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PEP SCIENCE SUMMARY
Written by Janice Gaynor
PEP and Reading and Spelling private tutor and author of books.
Copyright © 2026. All right reserved.
* This summary will take just about three hours to read. *
This summary can be used as a crash course for PEP Science, as a revision or something to introduce the student to the subject before studying it more in-depth from more comprehensively written books.
Repetition is good, therefore read this summary over and over, as time permits, before you have to do the exam.
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NUTRITION
Your diet is the different foods that you eat daily.
A balanced diet contains the right amounts of foods or nutrients that the body needs.
There are six different types of nutrients:
(1) water
(2) fats
(3) proteins
(4) carbohydrates
(5) vitamins
(6) minerals
Water – Water carries the different nutrients around the body, helps with the removal of waste products in the body, keeps the body hydrated and helps with regulating body temperature. You should drink about six cups (8 oz. / 250 ml.) of water each day. That is about 1.5 litres.
Fats – Fat supplies the body with heat and energy. It also helps to protect the organs of the body. Excess fat in the foods that we eat is stored under the skin. Fat also helps the organs to function properly. Fat should be eaten sparingly. Too much of it is not good for the body. Some foods high in fat include: avocado pear, ackee, kidney, butter, cooking oil and mayonnaise.
Proteins – There are different types of proteins. Proteins are essential for the repairing of worn-out or damaged tissue in the body, body maintenance and body growth. Lack of adequate protein in the diet causes a disease known as Kwashiorkor. Symptoms of this disease include: swelling in the abdomen, legs and feet, changes in skin and hair colour, diarrhea (excessive defecation or passing out of feaces), fatigue (tiredness), stunted growth, flaky skin, infection, brittle hair and nails, and anemia. Foods that are good sources of protein include meat, fish, bread and rice.
Carbohydrates – Carbohydrates provide the body with heat and energy. Many foods contain much carbohydrate. They include: fruits, vegetables, peas, bread, rice, milk and sugar. Meat contains no carbohydrate, however.
Vitamins – There are different types of vitamins. They include: vitamin A, vitamin B, vitamin C, vitamin D, vitamin E and vitamin K. Vitamin B has a group of vitamins – vitamin B1, vitamin B2, vitamin B3, vitamin B5, vitamin B6, vitamin B7, vitamin B9 and vitamin B12. Vitamins are generally very essential. They help the body to function properly and help fight against diseases. For example, vitamin A helps the eyes to see, vitamin C fights diseases, vitamin D helps with bone health, vitamin E helps protect the body’s cells from damage, vitamin K helps the blood to clot, vitamin B3 supports healthy skin, vitamin B6 is important for cell development during pregnancy and vitamin B12 is important for nerve function and red blood cell formation. Foods high in the various vitamins include: egg, avocado pear, milk, beef, meats, callaloo, lettuce, vegetables, potato, fish, peanuts, peas, beans, broccoli, carrot, fruits, oats and cereal. Deficiencies in the various vitamin cause different diseases.
Minerals – minerals are similar to vitamins. They have the same kinds of functions in the body generally. Some of the minerals used by the body include: calcium, sodium (salt), phosphorus, potassium, chloride, magnesium, iron, zinc, iodine, manganese and sulfur. The functions of some of the minerals needed by the body are:
calcium – bone and teeth health
phosphorus – energy production
magnesium – helps with muscle and nerve functioning
sodium, potassium and chloride – essential for nerve transmission and muscle contractions.
Deficiency in the different minerals results in different diseases. All foods – milk, fruits, vegetables, meats – contain minerals. Milk is particularly high in calcium. Meat is particularly high in iron. Iron helps to prevent anemia.
Fibre – Fibre (pronounced ‘fi-ber) helps you to defecate or pass out your faeces easily. Fibre is also called ‘roughage’. Foods high in fibre include: fruits and vegetables such as American apple, broccoli, peas, sweet potato, ripe banana, callaloo, cereals such as oats, whole wheat bread and brown rice.
The food pyramid is a guide to the foods needed to be eaten daily. It groups the foods in terms of how much meats, dairy, carbohydrates, etc. should be eaten daily. The food pyramid is shaped like a triangle. At the bottom is water, taking up the most space and showing that water is needed most abundantly. Above water are carbohydrates and legumes and nuts. Therefore, you should eat less carbohydrates and legumes and nuts than water. Above carbohydrates, legumes and nuts come vegetables and fruits. This means that you should eat fruits and vegetables in a smaller quantity than carbohydrates, legumes and nuts. Above fruits and vegetables comes dairy. Finally, at the top of the food pyramid, above dairy and in the smallest proportion, you should have fats, oils and sweets. You may find a photo of the food pyramid on some food packages, on the internet, some books, etc.
