Nervous and Hormonal control Biology Summarized Notes

Learning Objectives

● Compare nervous and hormonal control systems in terms of speed and longevity of action
● define a drug as a substance taken into the body that modifies or affects chemical reactions in the body
● describe the use of antibiotics for the treatment of bacterial infection
● explain why antibiotics kill bacteria but do not affect viruses
● describe the effects of excessive alcohol consumption and heroin limited to:
+ powerful depressant drugs
+ negative social implications, e.g. crime, rape,
+ effect on reaction times and self-control and so on
+ liver damage
+ addiction and withdrawal symptoms
+ cause infections, such as HlIV
● state that tobacco smoking can cause chronic obstructive pulmonary disease (COPD)
● define a hormone as a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
● identify specific endocrine glands and their secretions limited to adrenal glands, pancreas and insulin, testes and testosterone, and ovaries and oestrogen
● discuss the role of the hormone adrenaline in the chemical control of metabolic activity,including increasing the blood glucose concentration and pulse rate.

 Nervous and hormonal control

The nervous and endocrine systems in animals share the same basic function of controlling and coordinating the majority of activities in the body. There the similarity bends. The nervous system functions by sending electrical impulses at very high speeds along nerve cells, whereas hormones travel more slowly from one place to another through the bloodstream. Nerves transmit their impulses to one particular part of the body. The information they transmit is very precise and can be controlled with a high degree of accuracy. The effects of hormones are much more widespread and diffuse. Only the  hormone's target cells will respond to its stimulus.

Once a nerve sends an impulse to another part of the body, the response is immediate and final. Any further stimulation or activity from that part of the body will need another impulse from the nervous system. The effects of hormones are longer lasting and they exert their effect over the target cells for several hours or even days. The two systems work alongside each other to produce and coordinate a variety of activities that, although different from each other, help to control the body.

Antibiotics

Antibiotics are used tor the treatment of bacterial infections. They either stop the bacteria from reproducing or kill it. Antibiotics are not effective against viruses because bacteria have a ditfferent cell structure and replicate in a different way compared to viruses. In some Viral infections, such as the flu, shingles (herpes zoster), or chicken-pox (varicella), the doctor may prescribe an antiviral drug to shorten the infection and help prevent complications. Antivirals need to be taken early in the infection - usually in the first 24 to 48 hours - to be most effective. Sometimes, in complicated or prolonged. Viral infections, bacteria may invade as well, and cause what is known as a secondary bacterial infection. Then the doctor may prescribe an antibiotic to kill the specific invading bacteria, but the antibiotic is not being prescribed for the viral infection. Viruses are structurally different from bacteria. Viruses live and replicate inside of a human cell; they cannot live outside of a human cell. Viruses insert their genetic material into a human cell's DNA in order to reproduce. Antibiotics cannot kill viruses because bacteria and viruses have different mechanisms and machinery to survive and replicate. The antibiotic has no target to attack in a virus.

However, antiviral medications and vaccines are specific for viruses. Vaccines stimulate the immune system to produce antibodies, which then go out and 'recognise' the virus to inactivate it before it can cause disease. The best way to help prevent the flu, shingles and chicken-pox is with a vaccine.

Difference between a Bacteria and Virus

Using antibiotics for a virus:

● will not cure the infection
● won't help you feel better
● will not prevent others from catching your virus.
Many bacterial infections will require an antibiotic; however, the type of antibiotic will vary based on the type of infection. An antibiotic either prevents bacterial growth (bacteriostatic) or kills bacteria outright (bactericidal). For example, amoxicilin (a penicilin-type drug) can be used to treat a strep throat, but will not work for some common pneumonias or bladder infections. This is one reason why it is very important not to share your antibiotics with someone else. The bacteria causing the infection may not be susceptible to your prescribed antibiotic. Then those bacteria may not die, and the infection can worsen. Plus, the person you share you antibiotic with may unnecessarily experience side effects from your drug.

Examples of illnesses caused by bacteria:
● strep throat
● bacterial pneumonia
● whooping cough (pertussis)
● many skin infections
● some ear or eye infections
● some sinus infections, but usually these are viral
● bacterial meningitis
● tuberculosis
● urinary tract infections.

Antibiotics work by interfering with the bacterial cell wall and preventing bacterial replication. However, these drugs have been widely used for a long period of time. The bacteria that the antibiotics are designed to kill have adapted to  them, making the drugs less effective. Bacteria can fight back in many ways by strengthening their own cell walls by producing enzymes that can inactivate the antibiotic, and even by helping out fight fellow bacteria that are less able to be resistant to the antibiotic. Bacteria learn to fight off the antibiotic. Thats one reason why it's important to finish all of your prescribed antibiotic, even if you feel 100% better. Antibiotic resistance can occur if you do not finish all of your medication and resistant bacteria are stronger and harder to kill. A broad-spectrum antibiotic can be used to treat a wide range of infections. A narrow-spectrum antibiotic is only effective against a few types of bacteria.

 Recreational drugs

alcohol nicotine and catfeine are socially acceptable in many, but not all, cultures. People drink caffeine in tea and coffee, and this is socially acceptable. Alcohol, in moderation, can have beneficial effects on the body. If taken in excess, alcohol can be harmful. Heroin, cannabis and cocaine have potentially dangerous effects on the body. Alcohol is readily available and widely used in some countries. It is also one of the most abused drugs. The effect of excessive alcohol intake on the liver can cause it to become permanently damaged. This is because alcohol is broken down into fats by the liver. If someone drinks too much alcohol, the cells of the liver are damaged and the kidney cells may die, shortening their life. This will lead to health problems because of the many important functions carried out by the liver. Alcohol taken by preqnant women can have a negative effect on the growth and development of the fetus. Alcohol is a depressant drug, which means it can disrupt mental balance affecting thoughts, feelings and actions. Alcohol is generally taken for its calming and relaxing effect on the body. lt slows down the rate of transmission of nerve impulses. This becomes dangerous if a person drinks alcohol and then drives a car, operates machinery, or has to make important decisions. Alcohol slows reaction time, leads to a lack of coordination, reduces concentration, decreases vision, and inhibits judgement of distance. This can lead to drivers causing accidents if they drink alcohol and drive. Alcohol also affects the way people think, behave and make decisions. When under the influence of alcohol, they will often say and do things they would not usually do. Alcohol prevents people from making sensible decisions and can lead to them becoming violent or committing criminal offences. Alcohol can make people aggressive, angry, anxious or depressed. When you're under the influence of alcohol or drunk, you're more likely to make decisions that put you at risk for getting or transmitting HIV, such as having sex without a condom, than when sober. Regular drinking leads to dependence on alchol. This is called addiction. Because alcohol is addictive for some people the more they drink it the more they need it. The user may reach a point where they cannot do without alcohol; this is when they become alcoholics. When this stage is reached, medical assistance is required to heln the person to overcome the problem. As with many things in life, moderation is required. Alcohol, if used regularly, becomes a habit and this can lead to addiction and abuse. Many of us have witnessed the outward signs of heavy drinking: the stumbling walk, slurred words and memory lapses. People who have been drinking have trouble with their balance, judgement and coordination. They react slowly to stimuli, which is why drinking before driving is so dangerous. All of these physical signs occur because of the way alcohol affects the brain and central nervous system. Heroin is a narcotic drug. This means that it relieves pain and induces sleep. The drug heroin is also said to be addictive, which means the user becomes dependent on the drug. This can be physiological, physical or psychological dependency and the user suffers from withdrawal symptoms, which means the user cannot do without the drug. Heroin is extracted from a plant called the opium poppy. For addicts, heroin becomes the number one priority in their lives. They will do anything to get the drug, even become criminals and become a threat to their society. If not rehabilitated, a heroin abuser will end up homeless or dead. Some heroin users inject the drug in their veins by an unsterilised, shared needle; this increases the risk of getting HIV, hepatitis and septicaemia. Some heroin users inhale it and this causes damage to the membranes of the nose, throat and lungs.

 There are symptoms you would look for if you suspected that a person was a regular heroin user:

● periods of drowsiness
● constricted pupils or black panda eyes
● mood swings
● lack of appetite
● blue/black lips
● injection marks
● abscesses on limbs where injecting
● Constipation.

The change in the behaviour of a person, who may be still be a learner at school, has a great impact on their family and friends. People may not understand the dependency of the drug user, nor understand how best to help the user. It is best to seek professional advice and support.

Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a progressive and eventually debilitating lung disease, which means the condition gets worse over time. The disease usually causes Coughing, wheezing, and shortness of breath, making it difficult to breathe. Smoking of tobacco is a direct cause of COPD. Knowing how the lungs work can help you understand how COPD affects the lungs. When you breathe in, oxygen-rich air goes down your windpipe and into small tubes located in your lungs. These tubes are called bronchial tubes or airways. They branch off into numerous tinier and thinner tubes known as bronchioles. At the end of the bronchioles are small, round air sacs called alveoli, which have tiny blood vessels called capillaries. When air enters the alveoli, oxygen moves through the capillaries and into the bloodstream. At the same time, carbon dioxide, which is a gas your body doesn't need, moves into the alveoli so you can breathe it out. Your lungs, airways, and air sacs are normally elastic. When you breathe in, they fill up with air, similar to a balloon. When you breathe out, they deflate and the air leaves the body.

 In people with COPD, however, less air flows into and out of the airways for these reasons:

● The lungs, airways, and air sacs lose their elasticity.
● The walls between the air sacs are destroyed.
● The walls of the airways thicken and become swollen.
● The airways make more mucus than normal, which can clog airways.

These problems are usually Caused by emphysema or chronic bronchitis. Both of these conditions are referred to as COPD. Emphysema occurs when cigarette smoke or other air pollutants, such as dust or fumes, damage the walls between your air sacs over time. As the air sacs weaken, their walls break open, creating one large air sac instead of many smaller ones. This makes it more difficult for the capillaries to absorb enough oxygen and for the body to expel carbon dioxide, making it harder to breathe.

Hormones in humans

The endocrine system

Hormones are chemical substances, produced by glands and transported by the blood, which alters the activity of one or more specific target organs. The endocrine glands have no ducts; therefore they secrete their hormones in minute amounts directly into the bloodstream. The blood transports hormones throughout the body. Each hormone has a specific organ (effector) in the body where it has an effect. This organ is called a target organ. Some of the hormones that you need to know are adrenaline, insulin and glucagons. Figure below shows the position of the main endocrine glands and the hormones that they secrete.

 Adrenaline

When you are frightened or excited, for example, when running away from danger, watching a frightening film or even writing an exam, your brain sends messages along a nerve to your adrenal glands. This makes the adrenal glands secrete a hormone, called adrenaline, into the blood. Adrenaline causes the liver to break down stored glycogen and to release glucose into0 the bloodstream. Adrenaline is usually described as the fight or flight hormone because it prepares your body for action. When you are under stress, for example, in an emergency situation, adrenaline increases the rate of metabolic activity to prepare your body for action. Adrenaline makes your heart beat faster and speeds up your rate of breathing. These changes supply more oxygen and glucose to your muscles to provide extra energy to fight or run away.

 Insulin

The Islets of Langerhans in the pancreas secrete insulin. Insulin controls the level of glucose in the blood. If there is a high glucose level, insulin is secreted to stimulate the liver to remove some glucose from the blood and convert it to glycogen. Glycogen is then stored in the liver tissues and muscles for later use. People with insufficient insulin tend to suffer from sugar diabetes.

Glucagons

Glucagons are also hormones that control the sugar level in the blood, but they work in an opposite way to insulin. The Islets of Langerhans secrete glucagons when glucose levels fall below normal. Glucagons trigger the liver to convert some of the stored glycogen back to glucose.

Summary

● Drugs affect the normal functioning of the nervous  system. Drug abuse, such as abuse of alcohol and heroin can  cause personal and social problems, such as loss of employment, the breakdown of relationships with family and friends, and criminal activities to pay for drugs.
● Tobacco smoking can cause chronic obstructive pulmonary disease.
● Hormones are chemicals produced by glands and carried by blood, which alter the activity of target cells in one or more specific organs.
● Adrenaline increases the rate of metabolism by stimulating the liver to break down stored glycogen and release glucose into the bloodstream to prepare the body for action, that is, fight or flight.
● Blood glucose levels are controlled by insulin and glucagon secreted by the Islets of Langerhans of the pancreas.
● Insulin stimulates the liver to convert excess glucose to glycogen and reduce blood glucose
level. Glucagon stimulates the liver to convert giycogen to glucose and increase the blood glucose level.

The End, Next Post Inheritance.