UNIT 3

TOPIC I : THE LOCOMOTIVE SYSTEM

1.-THE SKELETAL SYSTEM:Our skeleton has 206 bones . We have bones in our head , trunk and limbs. Bones have different shapes and sizes. There are long bones , like the ones in our arms and legs .There are short bones , like the ones in our fingers and toes.

A.- FUNCTIONS OF THE SKELETAL SYSTEM.The skeletal system has 4 functions:

Our skeleton gives shape to our body .

Our skeleton holds us upright.

Bones work with muscles to allow us to move.

Different parts of our skeleton , like the skull , protect our soft organs.

B) JOINTS HELP US MOVE.The place where two or more bones meet is called a JOINT. By themselves , bones cant move , because they are rigid. Joints allow movement and let our skeleton bend and turn . The ends of bones are covered by a layer of a rubbery tissue . This tissue is called CARTILAGE.We can put them into three groups :- Fixed like the skull bones.-Movable like the elbow or knee.- Semi movable like vertebrae.Our bones are linked to each other by tissues called LIGAMENTS. Ligaments are very strong and flexible.

IMPORTANT BONES

We classify the bones of the skeleton by where they are in the body.1.- HEAD BONES. There are two groups. * Skull bones protect the brain, like the frontal, temporal , parietal and occipital bones.* Facial bones, like the nasal, cheekbones and jawbones.

2.- TRUNK BONES. There are two sections:THE SPINE is made up of vertebrae that protect the spinal cord.

THE RIB CAGE is made up of ribs and the sternum. It protects the heart and lungs.

3.- LIMB BONES they can be upper limbs when they are located in the arms, and lower limbs when they are in the legsUpper limbs : The humerous , the ulna and radius. ( arm)the carpal , metacarpal and phalanges ( hand and fingers).

Lower limbs: The femur , tibia and fibula ( leg)The tarsal , metatarsal and phalanges ( ankle and toes)

The hip connects them all to the trunk. Each have three bones: the ilium, ischiums and the pubis

THE MUSCULAR SYSTEM

Our mus cular system has more than 600 muscles. A muscle is a tissue , made of muscular cells . Most of the muscles in our body move bones. There are also muscles that move different body parts that are not bones, like our lips and eyes.

A) FUNCTION OF THE MUSCULAR SYSTEM.The muscular system has several functions:Our muscles give shape to our body.

Muscles make other parts of our body move.

Some muscles also help to protect soft organs of our body

TENDONS :Muscles are attached to the bones by tendons. A tendon is a strong cord that attaches a muscle to a bone.

B) HOW MUSCLES HELP US MOVE OUR BONES.Muscles cells can change their shape . When muscle cells contract, , the muscle they are part of gets shorter. Muscles work in pairs. If a muscle pulls a bone one way the other pulls the same bone in the opposite direction. We say muscles shorten and relax .

C)TYPES OF MOVEMENTThere are two types of movement.Voluntary movements. These movements respond to an order from the brain.

Involuntary movement. These movements respond to an order from somewhere else:- From the spinal cord , like when you move your hand when you are pricked. These movements are also called reflexives.

From the brain stem, like when your diaphragm moves when you breathe.

IMPORTANT MUSCLESThere are :LONG MUSCLES like the bicepsFLAT AND WIDE like the buttock ROUND like the mouth and eye muscles.

- We also clasify muscles by where they are in the body:HEAD MUSCLES:- the masseter help you to chew.- the buccinator let you open and close your lips.The orbicular let you open and close your eyes.TRUNK MUSCLES- In the neck the sternocleidomastoideo- In the front the abdominal and pectoral muscles.- In the back the trapezius.LIMB MUSCLES- Upper limbs: the biceps and triceps- Lower limbs: the quadriceps and the calf muscles.

TOPIC - II: RELATION

OUR SENSESOur nervous system receives information from the outside world through receptors that are in our tongue, eyes, nose, skin and ears. These receptors form our senses.* Our brain interpretes information about the world around us . Our senses give this information to our brain.* What is a stimulus? It is anything that affects any of the body activities Ex: and object you can see and touch, a smell , a sound.* There are two types of stimuli:- Internal: they come from inside our body like feelings .-External. They come from outside the body like the smell of a succulent chicken * What is a response ? The body answer to a stimulus. We eat when we are hungry.There are two types of responses:- Muscular responses like removing your hand when you touch something very hot.- Glandular responses like when you sweat in response to heat.

STIMULUS RECEPTORS.The body has different receptors to receive different differenr types of stimuli:- Internal receptors: they receive the internal stimuli our body produce. They are all over the body. They perceieve hunger, thirst, pain of sore muscles.- External receptors. They receive external stimuli. They are in the sensory organs.Our eyes let us see each other.Our nose lets smell.Our ears let us hear the soundsOur tongue lets us taste food .Our skin lets us perceive temperature and the Surface of an object .

THE SENSE OF SIGHTThe eye is the organ used for sight.*Light enters the eye through the pupil.*The iris contracts or dilates to regulate the amount of light you need.* Then the light crosses the lens and reaches the retina.* The retina transmits the information to the brain through the optic nerve.- The humours are liquids that fill the inner part of the eye.- The cornea is a transparent membrane that protect the eye from the exterior.

THE SENSE OF HEARINGWe hear sound with our ears.* Sound waves travel to our external earand this transmit these vibrations to our eardrum.* In the middle ear, the vibrations pass on to three tiny bones ( hammer, stirrup and anvil). They carry the vibrations to the inner ear.* Sound passes into the cochlea and finally to the brain along the auditory nerve

THE SENSE OF TASTE

The sense of taste is located in our tongue. * The tongue is a muscular organ with about 3,000 taste buds. These transmit sensation of taste.* We can distinguish four different flavours: sweet, sour, salty and bitter.

THE SENSE OF SMELLThe sense of smell is found in the nasal cavity, inside our nose, where we perceive different smells.* When a smell enters our nose , these cells gather information and send a message to our brain.

THE SENSE OF TOUCHThe sense of touch is located in our skin* The top part of the skin is called the epidermis.*The inner part of the skin , where nerve receptors and blood vessels are , is called the dermis.* Touch detectors are located in our epidermis . They send information to the brain. The brain can interpret different kind of sensations: temperature, texture, shapes and sizes

THE NERVOUS SYSTEM

The nervous system receives and interpret the information of the internal and external receptors and it develops and transmits a response. It coordinates and controls all the processes of the bodyIt is made up of nerves and nerve centres.Nerves transmit information. They form the peripheral nervous system.

The nerve centres interpret the information and develop responses. They form the central nervous system.

A) THE CENTRAL NERVOUS SYSTEMIt has two parts:Brain: it is inside the skull . It has three main parts: The cerebrum, the cerebellum and the braim stem.

Spinal cord. It is protected by vertebrae. It is a thick cord made up of many neurons that goesthrough the inside of the spine.

B) THE PERIPHERAL NERVOUS SYSTEM It is made up of nerves.Sensory nerves : They transmit information from the sensory organs to the central nervous system.

Motor nerves: They transmit responses from the central nervous system to the muscles and glands of our body.

NEURONS ARE THE CELLS OF THE NERVOUS SYSTEM. THEY ARE MADE UP OF A CELL BODY , DENDRITES AND AXONS

Seccin Bilinge CEIP COLN 6 Primaria