Organs of the respiratory system
Nose, pharynx, larynx, trachea, bronchi, lungs & alveoli (see diagram)
Functions
Manages gas exchanges between the blood and external environment
Purifies, warms, and humidifies air as it travels to the lungs
Nasal Cavity Anatomy - air enters in the External Nares and goes into the Nasal Cavity
Divided by nasal septum
Lined with respiratory mucosa - rests on veins that help warm the air
Olfactory receptors - sense of smell
Separated from the oral cavity by the palate
Cleft palate
Paranasal sinuses - cavities within bones surrounding the nasal cavity
Frontal, sphenoid, ethmoid, maxillary
Functions
Lighten the skull
Resonance chambers for speaking
Produce mucus
Paranasal Sinus Disorders
Rhinitis - inflammation of the nasal mucosa
Sinusitis - inflammation of the sinuses, can cause headaches
Pharynx (throat) - passage from nasal cavity to the larynx
Average size is 5 inches long
Food and air enter here
3 regions
1. Nasopharynx - superior region behind nasal cavity
2. Oropharynx - middle region behind mouth, breathes in
3. Laryngopharynx - inferior region attached to larynx, where food and air are separated
Pharynx structures - drain from the middle ear
Auditory tubes enter the nasopharynx
Tonsils
Pharyngeal tonsil (adenoids) - in the nasopharynx
Palatine tonsils - in the oropharynx
Lingual tonsils - at the base of the tongue
Larynx (voice box) (the turkey thing lol) - routes food and air into the right tunnels
Aids speech
Composed of 8 rigid hyaline cartilages and the Epiglottis - spoon shaped flap of elastic cartilage
Thyroid cartilage - adam’s apple
Vocal cords - vocal folds
Glottis - opening between vocal cords
Open when not swallowing, closes when swallowing, includes gag reflex
Trachea (windpipe) - connects larynx with bronchi
Lined with ciliated mucosa
Beat in the opposite direction of incoming airflow
Expel mucus loaded with debris away from the lungs
Walls are reinforced with C-shaped hyaline cartilage because the esophagus needs to be able to expand
Primary bronchi - formed by division of the trachea
Enters at the hilus - a medial depression
Right bronchus - wider, shorter, & straighter, easier to get objects lodged in
Divided into smaller branches
Lungs
Occupy almost all of the thoracic cavity
Apex - near the clavicle (superior part)
Base - lies on the diaphragm (inferior part)
Each lung is divided by fissures
Left lung - 2 lobes
Right lung - 3 lobes
Mediastinum - separates rights and left sides, houses the heart
Lung coverings
pulmonary (visceral) pleura - covers the surface
Parietal pleura - lines the walls of the thoracic cavity
Pleural fluid - fills the pleural space to reduce friction
The respiratory / bronchial tree
All have reinforcing cartilage walls except terminal bronchi
1. Primary bronchi - separates from trachea
2. Secondary bronchi
3. Tertiary bronchi
4. Bronchiole - the smallest
5. Terminal bronchiole - the end
6. Respiratory zone
Respiratory zone - only place of gas exchange
Only 2.5 pounds
Structures
1. Respiratory bronchiole
2. Alveolar duct
3. Alveoli - air sacs
Grape shape, site of gas exchange
Respiratory Membrane
Squamous epithelial layer - lines alveoli walls (super thin)
Pulmonary capillaries - cover external surfaces of alveoli
Gas exchanges
Cuboidal cells - produce surfactant (a lipid molecule)
Alveolar pores - help connect air sacs in case there is a blockage
Air blood barrier - air and blood are exchanged right along each other, through simple diffusion
 Events of respiration
1. Pulmonary ventilation - movement of air in and out of the lungs (breathing)
Completely mechanical
Volume changes → pressure changes → flow of gases to equalize pressure
2 phases
1. Inspiration - flow of air into lung
2. Expiration - air leaving lung
2. External respiration - exchange of gas between pulmonary blood & alveoli
1. Oxygen moves into the blood
Alveoli always have more oxygen than the blood
Moves by diffusion towards the area of lower concentration (high-low)
Pulmonary capillary blood gets oxygen
2. Carbon Dioxide moves out of the blood
Alveoli always have less carbon dioxide than blood
Moves by diffusion to lower concentration (high - low)
Pulmonary capillary blood gives up carbon dioxide
3. Respiratory gas transport - transport of oxygen and carbon dioxide via the bloodstream
Oxygen transport
Oxygen attaches to hemoglobin inside RBCs to form oxyhemoglobin
A small amount is dissolved into plasma
Carbon dioxide transport
Most is transported as bicarbonate ion HCO3- in plasma
Helps keep pH level balanced as the buffer system
A small amount is carried by hemoglobin in RBCs
4. Internal respiration - exchange of gas between blood & body cells in systemic capillaries
An opposite reaction to what happens in the lungs
Carbon dioxide diffuses out of tissue into blood
Oxygen diffuses from blood into tissue
Inspiration - diaphragm & intercostal muscles contract
Thoracic cavity volume increases
Ribcage is lifted
When you inhale, pressure in lungs becomes less than atmospheric pressure, which sucks air in like a vacuum