Four conditions that can result from poor eating habits or prolonged unbalanced diet are:
(1) obesity
(2) malnutrition
(3) diabetes
(4) high cholesterol
Obesity – Obesity is the condition of a person being very fat. It is caused basically by over-eating or continuously eating too much. Having excess carbohydrates and fats in the diet causes obesity. A person may eat less food each time he/she eats or eat less meals in a day. He/she may also reduce the amount of snacks he/she eats. Exercising a few times each week also helps obesity as exercise burns calories or fat or the energy that food produces. Some persons opt to do some sort of surgery to help them with obesity. Such surgeries may include making the stomach smaller so that the person feels full with less food when he/she eats. Also, a person may opt to surgically remove the fat from his/her body. Some manufacturers claim to be able to reduce a person’s appetite, increase metabolism, burn fat, etc. with pills. Obesity may be caused by other factors such as taking certain medications, genes, hormone imbalance and living a very sedentary life (not exercising much). Exercise does not have to be very rigorous. Regular walking and cleaning the house are examples of exercise that are not rigorous but still burn calories.
Malnutrition – malnutrition is the condition of a person having ill-health due to either too much or too little of one or more nutrients in his/her body. Each nutrient has different diseases that result from having too much or too little of it in the body.
Diabetes – Diabetes is a disease resulting from too much sugar in the body. It is a serious disease, sometimes causing kidney disease, blindness, damaged nerves, loss of limb (feet) and even death. Diets high in carbohydrates and sugar can lead to the development of diabetes. Persons who develop diabetes have to subsequently watch their sugar intake and also take certain medications to help lower the sugar in their bodies.
High Cholesterol – High cholesterol is generally caused by the intake of too much fat in the body. There are actually ‘good’ fats and ‘bad’ fats. Generally, meats and other animal products like milk, cheese and egg carry ‘bad’ fats. Red meats have high concentrations of ‘bad’ fat than white meat. Fish carry ‘good’ fat, however. Fruits, vegetables and non-meat products like bread and rice, carry ‘good’ fats. ‘Bad’ fats raise your cholesterol, whereas ‘good’ fats lower your cholesterol. You have to eat foods carrying both ‘bad’ and ‘good’ cholesterol to have a balanced diet, however. You should therefore eat them all in a balanced way. That is, not too much or too little of any type of food. You should eat all foods in moderation.
For a balanced diet, you should eat all types of food – nuts, peas, beans, fruits like orange, banana, apple, naseberry, jack fruit and pawpaw, vegetables such as yam, pumpkin, beet root, callaloo, ginger and onion, red meat, white meat, fish, bread, pastries, dairy such as milk and cheese, and yes, ‘feel-good’ foods such as snacks, ice cream, cakes, biscuits and sweets. Just try to eat them all in moderation – not too much and not too little. To ensure that you have a balanced diet, it’s best to eat a little of all foods (as long as it’s not poisonous).
ABOUT DRUGS
Drugs are chemical substances that are not food that are swallowed, inhaled, injected, rubbed on the skin, etc. that affect the way the body or mind works. Drugs are either legal, illegal, prescription and/or over-the-counter.
Legal Drugs – Legal drugs are drugs that the law allows a person to use. They are drugs that are either prescribed by a doctor to a patient or freely bought anywhere. You may go to a pharmacy, store or shop and purchase legal drugs. Examples of legal drugs are cold medicines, headache pills and vitamin tonics.
Illegal Drugs – Illegal drugs are drugs that the law does not allow a person to use. A person would get into trouble if persons such as the police find out that they use illegal drugs. That’s because these drugs are harmful to the body. Some of these drugs are addictive as well. A person addicted to these drugs constantly yearn to take them and may even steal and not pay his bills needed to liv e comfortably to have them. These drugs include: large amounts of ganja, any amount of cocaine and ecstasy.
Prescription Drugs – Prescription drugs are basically the same as legal drugs – with the exception that a doctor has to prescribe them. So a doctor has to write the name of the drug and probably the amount to be taken, how it should be taken, how long it should be taken, etc. on a prescription paper for a patient. The patient will not be able to get the drug without a prescription.
