In the human heart diagram, there are four chambers in this tireless pumping organ. All the chambers work in coordination pump blood round the body.The left chambers contain the oxygenated blood from the lungs.
This blood is pumped out of the heart via the arteries which transport the this oxygenated blood round the body to the muscles and vital organs.
The blood returns to the heart via veins. The veins return to the right side of the heart carrying carbon dioxide. The heart pumps this returning blood to the lungs.
In the lungs the carbon dioxide is removed from the blood and breathed out. The carbon dioxide is replaced with oxygen and returned to the left side of the heart to be pumped around the body again.
Your tongue is a mass of muscles. The specific arrangement of muscle fibres allows it to move freely in any direction inside the mouth to performs several different tasks, including eating, swallowing, speaking, licking, sucking, and helping to pronounce words when we speak.
Your tongue contains thousands of taste buds. Taste buds are small organs, embedded in the tongue that enable us to experience taste.
The tip or apex of the tongue accounts for the front one-third of the tongue. It is very mobile and rests against the incisor teeth in the mouth. The taste buds for “sweet” are on this part of the tongue.
The back two-thirds of the tongue form its body. The surface is slightly rough. This is this part of the tongue where the tongue tastes salty, bitter and sour flavours.
The function of nose in respiratory system is very important. It is responsible for filtering and inhaling air containing vital oxygen .
The septum divides the nasal cavity to create two equal sized nostrils. The fine hair or cilia in the nose behave like a mechanical filter removing particles from the air we breathe in.
The nose also pre-warms the air we breathe during inhalation to match body’s temperature .
Of course, the nose is also the organ responsible for our sense of smell. The nostrils contain six million cells that are sensitive enough to detect a huge number of different smells. Humans have the ability to detect as many as over one trillion distinct scents.
The major functions of the ear are to help us to maintain the balance and to aid in hearing capabilities.The ear has three main sections:
The outer ear is the pinna, and its function is to gather the sound waves like a funnel and transmit to the middle ear through the ear canal.
The ear drum covers the other end of the canal.
The sound waves that strike the ear drum setup a vibration. This vibration then travels to the three small bones (ossicles) of the middle ear, (the malleus, stapes and incus). The bones of the middle ear move and strike the oval window. The vestibular window separates the middle ear from the inner ear.
The inner ear is also called the cochlea, which is a dual membrane, delicate in structure, with fluid between the membranes and lined with hair cells. The movement of the hair cells that line cochlea, in response to the sound waves, sends electrical impulses to the brain which interprets the sounds we hear.
The human eye is the organ which enables us to see. The eyes are two in number and each is placed inside specialised compartments or sockets in the skull.
The white part of our eyes is known as sclera. It consists of fibrous tissues. The job of this part it to protect the internal parts of the eye.
The transparent tissue through which light enters the eyes is called cornea. It exists in front of the eye.
The iris is made up of muscles which contract or relax in order to adjust the amount of light which enters the eye.
The pupil is an aperture controlled by the iris muscles; when it is dark, the iris muscles relax, causing the pupil to open up wider so that more light enters the eyes to enable us to see better. Conversely, the pupil becomes narrow due to the contraction of the iris muscles when there is excessive light in order to protect the cells of the eyes.
The lens is present behind the pupil. Light enters the pupil, passes through the lens and is focused on the retina of the eye. The lens is capable of changing its shape in order to help us see near or far off objects.
The retina converts light into electrical signals which are transferred to the brain for processing. The retina contains two types of cells: rods and cones. These cells are sensitive to light. Rods are important for night-time vision when there is little light; cones play an important role in helping us see colours.
The optic nerve takes electrical signals from the retina of the eye to the brain.
The human eye does not only let us view the scenes and phenomena in our surroundings, but also enables us to differentiate between colours, though sometimes, there is a minor defect in the eye function and the individual cannot make difference between the red and green colour.