Structure and Function of Respiratory System

main function of respiratory system

gas exchange blood storage regulate vasoconstricting substances

Structure of the lungs

soft spongy cone shaped organs located side by side in the chest cavity

apex

upper part of the lung lying against top of thoracic cavity

base

lower part of the lung lying on diaphragm

ventilation

movement of air in and out of the lungs

perfusion

movement of blood through the lungs

respiration

diffusion of gases between the lungs and the blood

Larynx structure

connects the oropharynx with the trachea

Larynx function

produce speech protect lungs

type I alveolar cells

flat squamous epithelial cells across which gas exchange takes place

type 2 alveolar cells

produce surfactant decreasing surface tension

pulmonary circulation

arises from the pulmonary artery and provides for gas exchange function of the lungs

bronchial circulation

arises from thoracic aorta, supply blood to airways and supporting structure of lung, distributes blood to airways and humidifies air

lymphatic circulation

superficial vessels drain the surface of the lung and travel in connective tissue of visceral pleura

intrapulmonary pressure

inside the airways and alveoli

intrapleural pressure

pressure in the pleural cavity

intrathoracic pressure

pressure in thoracic cavity

diaphragm

principal muscle of inspiration

example of accessory muscles of inhalation

ribs

airway resistance

the impediment to flow that air encounters as it moves though airways, related to pressure different in lungs and atmosphere

laminar flow

low flow rates, air is parallel to sides of airway

turbulent

disorganized flow accounts for respiratory sounds that are heard during chest auscultation

pulmonary ventilation

total exchange of gases between atmosphere and lungs

alveolar ventilation

ventilation in the gas exchange portion of the lungs

distribution ventilation

varies with lung volume and body position

dead air space ventilation

air moved with each breathe but not in gas exchange

perfusion

blood flow through the pulmonary capillary beds

shunt

blood moving side to side of circulation without oxygen

dead air space

areas of the lung are ventilated but not perfused

shunt

areas of the lung perfused but not ventilated

diffusion is influenced by:

surface area thickness of alveolar-capillary membrane and differences in partial pressure of gas on either side of membrane

Arterial blood gas

blood drain from arteries

hypoxemia

lack of oxygen in the blood

peripheral chemoreceptors

measure PO2 in arterial blood

automatic regulation of ventilation

controlled by input from chemoreceptors or lung receptors

cough reflex

protects the lung from accumulation of secretions from artery or irritating destructive substances

Cheyne stokes

abnormal breathing, characterized by oscillation

associated dyspnea conditions

heart disease and neuromuscular disorders