RESPIRATORY SYSTEM

 •AIRFLOW IN LUNGS

Bronchi – bronchioles – alveoli

 

CONDUCTING DIVISION

Passages that serve only for airflow.

Nostrils to bronchioles

 

RESPIRATORY DIVISION

Alveoli and distal gas-exchange regions

 

•UPPER RESPIRATORY TRACT

ORGANS IN HEAD AND NECK, NOSE THROUGH LARYNX

 

•LOWER RESPIRATORY TRACT

ORGANS IN THE THORAX, TRACHEA THROUGH LUNGS.

 

NOSE

•FUNCTIONS.

•Warms, cleanses, humidifies inhaled air

•Detects odors

•Resonating chamber that amplifies the voice.

  

NASAL CAVITY

•EXTENDS FROM NOSTRILS TO CHOANAE     ( posterior nares ) ( ethmoid and sphenoid bones compose the roof, palate forms the floor )

•VESTIBULE – dilated chamber inside ala nasi    ( stratified squamous epithelium and guard hairs )

•NASAL SEPTUM DIVIDES CAVITY INTO RIGHT AND LEFT CHAMBERS CALLED NASAL FOSSAE.    ( Made of vomer, ethmoid bone and septal cartilage )

•LATERAL WALL OF NASAL FOSSA GIVES RISE TO THREE FOLDS OF MUCOUS MEMBRANES SUPPORTED BY TURBINATE BONES.

•INFERIOR NASAL COCHAE ( most common site –epistaxis )

•MIDDLE NASAL CONCHAE

•SUPERIOR NASAL CONCHAE

 

•BENEATH EACH CONCHAE IS A NARROW AIR PASSAGE – MEATUS

( Turbulence cleanse, warm, and humidify the air )

 

OLFACTORY MUCOSA

•LINES ROOF OF NASAL FOSSA

•THE REST OF THE NASAL CAVITY IS LINED WITH CILIATED PSEUDOSTRATIFIED RESPIRATORY EPITHELIUM

•Mucus traps inhaled particles

•Bacteria is destroyed by lysozyme in the mucus

•Lymphocytes protect too

•Ig A ( antibodies ) secreted by Plasma cells

  

PHARYNX

•NASOPHARYNX – ( Pseudostratified epithelium ) Lies posterior to choanas, dorsal to soft palate, Receives AUDITORY TUBES and contain PHARYNGEAL TONSIL

•OROPHARYNX – (stratified squamous epithelium)            Space between soft palate and root of the tongue, inferiorly as far as hyoid bone, contains PALATIN and LINGUAL TONSILS.

•LARYNGOPAHRYNX – ( stratified squamous epithelium )                                                                    From hyoid bone to the level of cricoid cartilage

  

LARYNX

•CARTILAGINOUS CHAMBER. 1.5 in long.

 

FUNCTIONS:

•Directs food and drink to esophagus

•Producing the sounds

 

•GLOTTIS- superior opening

•EPIGLOTTIS- flap of tissue that guards glottiS

  

FRAMEWORK OF THE LARYNX

•EPIGLOTTIC CARTILAGE ( superior ) (elastic cartilage)

•THYROID CARTILAGE ( largest, has the Adam’s apple )

•CRICOID CARTILAGE ( connects larynx to trachea )

•ARYTENOID CARTILAGES (2) (function in speech)

•CORNICULATE CARTILAGES (2)(function in speech)

•CUNEIFORM CARTILAGES (2)

 

WALLS OF THE LARYNX

•INTERIOR WALLS HAS 2 FOLDS ON EACH SIDE, FROM THYROID TO ARYTENOID CARTILAGES

•VESTIBULAR FOLDS: superior pair, close glottis during swallowing

•VOCAL CORDS: produce sound

•INTRINSEC MUSCLES (operate vocal cords)

•EXTRINSIC MUSCLES  (elevates larynx during swallowing )

 

TRACHEA

•RIGID TUBE, 4.5 in. long and 2.5 in. diameter, anterior to the esophagus.

