Stimulus and response

In the body 'coordination' means making things happen at the right time by linking up different body activities. Humans and other animals have two organ systems which do this. The first is the nervous system. Let's look at that after stimulus and response as well as receptors.

Stimulus and response
 If you're nerves are working properly, you will be able to respond to the following example in real life. (Or would you?)
E.g. You see a football coming your way, what would u do?
a. Stand there and get hit in the face
b. Move away without standing there/ duck/ catch it, before getting admitted into the hospital?

I think everyone would choose option b, if not get ready to have a football in your face!

Another situation is where you smell something great (or something that you love), you mouth starts to secrete saliva.

Those are examples of  stimulus and response.
A stimulus is a change in an animal's surroundings.
A response is the reaction taken for that change.

A summary of the sequence that happens is,

Stimulus --> Receptor --> Coordination --> Effector --> Response

This will be explained in the next post.

Coordination

In coordination, your nervous system comes in handy. Also your eyes and brain come in handy too, not only to read though! Do you have any idea on what your parts of the eye are? What about your brain? Let's find out, shall we? The next post will start this! Hope you ace coordination!

Good luck!

Blood And Circulation! (Introduction)

Small, single-celled organisms can gain no use by a circulatory system. But large, multicellular organisms (i.e. animals) need a circulatory system.

I think I already have 9 or something systems in my body. Do I have to have some nore extra weight into this body of mine?!

The answer is (drumroll please!)  Yes! You need this body system because it is very important! I mean you need your blood up and pumping to get to work right? Who doesn't? Well, I guess single-celled organisms won't but I certainly do!

Well.. Check out the next post about the types of the circulatory systems and the need of circulatory systems!

Respiratory diseases - Asthma

Asthma affects the small airways (bronchioles) that carry air in and out of the lungs. If you have asthma your airways can become inflamed, swollen and constricted (or narrowed) and excess mucus is produced. The symptoms of an asthma attack include:
▪Wheezing
▪A tight chest
▪Difficulty breathing
▪Cough
▪Shortness of breath

Asthma symptoms flare up from time to time and there are certain things that may trigger asthma symptoms in a sufferer.  Some of these triggers are listed below:

Asthma symptoms flare up from time to time and there are certain things that may trigger asthma symptoms in a sufferer.  Some of these triggers are listed below:

Infections E.g. colds, coughs, chest infections.
Irritants or allergens - substances which induce an allergic reaction such as house dust mite, pollen, perfumes
Exercise – This can exacerbate asthma, nonetheless exercise is good for asthma sufferer.  if necessary patients can use an inhaler before exercise to prevent symptoms from developing.
Certain drugs – 1 in 50 people with asthma are allergic to aspirin
Smoking and cigarette fumes
Other fumes and chemicals - E.g. from paints, solvents and air pollution.
Emotion - Stress, emotional upset, or laughing may trigger symptoms.
Allergies to animals - Such as pet cats, dogs, and horses.

Digestion

Digestion is the break down of large, insoluble food molecules into small, soluble food molecules so that they can be absorbed into the blood stream

The digestive system

The digestive system also known as the gut is essentially a long tube about 9 metres long. It starts at the mouth and ends at the anus. There are many different parts to the digestive system but each part has its’ specific function.

Mouth

The mouth is the beginning of the digestive tract. In fact, digestion starts here as soon as you take the first bite of a meal. Chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form your body can absorb and use.

Throat

Also called the pharynx, the throat is the next destination for food you've eaten. From here, food travels to the esophagus or swallowing tube.

Esophagus

The esophagus is a muscular tube extending from the pharynx to the stomach. By means of a series of contractions, called peristalsis, the esophagus delivers food to the stomach. Just before the connection to the stomach there is a "zone of high pressure," called the lower esophageal sphincter; this is a "valve" meant to keep food from passing backwards into the esophagus.

Stomach

The bolus enters the stomach. The stomach cells makes gastric juices which mix with the food.

