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

Respiratory diseases - Smoking

SMOKING

Smoking severely damages your health and contributes to thousands of deaths every year.  Cigarettes contain lots of harmful chemicals and these cause a lot of damage to the lungs and the heart.

Passive smoking

Smoking is not only harmful to the smoker but can also have a very bad effect on those around them. Inhaling other peoples' smoke from cigarettes is called passive smoking. Passive smoking can affect any age.

Passive smoking  has been linked with the following health problems in:

Children and babies

Children and babies are more likely to get asthma, ear, nose and chest infections. Will suffer from wheezing and chronic coughs. They have an increased risk of dying from cot death. Are more likely than average to become smokers themselves when older. They're at an increased risk of developing cancer as adults.

Adults

Adults have an increased risk of lung cancer and increased risk of heart disease. Passive smoking can make asthma worse. It causes irritation to the eyes, nose and throat

Smoking and pregnancy

Smoking is extremely harmful during pregnancy and can lead to:

Miscarriage
Bleeding during pregnancy
Premature birth
Low birth weight (Premature and low birth weight babies are more prone to illness and infections.)
Congenital defects in the baby
Stillbirth or death within the first week of life.
Asthma

The structure of the gas exchange system

Below is the process of the gas exchange system:
▪Firstly air enters the body through the mouth or nose, from here it moves to the pharynx (throat), passes through the larynx (voice box) and enters the trachea. 
▪The trachea splits into two branches, the left and right bronchus, each bronchus divides many times into smaller branches called bronchioles.
▪Each bronchiole finally leads to a bunch of tiny air sacs, called alveoli, which inflate during inhalation, and deflate during exhalation.  
▪Air enters the body through the mouth and nose, from here it moves to the pharynx (throat), passes through the larynx (voice box) and enters the trachea.
▪The trachea splits into two branches, the left and right bronchus, each bronchus divides many times into smaller branches called bronchioles.
▪Each bronchiole finally leads to a bunch of tiny air sacs, called alveoli, which inflate during inhalation, and deflate during exhalation.
▪Gas exchange is the delivery of oxygen from the lungs to the bloodstream, and the elimination of carbon dioxide from the bloodstream to the lungs and out of the body. It takes place in the alveoli.
▪The walls of the alveoli are surrounded by a network of blood capillaries.
▪In fact the alveoli walls share a membrane with the capillaries which allows for oxygen to diffuse through the alveoli wall and enter the bloodstream and then travel to the heart.
▪At the same time it allows for carbon dioxide to diffuse from the bloodstream into the alveoli and exhaled out of the body.
▪Both oxygen and carbon dioxide move from areas of high concentration to areas of lower concentration.

 

Chapter 3 - Breathing and Gas Exchange

We breathe everyday, hour, minute and second but what is breathing? You know it's that inhaling and exhaling thing we do everythin' mate! But guys, I'll tell you that it's more than that!

Breathing is the process of getting oxygen into the lungs and carbon dioxide out of the lungs. It allows for gas exchange to take place so that oxygen can be absorbed from the lungs into the blood and carbon dioxide is removed from the blood and breathed out from the lungs.

Many people say that breathing and respiration are the same. Nope, they are not the same.

Respiration is the release of energy from the break down of glucose in living cells. Respiration takes place in every living cell and all cells need to respire to produce the energy they need.

BIG difference!!

Chapter 2 - The Variety Of Living Organisms

There is an enormous variety of living organisms. The living organisms are classified into groups by their structure and function. Each group of organisms share common features.

The major groups of organisms are the following:-

▪Plants
▪Animals
▪Fungi
▪Protoctists
▪Bacteria
▪Viruses

Plants


This group or kingdom contains flowering plants as in the picture

on the left of this text. It also contains simpler plants like mosses and ferns.Plants are also multi cellular organisms.

Animals

I think all of us are familiar with this kingdom with homo sapiens in it! Wait, you don't know? 

Oh! I meant humans, homo sapiens is just the scientific name !! Yep, humans are 

People are a mystery!

considered in the animal kingdom because they  share 

common features between animals.

Fungi

Fungi.. I like them, then at the same time I dislike it! Yeast, mushrooms, toadstools and 

moulds. How are these supposed to go together? The are all fungi... Yep, even moulds 

(ewww...). Different species of yeast live everywhere - on the surface of fruits, in soil, water 

and even on the dust in the air. The cells of fungi never contain chloroplasts, so they 

cannot photosynthesise.  Their cells have cell walls. The cell walls are made of chitin, not by cellulose.

Yeast cell, highly magnified.

Yeast cell structure

Protoctists

The dustbin kingdom, that's what it's called. It is called the dustbin kingdom because the organisms don't fit into plants, animals or fungi. Most of them are single - celled organisms and most if them look like animal cells. I'm sure you know Amoeba, it's a protoctist.


Bacteria
Bacteria are small single celled organisms. Bacteria cells are smaller than animal cells, plant cells and protoctists.

Viruses

Viruses are many times smaller than bacteria. They are among the smallest organisms known and consist of a fragment of genetic material inside a protective protein coat.

