Chapter 14 - Respiratory System Ensures O2 gets to cells & CO2 removed from cells, helps maintain a constant environment in the body Organs - designed.

• Chapter 14 - Respiratory System

• Ensures O2 gets to cells & CO2 removed from cells, helps maintain a constant environment in the body

• Organs - designed to perform 2 basic functions:

• Air Distributor - Gas Exchanger -

• Also -filters, warms, humidifies air

• Sinuses - speech, sound, smell (olfaction)

• Structural Plan -• Basic structure is like a many branched tube

(respiratory tree) - nose, pharynx, larynx, trachea, bronchi, lungs

• Alveoli - thin-walled sacs at end of tubes where gas is exchanged– Millions in each lung - > surface area

– Each is covered with a network of capillaries (like a hairnet), also, wall is single layer thick

– Gases (O2 & CO2) are exchanged by passive diffusion through the respiratory membrane (very thin - 1 micron thick)

• Respiratory Tract -

• Divided to assist in description of symptoms associated w/ problems

• Upper - nose, pharynx, larynx (URI - head cold)– Located outside thoracic cavity

• Lower - trachea, all parts of the bronchial tree, & lungs (LRI - chest cold)– Located inside thoracic cavity

• Respiratory Mucosa -– Membranes that lines most of the distribution tubes

– Air entering nose - contaminated w/ irritants (insects, dust, pollens, bacteria)

– Mucous acts as most important air purification mechanism, traps almost everything < air to alveoli

– 125ml mucous / day

• Mucous blanket - continuous sheet– Moved upward to pharynx by cilia that cover

epithelial cells (beat one way) [smoking-paralyze]

• Nose -• External nares (nostrils) air enters & moves to

R & L nasal cavities (lined w/ mucosa), parititioned by nasal septum– Surface - moist (mucous), warm (many blood

vessels), olfactory receptors that are nerve endings (sense of smell)

• Paranasal sinuses - continuous mucosa (4- frontal, maxillary, sphenoidal, ethmodial) all drain into the nasal cavities, hollow help lighten skull & serve as resonant chambers for production of sound

• Lacrimal sacs - two ducts located inner

aspect of eyes, drain tears into nasal cavity

• Conchae (KONG-kee) - three shelf-like structures that protrude into the nasal cavity (both sides)– Mucosa-covered

– > Surface area to warm and humidify

• Supplemental O2 - bubbled thur water to humidify (if not dries & irritates resp. tract)

• Pharynx - • Called the throat - about 5 inches long• 3 portions -

– Nasopharynx - upper part, behind nose - contain auditory (eustachian) tubes which connect to middle ear (equalizes air pressure between middle & exterior ear), continuous mucosa (infections)

– Oropharynx -behind mouth– Laryngopharynx - lowest portion

• Serves as passage of air (shared w/ GI)

• Tonsils -

– Masses of lympathic tissue in pharynx

– Pharyngeal tonsils - nasopharynx• Called adenoids if swollen, make

breathing thru nose difficult

– Palatine tonsils - oropharynx

– Tonsillectomy - removal of tonsils

– Tonsillitis - inflammation

• Larynx - voice box (just below pharynx)– Made of cartilage (largest - thyroid cartilage -

Adam’s apple)

• Vocal cords - 2 fibrous bands, stretch across interior of larynx– Muscles cause them to tense (high pitched) &

relax (low pitched)

• Glottis - space between vocal cords

• Epiglottis - cartilage, partially covers the opening of larynx (trapdoor), closed when swallowing

• Trachea -

• Windpipe - 4 1/2 inches long– From larynx to bronchi– Lined with mucous membrane

• Vital function - furnishes open airway

• Considerable force to squeeze closed– Almost Noncollapsible material - 15 to 20 C-shaped

cartilage, stacked (soft tissue between)– Obstructed by: tumors, enlarged lymph nodes,

aspirate food (choking-5th leading cause of accidental death in US)- Heimlich Maneuver - open windpipe that is suddenly obstructed

• Bronchi, Bronchioles, & Alveoli -

• Upside down tree (bronchial tree)

• Larger tubes are ringed with cartilage

• Primary bronchi -R & L >R & L lungs

• Secondary bronchi - branches in each lung

• Divide into smaller & smaller tubes - ultimately into tiny tubes made of smooth muscle - bronchioles > divide into microscopic tubes - alveolar ducts end in several alveolar sacs (cluster of grapes)

• Alveolar sacs - (cluster of grapes) - each

cluster made up of numerous alveoli (single grape)

• Alveoli - very effective in gas exchange– Thin walled, each in contact w/ blood

capillary– Surfactant - substance that covers the resp.

membrane in the alveoli• Helps reduce surface tension > keeps

alveoli from collapsing as air moves in & out

• IRDS (Infant resp. distress syndrome) -

– Premature infants (< 37 weeks gestation or wt. < 5 lbs. at birth), sacs collapse during expiration - inspiration requires more force to reinflate > labored breathing

• Lungs & Pleura –

• R - three lobes L - two lobes

• Apex - upper end toward collarbone

• Base - of lungs rest on diaphragm

• Pleura - serous membrane linings, thin, moist, slippery– Parietal pleura - lines walls of thorax

– Visceral pleura - covers the lungs

– Intrapleural space - between , small amt. fluid

• Pleurisy - inflammation of parietal pleural– Difficulty breathing, stabbing pain (rubs)

– Caused by infection, tumors, etc.

