Structures and Functions Respiratory System Structures and Functions

Parts of Respiratory System Nasal Cavity Pharynx Larynx Trachea Bronchi Bronchioles Alveoli Lungs Pleura

Functions of the Respiratory System Provides oxygen for the body and removes carbon dioxoide through respiration Production of sound

Respiratory System Body has an average oxygen reserve to last about 4 –6 minutes If reserve is not replenished , death is the outcome

Respiratory Tract Upper Respiratory Tract Nose Pharynx Larynx Lower Respiratory Tract Trachea All segments of the bronchial tree Lung

Nasal Cavity Air enters body through nostrils (anterior nares) Inside the nostrils, are 2 spaces known as nasal cavities Nasal cavities are lined with mucous membranes

Nasal Cavity Nasal Septum—divides nasal cavities into right and left sides Three turbinates or bones that protrude into the nasal cavity—they increase surface area for filtering dust and dirt Cilia—the hairs in your nose that trap larger dirt particles

Changes To The Air As It Comes In Contact With the Lining of the Nose Foreign bodies filtered out by cilia and mucous membrane Air is warmed Air is moistened

Effect of Smoking on Cilia Cigarette smoke paralyzes the cilia and results in accumulations of mucus and the typical smoker’s cough, which is an effort to clear the secretions

Sense of Smell Originates in your nose! Olfactory nerves (which provide the sense of smell) are located in the mucus membrane.

Sinuses Cavities in skull Ducts connect sinuses to nasal cavity Named: frontal, maxillary, sphenoid, and ethmoid Give resonance to voice (nasal sound when you have a cold due to blockage or sinuses)

Pharynx The throat Common passageway for air and food 5 inches long

Pharynx When food is swallowed, the EPIGLOTTIS closes over the opening to the larynx, preventing food from entering the lungs Eustachian tube connect the middle ear to the nasopharynx

Larynx The voice box Triangular chamber below pharynx Within the larynx are vocal cords (GLOTTIS) It is composed of several pieces of cartilages – the largest is the Adams’s Apple

Trachea Windpipe 41/2 inches long Walls are bands of C-shaped rings of cartilage—to keep trachea open Lined with ciliated mucous membrane Coughing and expectoration gets rid of dust-laden mucous

Bronchi and Bronchioles Bronchial tubes have cartilaginous plates instead of rings Bronchial tubes lead to even smaller bronchioles Bronchioles—thinner walls of smooth muscle At the end of the bronchiole is the alveoli Lower end of trachea divides into right and left bronchus Bronchi—similar to trachea with ciliated mucous and rings of cartilage As they enter lungs divide into smaller bronchial tubes

Bronchi, Bronchial Tubes and Bronchioles

Alveoli Composed of single layer of epithelial tissue Inner surfaces covered with SURFACTANT (keeps alveoli from collapsing) Each alveolus is surrounded by capillaries Oxygen and carbon dioxide exchange takes place between alveoli and capillaries

Lungs Fill thoracic cavity Upper part—apex Lower part—base Lung tissue is porous and spongy—it floats Right lung—larger and shorter (displaced by liver) Has 3 lobes Left lung—smaller (displaced by heart) Has two lobes

Pleura Thin, moist, slippery membrane that covers lungs Double-walled sac Space is pleural cavity—filled with pleural fluid to prevent friction

Pulmonary Ventilation (Breathing) Inspiration Intercostal muscles lift ribs outward Sternum rises Diaphragm contracts and moves downward This increases the volume of the lungs and air rushes in Expiration (exhalation) Opposite action takes place Exhalation is a passive process

Breathing Process

Respiratory Movements 1 inspiration + 1 expiration = 1 respiration Respiratory rate for normal adult is 14-20

Factors that Affect Respiratory Rate Increases with exercise, fever, certain diseases Age—newborn = 40-60 per minute Sleep—respirations decrease Emotion can increase or decrease

Coughing Deep breath followed by forceful expulsion of air—to clear lower respiratory tract

Hiccups Spasm of the diaphragm and spasmotic closure of the glottis Caused by irritation to diaphragm or phrenic nerve

Sneezing Air forced through nose to clear respiratory tract

Yawning Deep prolonged breath that fills the lungs and increases oxygen within the blood

Control of Breathing Then the phrenic nerve stimulates the diaphragm Chemical Factors Depends on levels of carbon dioxide in blood Chemoreceptors in aorta and carotid arteries are sensitive to the amount of oxygen in blood Controlled by neural and chemical factors Neural Factors Respiratory center in medulla oblongota Increase in carbon dioxide or decrease in oxygen will trigger respiratory center