Category Zoology

Why do I need a skeleton?

                           Bones provide the framework that holds the whole body together. Without a skeleton you would simply flop about, and you would not be able to move. The skeleton also gives protection to delicate organs such as the brain, heart and lungs. It acts as a support to the soft parts of the body. The skeleton also provides a system of levers that your muscles can work on, enabling you to make all your movements.

Which is the largest bone in the body?

                         The thigh bone, or femur, is the largest single bone in the body. It is also the strongest bone, because it has to support all of our weight. An adult male who is 1.8 m tall has a femur 0.5 m in length.

Which is the smallest bone in the body?

                      The smallest bone in the body is called the stirrup. It is in the middle ear and is part of the system that carries sound signals to the brain. At only 3 mm long, the stirrup is about the size of a grain of rice. It is connected to two other very small bones called the hammer and anvil. All three of these bones are joined to the eardrum, where sound is collected before it is sent in the form of nerve signals to the brain.

What are glands?

                      Glands produce substances the body needs to maintain itself. Salivary glands in the mouth produce saliva that wets food so you can swallow it. Other glands produce substances called hormones. These help control conditions within the body.

Why is the body so complicated?

                         If we were simple single-celled animals, we would not need a complicated body system to stay alive. Single-celled animals absorb oxygen directly from the water around them, and they get rid of waste in the same way. Many feed by simply crawling over food material and absorbing it, or by letting food pass through the flexible membrane around it.

                        Human cells operate in a similar way. Our organ systems simply provide the basic conditions that the billions of individual cells in our bodies need to survive. In general, the bigger an animal is, the more complicated its body needs to be in order to survive and reproduce.

What is metabolism? 

                             Metabolism is the term for all of the chemical activity that takes place inside the cells. Metabolism breaks down more complicated substances obtained from food. This allows these substances to be changed into other materials that the body needs.

What are the essential substances the body needs for life?

                           Apart from oxygen, the human body needs food. Your food contains fats, proteins, carbohydrates and fibre, as well as vitamins and minerals. You need all these substances to stay healthy. They are first broken down in the process of digestion. They are then built up again inside the cells to make useful substances.

What are tissues?

Millions of cells that do the same job are grouped together into tissues, so they can be put to work by the body. There are many different types of tissue, for example muscle tissue. Muscle is built up from millions of thread-like muscle cells.

What do cells need to survive?

Cells need food, oxygen and a watery environment in order to survive. Food and water are supplied by the blood and other body fluids, which also carry away wastes. Blood also contains all of the food substances and chemicals needed by the cell.

What are organs?

Organs are made up from different types of tissue that are grouped together to carry out a particular body function.

The heart, for example, is a collection of muscle tissue, connective tissue and nervous tissue. These tissues work together to pump blood around the body.

Different types of organs are in turning grouped together to form systems, such as the circulatory system. It includes the heart and all the body’s blood vessels. The digestive system includes the mouth, gullet, stomach and intestines, while the nervous system includes the brain, spinal cord and nerves extending throughout the body. The human body also has a skeletal system, a muscular system, an endocrine system (glands), a respiratory system, a urinary system and a reproductive system.

What is the body made of?

More than half of the human body is made of water. The rest of the body is built from a huge number of complicated chemicals. These chemicals, together with water, are assembled into tiny building blocks called cells. Each cell is self-contained and has a particular function in the body. There are more than 50,000 billion cells in your body.

What do cells look like?

The shape and appearance of a cell depends on what job it does. Nerve cells are long and thread-like so they can carry messages around the body along the nervous system. Red blood cells are like flattened discs that are pinched in at the centre. White blood cells are shapeless so they can squeeze between other cells and attack invaders such as bacteria.

What’s inside a cell?

Cells consist mostly of a watery jelly-like material called cytoplasm. Each cell is held together by a very thin flexible membrane, rather like a balloon filled with water inside the cell the cytoplasm is organized into special areas called organelles. These control the functioning of the cell, for example, the production of essential substances called proteins. Tiny grains called mitochondria use oxygen to break down food and release the energy that powers the cell. An area called the nucleus contains 46 thread-like chromosomes that control the working of the cell. Some cells, such as those lining the intestines, only live for a few days, while other nerve cells within the brain can survive throughout your entire life.