Respiratory system

Function of the respiratory system Primary function: obtaining O 2 and removing CO 2 Other functions: filter air, produce sound, sense smell

Respiration Respiration – the process of gas exchange between the atmosphere and body cells Happens in 4 steps: 1.Movement of air into lungs (ventilation) 2.Air-blood gas exchange (external respiration) 3.Gas transport in blood 4.Gas exchange between blood and body cells (internal respiration)

The “4U” respiration… Cellular respiration – the consumption of O 2 and production of CO 2 and energy at the cellular level

Pharynx Larynx

Upper respiratory tract Nasal/oral cavity ◦entry point for air passage Nasal septum ◦divides the nose making 2 nostrils Paranasal sinuses (‘sinuses’) ◦cavities within the face that reduce skull weight and aid in voice resonation Pharynx (‘throat’) ◦a space (not structure) where the nasal and oral cavity meet Epiglottis ◦flap that prevents food from entering the air passage

Lower respiratory tract Larynx ◦top of trachea conducts air in/out of wind pipe, houses vocal chords and Adam’s apple) Trachea (wind pipe) ◦flexible tube of cartilage (prevents collapse) that leads to lungs Bronchi & bronchioles ◦branched airways leading to alveoli in lungs Alveoli ◦air sacs that form the end of bronchioles Lungs ◦spongy organs, left (2 lobes) and right (3 lobes) contain fluid to lubricate surfaces during breathing

Try this… Pg. 293, #1 – 6

Breathing Inspiration (inhalation): 1.Diaphragm moves downward, dropping pressure in the alveoli and forcing air into airways 2.Muscles in the chest expand, enlarging lungs even more FYI: A newborn’s 1 st breath is the hardest because its alveoli are only partially inflated

Breathing cont’d Expiration (exhalation): 1.Diaphragm relaxes, raising air pressure and forcing air out of lungs 2.Elastic recoil from alveolar surface tension purges air from sacs 3.For a deeper exhalation abdominal muscles can help squeeze lungs Breathing is an involuntary act but the muscles are under voluntary control (eg. we can hold our breath)

Non-respiratory movements NRMS are caused by reflexes and are used to… a)Purge airways (eg. coughing, sneezing) b)Express emotion (eg. laughter, crying) Hiccups = sudden inhalation due to diaphragm spasms (air striking vocal folds make sound) Yawns = we don’t know!

Respiratory measurements Spirometry – measures the volume of air entering/exiting the lungs 4 distinct volumes 1.Tidal volume ◦volume of air entering the lungs per regular cycle 2.Inspiratory reserve volume ◦volume of air forcefully inhaled 3.Expiratory reserve volume ◦volume of air forcefully exhaled 4.Residual volume ◦volume of air remaining in lungs after forceful exhalation

Spirometer

Gas exchange ◦Gas exchange occurs in the alveoli ◦Thin wall of alveoli separates air from a dense network of capillaries ◦O 2 and CO 2 are exchanged via diffusion across this blood-air barrier

Gas exchange cont’d 1.Red blood cells carrying CO 2 from the body reach alveolus 2.O 2 in alveolus preferentially binds RBC, displacing CO 2 which enters alveolus for exhalation 3.O 2, now bound to iron-containing hemoglobin, rides RBC through body until diffusing into O 2 -poor cells 4.RBC now free to pick up excess CO 2 for trip back to alveoli

Try this… Pg. 299, #2 – 5, 7