Respiratory System

Diaphragm

a powerful, dome-shaped muscle essential to breathing, that also separates the thoracic cavity from the abdominal cavity

Negative and positive pressure

- During inhalation the diaphragm moves slightly downward, flaring the lower portion of the rib cage, which moves upward and outward. This creates a negative pressure in the thorax, which causes air to flow into the lungs - During exhalation the diaphragm moves upward, and the ribs move downward and inward. This creates a positive pressure within the thorax that causes air to flow out of the lungs

Capillary/cell exchange of oxygen and carbon dioxide

Carbon dioxide - cells to the capillaries oxygen - capillaries to the cells

Differences in respiratory anatomy between adults and children

Children: - smaller nose and mouth - more space is taken up by the tongue - trachea is narrower - cricoid cartilage is less rigid and less developed - airway structures are more easily obstructed

Alveolar/capillary exchange of oxygen and carbon dioxide

In the lungs, oxygen and carbon dioxide are exchanged through the thin walls of the alveoli and the capillaries. In alveolar/capillary exchange, oxygen-rich air passes through the capillary walls into the bloodstream. Carbon dioxide and other waste gases then move from the blood through the capillary walls into the alveoli and are exhaled.

Upper Airway

nose, mouth, pharynx, nasopharynx, larynx

Epiglottis

small, leaf-shaped flap that protects the trachea

Lower Airway

trachea, bronchi, bronchioles, alveoli

Lungs

two large, lobed organs that house thousands of tiny alveolar sacs responsible for the exchange of oxygen and carbon dioxide

Nervous system control of respiration

- The diaphragm receives its stimulation to contract from the phrenic nerve that exits the spinal cord at the cervical spine between vertebrae C3 and C5 So if the spinal cord is injured between C3 and C5, the phrenic nerve may be damaged and the diaphragm will not receive a nervous impulse to contract, no longer allowing it to contribute to ventilation. - The intercostal muscles will not work properly because the nerves that stimulate them exit from the lower thoracic vertebrae

Use of intercostal muscles and diaphragm

- inhalation; the diaphragm and the intercostal muscles contract, increasing the size of the thoracic cavity. - exhalation; the intercostal muscles and diaphragm relax, decreasing the size of the thoracic cavity the diaphragm contributes 60-70% of the effort to breathe while the intercostal muscles contribute the remaining 30-40%

Pleura

- visceral pleura covers the outer surface - parietal pleura covers the internal chest wall - pleural cavity is a small space in between the two that allows the lungs to stay inflated with air

Characteristics of adequate and inadequate breathing

Adequate breathing: - Adults = 8-24 breaths per minute - Children = 15-30 breaths per minute - Infants = 25-50 breaths per minute - respirations should be regular in rhythm and free of unusual sounds such as wheezing - breathing should be virtually effortless and the chest wall should rise about 1 inch with each inhalation Inadequate breathing: - rates that are either too slow or too fast - irregular pattern of breathing - diminished or absent breath sounds - unequal/inadequate chest expansion - cool/clammy, pale/blue skin - nasal flaring - "seesaw" breathing in infants (chest and abdomen move in opposite directions) - agonal respirations - grunting