•SUPPORTED BY 16-20 C-SHAPED CARTILAGINOUS RINGS

•LARYNX AND TRACHEA are LINED WITH CILIATED PSEUDOSTRATIFIED EPITHELIUM which functions as mucociliar escalator.

 

THE LOWER RESPIRATORY TRACT

  

BRONCHIAL TREE

•PRIMARY BRONCHI ( C-shaped rings )  Arise from trachea, after 2-3 cm enter hilum of lungs. Right bronchus slightly wider and more vertical.

•SECONDARY (LOBAR) BRONCHI – branches into one secondary bronchus for each lobe.

•TERTIARY (SEGMENTAL) BRONCHI – 10 right and 8 left.

  

•BRONCHIOLES ( LACK CARTILAGE ) Have a layer of smooth muscle that enables them to dilate or constrict. ( PULMONARY LOBE- is the portion ventilated by one bronchiole ) Divides into 50-80 terminal bronchioles. Terminal bronchioles have cilia, give off 2 or more respiratory bronchioles. Respiratory bronchioles divide into 2-10 alveolar ducts.

 

•ALVEOLAR DUCTS – end in alveolar sacs         ( clusters of alveoli )

•ALVEOLI – bud from respiratory bronchioles, alveolar ducts and alveolar sacs.

   

EPITHELIUM OF BRONCHIAL TREE

•BRONCHI – pseudostratified columnar

•BRONCHIOLES – simple cuboidaL

•ALVEOLAR DUCTS,SACS, AND ALVEOLI- simple squamous

  

THE LUNGS

•APEX AND BASE

•HILUM

•RIGHT LUNG –LEFT LUNG

 

STRUCTURE OF AN ALVEOLUS

•ITS WALL CONSISTS OF SQUAMOUS ALVEOLAR CELLS. ( SOME OF THESE SECRET A DETERGENT-LIKE PROTEIN CALLED PULMONARY SURFACTANT )

•ALVEOLAR MACROPHAGES defend the tissue.

•SURROUNDED BY BLOOD CAPILLARIES, SUPPLIED BY PULMONARY ARTERY, AND EXTENSIVE LYMPHATIC DRAINAGE

 

THE PLEURAE

•VISCERAL AND PARIETAL LAYERS

•PLEURAL CAVITY and PLEURAL FLUID

 

•FUNCTIONS

•Reduction of friction

•Creation of a pressure gradient ( Lower pressure assists in inflation of lungs )

•Compartmentalization ( prevent spread of infection )

   

MECHANICS OF VENTILATION

  

PRESSURE AND FLOW

•ATMOSPHERIC PRESSURE DIRVES RESPIRATION.

•INTRAPULMONARY PRESSURE ( pressure within the alveoli ) IS INVERSELY PROPORTIONAL TO VOLUME

•DIFFERENCE BETWEEN ATMOSPHERIC AND INTRAPULMONARY PRESSURE MAKES THE MAIN PRESSURE GRADIENT.

 

INSPIRATION

•REQUIRES A MUSCULAR EFFORT ( ATP )

•DIAPHRAGM IS THE MAIN MUSCLE INVOLVED. But…

•SCALENES fix first pair of ribs

•EXTERNAL INTERCOSTALS elevate 2-12 pairs ribs

•PECTORALIS MINOR, STERNOCLEIDOMASTOID, AND ERECTOR SPINAE MUSCLES used in deep inspiration.

 

During INSPIRATION..

•Intrapleural pressure decrease ( volume increase)

•Intrapulmonary pressure decrease ( lungs expand with the visceral pleura )

•Inflation of the lungs is aided by warming of inhaled air.

