Chapter 23: Respiratory System

4 Parts of Respiration Ventilation – the movement of air into and out of the lungs External gas exchange – between the air in the lungs and the blood Transport – oxygen and carbon dioxide in the blood Internal gas exchange – between the blood and the tissues

Other Respiration Functions Regulation of blood pH by changing carbon dioxide levels Voice production Olfaction – sense of smell Protection against microorganisms by producing mucus.

Upper vs Lower Respiratory Tract Upper Nose Pharynx (throat) Larynx Conducting zone Lower Trachea Bronchi Bronchioles Lungs Respiratory zone

Conducting Zone: Nose External nose Nasal Cavity Nares – nostrils Choanae – openings into pharynx Hard palate – separates nasal cavity from oral Nasal septum – partitions nasal cavity into right and left Serves as a passageway for air Cleans air by using nose hair and mucus to trap particles Humidifies and warms air

Conducting Zone: Pharynx Pharynx – opening for both respiratory and digestive systems Divided into three regions Nasopharynx – superior to the soft palate Soft palate prevents food and other materials from entering the nose Uvula is an extension of the soft palate Tonsils and Adenoids Oropharynx – extends from the soft palate to the epiglottis Fauces – oral cavity opening Laryngopharynx – extends from the tip of the epiglottis to the esophagus

Conducting Zone: Larynx The anterior part of the throat Extends from the base of the tongue to the trachea Passageway for air Hyoid bone and 9 cartilage rings form a protective outer casing Voice box – contains both true and false vocal chords

Respiratory Zone: Tracheobronchial Tree Trachea is called the Windpipe Membranous tube attached to the larynx Divides into two smaller tubes called main (primary) bronchi Main bronchi divide to form smaller and smaller bronchi Right main bronchus is larger than the left Bronchi eventually end as bronchioles

Respiratory Zone: Alveoli Bronchioles are like hallways, alveoli are like doors Site of gas exchange between blood and lungs Approximately 300 million alveoli in the lungs Covered in surfactant that helps keep these pockets open

Respiratory Zone: Lungs Principal organs of respiration Right lung has 3 lobes, left has 2 Lobes are subdivided into bronchopulmonary segments 9 bronchopulmonary segments total

Thoracic Cavity and Muscles of Respiration Thoracic cavity is the space enclosed by the thoracic wall and the diaphragm Muscles of inspiration Diaphragm External intercoastals Pectoralis minor Muscles of expiration Internal intercoastals

VENTILATION

Air Pressure Boyle’s Law states that pressure and volume are inversely related to each other P 1 V 1 = P 2 V 2 When pressure goes up, volume goes down In order to move air in, pressure is greater outside than inside your lungs (muscles pull in to create more volume) In order to exhale, pressure in the lungs has to be greater than outsides (muscles push out to create more pressure)

Pulmonary Volumes Tidal volume = the volume of air inspired or expired with each breath Inspiratory reserve volume = the amount of air that can be inhaled after the inspiration of the tidal volume Expiratory reserve volume = the amount of air that can be forcefully exhaled after each expiration of the tidal volume Residual Volume = the amount of air that remains in your lungs after you’ve forcefully exhaled as much as you can

Pulmonary Capacities Inspiratory capacity = tidal volume + inspiratory reserve volume (approximately 3500L at rest) Equals the amount of air a person inspire maximally Functional residual capacity = expiratory reserve volume + residual volume Equals the amount of air remaining in the lungs at the end of a normal expiration Vital capacity = inspiratory reserve volume + expiratory reserve volume Equals the maximum volume of air a person can expel Total lung capacity = inspiratory + expiratory reserve volume + tidal volume + residual volume

REGULATION OF VENTILATION

What part of the brain controls breathing? Brainstem = the hard drive of the computer Made of three main parts: Midbrain, pons, medulla oblongata Medulla regulates breathing rhythm Pons regulates breathing rate