Over-The-Counter Drugs – OTC (short for over-the-counter) drugs are basically the same as legal drugs – with the exception that you do not need a doctor to prescribe or authorize the use of them. If you feel like using them, you just go and purchase them as you wish. Examples of OTC drugs are some cold medicines, some eardrops, some eye drops, some nose drops; some headache pills, some laxatives, some sleeping pills and some vitamin pills.
Addiction is the condition of craving the use of a drug even when it’s not needed. A person may become addicted to legal as well as illegal drugs.
Even legal drugs must be used with care. Follow the instructions outlined on the container that the drug came in. Do not use more than or less than is prescribed. Take the drug before or after meals as prescribed. Take before bedtime or in the mornings as prescribed. Whatever instructions there are on the container that the drug came in, follow them. Not following the instructions could result in harm to you, your illness not going away or even your death. Also, check the expiration date on the drug to make sure that the drug is still good.
All drugs have side effects. Before taking any drug, research in various ways to know its side effects, then decide if taking the drug is worth it.
Drugs, legal and illegal, may harm a person physically as well as mentally.
MIXTURES
Matter is a mixture of different substances. Example – The earth’s atmosphere is a mixture of many gases; your blood is a mixture of water, blood cells, nutrients and plasma; your urine is a mixture of water, urea and other substances and the soil is a mixture of dead animals, dead plants, rocks and other substances.
A mixture is made up of two or more substances.
The value of the substances in a mixture remain the same when they are mixed. For example, if you mix some water, an orange, a ripe banana, a slice of melon, a slice of pineapple, some milk and some sugar together, the mixture will contain all the same amount of nutrients from the orange, banana, melon, pineapple, milk, sugar and water. If you strain the mixture, you will not be able to identify the different ingredients separately, but they are all still there and their nutrients are all still there in the mixture.
Mixtures exist as solids, liquids, gases or semi-solids.
There are three types of mixtures: (1) solutions (2) colloids and (3) suspensions.
Solutions – In a solution, one substance is dissolved into another. For example, drink mix and water. When you mix the drink mix with the water and stir them together thoroughly with a spoon, you will be unable to differentiate the drink mix from the water. They subsequently look like one mixture. The drink mix is an example of a substance that is soluble in water. The drink mix is called the solute and the water is called the solvent. Water is actually called the universal solvent. Other examples of solutes may be coffee, sugar and blended fruits and vegetables. Other examples of solvents may be milk and fruit juice.
The different components of a solution may be separated by: heating, cooling, evaporating or dissolving.
You may heat rice and water until the rice alone is left in the pot. This is an example of separating solutions.
Colloids – Colloids, unlike solutions, do not completely dissolve in each other. There are some substances that do not mix completely together, but will instead probably contain some unsettled substances. Examples are seeds, nuts, meats and callaloo.
Suspensions – When two or more particles cannot mix together at all, no matter how much you try to mix them, the mixture is called a suspension. Examples are: pebbles and water, sand and water, and wood and water.
Some substances in mixtures may be separated by: (1) filtration (2) evaporation (3) decanting (4) magnetism
You may use filtration to separate the residue of blended juice and the juice itself using a blender for example.
Evaporation – You may use evaporation to separate salt and water. You could leave the salt and water mixture out in the sunlight for a few days. At the end of that time, only salt will be left in the container. The water will have all evaporated away into the air.
Decanting – When a component settles on top of a liquid, it is called decanting. Examples are when mud settles on top of water and when milk powder settles on top of cold water.
Magnetism – A magnet may be used to separate a magnetic substance from a non-magnetic substance. For example – separating iron nails from glass clippings.
MATERIALS
All materials are made from substances such as cloth, wood, plastic, glass, paper, metal, iron and cement.
Some properties or characteristics of materials are: hardness, softness, heaviness, lightness, roughness, smoothness, shininess, dullness, transparency, absorbency, strength, flexibility, magnetism, heat conductivity and electrical conductivity.
Materials can be changed using different methods. Some materials can change into new substances, while other materials cannot.
A reversible change is a change that can be reversed. That is, can be undone or go back to its original state. Examples of reversible change are: freezing, melting, evaporating, condensing, dissolving and filtering. The shape, position, colour, size or state of the material may change and reverse back to its original form.
