HESI- Respiratory System 1

Terms	Definitions
Upper respiratory tract	-Contains organs located outside the chest cavity: nose, nasal cavities, pharynx, larynx, and upper trachea
Nasal cavity	-Seperated into right & left halves called "nasal septum" -Septume is made of bone & cartilage -Air enters nasal cavities through two openings called "nostrils" -Nasal hairs in nostrils filter large particles of dust -Contains receptor cells for the sense of smell
Pharynx (throat)	-Located behind the oral cavity & between the nasal cavities & the larynx -Includes 3 parts: 1) Nasopharynx- upper section 2) Oropharynx- middle section 3) Laryngopharynx- lower section -Pharynx conducts food toward esophagus & air to the larynx as it moves toward the lungs -Contains 2 other structures: 1. the openings from Eustachian tubes (auditory tubes); connects the nasopharynx w/middle ear 2. tonsils
Larynx (voicebox)	-Located between pharynx & trachea -Functions: 1. Passageway for air during breathing 2. Produces sound (your voice); voicebox 3. Prevents food & other foreign objects from entering the breathing structures (trachea)
Epiglottis	-Acts as a flap; covers the opening of the trachea during eating so food does not enter the lungs
Trachea (windpipe)	-Extends from lower edge of larynx downward into thoracic cavity & splits into right and left bronchi
Lower respiratory tract	-Consists of organs located in the chest cavity: the lower trachea, brochi, brochioles, alveoli, and lungs
Bronchi	-Convey air to and from the lungs -Right & left primary bronchi form lower part of trachea, dividing into 2 tubes: 1. Primary bronchi- enter the lungs at a region called, "hilus" 2. Primary bronchi branch into secondary bronchi, which branch into smaller tertiary bronchi
Bronchioles	-Walls contain smooth muscle & no cartilage -Regulate the flow of air to the alveoli
Alveoli	-Tiny air sacs that form at the ends of respiratory passages; pulmonary capillary surrounds each alveolus -Exchanges oxygen and carbon dioxide across alveolar-pulmonary capillary membrane
Pleura	-Continuous serous membrane lining on the outside of each lung & inner chest wall
Pleural membranes: Visceral pleura	-Outer surface of each lung
Pleural membranes: Parietal pleura	-Lines the chest wall
Pleural membranes: Intrapleural space	-Space between visceral and parietal pleura
Surface tension (a force)	-Thin layer of water lines the inside of the alveolus; water is a polar molecule; one end of water molecule is (+) and other end is (-), causing each water molecule to pull on the other; making the alveolus smaller (collapsing the alveoli) -Surface tension of pure water is very high; in a mature, normal lung it secrete pulmonary surfactants
Surfactants	-Surfactants decrease surface tension by interfering w/electrical attraction between water molecules on inner surface of alveolus -Surfactants are stimulated by a sigh; the sigh stretches the alveoli promoting the secretion of surfactant -Surfactants lower surface tension, but do not eliminate it
Ventilation	-Movement of air into and out of lungs (breathing)
Inhalation (inspiration)	-Breathing-in phase; oxygen-rich air moves into tiny air sacs in the lungs
Exhalation	-Air rich in carbon dioxide is moved out of the lungs
Boyle's Law: Pressure and Volume	-Principle upon which ventilation is based -The smaller the volume, the higher the pressure, OR -The greater the volume, the lower the pressure; -If volume changes, pressure changes.
Boyle's Law and Breathing	-Lung volume higher, pressure decreases (lungs expand); air flows into the lungs (inhalation) -Lung volume lower, pressure increases (lungs get smaller); air flows out of the lungs (exhalation)
Muscles of Respiration: Inhalation	-Diaphragm & intercostal muscles contract -Diaphragm is the chief muscle of inspiration; pulled downward as it contracts -Intercostal muscles (external) rib cage moves up & out, increasing width of thoracic cavity -Energy is used during half the respiratory cycle (active)
Muscles of Respiration: Exhalation	-Ribs & diaphragm return to original positions -Rib cage moves down & in -Involves muscle relaxation; no energy is required (passive)
Nerves of Respiration	-Respiratory muscles are stimulated by motor nerves in order to contract, which include, phrenic & intercostal nerves 1. Phrenic nerves- exits from spinal cord at C4, travels within cervical plexus & distributed to the diaphragm; firing of phrenic nerves stimulate the diaphragm to contract 2. Intercostal nerves- supply the intercostal muscles -Inhalation is initiated by firing both the phrenic & intercostal nerves
Lung Volumes: Tidal volume	-Breathe in and out; amount of air moved into or out of the lungs with each breath -Normal quiet breathing -Amount 500 ml
Lung Volumes: Inspiratory reserve volume	-Inhale a normal volume of air; in addition to this normal amount of air, inhale as much as you possibly can -Additional volume of inhaled air -Amount 3000 ml
Lung Volumes: Expiratory reserve volume	-Exhale a normal amount of air; in addition to this normal amount of air, exhale as much as you possibly can -Extra volume of exhaled air -Amount 1100 ml
Lung Volumes: Residual volume	-Amount of air that remains in the lungs after a forceful exhalation -Amount 1200 ml
Lung Capacities: Vital capacity (4600 ml)	-Combination of: * Tidal volume (500 ml) * Inspirtatory volume (3000 ml) * Expiratory volume (1100 ml) -Maximal amount of air exhaled after a maximal inhalation
What is the major regulator of respirations?	-Partial pressure of carbon dioxide (PCO2)