Respiration. Ontogenesis of respiration.

The Respiratory System Cells continually use O2 & release CO2 Respiratory system designed for gas exchange Cardiovascular system transports gases in blood Failure of either system rapid cell death from O2 starvation

Respiratory System Anatomy Nose Pharynx = throat Larynx = voicebox Trachea = windpipe Bronchi = airways Lungs - upper respiratory tract is above vocal cords lower respiratory tract is below vocal cords 4/24/2017 Shina Alagia

External Nasal Structures Skin, nasal bones, & cartilage lined with mucous membrane Openings called external nares or nostrils 4/24/2017 Shina Alagia

Nose -- Internal Structures Large chamber within the skull Roof is made up of ethmoid and floor is hard palate Internal nares are openings to pharynx Nasal septum is composed of bone & cartilage Bony swelling or conchae on lateral walls 4/24/2017 Shina Alagia

Functions of the Nasal Structures Olfactory epithelium for sense of smell Pseudostratified ciliated columnar with goblet cells lines nasal cavity warms air due to high vascularity mucous moistens air & traps dust cilia move mucous towards pharynx Paranasal sinuses open into nasal cavity found in ethmoid, sphenoid, frontal & maxillary lighten skull & resonate voice 4/24/2017 Shina Alagia

Pharynx Muscular tube (5 inch long) hanging from skull skeletal muscle & mucous membrane Extends from internal nares to cricoid cartilage Functions passageway for food and air resonating chamber for speech production tonsil (lymphatic tissue) in the walls protects entryway into body Distinct regions -- nasopharynx, oropharynx and laryngopharynx 4/24/2017 Shina Alagia

Nasopharynx From internal nares to soft palate openings of auditory (Eustachian) tubes from middle ear cavity adenoids or pharyngeal tonsil in roof 4/24/2017 Shina Alagia

Oropharynx From soft palate to hyoid bone fauces is opening from mouth into oropharynx palatine tonsils found in side walls, lingual tonsil in tongue Common passageway for food & air 4/24/2017 Shina Alagia

Laryngopharynx Extends from hyoid bone to cricoid cartilage Common passageway for food & air & ends as esophagus inferiorly 4/24/2017 Shina Alagia

Larynx Cartilage & connective tissue tube Anterior to C4 to C6 Constructed of 3 single & 3 paired cartilages 4/24/2017 Shina Alagia

Vocal Cords False vocal cords (ventricular folds) found above vocal folds (true vocal cords) True vocal cords attach to arytenoid cartilages 4/24/2017 Shina Alagia

Trachea and Bronchial Tree Full extent of airways is visible starting at the larynx and trachea 4/24/2017 Shina Alagia

Trachea Ciliated pseudostratified columnar epithelium Hyaline cartilage as C-shaped structure closed by trachealis muscle 4/24/2017 Shina Alagia

Bronchi and Bronchioles Primary bronchi supply each lung Secondary bronchi supply each lobe of the lungs (3 right + 2 left) Tertiary bronchi supply each bronchopulmonary segment Repeated branchings called bronchioles form a bronchial tree 4/24/2017 Shina Alagia

Pleural Membranes & Pleural Cavity Visceral pleura covers lungs --- parietal pleura lines ribcage & covers upper surface of diaphragm Pleural cavity is potential space between ribs & lungs 4/24/2017 Shina Alagia

Gross Anatomy of Lungs Base, apex (cupula), costal surface, cardiac notch Oblique & horizontal fissure in right lung results in 3 lobes Oblique fissure only in left lung produces 2 lobes 4/24/2017 Shina Alagia

Mediastinal Surface of Lungs Blood vessels & airways enter lungs at hilus Forms root of lungs Covered with pleura 4/24/2017 Shina Alagia

Structures within a segment of Lung Branchings of single arteriole, venule & bronchiole are wrapped by elastic CT Respiratory bronchiole simple squamous Alveolar ducts surrounded by alveolar sacs & alveoli sac is 2 or more alveoli sharing a common opening 4/24/2017 Shina Alagia

Cells Types of the Alveoli Type I alveolar cells simple squamous cells where gas exchange occurs Type II alveolar cells (septal cells) free surface has microvilli secrete alveolar fluid containing surfactant Alveolar dust cells wandering macrophages remove debris 4/24/2017 Shina Alagia

Alveolar-Capillary Membrane Respiratory membrane = 1/2 micron thick Exchange of gas from alveoli to blood 4 Layers of membrane to cross alveolar epithelial wall of type I cells alveolar epithelial basement membrane capillary basement membrane endothelial cells of capillary 4/24/2017 Shina Alagia

Details of Respiratory Membrane Find the 4 layers that comprise the respiratory membrane 4/24/2017 Shina Alagia

Double Blood Supply to the Lungs Deoxygenated blood arrives through pulmonary trunk from the right ventricle Bronchial arteries branch off of the aorta to supply oxygenated blood to lung tissue Venous drainage returns all blood to heart Pulmonary blood vessels constrict in response to low O2 levels so as not to pick up CO2 on there way through the lungs 4/24/2017 Shina Alagia

Respiration Respiration is exchange of primarily oxygen and carbon dioxide between atmosphere and human body 4/24/2017 Shina Alagia

Respiration: Steps Respiration is achieved in four steps Pulmonary ventilation: Inspiration + Expiration External respiration: Diffusion across alveolar-capillary membrane Gas transport: Transport of O2 and CO2 Internal respiration: Exchange between ICF and tissue capillary 4/24/2017 Shina Alagia

Breathing or Pulmonary Ventilation Air moves into lungs when pressure inside lungs is less than atmospheric pressure How is this accomplished? Air moves out of the lungs when pressure inside lungs is greater than atmospheric pressure Atmospheric pressure = 1 atm or 760mm Hg 4/24/2017 Shina Alagia

Boyle’s Law As the size of closed container decreases, pressure inside is increased The molecules have less wall area to strike so the pressure on each inch of area increases. 4/24/2017 Shina Alagia

Dimensions of the Chest Cavity Breathing in requires muscular activity & chest size changes Contraction of the diaphragm flattens the dome and increases the vertical dimension of the chest 4/24/2017 Shina Alagia

Quiet Inspiration Diaphragm moves 1 cm & ribs lifted by external intercostal muscles Intrathoracic pressure falls and 2-3 liters inhaled 4/24/2017 Shina Alagia

Quiet Expiration Passive process with no muscle action Elastic recoil & surface tension in alveoli pulls inward Alveolar pressure increases & air is pushed out 4/24/2017 Shina Alagia

Intra-pleural Pressures Always subatmospheric (756 mm Hg) As diaphragm contracts intrapleural pressure decreases even more (754 mm Hg) Helps keep parietal & visceral pleura stick together and alveoli inflated 4/24/2017 Shina Alagia

Summary of Breathing Alveolar pressure decreases & air rushes in Alveolar pressure increases & air rushes out 4/24/2017 Shina Alagia

External Respiration Exchange of gas between air & blood Gases diffuse from areas of high partial pressure to areas of low partial pressure Deoxygenated blood becomes oxygeneted Compare gas movements in pulmonary capillaries to tissue capillaries 4/24/2017 Shina Alagia

Internal Respiration Exchange of gases between blood & tissues Conversion of oxygenated blood into deoxygenated Observe diffusion of O2 inward at rest 25% of available O2 enters cells during exercise more O2 is absorbed Observe diffusion of CO2 outward 4/24/2017 Shina Alagia