Respiration and Mechanics of Breathing

Respiration

• Respiration is the exchange of air between the atmosphere and the lungs.
• Breathing involves inhalation (inspiration) and exhalation (expiration).
• Inhalation involves the contraction of intercostal and rib muscles, causing the ribs to move up and out, and the diaphragm to move down. This increases the size and volume of the thoracic cavity, leading to a decrease in air pressure in the lungs. Air moves from the higher pressure atmosphere into the lower pressure lungs.
• Exhalation involves the relaxation of intercostal and rib muscles, causing the ribs to move down and in, and the diaphragm to move up. This decreases the size and volume of the thoracic cavity, leading to an increase in air pressure in the lungs. Air moves from the higher pressure lungs to the lower pressure atmosphere.
• Breathing is an active process during inhalation and a passive process during exhalation.

Mechanics of Breathing

• Breathing relies on the movement of gases from areas of high pressure to areas of low pressure.
• A difference in air pressure is necessary for breathing to occur.

Muscles for Breathing

• The diaphragm is a dome-shaped muscle at the bottom of the thoracic cavity.
• Intercostal muscles, also called rib muscles, are found between the ribs on the inside surface.

Types of Breathing

• Inhalation, also known as inspiration, is the process of air entering the lungs.
• Exhalation, also known as expiration, is the process of air exiting the lungs.

Inhalation

• Inhalation is an active process that requires energy.
• Intercostal and rib muscles contract, moving the ribs up and out.
• The diaphragm moves down.
• The size and volume of the thoracic cavity increase.
• Air moves from higher atmospheric pressure to lower lung pressure; air enters the lungs.

Exhalation

• Exhalation is generally a passive process.
• Intercostal and rib muscles relax, moving the ribs down and in.
• The diaphragm moves up.
• The size and volume of the thoracic cavity decrease.
• Air moves from higher lung pressure to lower atmospheric pressure; air leaves the lungs.

Stages of Respiration

• Breathing involves the exchange of air between the atmosphere and the lungs, including inhalation and exhalation.
• External respiration is the exchange of gases between the air in the alveoli and the blood in the capillaries within the lungs. Oxygen moves from the air to the blood, and carbon dioxide moves from the blood to the air.
• Internal respiration is the exchange of gases between the blood and the body's cells. Oxygen moves from the blood to the cells, and carbon dioxide moves from the cells to the blood.
• Cellular respiration is the process where body cells use oxygen to break down nutrients and produce energy.

External Respiration

• External respiration occurs in the lungs where gases are exchanged.
• Oxygen moves from the high concentration in the air to the low concentration in the blood by diffusion.
• Carbon dioxide moves from the high concentration in the blood to the low concentration in the air by diffusion.

Transport of Oxygen

• In the blood, nearly 99% of oxygen is carried bound to hemoglobin within red blood cells.
• A small portion of oxygen remains dissolved in the plasma.

Transport of Carbon Dioxide

• Approximately 23% of carbon dioxide is carried by hemoglobin.
• About 7% is dissolved in the blood plasma.
• Approximately 70% is transported as bicarbonate ions.
• Carbonic acid dissociates into hydrogen ions and bicarbonate ions in red blood cells, then diffuses into the plasma.

Internal Respiration

• Internal respiration occurs in various tissues of the body.
• Gases are exchanged between the capillaries and the body cells.
• Oxygen moves from the blood to the body cells by diffusion.
• Carbon dioxide moves from the cells to the blood by diffusion.

Regulation of Breathing

• Chemoreceptors are specialized sensory cells detecting changes in blood chemistry (like pH from CO2 levels) that can stimulate the medulla oblongata.
• The medulla oblongata is a part of the brainstem that regulates breathing; it receives input from chemoreceptors and controls breathing rate and depth.
• The medulla oblongata also regulates other systems like the cardiovascular system.
• High CO2 levels in the blood stimulate a nerve response to increase breathing movements.
• Low levels of oxygen also trigger increased breathing.
• Individuals can consciously override the automatic breathing regulation of the medulla oblongata, but if CO2 levels get too high, automatic controls take over to prevent dangerous conditions.

This quiz covers the fundamentals of respiration, including the processes of inhalation and exhalation. It explores how air exchange occurs between the atmosphere and the lungs, detailing the mechanics involved during these processes. Understand the active and passive phases of breathing for a comprehensive view of respiratory mechanics.