Physiology of breathing Respiratory System Physiology of breathing

Regulates blood oxygen and carbon dioxide levels. Human Respiratory System Functions: Works closely with circulatory system, exchanging gases between air and blood: Takes up oxygen from air and supplies it to blood (for cellular respiration). Removal and disposal of carbon dioxide from blood (waste product from cellular respiration). Homeostatic Role: Regulates blood pH. Regulates blood oxygen and carbon dioxide levels.

Copyright Pearson Prentice Hall What Is Respiration? What Is Respiration? In biology, respiration means different things. Cellular respiration is the release of energy from the breakdown of food in the presence of oxygen (occurs in the?????) At the organism level, respiration is the process of gas exchange—the release of carbon dioxide and the uptake of oxygen that occurs between RBCs and alveoli Breathing is the actual mechanical intake of air Copyright Pearson Prentice Hall

External Respiration Gas exchange between pulmonary blood and alveoli Movement occurs toward the area of lower concentration of the diffusing substance Un-oxygenated blood is transformed into oxygenated blood and returned to heart

Copyright Pearson Prentice Hall Gas Exchange Gas exchange takes place in the alveoli. Oxygen diffuses into the blood. Carbon dioxide in the blood diffuses into the alveolus. Let’s examine this up close O2 CO2 Gas exchange occurs by diffusion across the membrane of an alveolus and a capillary. Capillary Copyright Pearson Prentice Hall

Diffusion Gradients Oxygen Carbon dioxide Moves from alveoli into blood. Blood is almost completely saturated with oxygen when it leaves the capillary P02 in blood decreases because of mixing with deoxygenated blood Oxygen moves from tissue capillaries into the tissues Carbon dioxide Moves from tissues into tissue capillaries Moves from pulmonary capillaries into the alveoli

Internal Respiration At capillaries, gas exchanges must be made between blood and tissue cells Oxygen is dropped off and carbon dioxide is loaded into the blood from tissues

Respiratory Sounds Bronchial Sounds: Produced by air rushing through the large respiratory passageways like the trachea and bronchi Vesicular Sounds: Produced as air fills the alveoli

Copyright Pearson Prentice Hall Ventilation Also known as BREATHING Lungs are sealed in pleural membranes inside the chest cavity. At the bottom of the cavity is a large, flat muscle known as the diaphragm. During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall

Ventilation - Breathing During inhalation, the diaphragm contracts and the rib cage rises up. This expands the volume of the chest cavity. The chest cavity is sealed, so this creates a partial vacuum inside the cavity. Atmospheric pressure fills the lungs as air rushes into the breathing passages. During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity. Copyright Pearson Prentice Hall

Inspiration Inspiration or inhalation Diaphragm and external intercostals contract, thoracic cavity increases Diaphragm moves inferorily External intercostals lift the rib cage and thrust out the sternum

Muscles of Inhalation Intercostal muscles: Accessory muscles Diaphragm: contraction draws air into lungs 75% of normal air movement Intercostal muscles: assist inhalation 25% of normal air movement Accessory muscles sternocleidomastoid serratus anterior pectoralis minor scalene muscles

Ventilation - Breathing Often exhaling is a passive event. When the rib cage lowers and the diaphragm relaxes, pressure in the chest cavity is greater than atmospheric pressure. Air is pushed out of the lungs. During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity. Copyright Pearson Prentice Hall

Expiration Expiration or exhalation Passive process that relies on natural elasticity Expiration is effortless, but if the respiratory is narrowed by spasms, mucus or fluid this process becomes active

Muscles of Respiration

Ventilation - Breathing Movement of air into and out of lungs via negative pressure pump mechanism Air moves from area of higher pressure outside the lung to area of lower pressure created in the thorax and lungs by diaphragm Pressure is inversely related to volume in that as pressure goes down lung volume goes up

Normal Breathing Cycle

Tidal Volume (TV) Amount of air moved into and out of lungs with a normal breath about 500ml

Vital Capacity The total amount of air that a person can exhale. About 4600 ml

Residual Volume After the most forceful expiration this is the amount of air that remains in the lungs About 1200 ml

Total Lung Capacity Vital capacity plus residual volume About 5800 ml

Non-respiratory Movevents All of these move air out of the respiratory system for function other than breathing Examples: cough, sneezing, crying, laughing, hiccups, and yawn.

Cough The cough is a reflex action--when there is an irritant present in the lungs the body responds by coughing.

Sneezing Sneezing is caused by irritation to the mucous membranes of the nose or throat. Clears the Upper respiratory tract

Hiccups Irritation of the diaphragm that causes spasms Could be from eating too fast, excitement, or irritation in the stomach or throat.

Yawn Yawning is an involuntary action that causes us to open our mouths wide and breathe in deeply.

Interesting Yawning Facts The average yawn lasts about six seconds. Your heart rate can rise as much as 30 percent during a yawn. 55 percent of people will yawn within five minutes of seeing someone else yawn. Blind people yawn more after hearing an audio tape of people yawning. Reading about yawning will make you yawn. Olympic athletes often yawn before competition.

How Breathing Is Controlled Breathing is controlled by the medulla oblongata. The medulla oblongata monitors carbon dioxide in the blood. As carbon dioxide increases, nerve impulses make the diaphragm contract, bringing air into the lungs. The higher the carbon dioxide level, the stronger the impulses. Copyright Pearson Prentice Hall

What can affect the medulla oblongata? Suppression as with an overdose of sleeping pills, morphine, or alcohol can cause respiration to stop. Death will occur!!

Factors Influencing Respiratory Rate and Depth Physical Factors Increased body temperature Exercise Speech Singing Non-respiratory air movements Chemical Factors Changes in levels of carbon dioxide more so than the need to intake oxygen Conscious Control Emotional Factors Fear, Anger, Excitement

Changes in Respiratory System at Birth Before birth: pulmonary vessels are collapsed lungs contain no air, filled with fluid During delivery: placental connection is lost At birth: Fluid is drained and the respiratory passage is filled with air Baby’s first breath!!

3 Effects of Aging on the Respiratory System Elastic tissues deteriorate: reducing lung compliance lowering vital capacity Arthritic changes: restrict chest movements limit respiratory minute volume Emphysema: affects individuals over age 50 depending on exposure to respiratory irritants (e.g., cigarette smoke)

Copyright Pearson Prentice Hall Lung Capacity Lab Objective: Measure the amount of air your lungs can hold Copyright Pearson Prentice Hall