Respiratory System

Inhalation and exhalation

Ventilation

The Respiratory Centers of the Brain

• PONS. • The apneustic center causes strong and sustained inspiratory

movements. • The pneumotaxic center controls medullary activity

– Turns off inspiration

– Medulla• Dorsal respiratory group- Inspiratory

– Acts as pacemaker, expiration occurs when signal from these nerves stops.

• Ventral respiratory group- both inspiratory and expiratory– Inactive during normal breathing, speed up inspiratory activity when

demands are high

Nervous control of breathing

• Chemoreceptors detect changes in pH of blood– Send signal to

breathing control centers in pons and medulla oblongata.

• Nerve signals tell lungs to inhale

Oxygen/CO2 transport in blood

• Oxygen– Dissolved in blood

1.5%– Bound to hemoglobin

98.5%

• CO2 – Dissolved in blood

10%– Bound to hemoglobin

30%– As bicarbonate

60%

carbon dioxide transport in blood

• From cells– RBC’s and blood pick

up CO2 and transport it as carbonic acid (HCO3)

– In lungs (at alveoli) CO2 is released and travels by diffusion to alveoli.

Compare PO2 and PCO2 in blood and air

• Inhaled air• Blood leaving alveolar

capillaries• Blood leaving tissue

capillaries• Exhaled air

Structures of the respiratory system

Pathway of air traveling through the respiratory systemmouth/nasal cavity– pharynx– trachea– bronchus– bronchiole– alveoli

Tissues of voice production

• epiglottis• Vocal folds (chords)• Larynx

Larynx

• specialized structure atop the windpipe, responsible for – sound production, – air passage during

breathing– protecting the airway

during swallowing

Vocal Folds (aka Vocal Cords)

• “Fold-like" soft tissue that is the main vibratory component of the voice box; comprised of a – cover (epithelium and superficial lamina propria), – vocal ligament (intermediate and deep laminae propria), – body (thyroarytenoid muscle)

Vocal folds

Glottis

• Opening between the two vocal folds; – the glottis opens during breathing and – closes during swallowing and sound

production

How we get voice

• voice has three components – Voiced sound: The basic sound produced by

vocal fold vibration is called "voiced sound." • This is described as a "buzzy" sound.

– Resonance: Voice sound is amplified and modified by the vocal tract resonators (the throat, mouth cavity, and nasal passages).

• This produces a person's recognizable voice.

– Articulation: The vocal tract articulators (the tongue, soft palate, and lips) modify the voiced sound.

• This produces recognizable words.

Comparing external and internal respiration

• External respiration involves the exchange of gases between the alveolar air and the pulmonary capillaries.

• Internal respiration occurs when gas diffuses between peripheral capillaries and the fluid surrounding cells.

Decompression Sickness (the bends)

• It is the result of diffusion between liquids and gases: – Differences in pressure moves

air from one place to another and force gas molecules into solution.

• The bends occur when pressure decreases rapidly, and gas molecules leave solution to form bubbles in body fluids. – Nitrogen is usually the gas

responsible for the observed symptoms.

How “the bends” got its name

Pneumothorax• occurs when air leaks

from inside of the lung to the space between the lung and the chest wall.

• The lung then collapses. • The dark side of the chest

(right side of the picture) is filled with air that is outside of the lung tissue. – Can result from

• ascent in diving without exhaling

• A bone or other object puncturing the lung

Tuberculosis

• characterized by white lesions or tubercles which replace alveoli with scar tissue. – Creates poor gas

exchange in the lungs. – Symptoms: coughing,

sputum production, lethargy and breathlessness.

• Caused by a bacterial infection– Spread through the

air.• Almost impossible to

transmit b/w people except with repeated exposure.

• Most infected people never develop the disease.

Tuberculosis xray

Emphysema

• Cause– Lung has a balance b/w

two chemicals that help maintain elastic fibers around alveoli.

– When balance is altered, elastic fibers are destroyed and alveoli are enlarged.

– Enlarged alveoli are less efficient at gas exchange.

– Patient is left short of breath

– Smoking is primary culprit.

Asthma• a disease of the bronchial

tubes, – During normal breathing, the

bands of muscle that surround the airways are relaxed,

– with asthma, allergy-causing substances or environmental triggers make the bands of muscle surrounding the airways tighten, and air cannot move freely.

• Causes– People have very sensitive

airways that react to many environmental "triggers."

• Contact with these triggers cause asthma symptoms

– Triggers include• Infections (colds, viruses,

flu, sinus infection)

• Allergens such as pollens, mold spores, pet dander and dust mites

• Irritants such as strong odors from perfumes or cleaning solutions, air pollution,

• Tobacco smoke

• Exercise or exertion

• Weather -- changes in temperature and/or humidity, cold air

Oxygen unloads from hemoglobin more as pH decreases

Carbon Monoxide Poisoning

• Most common cause of toxin induced death.

• Difficult to detect, it is the great imitator of other conditions.

3 reasons why CO poisoning is toxic

• direct binding of CO to hemoglobin; – One molecule of CO blocks a whole hemoglobin from

carrying oxygen.

• shifting the oxygen-hemoglobin dissociation curve;– Hemoglobin gives up less oxygen to tissue when it is

bound to CO

• CO binding to myoglobin;– Slow twitch muscle fibers can’t use myoglobin and

they starve for oxygen.– Heart muscle tissue suffers the same fate.

Symptoms

• Headache, dizziness, agitation, stupor, seizures, and coma are the most common neurological symptoms. – In one study with acute CO poisoning, 90%

had headache. – physicians should attempt to identify the use

of gas stoves and other cohabitants with the same symptoms to determine a correct diagnosis.