• Atelectasis - collapse of the lung > effective breathing due to < ventilation

• Pneumothorax - Hemothorax

• Respiration - – Exchange of gases between living organism &

environment - Pair of lungs - place where air & circulating fluids (blood) can exchange gases

– Pulmonary ventilation - (breathing) air in & out of lungs (external respiration- exchange gases)

– Internal respiration - exchange gases between blood & cells

– Cellular respiration - use of O2 by cells

• Mechanisms of Breathing - Pulmonary Ventilation - 2 phases (inspiration - expiration)– Changes in pressure cause movement of air in-out

– Lungs inside thoracic cavity - changes in shape &

size of cavity (by muscles)- changes air pressure w/in cavity

– Air moves from area of high pressure to area of low pressure

• Inspiration - occurs when chest cavity enlarges > lungs expand > air rushes in & down to alveoli

• Inspiratory muscles - Diaphragm & external intercostals– When these muscles contract > ^ volume in cavity >

which < pressure - draws air in

• Diaphragm -

– Most important muscle of inspiration

– Dome-shaped muscle

– Flattens (contract) during inspiration > cavity elongate (top to bottom)

– Phrenic nerve - stimulates to contract

• External Intercostal -– Between the ribs

– When contract > enlarge cavity (front to back) ( side to side) > < pressure (air rushes in)

• Expiration - ordinarily passive process (quiet expiration)– Begins as inspiratory muscles relax

– Cavity returns to smaller size

– Lungs recoil - elastic nature < in size as air leaves

• Expiratory muscles - used when speaking, sing, do heavy work– Need more forceful expiration to > depth & rate of

ventilation

– Internal intercostals & abdominal muscles

– Cavity size < & pressure w/in > & air flows out

• Internal Intercostals Muscles-

– Depress the rib cage < cavity size front - back

• Abdominal Muscles - – Contract & push abd. organs against underside of

diaphragm(^ dome-shape)

– Shortens top to bottom thoracic size

• Exchange of Gases in Lungs -– Blood from R ventricle into pulmonary artery to

lungs > tiny capillary beds close to alveoli

– Diffusion occurs between tiny capillaries & alveoli (O2 & CO2)

• Movement of substances from high concentration to area of low concentration

– Oxyhemoglobin - O2 & hemoglobin combination in RBCs (to be carried to cells)

– Most CO2 carried to lungs as bicarbonate ion (HCO3) , some carried in RBCs as carbaminohemoglobin

• Exchange of Gases in Tissues -– Internal respiration - diffusion

– Oxyhemoglobin breaks down > O2 into cells (used) - CO2 out of cells

• Volumes of Air Exchanged in Pulmonary Ventilation -

• Spirometer - device used to measure amt. air exchanged in breathing

• Tidal Volume (TV) - (like ocean tides) amt. of air that comes & goes regularly– Normal Inspiration - 500 ml (one pint)– Normal Expiration - equal amt.

• Vital Capacity (VC) - largest amt. air we can breathe out in one expiration– Normal young adult = 4800 ml

• Expiratory Reserve Volume (ERV) -– Amount of air forcibly exhaled after tidal

volume

• Inspiratory Reserve Volume (IRV) -– Amount of air forcibly inspired over & above a

normal resp.

• As TV (normal breath) >, ERV & IRV < (reserve spaces)

• VC = TV + IRV + ERV

• Residual Volume (RV) - Air that remains in lungs after most forceful expiration

• Regulation of Respiration -– Need for O2 > as activity > (make more waste

products > removed)– Take more breaths (^ rate) & > tidal volume (depth)– Automatic adjustments - in resp. & circulation

(heart pumps faster & harder)

• Respiratory control centers - medulla & pons of brain - they stimulate resp. muscles– Receptors sense: Changes in O2 & CO2 levels in

blood, Acid levels, Amt. stretch in lungs > change resp. rate & depth

• Cerebral Cortex - – Modifying effect on inspiratory &

expiratory centers of the medulla

– Voluntarily change pattern of breathing

– Hold breath (swimming, speaking, eating)

– As limits - resume breathing when our bodies need O2 or has too much CO2

• Receptors Influencing Respiration -

• Chemoreceptors -in carotid & aortic bodies– Sense > CO2, < O2, acid levels in blood– Send nerve impulses to resp. regulation centers

• Pulmonary Stretch Receptors -– Located in lungs - throughout airways &

alveoli– Impulses influence normal breathing pattern to

protect from excess stretching (overinhalation) – When TV reached - stimulus sent to inhibit

more inspiration

• Types of Breathing -

– Eupnea - normal resp. rate, unaware of breathing

– Hypoventilation - slow & shallow

– Hyperventilation - rapid & deep

– Dyspnea - labored or difficult

– Orthopnea - upright position

– Apnea - breathing stops

– Cheyne-Stokes Resp. -apnea & hyperventilation

– Respiratory Arrest - failure to resume breathing after period of apnea