Respiratory Systems

Respiratory Tree

Nasopharyngeal Passages

Nares

• Aka Nostrils• Two pair of nares

– External– Internal (choanae)

• Separated by septum (cartilage and vomer bone)

• Each choanus contains appx. 1000 nasal hairs

Divisions of Nasal FossaRespiratory

• Contains three conchae (superior, medial, inferior) that alter airflow through nasal fossa

• Cools, filters and moistens air

Olfactory

• Cilia protrude through mucus covered epithelium.

• Cilia harbor 40 million olfactory receptor neurons capable of detecting 10,000+ odors

Nasal Cycle• Blood flow to nasal

conchae alternates every 2-2.5 hours, effectively changing which nostril we breathe through

• Example of a chaotic ultradian cycle (alternating throughout 24 hr period) controlled by hypothalamus

Pharynx

Pharyngeal Form & FunctionForm:

• Nasopharynx• Oropharynx• Larygopharynx

Function

• Common conductive pathway for digestive and respiratory system

Tonsils

• Lymphoid tissue = first line of immune defense for aerodigestive tract

• Largest pre-puberty; atrophy after puberty

Epiglottis

• Form:– Elastic cartilage– Contains gustatory

papillae (taste buds)• Function:

– Swallowing elevated hyoid bone, causing epiglottis to close off trachea, preventing aspiration

Larynx

Laryngeal Form & FunctionForm:

• 9 cartilaginous rings attached to hyoid bone

• Vestibular folds (protection)

• Mucosal folds (vibration)

Function

• Organ of phonation (vocal sounds)

In infancy, larynx corresponds to C2-C3 vertebrae

As child ages, larynx descends to C5-C6, allowing for development of speech

Trachea

Tracheal Form & Function

• Form• 22mm diameter x

10-16cm length• Ventral to

esophagus• C –shaped

cartilaginous rings• Mucosal • Ciliated

• Function• Conduct air to

bronchi

BRONCHI

Broncheal Form & FunctionForm

• D-shaped tubes with attached visceral muscle

• Each bronchus subdivides into– 2-3 Lobular

Bronchi• 10 bronchioles

– Terminal bronchioles

» Respiratory bronchioles

Function

Bifurcation of airflow from trachea to lungs

Lungs

Divisions of the Mammalian Lung

• Lobes– 3 right/2 left– Each lobe has

discreet Pleural Cavity for protection and lubrication

• Segments• Lobules

Pleurisy (pleuritis) is the inflammation of the pleural lining Inhalation and exhalation cause the pleura to rub against

each other, causing intense chest pain

ALVEOLI

ALVEOLAR FORM• 2-11 alveolar ducts per

respiratory bronchiole, each containing 5-6 alveolar sacs

• 700 million alveolar sacs = ~70-100 m2 surface area

• Interior of alveolus contains squamous epithelium, pulmonary surfactants and macrophages

• 70% of alveolus covered with capillary bed

ALVEOLAR FUNCTION

• Primary site of gas exchange in lungs

• Oxygen diffuses from alveolar lumen, through epithelium and into capillary bed.

• Carbon Dioxide diffuses from capillary bed into alveolar lumen

Thoracic Diaphragm

• Dome-shaped musculofibrous septum located between chest and abdominal cavities

• Movement of diaphragm changes pressure in chest cavity, facilitating inspiration and exhalation

What is the connection?

Gas Air entering lungs - Inhaled air

Air leaving lungs - Exhaled air

Oxygen 21% 16%

carbon dioxide 0.03% 3%

Nitrogen 78% 78%

water vapor small amount significantly moist

Inhaled v. Exhaled Air

Nitrogen Narcosis

Why Does Tissue Suffocation Occur When Trapped In A Fire?

Carbon Monoxide & Hemoglobin

Chemical Regulation of Respiratory Rate

• pH of blood measured in carotid arteries (neck)

• Info relayed to pons & medulla of the hindbrain

• If pH is too acidic, rate of breathing must increase

• If pH too basic, rate of breathing must slow down

• Messages sent to diaphragm via Vagus nerve

NEGATIVE PRESSURE BREATHING

RESPIRATION & BOYLE’S LAW

• P1V1 = P2V2

• Ambient Air Pressure = appx. 14.7 lb/in2

• As size of thoracic cavity increases, pressure in chest drops below ambient pressure

• As size of thoracic

cavity decreases, pressure increases above ambient pressure

High Altitude Cerebral Edema

Henry Heimlich

• Developed abdominal thrust maneuver to treat choking (1974)

• Technique downgraded by American Red Cross due to risk of injury (2006)

How Does The Heimlich Maneuver Work In Terms Of Boyle’s Law?

How Does Boyle’s Law Explain A Collapsed Lung?