* There are three states of matter. They are solid, liquid and gas.
An irreversible change is a change that cannot be reversed or undone or go back to its original form. Examples of irreversible change are: burning substances or mixing ingredients and using them to cook food.
THE THREE STATES OF MATTER
The three states of matter are solid, liquid and gas.
Matter has weight, it takes up space and is made up of atoms.
A solid object has a fixed shape and volume. The particles in a solid object are close together.
Liquids do not have a definite shape. Liquids take the shape of the container that they are in. The particles in a liquid are not fixed and close together. They move apart when the liquid is heated.
Gases do not have a definite shape. The particles are farther apart than the particles in liquids and gases.
Matter can change its state. Liquid water can freeze and become solid ice. Also liquid water or solid ice can become gas (water vapour) if heated long enough.
Evaporation is the process of a liquid becoming a gas. Example, heating water long enough.
Condensation is the process of a gas becoming a liquid. Example, water vapour in the sky forming into clouds.
LIGHT AND IMAGES
The sun is the main source of light on earth.
Light enables vision.
It travels in waves.
Light travels at a speed of 300,000 kilometres per second.
Light travels in a straight line.
Sir Isaac Newton was the first scientist to discover information about light many years ago.
When light hits an object, it is either transmitted, reflected or adsorbed.
When light goes through an object, it is transmitted. Example: Light rays passing through a glass door.
When light rays bounces off an object, it is reflected. Example: Light rays reflecting from a mirror.
Some of the light rays may be absorbed. Example: Light rays absorbed in a settee.
Materials are either transparent, translucent or opaque.
Materials that you can completely or clearly through are described as transparent. Examples are water, glass, air and clear plastic.
Materials that you can’t see completely or clearly through, but can see somewhat, are described as translucent. Images will look fuzzy or blurry through translucent materials. Examples are frosted glass, very sheer cloths and waxed paper. In translucent materials, some of the light pass through it, while some of the light is absorbed.
Materials that you can’t see at all through are described as opaque. In opaque materials, most of the light is either absorbed or reflected. Examples of opaque materials that absorb light are wood, thick cloth, wall and thick paper. An example of opaque materials that reflect light is mirror. Opaque materials that reflect light are shiny.
A shadow is formed when an opaque object blocks light. The shadow is formed on the opposite side of the light.
Refraction is apparently the bending of light as it passes from air to water. The density of water slows down the speed of light as it moves from the air to water. This causes objects to appear different. Examples are: (1) A pencil appearing bent in a glass of water. (2) A rainbow forming when sunlight passes through raindrops.
Reflection happens when an image bounces off a smooth and shiny surface. Example, looking at yourself in a mirror. The light rays actually bounce off the smooth and shiny surface.
When light rays hit a rough surface, even if the surface is shiny, the light rays will be scattered in all directions. Therefore, the image would not be reflected.
We get light by either natural or artificial means. Natural light includes light from the sun, stars and moon. Artificial light includes light from electric light bulbs, flash lights and candles. Objects that give off their own light are called luminous or self-illuminating objects. Examples include the sun, candles and light bulbs. Objects which give off light by reflecting light from some other object are called non-luminous or illuminated objects. Examples include shiny metals and the moon. Some organisms give off their own light. Examples are the firefly and some species of jelly-fishes.
A periscope is used to see objects that you otherwise wouldn’t be able to see. These are objects around a corner or that has some kind of obstacle in their way. The mirrors in a periscope serve the purpose of diverting or bending the path of the light from an image. A photos of an example of a periscopes are shown below for clarity. Submarines and some scientific equipment are examples of machines that use periscopes.
Concave lenses or mirrors curve inward towards the centre.
A concave mirror will make an image appear upright and larger when it is close to it. Examples are make-up mirror and medical instruments used to see body parts up-close.
A concave mirror will also make an image upside-down and smaller when it is far away from it. Examples are telescope, searchlight, headlight and microscope.
A convex mirror/lens curves outwards. Images in a convex lens/mirror always appear always appear upright and smaller. Examples are rear view mirrors in a motor vehicle, microscopes, telescopes, cameras, reading glasses and magnifying glass.
You may view both sides of a spoon to have an idea of how both convex and concave lenses and mirrors look.
Photos of concave and convex mirrors/lenses are shown below:
SOUND
Sound can produce energy.
