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8/12/2019 Anatomy Resp

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VI. ANATOMY AND PHYSIOLOGY

The Lungs

Structure

The lungs are paired (left and right), cone-shaped elastic organs

take up most of the space in our chests along with the heart.

role is to take oxygen into the body and to help us get rid of carbon dioxide

Responsible for ventilation, which requires movement of the walls of the thoracic wallsand its floor.

PLEURAE


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Serous membrane lining the wall of the thorax and the lungs.

Visceral pleura covers the lungs

Parietal Pleura covers the wall of the thorax

Both pleurae secrete pleural fluid in order to prevent friction rub between the thorax andthe lungs.

Allows smooth motion of the lungs in the thorax.

LOBES

The right lung has three lobes

Upper

Middle

Lower

The left lung has only two

Upper

Lower

-Each lobe is further subdivided into 2 5 segments.

-Separated by fissures and are extensions of the plurae

BRONCHI

-Several divisions in the lung

Lobar Bronchi Divided into segmental bronchi (10 on the right and 8 in the left.) Chosenfor the best positions in postural drainage position for the patient.

Segmental Bronchi divide into subsegmental bronchi.

Surrounded by connective tissue that contain arteries lymphatics and nerves.

Sub Segmental Bronchi Divide into bronchioles which contain no cartilage.

Bronchioles contain submucosal glands which produce mucus .

Covers the inside of the airways to trap dust and debris.

Bronchi and Bronchioles are lined with cilia.


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Cilia functions as a whip, to get rid of foreign substances up to the larynx and out of thelungs.

ALVEOLI

Lungs contain 30 million alveoli.

Arranged in clusters of 15 20.

3 Types

1) Type 1 Epithelial cells that form the alveoli walls

2) Type 2 Produce Surfactant

3) Type 3 Macrophages.

Blood Supply of The Lungs

The lungs are very vascular organs, meaning they receive a very large blood supply. This isbecause the pulmonary arteries, which supply the lungs, come directly from the right sideof your heart. They carry blood which is low in oxygen and high in carbon dioxide into your

lungs so that the carbon dioxide can be blown out of your lungs.

2 Types of circulations involving the lungs:


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Pulmonary Circulation Deoxygenated blood coming from the different systems of thebody enters the right side of your heart, it is then pumped into the left and right lungs bythe pulmonary arteries to be filled with oxygen. The oxygenated blood then travels to the

left side of the heart by the pulmonary veins and gests ready for the systemic circulation.

Systemic Circulation Oxygenated blood from the left side of the heart is then pumpedinto the aorta to supply nutrients and oxygen to the systems, which then makes theoxygenated blood deoxygenated. It is then drained back to the right side of the heart by

the superior and inferior vena cava to once again start its circuit.

Function Of the Lungs

Air enters your lungs through a system of pipes called the bronchi.

start from the bottom of the trachea as the left and right bronchi and later on throughoutthe lungs turn into bronchioles.,

eventually form the little thin-walled air sacs or bubbles, known as the alveoli.

The alveoli are where the important work of gas exchange takes place between the airand your blood. Covering each alveolus is a whole network of little blood vessel called

capillaries: -small branches of the pulmonary arteries.


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It is important that the air in the alveoli and the blood in the capillaries are very closetogether, so that oxygen and carbon dioxide can move (or diffuse) between them. So, when

you breathe in, air comes down the trachea and through the bronchi into the alveoli. Theoxygen, other gasses will travel across the walls of the alveoli into your bloodstream. Travelingin the opposite direction is carbon dioxide, which crosses from the blood in the capillaries intothe air in the alveoli and is then breathed out. In this way, you bring in to your body the

oxygen that you need to live, and get rid of the waste product carbon dioxide.

The Diaphragm and Intercostal Muscles

When you breathe in (inspiration), the diaphragm, a large, sheet-like muscle whichstretches across your chest under the ribcage, does much of this work. At rest, it is shaped likea dome curving up into your chest. When you breathe in, the diaphragm contracts and flattensout, expanding the space in your chest and drawing air into your lungs. Other muscles,including the muscles between your ribs (the intercostal muscles) also help by moving yourribcage in and out. Breathing out (expiration) does not normally require your muscles to work.This is because your lungs are very elastic, and when your muscles relax at the end ofinspiration your lungs simply recoil back into their resting position, pushing the air out as they

go.

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