Unit 1 and 2. Human Nutrition

We are going to divide this unit in two tests: one with the digestive and the respiratory system and the other with the circulatory and excretory system. 

THE TEST WILL BE NEXT MONDAY 18TH OCTOBER 2021(circulatory and excretory systems)

EXCRETORY SYSTEM 

Excretory system eliminates the waste from our body. The excretory system is made up of: 

• The kidneys are two organs that remove waste from the blood.
• The excretory tract:
  • Ureters: connect the kidneys to the bladder.
  • Bladder: stores the urine.
  • Urethra: expels the urine.

 HOW KIDNEYS WORK 

• The blood enters in the kidneys through the renal artery.
• The kidneys extract waste from the blood and the clean blood goes to the heart through the renal vein. The water and waste form the urine.
• The urine leaves the kidneys through the ureters to the bladder.

CIRCULATORY SYSTEM

CIRCULATORY SYSTEM Circulatory system uses blood to transport substances (nutrients and waste products) around our body. PARTS OF THE CIRCULATORY SYSTEM: 

• THE HEART: is a hollow, muscular organ. It is divided into 2 halves: the left side and the right side. The upper chamber is called the atrium and the lower chamber the ventricle. Between these two chamber is a valve.
• THE BLOOD VESSELS: BLOOD VESSELS: are a network of tubes that circulate blood.
  • ARTERIES: carry blood from the organs to the heart.
  • VEINS: carry blood from the organs to the heart
  • CAPILLARIES: are very fine vessels that exchanges substances between cells and the blood.

 Blood is a red liquid that is made up of: 

• PLASMA: is a yellowish liquid that consits of water and some substances (sugar, proteins, salt, nutientes, cellular waste)
• BLOOD CELLS: contains:
  • Red blood cells: transport oxygen and carbon dioxide.
  • White blood cells: defend us against infections.
  • Platalets: join together and sela up cuts so that we don´t lose blood.

BLOOD CIRCULATION

 HEARTBEAT: pushes the blood through the blood vessels. The beat has two parts: 

• The DIASTOLE: the heart expands and the blood enters in the heart through the VENAE CAVAE. It fills the atrium and then blood passes to the ventricle.
• The SYSTOLE: the heart contracts.
  • The left ventricle sends OXYGEN rich blood through the AORTA ARTERY.
  • The right ventricle send blood with CARBON DIOXIDE through the PULMONARY ARTERY.

 THE PULMONARY SYSTEM 

Blood (waste) enters into the right atrium from the venae cavae and passes to the right ventricle. The blood leaves the right ventricle through the pulmonary artery and travels to the lungs. In the lungs, the blood leaves the carbon dioxide and collects the oxygen.The blood is now full of nutrients and oxygen. 

THE SYSTEMIC CIRCUIT

 Blood (oxygen and nutrients) passes from the left atrium to the left ventricle. The blood leaves the heart through the aorta artery. It sends the blood to the organs. The blood leaves oxygen and nutrients in the cells and collects the waste. The blood goes back to the heart and enters through the venae cavae.

The first TEST will be this Thursday 30th September 2021:

-Vital functions and the systems of each function.

-Digestive system: parts and the digestion.

-Respiratory system: parts and the breathing process.

DIGESTIVE SYSTEM: we obtain nutrients from the food we eat.

The digestive system is made up of: 

• Digestive tract: mouth, pharynx, oesophagus, stomach, small intestine, large intestine and anus.
• Accessory organs: produce substances. These are:
• Salivary glands: produces saliva in the mouth.
• Liver: produces bile in the small intestine.
• Pancreas: produces pancreatic juices in the small intestine.

 DIGESTION 

• The teeth cut the food, which is mixed with the saliva by the tongue. The food turns into a ball called bolus.
• The bolus goes down through the pharynx to the oesophagus.
• Then, it reaches the stomach and the bolus mixes with gastric juices and it turns into chyme.
• The chyme reaches the small intestine, and it mixes with the pancreatic juice and bile. The chyme is transformed into the chyle.
• The nutrients in the chyle pass through the blood capillaries in the small intestine into the blood.
• Water and waste go to the large intestine where the water is absorbed.
• Faeces are formed and expelled through the anus.

RESPIRATORY SYSTEM In the respiratory system we breathe in oxygen and we expel carbon dioxide. The respiratory system is made up of: 

• The respiratory tract: nasal cavity, pharynx, larynx, trachea and bronchi. The bronchi become smaller and smaller bronchioles, and they end in the alveoli.
• The lungs: are two spongy organs found in the thorax. They are separated by the diaphragm.

PROCESS OF BREATHING

INHALATION is breathing in air to obtain oxygen. 

The diaphragm contracts and the lungs expand. Air enters through the mouth and the nasal cavity and it goes down through the pharynx, larynx and trachea. 

Then, it passes to the bronchi and the bronchioles, in the alveoli takes place the exchange of oxygen and carbon dioxide through the capillaries.

 The oxygen passes to the blood and the carbon dioxide passes to the alveoli. Then we expel this carbon dioxide during exhalation. 

The diaphragm relaxes and the lungs contract. The carbon dioxide travels up the respiratory tract. 

EXHALATION is breathing out air to expel carbon dioxide.