Vibrations produce sound.
An empty space is called a vacuum. You will hear no sound in a vacuum because matter has to be present to allow for vibration.
Sound travels in waves.
Sound travels through the three states of matter – solid, liquid and gas.
Sound travels faster in liquids than it does in gases, and faster in solids than it does in liquids.
The thicker the medium or material, the louder the sound that it produces.
Frequency in sound is the number of times a sound wave repeats itself per second. Frequency is measured in Hertz (Hz). Frequency produces pitch. High frequency produces high-pitched sounds and low frequency produces low-pitched sounds. The more air there is in the medium, the lower the pitch. The less air there is in the medium, the higher the pitch. Examples of high pitch/frequency sounds are siren, whistle, some children and women’s voices and some musical instruments. Examples of low pitch/frequency sounds are some men’s voices, drums and the thunder.
The thickness, tightness and length of the medium affects the sound. The thicker the medium, the lower the pitch. The tighter the medium, the higher the pitch. The longer the medium, the lower the pitch.
Intensity means strength. The intensity of sound is its strength. The more strength that a sound has, the louder the sound. The less strength, the softer the sound. Examples of soft sounds/low intensity are a whisper, rainfall and leaves rustling. Examples of loud sounds/high intensity are a motor bike riding, a lawn mower working and heavy traffic. Intensity is measured in decibels (dB).
Acoustics relates to sound and hearing. It relates to the way how sound behaves in space. Enclosed spaces with loud sounds such as a theatre use acoustics to control how much sound escapes its walls. They try to minimize echoes and the sound being heard outside of its walls.
An echo is the bouncing back of sound. If a place is enclosed and empty and has no soft material such as a bed, settee, plant or curtain, you will hear your if you shout. This is because the hard surface of the wall reflects the sound back to your ear. However, soft materials like a sofa will absorb the sound and it will not be reflected.
You could place a cushion over your mouth and speak. Your voice will be absorbed by the cushion and what you say will not be easily heard. That shows that sound can be absorbed by a soft material or surface.
Noise is an unpleasant sound.
Unpleasant sounds are painful to listen to. They may be loud and disorganized.
Pleasant sounds, on the other hand, may have organized rhythms and may be low-pitched and have low intensity.
Loud sounds, such as loud music, may be pleasant, but may also be unpleasant if it is too loud. Extremely loud sounds may even damage the ear drum and cause partial deafness.
Unwanted, very loud and prolonged noise is referred to as noise pollution.
Noise pollution can cause hearing problems, stress, sleep disturbance and high blood pressure.
Sources of noise pollution include: heavy traffic, social gatherings, industrial machines, very loud music and very loud household machines.
Noise pollution can be minimized in a few ways. They include: wearing ear plugs and ear muffs, prohibiting noise producing businesses from operating in residential areas and installing soundproof windows, doors, ceilings and walls in buildings.
OUR BODY ORGANS
The human body is made up of various parts all working together to provide life. First, there are cells. Cells are the basic unit of all humans. Lots of cells come together to form tissues. Examples include tissues in the brain, spinal cord, muscles, skin and blood. Lots of tissues come together to form organs. Examples of organs are the skin, heart, lungs and kidneys. Different organs come together to form systems. An example of a system is the nervous system. It contains the brain and spinal cord. The nervous system is responsible for communication in your body among the different organs and systems. If your brain is basically dead, you are basically dead for example. Another example of a system is the respiratory system. It contains the nose, mouth, windpipe, bronchial tubes and lungs. The respiratory system is responsible for inhaling and exhaling. That is breathing. We would die if we can’t breathe.
The brain is the single most important organ of the body. If the brain of a person is dead, the person is basically dead.
Below is listed some of the human body systems with the organs included in the systems, and the main functions of the systems.
1) The Respiratory System – Contains the nose, mouth, throat, voice box, windpipe, airways and lungs. The respiratory system supplies the body with oxygen and removes carbon dioxide (essential for life).
2) The Nervous System – Contains the brain and spinal cord. The most essential system for life and body functions. This system sends and receives ‘messages’ to and from all the other systems, organs and parts of the body. Without the nervous system, no part of the body would work.
3) The Skeletal System – Contains the bones, cartilage, ligaments, tendons and joints. This system allows humans to move around and also supports and protects all the organs of the body.