Viruses can only reproduce inside host cells, and they damage the cell when they do this. A virus can get inside a cell and, once there, take over and make hundreds of thousands of copies of itself. Eventually the virus copies fill the whole host cell and burst it open. The viruses are then passed out in the bloodstream, the airways, or by other routes.

Cells

What are cells?

Cells are what make up living things. They are also called building of life.

Below are the cell structures of animal and plant cells.

Movement in and out of cells

Water is the main component of all cells. We find water in the cytoplasm and in cell sap. This water contains many dissolved substances and these substances plus the water enter and leave the cells through the cell membrane.  The cell membrane allows certain particles through it but it blocks the passage of others. Because of this nature it is described as a partially (or selectively) permeable membrane. Particles enter and leave cells by three processes:

Diffusion

Osmosis

Active Transport

Diffusion

Many substances can pass through the membrane by diffusion. Diffusion happens when a substance is more concentrated in one place than another. 

Osmosis

Osmosis is a special kind of diffusion involving water molecules. It occurs when two solutions are separated by a partially permeable membrane.

 The definition of osmosis is as follows:

Osmosis is the movement of water molecules from an area of high water concentration (weak/dilute solution) to an area of low water concentration (strong/concentrated solution) through a partially permeable membrane.

Active Transport

Sometimes organisms require certain substances and therefore need to move dissolved substances from a region of low concentration to a region where they are at a higher concentration. This process is of course the opposite to the direction in which particles would normally move in diffusion. This is active transport. In active transport particles move against a concentration gradient and therefore require energy which must be supplied by the cell. Carrier proteins that are found in the cell membrane of cells use energy to transport molecules or ions across the membrane, against the concentration gradient. When organisms utilise active transport the energy for the process comes from respiration. Due to this the cells capable of active transport usually have more mitochondria, in which respiration takes place than other cells.

Life Processes

All living organisms are made out of/ composed of cells. The cells of all living organisms have common features.

Most living organisms share eight life processes . They:

• Require Nutrition

• Excrete

• Move

• Grow and Develop

• Respire

• Respond to Stimuli

• Reproduce

• Control

On most websites / videos / books, these processes are ordered as MRS GREN or MRS NERG or even MRS H GREN.
MRS GREN stands for: M -MovementR - RespirationS - Sensitivity
H - Homeostatis
G- GrowthR- ReproductionE- ExcretionN- Nutrition
MRS NERG is the backward version of GREN in MRS GREN. And as you can tell, if you cut the H off you can find the solution to MRS GREN.
Please note that all of these are life processes are common in most living organisms.
Movement

Both animals and plants have the ability to move. Plants are rooted and move slowly as they grow. Their roots move down into the soil and their stems move up towards the light. Animals on the other hand move quickly and can move their entire bodies. They can move in search of food, shelter or to avoid danger.

Respiration

Respiration is the process of extracting energy out of the food we eat. All living things respire because they need energy to grow, to replace worn out parts and to move. Respiration takes place in the mitochondria of the cell. There are two types of respiration, with and without oxygen. Aerobic respiration uses oxygen and releases a large amount of energy. Anaerobic respiration does not require oxygen and releases a smaller amount of oxygen.

Sensitivity

All living organisms are sensitive, this means that they have an awareness of changes in their environment. Animals respond quickly to stimuli such as heat, light, sound, touch and chemicals which have taste and smell. On the other hand plants generally appear less sensitive and their response is slower. Plants respond to light by moving their leaves towards it, the flowers of some plants open in the morning and close at night when it is dark. Some plants, however, do respond quickly such as the Venus flytrap response to touch.

Growth

All living organisms grow. Plants continue growing throughout their lives. Animals stop growing once they reach adulthood. Even when growth stops, materials within an animal’s body are still being replaced from its food.

Excretion

All living things make waste products these can be useless or harmful to it and therefore need to be got rid of. Excretion is the process of getting rid of metabolic waste. Plants store waste substances in their leaves, the waste is removed when their leaves fall off. Animals breathe out waste carbon dioxide, other waste substances leave the body in urine and sweat. Note: Getting rid of faeces or undigested food is not excretion but egestion.

Reproduction

All living things must produce offspring like themselves in order for their species to survive. This is the process known as reproduction. Plants produce seeds that give rise to new plants of the same species. Animals lay eggs or have babies. Reproduction can be of two types, Sexual which involves two parents and the union of two gametes and Asexual where one parent can reproduce itself.

Nutrition

Nutrition is needed for energy and growth, both plants and animals need food. Plants are able to make their own food by photosynthesis. They use sunlight to turn simple molecules like carbon dioxide and water into more complex carbohydrate molecules. Animals are unable to make their own food so rely on other plants and other animals for their nutrition. Animals take in complex substances and break them down into small, simple, soluble molecules which can be used for energy and growth.

Chapter 1 - Life Processes

Characteristics Of Living Organisms

Structure and Functions of The Cell

Enzymes

          How The Cells Gets Its Energy

                         Movement of materials in and out of cells