NATURAL SCIENCE SUMMARIES- DIGESTIVE, RESPIRATORY AND CIRCULATORY SYSTEMS
DIGESTIVE SYSTEM
In the mouth:
We eat solid
food and we bite, crush and chew it with our teeth.
Our salivary glands produce saliva.
The tongue forms a ball called bolus. It is swallowed and passes into
the oesophagus.
The epiglottis covers the trachea and stops
food from going into our lungs.
In the stomach:
When the
bolus reaches the stomach, it combines with gastric juices that break down the food and kill bacteria. The chyme it is formed.
In the small intestine:
The chyme
passes from the stomach to the small intestine. It mixes with:
-bile from the liver
-pancreatic juices from the pancreas.
They break
down the food into basic nutrients.
They pass through the walls of the small intestine and into the blood.
In the large intestine:
Food waste that the body does not need passes
into the large intestine. Extra water is
absorbed into the body. The rest passes into the rectum and then leaves the body through the anus.
THE RESPIRATORY
SYSTEM
RESPIRATION PROCESS
1. The air enters the nostrils and
passes into the trachea.
2. The trachea divides into two bronchi
3. Each bronchi divides into several
bronchioles
4. At the end of every bronchiole there
is an alveoli. They are covered by many capillaries.
GAS EXCHANGE
It takes
place in the alveoli.
Oxygen passes from the alveoli into the
blood.
Carbon dioxide passes from the blood to the
alveoli.
INHALATION
The diapragm
contracts
The lungs
inflate
EXHALATION
The diapragm
relaxes
The lungs
deflate
The rigcage
contracts
CIRCULATORY SYSTEM
BLOOD
COMPONENTS:
Plasma
It is 90% water
It carries nutrients and waste products
Red blood cellls
They carry
oxygen and carbón dioxide. They give blood its red color.
White blood cells
They fight
infections. They attack bacteria and virus.
Platelets
They join
together when there is a cut in the skin. This helps to stop bleeding
(coagulation)
BLOOD VESSELS:
Arteries: they carry oxygenated blood from the
heart to the capillaries
Capillaries: they are very tiny and have very thin
walls.
Veins: they carry deoxygenated blood from
the capillaries to the heart.
CIRCULATION
-pulmonary circulation:
The heart
pumps deoxygenated blood to the lungs, where the blood absorbs oxygen.
Then, the
oxygenated blood flows back to the heart.
Systemic circulation:
The heart
pumps oxygenated blood to the rest of the body.
When this
blood returns to the heart, it is deoxygenated.
1.
First, the deoxygenated blood enters the right
atrium.
2.
From there, the blood goes through
the tricuspid valve and passes to
the right ventricle.
3.
Next, it pumps the blood though the pulmonary valve and then through the pulmonary artery directly into the lungs.
4.
In the lungs, the blood mixes with
the oxygen. The oxygenated blood
travels through the pulmonary vein
into the left atrium,
5.
Then, it is pumped through the mitral valve into the left ventricle.
6.
Finally, it is pumped out to the rest
of your body through the aortic valve
and then through the aorta artery.