4) The Digestive System – Contains the mouth, tongue, salivary glands, esophagus, stomach, small intestine, large intestine, gall bladder, liver, pancreas, rectum and anus. This system is responsible for the breaking down of food, absorption of nutrients from food into the body, transportation of nutrients throughout the body and the elimination of wastes from foods from the body.
5) The Circulatory System – Contains the heart, the blood vessels and the blood. The job of this system is to transport oxygen, nutrients from foods and other essential substances around the body, as well as remove wastes from the body such carbon dioxide, urine, faeces and cell wastes.
6) The Excretory System – Contains the kidneys, ureters, urinary bladder, urethra, liver, small and large intestines, skin and lungs. This system is responsible for the elimination unwanted and harmful wastes from the body. These wastes include sweat, carbon dioxide, excess water, toxic materials, urine and faeces.
7) The Muscular System – Contains the skeletal muscles, cardiac muscles and smooth muscles. The skeletal muscles are attached to bones and allow posture and movement of the body. The cardiac muscles are attached to the heart and enables blood circulation throughout the entire body. The smooth muscles are located in the walls of the various organs throughout the body and allow involuntary movements. Involuntary movements are movements that you cannot control – they happen automatically, like the blinking of your eyes, your breathing and the pushing of food substances in your intestines.
8) The Reproductive System – Males and females have different reproductive systems. In males, the reproductive system includes the penis, scrotum, testes, urethra (yes, the urethra) and prostate gland. In females, the reproductive system includes the vagina, fallopian tubes, ovaries, uterus and cervix. The job of the reproductive system is to produce babies or make other human beings.
THE RESPIRATORY SYSTEM
The respiratory system is responsible for taking in oxygen into the body and removing carbon dioxide from the body. The body needs carbon dioxide to function and carbon dioxide is a waste product of the body.
Respiration involves breathing in (inhaling in) and breathing out (exhaling out).
When you breathe in or inhale, your diaphragm contracts and moves downward. This increases the space in your chest and thus your lungs are able to expand in your chest. Your ribs cover and protect your lungs. When you inhale, the muscles between your ribs also contract and pull your rib cage upwards and outwards, thereby increasing the space in your chest cavity and allowing the oxygen to enter your lungs. The air (containing the oxygen) enters your lungs through your nose or mouth. The air from your mouth or nose travels down your trachea (also called the windpipe) and then enters your lungs. Your two lungs contain the left bronchi and right bronchi (one bronchi in each lung). Inside the lungs, the bronchi divide into many smaller branches called bronchioles. Tiny air sacs called alveoli are attached to the end of the bronchioles. The alveoli are surrounded by tiny blood vessels called capillaries. When you breathe in and the air travels down the trachea and then enters your lungs. It then travels through the bronchi, bronchioles, alveoli then into the capillaries.
At the same time that oxygen enters the capillaries, carbon dioxide also enters the capillaries. Oxygen is used by the cells of your body to produce energy. Carbon dioxide is a waste product of this activity. Your body has to get rid of this waste product. It does this by letting the carbon dioxide leave the body in the same way that the oxygen enters it. The carbon dioxide goes through the capillaries, alveoli, bronchioles and bronchi in the lungs, then the trachea and finally out through the nose or mouth. The capillaries, alveoli, etc. carry blood and the exchange of oxygen and carbon dioxide is done in your blood.
When you breathe out, or exhale, your diaphragm and rib muscles relax, thereby reducing the space in your chest cavity. When the space in your chest cavity is smaller, your lungs will deflate and let out the air, laden with carbon dioxide, out of it. The air will leave the lungs first, then pass through the trachea, then pass out of the mouth or nose.
The Nervous System
The nervous system is made up of the brain and the spinal cord. The nervous system is made up of two main systems: The central nervous system (CNS) and the peripheral nervous system (PNS). The CNS is comprised of the brain and the spinal cord, while the PNS is comprised of all the other nerves throughout the body.
The brain is the most important part of the nervous system. It has three parts.
(1) The cerebrum controls our imagination, thoughts and senses (seeing, hearing, touching, tasting and smelling). The cerebrum is the largest part of the brain.
(2) The cerebellum controls our posture and muscle movements. It is the smallest part of the brain.
(3) The brain stem connects the brain to the spinal cord.
The Skeletal System
The skeletal system contains the bones that give our body its shape and support and protect the organs of our body.
The skeleton includes the bones of the shoulder, hip, arm. leg, backbone, skull, fingers, toes, chest and face.
