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Basic functions of the respiratory system
Breathing: intake of O2 into blood, elimination of CO2 out of blood
Maintenance of homeostasis: regulates blood pH/acidity by speeding up / slowing down the rate of respiration
Sensory information: contains receptors for sense of smell in the nasal passages
Filters/warms/moistens air that enters the body
Produces sounds: air moves over vocal cords in the larynx (voicebox)
Conduction zone
air/gases enter and exit through passageways of the respiratory system
Respiratory zone
location of gas exchange between the respiratory and circulatory system
Structures of the conduction zone
Nostrils
Mouth
Trachea
Primary bronchus
Secondary bronchus
Tertiary bronchus
Bronchioles
Structures of the respiratory zone
Alveoli
Alveolar ducts
Capillaries
Inhalation / Inspiration
act of drawing air into the lungs
Exhalation / expiration
act of expelling air from the lungs
Inhalation thoracic cavity size
Diaphragm contracted / moves downward
Rib cage moves up / out; intercostal muscles contract
Pressure within thoracic cavity decreases, volume increases
Lungs expand due to decreased pressure
Exhalation thoracic cavity size
Diaphragm relaxed / moves up
Rib cage moves down / in; intercostal muscles relax
Pressure within thoracic cavity increases as volume decreases
Lungs squeezed and air forced out
Alveoli
Sac-like structures with single-cell layer thick walls
Found in clusters at the end of alveolar ducts
Encased in a network of capillaries
Alveoli are the site of gas exchange between the lungs and the blood
Purpose of gas exchange
Aerobic cellular respiration
Tissues/cells take in oxygen for cellular respiration
Tissues make carbon dioxide as a product of cellular respiration
Factors affecting gas exchange at respiratory membrane
Thickness of membrane: increased thickness results in decreased rate of gas exchange (scar tissue build up in alveoli)
Surface area: decrease in surface area results in decrease in gas exchange (surface area decreases when thickness increases)
Gas pressure gradients: must have the correct pressure gradient in order to exchange gas properly
What happens when carbon dioxide enters the blood?
It is converted into carbonic acid/bicarbonate and dissolved in blood
What happens when oxygen enters the blood?
It binds to hemoglobin in red blood cells.
Hemoglobin
an iron containing molecule found in red blood cells that binds to oxygen gas so it can be transported in the bloodstream
Ventilation level too low (blood pH too low = acidic)
triggers central chemoreceptors in medulla to speed up ventilation rate by increasing stimulation of respiratory muscles
Ventilation level too high (blood pH too high = basic)
triggers central chemoreceptors in medulla to slow down ventilation rate by decreasing stimulation of respiratory muscles
Baroreceptors
sense air pressure changes and can lead to ventilation rate changes as well
Spirometry
the process of measuring volumes of air that move into and out of the respiratory system
Spirometer
device used to measure pulmonary volumes and assist in diagnosing pulmonary disorders
Tidal volume
air inspired/expired during a normal breath
Inspiratory reserve
air that can be forcefully inspired after a normal inspiration
Expiratory reserve
air expelled forcefully after expiration of normal tidal volume
Residual volume
volume of air still remaining in lungs after a maximum expiration
Vital capacity
Inspiratory reserve volume + tidal volume + expiratory volume
Maximum amount of air a person can expel after a maximum inspiration
Depends on height, age, health, biological sex
Effects of aging on respiratory system
Alveoli, respiratory tract and chest wall become more rigid and less elastic
Results in decreased lung capacity; reduced vital capacity
More susceptible to pulmonary disorders
Hypoxia
insufficient oxygen for cellular respiration
Apnea
absence of ventilatory movements
Dyspnea
painful or labored breathing
Hyperventilation
Increased rate of breathing in excess of metabolic needs
Results in excessive intake of O2 and increased elimination of CO2 leading to disturbance of acid-base balance
Causes dizziness, tingling in extremities, and may cause faintin
Hypoventilation
Reduced rate of breathing inadequate to meet metabolic needs
Decreased levels of O2 and increased levels in CO2 in the blood
Causes cyanosis
Decreased ventilatory activity is associated with overdose of drugs and SIDS