•A quiet breathe flows 500ml of air throug lungs

  

EXPIRATION

•DURING QUIET BREATHING, EXPIRATION ACHIEVED BY ELASTICITY OF LUNGS AND THORACIC CAGE

•AS THE VOLUME OF THORACIC CAVITY DECREASE,  INTRAPULMONARY PRESSURE INCREASE AND AIR IS EXPELLED  

  ( INTERNAL INTERCOSTAL MUSCLES AND ABDOMINAL MUSCLES AID IN FORCED EXPIRATION )

  

RESISTANCE TO AIRFLOW

•DISTENSIBILITY OF THE LUNGS ( PULMONARY COMPLIANCE ) AFFECT RESISTANCE

 

•BRONCHIOLAR DIAMETER

•Primary control over resistance to airflow

•BRONCHOCONSTRICTION ( irritants, cold air, parsympathetic stimulation, histamine )

•BRONCODILATION ( sympathetic stimulation, epinephrine )

  

ALVEOLAR SURFACE TENSION

•THIN FILM OF WATER IS NECESSARY FOR GAS EXCHANGE but…create surface tension that acts to collapse alveoli and distal bronchioles

•PULMONARY SURFACTANT ( Great alveolar cells ) disrupts hydrogen bond and reduce surface tension.

•PULMONAR SURFACTANT is in alveolar epithelium and up the alveolar ducts and smallest bronchioles.

 

ALVEOLAR VENTILATION

•DEAD AIR  fills conducting division and cannot exchange gases.

•ANATOMIC DEAD SPACE is the conducting division of airway

•PHYSIOLOGIC DEAD SPACE includes anatomic dead space and any pathological alveolar dead space.

 

BREATHING is also important…

•Promotes bloow and lymph flow from abdominal to thoracic vessels.

•Speaking, sneezing, coughing

•Help to expel urine, feces, and to aid in childbirth

  

WE CAN MEASURE PULMONARY FUNCTION BY A SPIROMETER

 

RESPIRATORY VOLUMES

•TIDAL VOLUME – air inhaled or exhaled in one quiet breath.

•INSPIRATORY RESERVE VOLUME – air in excess of tidal inspiration that can be inhaled with maximum effort

•EXPIRATORY RESERVE VOLUME – air in excess of tidal expiration that can be exhaled with maximum effort

•RESIDUAL VOLUME – air remaining in lungs after maximum expiration ( keeps the alveoli inflated )

  

RESPIRATORY CAPACITIES

•VITAL CAPACITY – amount of air than can be exhaled with maximum effort after maximum inspiration; assess strength of thoracic muscles and pulmonary function.

•INSPIRATORY CAPACITY – maximum amount of air that can be inhaled  after a normal tidal expiration

•FUNCTIONAL RESIDUAL CAPACITY – amount of air in lungs after a normal tidal expiration.

•TOTAL LUNG CAPACITY – maximum amount of air lungs can  contain

 

•FORCED EXPIRATORY VOLUME is the % of vital capacity exhaled / time.                             NORMAL VALUE = 75-85% in 1 sec.

 

•MINUTE RESPIRATORY VOLUME can be obtained by multiply tidal volume x respiratory rate.              NORMAL VALUE = 500ml x 12= 6 L/min

  

AFFECTS ON RESPIRATORY VOLUMES AND CAPACITIES

•AGE – decrease lung compliance, respiratory muscles weaken.

•EXERCISE – maintains strength of respiratory muscles

•BODY SIZE – is proportional..big body=big lungs

•RESTRICTIVE DISORDERS – decrease compliance and vital capacity

•OBSTRUCTIVE DISORDERS – interfere with airflow, expiration requires more effort or less complete.

 

NEURAL CONTROL

•Breathing depends on repetitive stimuli from brain

•NEURONS IN MEDULLA OBLONGATA AND PONS CONTROL UNCONSCIOUS BREATHING

•VOLUNTARY CONTROL PROVIDED BY MOTOR CORTEX ( frontal lobe )

 

•INSPIRATORY NEURONS fire during inspiration

•EXPIRATORY NEURONS fire during forced expiration

 

•FIBERS TRAVEL DOWN SPINAL CORD TO LOWER MOTOR NEURONS, FIBERS OF PHRENIC NERVE GO TO DIAPHRAGM AND INTERCOSTAL NERVES GO TO INTERCOSTAL MUSCLES

  

RESPIRATORY CONTROL CENTERS

•TWO RESPIRATORY NUCLEI IN MEDULLA OBLONGATA

•INSPIRATORY CENTER  - more frequently they fire, more deeply you inhale. Longer duration they fire, breath is prolongated, slow rate.

•EXPIRATORY CENTER – involved in forced expiration

 

•PONS

•PNEUMOTAXIC CENTER – send continual inhibitory impulses to inspiratory center, breathe faster and shallower

•APNEUSTIC CENTER – prolongs inspiration, breathe slower and deeper.

  

AFFERENT CONNECTIONS TO BRAINSTEM

•INPUT FROM LIMBIC SYSTEM AND HYPOTHALAMUS  ( Respiratory effects of pain and emotion)

•INPUT FROM CHEMORECEPTORS  ( brainstem and arteries monitor pH, C02, and 02 leves )

•INPUT FROM AIRWAY AND LUNGS          ( response to inhaled irritants )

  

ALVEOLAR GAS EXCHANGE IS THE PROCCES OF 02 LOADING AND CO2 UNLOADING IN THE LUNGS

  

( Depends on erythrocytes )

FACTORS AFFECTING GAS EXCHANGE

•CONCENTRATION GRADIENT OF GASES

•GAS SOLUBILITY

•MEMBRANE THICKNESS AND SURFACE AREA

•GOOD VENTILATION AND GOOD PERFUSION

  

LUNG DISEASE AFFECTS GAS EXCHANGE

  

SYSTEMIC GAS EXCHANGE IS THE UNLOADING OF O2 AND LOADING OF CO2 AT SYSTEMIC CAPILLARIES

  

BLOOD CHEMISTRY and RESPIRATORY RHYTHM

•CHEMORECEPTORS monitor pH, P CO2, and P O2 of body fluids.

•PERIPHERAL CHEMORECEPTORS –              AORTIC BODIES (signals to medulla by Vagus nerves ) and CAROTID BODIES (signals to medulla by Glossopharyngeal nerves )

•CENTRAL CHEMORECEPTORS – monitor pH of CSF

 

pH

•Most powerful respiratory stimulus is pH of CSF.

 

•ACIDOSIS ( pH < 7.4 )  is caused by failure of pulmonary ventilation.

•CO2 easily crosses blood-brain-barrier, in CSF CO2 reacts w/H2O and releases Hydrogen ions, chemoreceptors detect and stimulate inspiratory center. –

•Corrected by HYPERVENTILATION.

 

•ALKALOSIS ( pH > 7.4 ) is corrected by HYPOVENTILATION.

 

CARBONIC ACID REACTION

CO2 + H20 = H2CO3 = HCO3 + H

 

Left to right = corrective response to alkalosis

( allows body to produce CO2 faster than it exhales it )

HYPOVENTILATION

 

Right to left = corrective response to acidosis

( blow off CO2  faster than the body produce it )

HYPERVENTILATION

  

RESPIRATORY DISORDERS

 

HYPOXIA
is a deficiency of oxygen  in a tissue or the inability to use oxygen

•HYPOXEMIC HYPOXIA – usually due to inadequate gas exchange. ( degenerative lung disease, aspiration, respiratory arrest, high altitudes )

•ISCHEMIC HYPOXIA – indequate circulation

•ANEMIC HYPOXIA - anemia

•HISTOTOXIC HYPOXIA – metabolism poison

  

CHRONIC OBSTRUCTIVE
PULMONARY DISEASES ( COPD )

•ASTHMA

•CHRONIC BRONCHITIS

•EMPHYSEMA

•COR PULMONALE   ( due to obstruction of pulmonary circulation  )

 

LUNG CANCER

•SQUAMOUS CELL CARCINOMA – most common type, begins with changes in bronchial epithelium into squamous, invade bronchial wall, replace funcional tissue

 •ADENOCARCINOMA – originates in mucous glands of lamina propia

 •SMALL-CELL (oat ) CARCINOMA – least common, most dangerous, originates in primary bronchi, metastasizes quickly – pericardium, bones, liver, lymph nodes, brain