Functions of the skeleton include:
(1) Giving the body its shape.
(2) Supporting the body as a whole.
(3) Protecting the organs inside the body such as the lungs.
(4) Allows the body to move with the help of muscles.
(5) Making blood cells inside the bone marrow.
There are two hundred and six (206) bones in the body.
The size of bones varies. Some of the smallest bones are located in the ear. Some of the largest bones are the thigh, hip and arm bones.
Bone is a living tissue.
Bone contains many types of cells. Bone is hard and stiff because some of the cells in it are surrounded by crystals of mineral salts.
Ligaments hold bones firmly together. Ligaments are strips of strong, elastic tissue.
There are different types of bones.
Bones whose length are longer than their width are called long bones. They are generally in the limbs. Examples are the thigh bone, lower leg bone, upper arm bone, forearm bone and finger/toe bones.
Bones that have the same length, width and thickness are called short bones. Examples are the bones in the wrist and in the ankle.
Bones that are thin and flat are called flat bones. They provide protection to certain organs of the body. Examples include some of the skull, rib, chest, shoulder and hip bones.
Bones that have no special shape and feature, and which do not fall in the category of long, short or flat bones, are called irregular bones. They include some bones of the face, hip, neck and spine.
Cartilage is tissue that protects bones and joints. It acts as a cushion between bones and joints, and allows smooth movements between them.
Our bodies are able to move with the help of joints. Joints are where two or more bones meet. Joints enable movement between the bones
There are different types of joints.
Ball and socket joints allow your limbs to rotate around.
Hinge joints allow your limbs to move back and forth.
Fixed joints do not allow any movement at all. Examples are the joints in your skull, ribs and hip.
The Digestive System
Digestion is the process of the breaking down of food by the body, making the food soluble enough to pass into the blood stream so that it can be transported and used throughout the body.
The organs involved in the digestive systems include: the alimentary canal (the oesophagus or gullet, the stomach, the small intestine, the large intestine or colon, the rectum and the anus), the mouth, the tongue, the teeth, the liver and the pancreas.
This is the process of digestion:
The mouth produces saliva or spit. The teeth chew the food in the mouth with the saliva. The saliva helps to soften the food. Thereby making the food easier to swallow. The saliva also contains enzymes which helps the process of digestion. After the food is chewed, it is swallowed. The swallowed food enters the oesophagus (prounced ee·so·fuh·guhs). Muscles in the oesophagus contract and slowly squeeze the food down into the stomach. These contractions are called peristalsis. The stomach’s wall contains cells which release acids and enzymes that further digest the food. After a few hours in the stomach, the food becomes liquid. This liquid food moves slowly into the small intestine. Most of the digestion takes place in the small intestine. The digested nutrients are absorbed through the wall of the small intestine into the blood stream. From the blood, the nutrients are carried throughout the body. Different nutrients have different uses to our bodies. They help us to see with our eyes, walk, grow, sleep, speak, breathe, etc. Undigested food and water then move on to the colon (a part of the large intestine). Here, excess water is removed, leaving a semi-solid waste called faeces (pronounced feces). The colon then squeezes the faeces to the rectum (another part of the large intestine). The faeces is stored in the rectum until nerves in the rectum signal to the body when the rectum is full and that faeces need to be expelled from the body. The faeces are expelled from the body through the anus. The time it takes to digest food is usually between about two to eight hours, depending on factors such as how much food is eaten and the amount of energy used up by the eater.
The Circulatory System
The circulatory system is the system that transports blood throughout the body. It transports things such as nutrients, wastes and oxygen. The three main parts of the circulatory system are the blood vessels, the blood and the heart. The blood vessels consist of arteries, veins and capillaries.
The heart is the main organ in the circulatory system. The heart pumps blood through the blood vessels in the body to all parts of the body. The muscle in the heart is called cardiac muscle. The heart is divided into four chambers. They are the left atrium, the right atrium, the left ventricle and the right ventricle. The right atrium receives carbon dioxide rich (deoxygenated) blood from the body, which it pumps to the right ventricle. The right ventricle then pumps this carbon dioxide rich blood to the lungs, where it is exchanged for oxygen. The left atrium, in contrast, receives oxygen-rich blood from the lungs, which it sends to the left ventricle. The left ventricle in turn pumps this oxygen-rich blood to the rest of the body.