Expiration - a passive process which depends on natural lung elasticity
Muscles relax and air is pushed out of lungs
When sick, fluid and mucus buildup and can it can be harder to do (active)
Impaired oxygen transport
Hypoxia - inadequate oxygen to body tissues
Cyanosis -  bluish skin
Due to carbon  monoxide poisoning “silent killer”
Competes for hemoglobins with oxygen
Pressure differences in the thoracic cavity
Intrapleural pressure - normal negative pressure in the pleural space
Differences in lung and pleural pressure keep lungs from collapsing
Atelectasis - collapse of a lung when the fluid bond between pleura is disrupted
Pneumothorax - occurs when air enters the pleural space
Nonrespiratory air movements - can be caused by reflexes or voluntary actions
Coughing, sneezing, laughing, crying, yawning, hiccups
Respiratory volumes & capacities
Affected by: A person’s size, sex, age, physical condition
Tidal volume - a normal, average, quiet breath that brings in about 500 mL of air (1 Pint)
Inspiratory Reserve Volume - amount of air that can be taken in forcibly over the tidal volume
2100 - 3200 mL
Expiratory reserve volume - amount of air that can be forcibly exhaled after a tidal expiration
About 1200 mL
Residual volume - air remaining in lungs after expiration
About 1200 mL
Allows gas exchanges to happen in between breaths
Vital capacity -  the total amount of exchangeable air
VC = TV + IRV + ERV
About 4800 mL for adult males
Dead space volume - air that remains in conductions zone and never reaches alveoli
About 150 mL per breath
Functional volume - air that actually reaches the respiratory zone
About 350 mL
Measuring respiratory capacities
Spirometer - measures how much you inhale and exhale to check for fluids
Stethoscope
1st sound - air rushing into bronchioles
2nd sound -  air filling alveoli
Neural regulation of respiration - activity of respiratory muscles is transmitted to the brain by the Phrenic and Intercostal nerves
Medulla - controls rate & depth of breathing
If  suppressed = suffocation, caused by overdosing
Pons - smooths out respiratory rate → self exciting inspiratory center
Eupnea - normal respiratory rate of 12-15 breaths/min
Hypernia - increased breathing due to extra oxygen needs
Stretch receptors - send impulses to exhale to the brain
Factors Influencing Respiratory rate & depth
Physical status: increased body temp, exercise, talking, coughing
Volition - control control, singing &  swallowing
Emotions - crying, scared
Carbon dioxide levels in the blood
Main chemical for respiration regulation (most important factor)
Increased CO2 = increased respiration
Oxygen levels
Changes are detected by chemoreceptors and send information to the medulla oblongata
Hyperventilation - too much CO2 in blood, deep and rapid breathing
Decreases CO2 in blood
pH increases
Leads to Apnea - cessation of breathing, caused by anxiety
Hypoventilation - too little CO2, shallow and slow breathing
Increases CO2 in blood
pH decreases
Respiratory disorders
Chronic Obstructive Pulmonary Disorder (COPD)-shown by chronic bronchitis & emphysema
Major cause of death & disability in the US
Patients have a history of smoking
Dyspnea - labored breathing becomes more severe
Coughing and many pulmonary infections
Retain carbon dioxide and have respiratory acidosis - pH is too low
Leads to respiratory failure
Emphysema - alveoli enlarge as chambers break through
Chronic inflammation
Airways collapse
Lots of energy needed to exhale
Permanently expanded barrel chest
Cyanosis
Chronic bronchitis -mucosa of the lower respiratory passages become inflamed
Mucus production increases
Mucus pools and impairs ventilation
Lung infection increases & pneumonia is common
Lung Cancer - ⅓ of all cancer deaths in US
Increased risk with smoking
3 types: Squamous cell carcinoma, adenocarcinoma, small cell carcinoma
Sudden Infant Death Syndrome (SIDS) - healthy babies stop breathing & die in their sleep
Asthma - chronic inflamed hypersensitive bronchial passages
Infant respiratory distress syndrome - occurs in babies at least 12 weeks immature
Alveoli collapse after each breath, energy needed to inflate them
Cystic fibrosis - most common lethal genetic disease in US
Over secretion of mucus → clogs air passages
Aging effects
Elasticity of lungs decrease
Vital capacity decreases
Blood oxygen levels decrease
Stimulating effects of carbon dioxide decrease
More risks of respiratory tract infection
Respiratory breaths throughout life per minute
Newborns: 40-80
Infants: 30
Age 5: 25
Adults: 12-18
Rate increases with old people
 Fun facts
Nasolacrimal ducts - produces tears that drain into cavities and can clog ducts
Coughing is a reflex - can’t do it when unconscious
Ear infections can lead to sore throats
Tonsillitis - caused by a bacterial infection
Heimlich maneuver used to get food out of trachea
Tracheostomy - surgery to get air to the lungs
Pleurisy - inflammation of the pleura, causes friction and stabbing pain
Hiccups - involuntary contractions of diaphragm → vocal cords close briefly and make the sound
The respiratory system is vulnerable to diseases