AP Chp 18 Respiratory system Flashcards
Respiration
Process of obtaining oxygen from environment and delivering it to cells
Phases of respiration
Pulmonary ventilation - O2 from atmosphere thru alveoli (inhale/exhale)
External gas exchange - Diffusion of O2 into alveoli and CO2 out of blood for elimination.
Gas transport in the blood - circulating blood carries gases to cells and tissues.
Internal gas exchange - Diffusion of gases between blood, cells and tissues in the body.
Structure of respiratory system
Conducts air into lungs.
Components:
Nasal cavities- Conchae - shell like projections increase surface area of mucous membrane. Warms/moistens air, filters foreign bodies.
Pharynx- Nasopharynx, Oropharynx, Laryngopharynx opens to the larynx.
Larynx- Voice box (Glottis- partially opened during normal breathing), (Epiglottis- leaf shaped cartilage that covers the larynx during swallowing.)
Trachea- windpipe, conducts air between the larynx and lungs.
Bronchi- Right larger, left downward more vertical. Foreign bodies inhaled likely to enter right lung.
Lungs- Organs where gas diffusion takes place.
Pleura- Connective tissue coverings of the lungs. Parietal pleura, Visceral pleura, Pleural space.
Transport of oxygen and Carbon dioxide
Most oxygen is transported in blood by hemoglobin.
97% of highly oxygenated blood in systemic arteries and pulmonary vens is saturated with oxygen
70% of deoxygenated blood in systemic veins and pulmonary arteries is saturated with oxygen.
Transport of Carbon dioxide
10% is dissolved in plasma and fluid in RBC’s
15% is combined with protein of hemoglobin and plasma proteins.
75% dissolves in blood fluids and is converted to bicarbonate ion.
CO2+H20 to H2CO3 (carbonic acid) breaks into H+ (hydrogen ion) and HCO3 (bicarbonate ion) in blood, then recombines in lungs for expulsion into environment.
Nervous control of respiration
Control center in medulla and pons
Central chemoreceptors respond to raised CO2 levels (hypercapnia)
Peripheral chemoreceptors located in neck and aortic arch respond to oxygen levels considerably below normal.
Abnormal ventilation
Hyperventilation - High O2 level and low CO2 level (hypocapnia), increases blood pH.
Hypoventilation - Insufficient air in alveoli, decreases blood pH.
Results of inadequate breathing
Cyanosis - bluish colored skin due to low oxygen in blood.
Hypoxia - lower than normal O2 in tissues
Hypoxemia - lower than normal O2 partial pressure in arterial blood.
Suffocation - cessation of respirations due to blockage of respiratory passages.
Lung volumes and capacities
Tidal volume - amount of air in/out of lungs during relaxed breathing 500mL
Residual volume - remaining air in lungs after max exhalation 1200mL
Vital capacity - amount of air exhaled after max inhalation 4000mL.
Total lung capacity - total volume of air that can be contained in lungs 5200mL.
Regulation of respiration
Central chemoreceptors in the medullary respiratory center respond to CO2 level in the blood a rise in CO2 known as Hypercapnia triggers ventilation.
Peripheral chemoreceptors in the carotid and aortic bodies respond to O2 in the blood, when levels fall below normal which rarely occurs then ventilation is triggered.
