Download Respiratory System

Respiratory
System
Structures and Functions
Structures of the Respiratory System

The human body has two lungs.
Each time you breathe in, air flows
through the trachea, into each lung
through a left and right bronchus
(pl= bronchi), then into
bronchial tubes, then smaller
bronchiole tubes, ending in a tiny
sac called an alveolus (pl=
alveoli).

Alveoli are surrounded by
capillaries. So oxygen (O2)
molecules can diffuse into the
blood stream while carbon dioxide
(CO2) molecules can diffuse out of
the blood stream into the alveoli to
be exhaled. This is gas exchange.
Structures of the Respiratory System

The order of structures in the respiratory system:
Nose, nasal cavity, pharynx (back of the mouth), epiglottis,
larynx, trachea, bronchi, bronchial tubes, bronchiole tubes, alveoli.

Air typically enters the body through the nostrils of the nose. Small hairs called cilia just inside the nostrils may
stop some of the unwanted dust and dirt particles found in the air. The air moves from the nostrils into the two
nasal cavities of the nose. A wall of cartilage and bone separates the two cavities. The air is heated at this point
by warm blood flowing through blood vessels in the nasal cavities. This acts like a radiator. Air taken in through the
nose is warmed before going to the lungs. Air can also be brought into the body through the mouth, but here there
are fewer opportunities for dust and dirt particles to be removed, and there will not be this warming process.

The nose produces a continuous supply of mucus. This mucus, which is replaced every 20 minutes, has two main
jobs. One is to add some moisture to the air so that the internal tissues of the respiratory system don’t dry out.
The other job is to catch unwanted particles and bacteria from the air. The unwanted particles are caught in the
mucus and then billions of small hair-like cilia move the mucus up into the esophagus that leads back down to the
stomach. The stomach releases digestive juices that contain hydrochloric acid. This acid destroys the foreign
material. Sometimes the particles caught in the mucus of the nasal cavities irritate the nose and causes sneezing.
This is another way to release unwanted particles from the body.
Structures of the Respiratory System

You can see, it is best to breath
through the nose because of the
warming, filtering, and moistening of
the air. From the nose, the air travels
into the throat.

At one point, the throat leads to two
separate paths. One is the esophagus,
which is the tube leading to the
stomach. The other is the trachea, a
tube leading to the lungs. At the top
of the trachea is a small flap called
the epiglottis. This flap covers
the opening to the trachea so that
food won’t go into the trachea when
you swallow. When we breathe, the
flap opens to allow the air to enter
the trachea and the rest of the
respiratory system.
Gas Exchange

Gas exchange in the body is based on the principle that gases tend
to move from areas of high concentrations to low concentrations. In
cells, it’s called diffusion and is a passive transport across the cell
membrane.

There are two areas of gas exchange across cell membranes:
1.
Inhaled O2 in the alveoli diffuse across the alveoli cell membranes,
through the capillary cell membrane, into the bloodstream, through a
red blood cell membrane, while CO2 diffuses reversely from the red
blood cells in the bloodstream into the alveoli to be exhaled.
2.
Cells around the body diffuse CO2 waste across their cell membranes,
then across the surrounding capillary cell membrane, into the blood
stream, across a RBC cell membrane to be taken back to the alveoli to
be exhaled.
Structures of the Respiratory System

A very strong bell-shaped muscle called the diaphragm is under the lungs. When it
contracts and relaxes with the rib muscles, it causes the movement of inhaling
and exhaling (the lungs are not muscle, so can not move on their own).

Diaphragm contracts = shortens = pulls down lungs = pulling air in.

Diaphragm relaxes = lengthens = pushes up lungs = pushing air out.
Gases in Earth’s Air:
Gases in Inhaled / Exhaled Air:
Function of the Respiratory System

FUNCTION: During inhalation, the lungs take in
oxygen from the air and move it into the
bloodstream and take carbon dioxide from the
bloodstream for exhalation.

The circulatory system takes this oxygen-rich blood
throughout our bodies so that cells can use the
oxygen, along with glucose obtained from the
digestive process, to PRODUCE ENERGY.

The lungs are the main structures of the
respiratory system and they work closely with the
circulatory system.

Using oxygen to produce energy is called
RESPIRATION.

When cells use oxygen and glucose to produce
energy (called ATP) it is called CELLULAR
RESPIRATION.

When energy is produced in the cells, carbon
dioxide waste is produced. The lungs exhale the
carbon dioxide waste from the blood stream.
Extra Info:

Above the trachea is the larynx. The larynx contains vocal cords.
These are elastic folds of tissue that vibrate to produce sound when
air is pushed between them. The longer the vocal cords, the deeper
the voice. The shorter the vocal cords, the higher the voice.

We can survive for days without food or water, but if deprived of
oxygen, we can only survive for a few minutes.

Not all living things use lungs for respiration.

Aquatic organisms use gills to take in O2 from the water.

Plants use an organ structure called a stomata to take in CO2 from
the air and release O2 waste.

Insects use holes along their bodies called spiracles.
More Extra Info: