Respiratory System Anatomy Physiology Function and Functional Anatomy

Respiratory System Anatomy & Physiology

Function and Functional Anatomy n Function: to supply the body with oxygen (O) and dispose it of carbon dioxide(CO 2) n Functional Anatomy: there are 2 zones of the respiratory system I. Conducting Zone II. Respiratory Zone

Upper and Lower Respiratory Tracts

I. Conducting Zone Function: to warm, cleanse and humidify incoming air n Structures of the conducting zone n – – – Nose Pharynx Larynx Trachea Primary bronchii Lungs

I. Conducting Zone: Nose n A&P of the nose: – External nares: nostrils; where air enters – Nasal cavity: interior of the nose – Nasal septum: splits the n. cavity into 2; contains: • Mucosa: warms air and traps bacteria • Cilia: moves particles to throat to be digested • Olfactory receptors: nerve endings to detect smell

I. Conducting Zone: Nose n There are 3 main nasal structures: – Conchae: mucosa covered projections; increases surface area and creates air turbulence within nose – Palate: separates nasal and oral cavities • Hard palate: bony anterior section • Soft palate: non-bony posterior section – Paranasal sinuses: • Lightens the skull • Resonance chambers for speech • Produces mucus to drain into nasal cavity

Paranasal Sinuses

I. Conducting Zone: Pharynx n AKA the throat n Muscular passageway for both food and air n About 5 inches long n Houses the tonsils (clusters of lymphatic tissue)

I. Conducting Zone: Pharynx n 3 parts to the pharynx: – Nasopharynx: meets the auditory tube from ear; houses pharyngeal (adenoids) tonsils – Oropharynx: palantine tonsils @ end of soft palate – Laryngopharynx: lingual tonsils @ base of tongue

I. Conducting Zone: Larynx AKA voice box n Located inferior to pharynx n Function: routes air and food into proper tubes n Formed from 8 rigid hyaline cartilages and the epiglottis n – Epiglottis: a flap of elastic cartilage; closes larynx while swallowing; open during breathing

Larynx

I. Conducting Zone: Larynx – Thyroid Cartilage: AKA adam’s apple; the largest of the 8 cartilaginous rings – Larynx holds the vocal folds (cords) • Vibrate with expelled air producing sound • Vocal folds surround glottis • Glottis: slit-like passageway in the larynx

I. Conducting Zone: Trachea & Primary Bronchi n Trachea – AKA the windpipe – ~4 inches long – Lined with ciliated mucus – Cilia beats to propel dust and bacteria away from lungs n Primary Bronchi – There are 2; right and left – Runs from trachea to lungs – Air @ this point is warmed, humidified and cleansed

I. Conducting Zone: Lungs n Large paired organs n Apex: narrow, superior region, lying posterior to clavicles n Base: broad and inferior region; rests on diaphragm n Lungs divided into lobes and fissures

I. Conducting Zone: Lungs n Right Lung: – 3 lobes – 2 fissures • Horizontal • Oblique n Left Lung: – 2 lobes

Lungs

I. Conducting Zone: Lungs n Visceral Pleura: serous membrane surrounding each lung n Parietal Pleura: serous membrane lining the wall of the thoracic cavity – Both work to produce pleural fluid allowing for reduced friction b/n lung and wall; allows lungs to cling to wall

II. Respiratory Zone n Function: Where gas exchange takes place n Structures of the respiratory zone: – Respiratory bronchioles – Alveolar ducts – Alveolar sacs – Alveoli

II. Respiratory Zone: Bronchioles n Respiratory Tree – Primary bronchi branch off into right and left lungs – They then further divide into secondary and tertiary bronchi---ends at bronchioles – Bronchioles: the smallest of conducting zone passageways leading to the respiratory zone

Respiratory Tree

II. Respiratory Zone: Alveoli n Alveoli: small air sacs – Surrounded by alveolar sacs and connected by alveolar ducts—resembles grapes – Only site of gas exchange – Millions per lung – Walls made of squamos epithelial tissue

Respiratory Membrane n AKA Air-Blood Barrier – External surfaces of alveoli covered by pulmonary capillaries – Alveolar walls + capillary walls = respiratory membrane

Respiratory Membrane: Gas Exchange n Simple Diffusion: exchange of gasses across the vessel walls---DOWN the concentration gradient – Alveoli: holds air-CO 2, O 2 – Pulmonary Capillaries: holds blood CO 2 – Oxygen exchange occurs from alveoli to capillaries – Carbon dioxide exchange occurs from capillaries to alveoli

Respiration n Divided into 4 different events: 1. 2. 3. 4. Pulmonary Ventilation External Respiration Respiratory Gas Exchange Internal Respiration

Respiration: Pulmonary Ventilation There are 2 parts to pulmonary ventilation: A. Inspiration n – Inspiratory muscles: the diaphragm and intercostal muscles – Diaphragm contracts—moves inferiorly – Intercostals contract and lift rib cage; pushes sternum anteriorly

Inspiration

Respiration: Pulmonary Ventilation n Inspiration continued – Intrapulmonary volume increases – Intrapulmonary pressure decreases • Pressure less than atm. pressure – Air moves into lungs from outside of body until pressure inside cavity = atm. pressure

Respiration: Pulmonary Ventilation B. Expiration AKA exhalation – A passive process in healthy people – Inspiratory muscles relax, descending rib cage---lungs recoil – Thoracic and intrapulmonary volume decreases – Intrapulmonary pressure increases above atm. pressure—forcing air out of the body

Respiration: Pulmonary Ventilation n Forced Expiration – If respiratory passageways are impeded, expiration is an active process and muscles have to contract to decrease the volume of the cavity • Asthma • Bronchitis • Pneumonia

Expiration

Respiration: External Respiration n The actual exchange of gas between alveoli and capillaries in the lungs.

Respiration: Respiratory Gas Transport n The transport of respiratory gases throughout the body – Oxyhemoglobin Complex: oxygen attaches to hemoglobin on RBC’s; transports oxygen through body – Some oxygen carried in plasma – Carbon dioxide transported in plasma as a bicarbonate ion (HCO 3 -); some carried on hemoglobin

Respiration: Internal Respiration n The exchange of gases occurring between blood in capillaries and tissue cells----opposite of exchange in lungs.

Internal and External Respiration

Respiratory Volumes and Capacities n Tidal Volume (TV): normal quiet breathing – ~500 ml moves into and out of lungs with each breath n Inspiratory Reserve Volume (IRV): amount of air taken in forcibly over TV – ~2100 -3200 ml

Respiratory Volumes and Capacities n Expiratory Reserve n Residual Volume: Volume (ERV): after strenuous amount of air forcibly expiration exhaled over tidal – ~1200 ml air remains in lungs & cannot be expiration – ~ 1200 ml expelled voluntarily – Allows for continuous gas exchange between breaths

Respiratory Volumes and Capacities n Vital Capacity (VC): n Dead Space the total amount of Volume: air that exchangeable air enters the resp. tract & remains in the – ~4800 ml in healthy males conducting zone— – VC =TV+IRV+ERV never reaches alveoli – ~150 ml

Respiratory Control Centers n Located in medulla and pons of brain stem – Inspiratory and expiratory centers in medulla keep respiration rate ~ 12 -18 breaths per minute

Receptors Influencing Respiration n Chemoreceptors – Located in carotid and aorta arteries – Detect rising carbon dioxide levels and low oxygen levels in blood

Types of Breathing n Eupnea: normal respiratory rate n Dyspnea: labored/difficulty breathing n Orthopnea: dyspnea relieved by sitting upright n Apnea: momentary cessation of breathing

Types of Breathing

Types of Breathing n Hyperventilation: rapid and deep breathing (too much oxygen/too little carbon dioxide) n Hypoventilation: slow and shallow breathing (too little oxygen/too much carbon dioxide)