Respiration PDF OCR

Respiration Outcome D1b, Lesson 2  Take a deep breath How does it feel? What do you notice in terms of the movement and structures involved? Mechanics of Breathing Breathing relies of the movement of gases from an area of high pressure to area of low pressure In order for b...

Respiration Outcome D1b, Lesson 2  Take a deep breath How does it feel? What do you notice in terms of the movement and structures involved? Mechanics of Breathing Breathing relies of the movement of gases from an area of high pressure to area of low pressure In order for breathing to take place, there must be a difference in air pressure Muscles for Breathing Diaphragm Dome-shaped layer of muscle at the bottom of the thoracic cavity Intercostal muscles Also called the rib muscles Found between ribs on the inside surface of the ribs Muscles for Breathing Types of Breathing Inhalation Also known as inspiration Air entering lungs Exhalation Also known as expiration Air exiting lungs Inhalation An active process (using energy) where air is drawn into the lungs with the aid of muscle contractions Steps: Intercostal and rib muscles contract Ribs move up and out Diaphragm moves down Size and volume of the thoracic cavity increases Leads to a decrease in the air pressure of the lungs Air moves from an area of high pressure (atmosphere) to a region of low pressure (lungs) Air moves into lungs Exhalation Generally, a passive process where air is expelled from the lungs due to the relaxation of muscles Steps: Intercostal and rib muscles relax Ribs move back down and in Diaphragm moves back up Size and volume of the thoracic cavity decreases Leads to an increase in the air pressure of the lungs Air moves from an area of high pressure (lungs) to a region of low pressure (atmosphere) Air moves out of lungs Lower pressure Higher inside pressure inside compared to compared to outside outside Stages of Respiration Breathing Exchange of air between the atmosphere and the lungs Inhalation or exhalation External respiration Gas exchanged between the air in the lungs and the blood Internal respiration Gas exchanged between the blood and the body’s cells Cellular respiration Body cells use oxygen and make carbon dioxide in the process of producing energy for the cell External Respiration Occurs in the lungs Gases are exchanged between the air in the alveoli and the blood in the capillaries Oxygen moves from high concentration (air) to low concentration (blood) by diffusion However, this does not transfer enough oxygen into the blood Approximately 30% of oxygen transfer happens by facilitated diffusion Carbon dioxide moves from high concentration (blood) to low concentration (air) Transport of Oxygen Once in the blood, 99% of oxygen is carried in the red blood cells by hemoglobin A small portion remains dissolved in the plasma Transport of Carbon Dioxide Approximately 23% of carbon dioxide is carried by hemoglobin Approximately 7% is carried in the plasma Approximately 70% is dissolved and carried as a bicarbonate ion CO2 reacts with H2O to form carbonic acid (H2CO3) The carbonic acid quickly dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-) Happens in red blood cells H+ combine with hemoglobin and bicarbonate ions then diffuse out of RBCs into the plasma Process reverses when CO2 goes to the lungs to be breathed Internal Respiration Occurs in various tissues of the body Gases are exchanged between the capillaries and the body cells Oxygen moves from high concentration (blood) to low concentration (body cells) by diffusion Carbon dioxide moves from high concentration (body cells) to low concentration (blood) Regulation of Breathing Key terms: Chemoreceptors Specialized sensory receptor cells which generate a biological signal when something is not right Medulla oblongata Long stem-like structure that makes up the lower part of the brainstem It passes messages between your brain and your spinal cord It also regulates the cardiovascular and respiratory systems Regulation of Breathing Two ways to regulate breathing: High acidity of blood (due to high levels of CO2) detected by the chemoreceptors in the medulla oblongata This stimulates a nerve response to increase breathing movements, causing contractions of the diaphragm and intercostal muscles Expels more CO2 from the lungs to the atmosphere and acidity decreases Regulation of Breathing Two ways to regulate breathing: Chemoreceptors in carotid artery (in the neck) detect low levels of oxygen Send nerve impulse to medulla oblongata This stimulates a nerve response to increase breathing movements, causing contractions of the diaphragm and intercostal muscles Results in an increase in the amount of oxygen entering the lungs and diffusing into the blood This mechanism is less sensitive, the acidity of blood is more likely to regulate breathing Regulation of Breathing You can override the medulla oblongata by consciously thinking about your breathing However, if CO2 levels get too high, the medulla oblongata will take over This occurs if you are holding your breath Your brain will trigger you to spontaneously take a breath in, even if you are in water