machines. The basic components of any control system are summarized in this figure. 
 basic components of control system


Any change from the set point activates the control system and returns condition towards the optimum level. When a mechanism is controlled by its own production it is called feedback mechanism. It is of two types

1. Negative feedback
2. Positive feedback

1.    Negative feedback: It is associated with increasing the stability of systems e.g. thermostat. In the electric oven the control system includes an effector (an input) and output (the oven temperature and a thermostat) which can be set to a desired level, the set point.


The thermostat acts as a detector (or receptor) and a regulator. The stimulus is heat. If the thermostat is set to reach 150 degree Celsius and electric current will provide the source of heat which will flow until the temperature of the oven passes the set-point of 150 degree Celsius, then the thermostat will cut out and no more heat will be supplied to the oven. When the temperature of the oven falls below 150 degree Celsius the thermostat will cut in again and the electric current will increase the temperature and restore the set-point. In this system the thermostat is functioning as an error detector where the error is the difference between the output (the heating element) being switched on or off. This is an example of steady-state negative feedback system which is typical of many of the physiological control mechanism found in organisms. 

The Control Of Thyroxine Production

The control of thyroxin production: This is a biological example of a simple control system. The production of thyroxin is controlled by thyroid releasing hormone or factor (TRH), and thyroid stimulating hormone (TSH). The figure illustrates the role of negative feedback in the control of thyroxin release by the thyroid gland. In this example the detector is the hypothalamus, the regulator is the pituitary gland and the effector is the thyroid gland.

12.   Positive Feedback: It is rare in biological systems since it leads to an unstable situation and extreme states. During labor when the hormone oxytocin stimulates muscular contractions of the uterus, which in turn stimulate the release of more oxytocin.

Importance of feedback mechanism: It helps the proper functioning of the body machinery. Biological negative feedback mechanisms include the control of (a) Oxygen and CO2 levels in the blood by controlling rate of breathing (b) rate of heart beat (c) blood pressure (d) hormone level (e) water balance for the regulation of pH (f) body temperature. These show the importance of a negative feedback mechanism for existence of an animal. 





Homeostasis

Plants and animals are found in Snow Mountains, deserts, grassland, almost in all types of environment. The surroundings in which an organism lives is called environment. The environment in which an organism lives is called external environment and the environment in which individual cells live is called internal environment. The ability to maintain a steady state within a constantly changing environment is essential for the survival of living organism. In order to maintain this condition, organisms from the simplest to the most complex ones, have developed a variety of structural, physiological and behavioral mechanisms designed to achieve a constant internal environment. The maintenance of a constant internal environment is called homoeostasis. (GK: homois means ‘Like or Resembling’ and stasis means ‘Standing’). This term was introduced by Walter Cannon in 1932.
The three elements of homeostasis are:

a.    Osmoregulation: It is the control of gain and loss of water and dissolved solutes.
b.    Excretion: The disposal of nitrogen containing wastes.

c.    Thermoregulation: The maintenance of internal temperature within a range that allows cells to function efficiently.

U.S. journalist james foley's beheading video "RATED R"

James Foley was kidnapped by the ISIS in Syria. They killed him and videotaped the whole process. The video is extremely disturbing if you are someone sensitive. The video is linked to a torrent website. You will need a torrent downloader like BitTorrent and then you will need to add a Chrome browser extension to Chrome called Zenmate. Zenmate will help you access thepiratebay, on which the torrent is hosted.

Here is the link to the video. Click here to download.

Reasons why you should circumcise your baby boy

Penis is the organ used for sexual activity, having a reproductive and intermittent importance and also serves as urinary duct.

In different religions such as Islam and Christianity it us must for the males to go through the process of circumcision, however critics also disagree, saying that it has some disadvantages. So in the following we will focus on advantages and disadvantages of circumcision.

Advantages of Circumcision

“Circumcision of newborn boys (i.e., within the first month of life) brings numerous health benefits, including: 

1 – Protection against local infection in the penis, which may result from the presence of the foreskin, causing tightening of the foreskin, which may lead to retention of urine or infections of the glans (tip) of the penis – which require circumcision in order to treat these problems. In chronic cases, the child may be exposed to numerous diseases in the future, the most serious of which is cancer of the penis. 

2 – Infections of the urethra. Many studies have proven that uncircumcised boys are more exposed to infection of the urethra. In some studies the rate was 39 times more among uncircumcised boys. In other studies the rate was ten times more. Other studies showed that 95% of children who suffered from infections of the urethra were uncircumcised, whereas the rate among circumcised children did not exceed 5%. 
In children, infection of the urethra is serious in some cases. In the study by Wisewell on 88 children who suffered infections of the urethra, in 36 % of them, the same bacteria were found in the blood also. Three of them contracted meningitis, and two suffered renal failure. Two others died as a result of the spread of the micro-organisms throughout the body. 

3 – Protection against cancer of the penis:  the studies agree that cancer of the penis is almost non-existent among circumcised men, whereas the rate among uncircumcised men is not insignificant. In the US the rate of penile cancer among circumcised men is zero, whilst among uncircumcised men it is 2.2 in every 100,000 of the uncircumcised population. As most of the inhabitants of the US are circumcised, the cases of this cancer there are between 750 and 1000 per year. If the population were not circumcised, the number of cases would reach 3000. In countries where boys are not circumcised, such as China, Uganda and Puerto Rico, penile cancer represents between 12-22 % of all cancers found in men; this is a very high percentage. 

4 – Sexually transmitted diseases (STDs).  Researchers found that the STDs which are transmitted via sexual contact (usually because of fornication/adultery and homosexuality) spread more among those who are not circumcised, especially herpes, soft chancres, syphilis, candida, gonorrhea and genital warts. 

There are numerous modern studies which confirm that circumcision reduces the possibility of contracting AIDS when compared to their uncircumcised counterparts. But that does not rule out the possibility of a circumcised man contracting AIDS as the result of sexual contact with a person who has AIDS. Circumcision is not a protection against it, and there is no real way of protecting oneself against the many sexually transmitted diseases apart from avoiding fornication/adultery, promiscuity, homosexuality and other repugnant practices. (From this we can see the wisdom of Islamic sharee’ah in forbidding fornication/adultery and homosexuality). 


5 – Protection of wives against cervical cancer. Researchers have noted that the wives of circumcised men have less risk of getting cervical cancer than the wives of uncircumcised men. 

YouTube opened in Pakistan

Okay so a while ago I tried to access YouTube, it worked. I tried it again like after 2 hours, it again opened. This probably means people behind PTCL are working on sorting out something. But whatever it is, I can access YouTube without any hassle and proxy or VPN. I am sure it has been opened, but not announced officially. Guys, go to www.youtube.com and you will be able to access it.

Comment below if you have anything to say, and also, if you still cannot access it, then HERE, install the zenmate for Google Chrome, register it, and you're good to go.