The three vital functions There are three vital functions: nutrition (eating),

interaction (the relationships between us and with theenvironment) and reproduction (having babies).

Human body and nutrition

Human body and nutrition There are four body systems that enable us to carry out

nutrition:

Digestive system

Respiratory system

Circulatory system

Excretory system

Digestive system Breaks down the food we

eat so our body can absorb the nutrients.

The stomach and intestines are organs of this system.

Respiratory system Absorbs oxygen into the

body and releases carbondioxide.

The lungs and thetrachea are organs of thissystem.

Circulatory system Transports blood all over

the body.

The heart is an organ of this system.

Excretory system Eliminates the waste our

body produces.

The kidneys are organsof the excretory system.

The interaction function

We are able to control and coordinate our activitiesthrough the interaction function.

It help us to receive information either from theenvironment or from own body through the senseorgans and respond to it.

The interaction function We follow three steps to

process information:

Stimulus-sensation: any action or change thatwe can feel.

For example: freezingtemperatures

The interaction function

The body sendsinformation about thesensation to the brain.

The brain processes theinformation and decides the order tosend.

The interaction function

The order becomes a response to the stimulithat makes us performan action.

For example: wearclothes that makes usfeel warmer.

Types of stimuli External stimuli

(sounds):

Are changes that happenin our environmentoutside the body.

The sense organs capture these stimuli and send a message to the brain.

Internal stimuli(hunger):

Are changes that happeninside our body.

Receptor organs insideour body receive thisstimuli. Then they send a message to the brain.

Types of response Motor responses:

Happen when ourmuscles move.

For example: stretc yourarms to catch a ball.

Glandular responses:

Happen when organscalled glands produce a substance.

For example: when thebody is very hot, thebody sweats.

The sensory system

Sight Eyes are the sense organ

of sight.

Light enters the eyethrough the pupil, thelens and the retina.

The retina sends stimulito the brain through theoptic nerve.

Touch

The skin is the senseorgan of touch.

Touch receptors can detect temperature, pressure, pain and texture.

Hearing The ears are the sense

organs of hearing.

The outer ear collectssounds. This passesthrough the inner earcanal, the middle ear and the three small bones.

Then, the sounds reach thecochlea and the auditorynerve and it sends it to thebrain.

Taste

Taste receptors are onthe tongue. They are small bumps called taste buds.

They help us taste thedifferent flavours: sour, bitter, sweet and salty.

Smell

Olfactory receptors are in the nasal cavity nextto the pituitary area.

The sense of smell needsthe sense of taste in order to work properly.

The nervous system

It controls our entire body sending, receiving and interpreting information.

These messages travel through the body as nerveimpulses in the following sequence:

Sense organs: they respond to a stimulus and sendimpulses along the sensory nerves.

The nervous system Sensory nerves: carry information from the sense organs

and internal organs to the central nervous system.

Central nervous system (C.N.S.): receives and interpretsinformation and produces responses. It is made up of spinal cord and brain.

Spinal cord: produces fast and automatic responses.

Brain: is inside the cranium, makes decisions and giveorders.

The nervous system

Motor nerves: CNS coordinates the informationreceived and sends impulses along motor nerves. These carry signals from the CNS to which can beeither voluntary or invol the muscles.

Musculoskeletal system: it brings a response whichcan be either voluntary or involuntary.

The nervous system Involuntary: are produced by the spinal cord action.

They are fast and automatic responses. For example: our reflexes.

Voluntary: are produced by brain activity. It receivesinformation from sense organs and produces a response. They are slower than involuntary responses.

The brain It has three parts:

Cerebrum: produces voluntary responses. Controls thinking, memoryand language.

Brain stem: controlsorgan functions.

Cerebellum: controlsbalance and coordination.

The musculoskeletal system Ligaments connect bones

to each other.

Muscles can stretch and contract. It helps bones tomove.

Bones give shape to thehuman body and protectinternal organs.

Tendons attach muscles tobones.

Joints

Joints

Joints A joint is the place where two bones meet. There are

different types of joints:

Fixed: can’t move. For example: the cranium.

Hinge: it moves or swings like a door. For example: theelbow.

Ball and socket: it can rotate. One piece is shaped like a ball and it goes inside another piece which is shaped like a round cup. For example: the shoulder.

Joints

Pivot: it rotates around one point. For example: thewrist.

Gliding: it moves in a smooth and easy way. Forexample: the clavicle.

Bones

Muscles