• The gastric juices contain a protease enzyme called pepsin which breaks down proteins into amino acids.
• The juices also contain hydrochloric acid, this is because pepsin works best in an acidic environment of pH 2.
• The acid in the juices also kills any germs.

The muscular walls of the stomach churn the food and mix it well with the secretions. After 2-3 hours of churning the food is a thick liquid called chyme.

Small Intestine

Made up of three segments, the duodenum, jejunum, and ileum, the small intestine is a long tube loosely coiled in the abdomen (spread out, it would be more than 20 feet long). The small intestine continues the process of breaking down food by using enzymes released by the pancreas and bile from the liver. Bile is a compound that aids in the digestion of fat and eliminates waste products from the blood. Peristalsis (contractions) is also at work in this organ, moving food through and mixing it up with digestive secretions. The duodenum is largely responsible for continuing the process of breaking down food, with the jejunum and ileum being mainly responsible for the absorption of nutrients into the bloodstream.

Large Intestine

Any indigestible or non absorbed chyme passes into the large intestine. Excess water and salts are absorbed and the remaining chyme is converted into faeces. The faeces is stored in the rectum until it is excreted through the anal canal.

Chapter 4 - Food and digestion

There are five groups of food substances your diet should include:

• Carbohydrates
• Lipids
• Proteins
• Minerals
• Vitamins

Remember!! Have water and fibre in your diet!

Carbohydrates

Carbohydrates only make up 5% of the mass of the human body, but the have a very important role. They are the body's main 'fuel' for supplying cells with energy.

Lipids

Simply, these are fats and oils. They contains Carbon, Hydrogen and Oxygen. 

Proteins
Proteins are used mainly for growth and repair of cells.

Minerals
Like vitamins, mineral ions are only needed in small amounts to maintain a healthy body. A lack of the correct mineral ions in the diet also leads to deficiency symptoms.

Calcium

Calcium is needed to maintain healthy bones and teeth, for normal blood clotting and to control muscle contractions. Good sources of calcium include: cheese, eggs, leafy greens (e.g.:- broccoli, cabbage), milk. 

Iron

Iron is needed to produce haemoglobin, found in red blood cells.

Vitamins

Vitamin A

Maintains good vision

Strong immunity against infection

Healthy skin

Good sources of vitamin A include: milk, dairy products, mackerel and other oily fish.

Vitamin C

Vitamin C is also known as ascorbic acid and has several important functions.

For example, it:

• helps to protect cells and keeps them healthy
• is necessary for the maintenance of healthy connective tissue, which gives support and structure for other tissue and organs
• helps wound healing

A lack of vitamin C can lead to scurvy.

Vitamin D

The human body can make vitamin D when our skin is exposed to sunlight.

Good dietary sources of vitamin D include:

• margarine and breakfast cereals fortified with vitamin D
• oily fish
• eggs

Vitamin D is needed to maintain healthy bones and teeth. Vitamin D deficiency leads to rickets and bone pain.

The effects of smoking in the lungs

Emphysema

Emphysema is a lung disease. It kills around 20 000 people in Britain every year, whether they are passive smoking or active smoking. Passive smoking is where the people who don't smoke, but inhale the smoker's smoke. The risk is very low for passive smokers to get emphysema. Active smokers, which you probably have guessed, are the people who smoke. These people have a very high risk of getting this illness because the smoke they inhale goes to the lungs. The smoke damages the walls of the alveoli, which break down and get together, and form irregular air spaces. 
This reduces the surface area for gas exchange. The blood of a person with emphysema carries less oxygen. 


Lung Cancer

Lung cancer is one of the most common and serious types of cancer. Over 41,000 people are diagnosed with the condition every year in the UK.

There are usually no signs or symptoms in the early stages of lung cancer, but many people with the condition will eventually develop symptoms including:

• a persistent cough
• coughing up blood 
• persistent breathlessness
• unexplained tiredness and weight loss
• an ache or pain when breathing or coughing