respiratory anatomy

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RESPIRATORY ANATOMY

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The primary role of the respiratory system is to: 1. deliver oxygenated air to blood 2. remove carbon dioxide from blood

The respiratory system includes: 1. the lungs 2. several passageways leading from outside to

the lungs 3. muscles that move into and out of the lungs.

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The term respiration has several meanings:

1. ventilation (breathing) 2. gas exchange (occurs between the air and

blood in the lungs and between the blood and other tissues of the body)

3. oxygen utilization by the tissues for cellular respiration.

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The Lungs

• located within the thoracic cavity/chest. • the lungs are asymmetrical. The right lung is

larger than the left lung because the heart takes up more space on the left side.

• The air passages of the respiratory system are divided into two functional zones:

1. The conduction zone 2. The respiratory zone

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The Conduction Zone

• the set of anatomical structures in which air passes before reaching the respiratory zone.

• Air enters through the nose and or mouth, where it is filtered, humidified, and adjusted to body temperature in the trachea (windpipe).

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The Conduction Zone

• The trachea branches into the right and left bronchi that enter the lung and continue to branch into smaller and smaller tubes called bronchioles and finally the terminal bronchioles.

• The whole system inside the lung looks similar to an upside-down tree that it is commonly called the “respiration tree”.

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The Respiration Zone

• The region where gas exchange occurs. • The functional units of the lungs are the tiny air sacs,

known as alveoli.• Alveoli are clustered in bunches like grapes, with a

common opening into an alveolar duct called an alveolar sac.

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The Structure of the Respiratory System

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The Alveolus

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Ventilation includes two phases, inspiration and expiration. Gas exchange between the blood and other tissues and oxygen utilization by the tissues are collectively known as internal respiration.

Ventilation

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Ventilation

• Involves the movement of air into (inspiration) and out of (expiration) the lungs.

• Changes in the size of the chest/thoracic cavity, and thus of the lungs, allow us to inhale and exhale air.

• Lungs are normally light, soft and spongy to allow for expansion in the thoracic cavity.

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Ventilation

• The muscles surrounding the thoracic cavity which result in size change include the:

Diaphragm External Intercostal muscles (expiration) Internal Intercostal muscles (inspiration)

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Ventilation

• During inspiration, the thoracic cavity expands via muscle contractions causing the air pressure inside to be lowered.

• The greater outside pressure causes a flow of air into the lungs.

• During expiration, thoracic cavity shrinks via muscle relaxation

• The greater outside pressure causes a flow of air out of the lungs

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Gas Exchange in the Lungs

• Gas exchange between the air and blood in the lungs occurs at the alveoli.

• Each bubble-like alveolus is surrounded a vast network of pulmonary capillaries.

• The atmospheric air which has made its way into each alveolus is rich in oxygen.

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• The blood in the pulmonary capillaries is loaded with the waste product of carbon dioxide. This difference in concentration of CO2 and O2 gases sets up ideal conditions for gas diffusion.

• Diffusion is the movement of molecules (in this case, gases) from a higher concentration to a lower concentration

• Therefore, oxygen diffuses through the alveolar membrane into deoxygenated pulmonary capillaries.

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• Carbon dioxide diffuses in the opposite direction, from the carbon dioxide rich pulmonary blood into the alveoli

• The oxygenated blood follows the pulmonary circulation to reach the heart and is distributed through systemic circulation.

• Carbon dioxide is exhaled out.

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Gas Exchange at the Alveolus

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Exercise Effects on the Cardiovascular and Respiratory Systems

• The cardiovascular system ensures that adequate blood is supplied to working muscles, the brain and the heart.

• Also, heat and waste products generated by the muscles are dissipated and removed.

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Aerobic Training Effect on the Cardiovascular and Respiratory Systems

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Cardiac Output1. Increase in heart size is one of the

benefits that may arise as a result of endurance training.

2. Larger atria and ventricles allow for a greater volume of blood to be pumped each time the heart beats.

3. Increased thickness of the walls of the heart (cardiac muscle) allows for increased contractility (rate of contraction)

Exercise Effects on the Cardiovascular and Respiratory Systems cont.

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Capillary Supply• Increased capillarization is another benefit that may

arise as a result of endurance training.

• Increased capillarization allows for:

1. a greater surface area and reduced distance between the blood and the surrounding tissues

2. increasing diffusion capacity of oxygen and carbon dioxide

3. easing transport of nutrients to cells.

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Capillary Supply cont

• The a-vO2 difference of the body can be also improved by endurance training.

• Endurance training increases circulation (blood flow) in the capillaries that are next to muscle fibers.

• Capillarization also occurs in cardiac muscle, reducing the possibility of cardiac disease and heart attacks.

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Blood Volume• Increase in total blood volume

along with the number and total volume of red blood cells.

This is done through the release of erythropiotin, resulting in erythropoiesis in the bone marrow.

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Ventilation• increases with exercise in order to meet the

increased demand of gas exchange. • During exercise ventilation can increase from 6 L /

min at rest to over 150 L/min during maximal exercise and to more than 200 L/min during maximal voluntary breathing

• With exercise/endurance training, the lungs become more efficient in gas exchange.

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Oxygen Extraction• similar to ventilation in that the increased

air flow allows for more gas exchange. • Additionally, during exercise, body

temperature increases. Increased body temperature promotes oxygen extraction, this is known as the Bohr effect.