THE
LUNGS
CHEST CAVITY
• EACH TREE HAS A TRUNK AND A
HUGE SYSTEM OF ROOTS. IF YOU'VE
EVER COME ACROSS A TREE THAT
HAS BEEN UPROOTED IN A FOREST,
YOU WOULD'VE NOTICED HOW THE
ROOTS GET SMALLER AND SMALLER
WITH EVERY BRANCHING.
TRACHEA, BRONCHI, AND ALVEOLI
• TRACHEA- COMMONLY CALLED THE
WINDPIPE. IT'S A CARTILAGINOUS TUBE
THAT IS SUPPORTED BY NUMEROUS CSHAPED CARTILAGE RINGS. ITS MAIN
ROLE IS TO ALLOW FOR THE PASSAGE
OF GASES TO AND FROM THE LUNGS
• .
• AS THE TRACHEA HEADS DOWNWARDS, DEEPER INTO
THE CHEST CAVITY, IT WILL DIVIDE INTO TWO
BRANCHES. THE LEFT AND RIGHT PRIMARY (MAIN)
BRONCHI, WITH EACH ONE ENTERING THEIR
RESPECTIVE LUNG.
• THE PRIMARY BRONCHI ARE LIKE THE FIRST LARGE
ROOTS OF THE TREE. THEY EVENTUALLY DIVIDE INTO
SMALLER ROOTS, KNOWN AS SECONDARY AND
TERTIARY BRONCHI.
• THESE BRONCHI SUBDIVIDE
INTO BRONCHIOLES, SMALLER
BRANCHES OF THE BRONCHI. AGAIN,
IT'S LIKE THE ROOT SYSTEM OF A TREE,
WHERE EVERYTHING GETS SMALLER
AND SMALLER AS WE DIVIDE AND
BRANCH OFF MORE AND MORE AS WE
GO DEEPER AND DEEPER.
• AT THE END OF THE
BRONCHIOLES ARE GRAPE-LIKE
CLUSTERS CALLED ALVEOLI, OR
AIR SACS, WHERE GAS
EXCHANGE OCCURS IN THE
LUNGS.
• THEY ARE VERY TINY 1/5 OF A
MM AND HAVE VERY THIN
MEMBRANES
• THE LUNGS ARE ORGANS OF RESPIRATION,
LOCATED ON EITHER SIDE OF THE HEART IN THE
CHEST CAVITY.
• THE RIGHT LUNG IS MADE OF THREE LOBES, THE
SUPERIOR, MIDDLE, AND INFERIOR.
• THE LEFT LUNG HAS TWO LOBES, THE SUPERIOR
AND INFERIOR.
• THE LUNGS THEMSELVES AND THE INSIDE OF THE CHEST CAVITY THEY SIT WITHIN ARE LINED
BY PLEURA, A VERY THIN, DELICATE, AND MOIST SEROUS MEMBRANE.
• THE VISCERAL PLEURA IS A THIN MEMBRANE THAT COVERS THE LUNGS
• THE PARIETAL PLEURA IS A THIN MEMBRANE THAT COVERS THE INSIDE OF THE CHEST WALL
AND THE DIAPHRAGM.
• THE SPACE BETWEEN THE VISCERAL AND PARIETAL PLEURA IS KNOWN AS THE PLEURAL SPACE
OR PLEURAL CAVITY.
REVIEW
• THE THORAX, OR CHEST, CONTAINS MANY STRUCTURES. RUNNING DOWN INTO AND
THROUGH THE THORAX IS THE TRACHEA, THE WINDPIPE. IT BRANCHES INTO THE PRIMARY
(MAIN) BRONCHI, THE TWO BRANCHES OF THE TRACHEA, WITH EACH ONE ENTERING THEIR
RESPECTIVE LUNG
• THESE EVENTUALLY BRANCH INTO SMALLER BRONCHI, WHICH THEN BRANCH INTO
THE BRONCHIOLES, SMALLER BRANCHES OF THE BRONCHI. AT THE END OF THE BRONCHIOLES
ARE THE ALVEOLI, OR AIR SACS, WHERE GAS EXCHANGE OCCURS IN THE LUNGS.
THE LUNGS ARE ORGANS OF RESPIRATION, LOCATED ON EITHER SIDE OF THE HEART IN THE
CHEST CAVITY. THE LUNGS AND CHEST ARE LINED BY PLEURA, A VERY THIN, DELICATE, AND
MOIST SEROUS MEMBRANE.
• THE VISCERAL PLEURA IS A THIN MEMBRANE THAT COVERS THE LUNGS, AND THE PARIETAL
PLEURA IS A THIN MEMBRANE THAT COVERS THE INSIDE OF THE CHEST WALL AND THE
DIAPHRAGM. THE SPACE BETWEEN THE VISCERAL AND PARIETAL PLEURA IS KNOWN AS
THE PLEURAL SPACE OR PLEURAL CAVITY. NOT TO BE CONFUSED WITH THE PLEURAL SPACE
IS THE AREA BETWEEN THE LUNGS, WHICH IS KNOWN AS THE MEDIASTINUM.