How Your body works Part 2

The Respiratory system

 

Respiration ≠ breathing

 

Respiration- The breaking down of food with the use of oxygen

Breathing - is the taking in of oxygen by the nose and mouth into the lungs

      The primary function of the respiratory system is to supply the blood with oxygen in order for the blood to deliver oxygen to all parts of the body. The respiratory system does this through breathing. When we breathe, we inhale oxygen and exhale carbon dioxide. This exchange of gases is the respiratory system's means of getting oxygen to the blood.

Respiration is achieved through the mouth, nose, trachea, lungs, and diaphragm. Oxygen enters the respiratory system through the mouth and the nose. The oxygen then passes through the larynx (where speech sounds are produced) and the trachea which is a tube that enters the chest cavity. In the chest cavity, the trachea splits into two smaller tubes called the bronchi. Each bronchus then divides again forming the bronchial (bronchioles) tubes. The bronchial tubes lead directly into the lungs where they divide into many smaller tubes which connect to tiny sacs called alveoli. The average adults' lungs contain about 600 million of these spongy, air-filled sacs that are surrounded by capillaries.

Inhale and exhale air

The inhaled oxygen passes into the alveoli and then diffuses through the capillaries into the arterial blood (oxygenated). Meanwhile, the waste-rich blood (deoxygenated) from the veins releases its carbon dioxide into the alveoli. The carbon dioxide follows the same path out of the lungs when you exhale.

The air we breathe in is a mixture of gases. The main gases found in the air are nitrogen (78%), oxygen(21% ), and nobles gases (about 1%), Carbon dioxide (0.03%)

When air from the atmosphere is taken into out lungs, we absorb the oxygen need by the body and get rid of waste carbon dioxide. We lose water vapour from the water  that lines the surface of the lungs

Gases	% in inhaled air	% in exhaled air
Oxygen	21	16
Carbon dioxide	0.03	4
nitrogen	78	78
Nobles gases	About 1	About 1
Water vapour	A little	A lot
heat	Room temp.	Body temp.

 The structure of the alveoli and gaseous exchange

 The alveoli are little sacs that are bunched together like grapes. They are covered with a network of blood capillaries. The blood entering the capillaries are coming from the body (deoxygenated blood) has high concentration of CO₂. Oxygen is in higher concentration inside the alveoli than in the blood, so it diffuses into the blood. CO₂ then diffuses out of the blood into alveoli. This air is exhaled and replace with fresh air when we inhale, to maintain the concentration gradients of the gases across the lung surface.

http://www.youtube.com/watch?v=XTMYSGXhJ4E 

Structures and functions of the respiratory system

Mouth, nose & nasal cavity: The function of this part of the system is to warm, filter and moisten the incoming air

Pharynx: Here the throat divides into the trachea (wind pipe) and oesophagus (food pipe). There is also a small flap of cartilage called the epiglottis which prevents food from entering the trachea

Larynx: This is also known as the voice box as it is where sound is generated. It also helps protect the trachea by producing a strong cough reflex if any solid objects pass the epiglottis.

Trachea

The trachea is sometimes called the windpipe. The trachea filters the air we breathe and branches into the bronchi.

The bronchi are two air tubes that branch off of the trachea and carry air directly into the lungs.

Diaphragm

      Breathing starts with a dome-shaped muscle at the bottom of the lungs called the diaphragm. When you breathe in, the diaphragm expands. When you breathe out, the diaphragm contracts reducing the amount of space for the lungs and forcing air out. The diaphragm is the main muscle used in breathing.