Organs of Respiratory System:

1)nose

2)Pharynx

3)larynx

4)trachea

5)bronchi

*plus smaller branches

6)lungs

-no exchanging of gases

-purify, humidify, & warm incoming air

The Nose

*basic structure*

-only externally visible par of resp. system

-air enters through nostrils

-interior of nose consists of nasal cavity

*divided by a midline nasal septum

-lateral walls uneven due to bony projections called conchae

-separated from oral cavity by palate

-surrounded by ring of paranasal sinuses

-3 bony projections

-increase surface area of nasal cavity

-lighten skull 

-act as resonance chambers for speech

-produce mucus

*drains into nasal cavity

Rhinitis

-inflammation of the nasal mucosa

-excessive mucus

-inflammed sinuses

-causes marked changes in voice quality

-headache caused by passageways to nasal cavity being blocked

*air in sinus cavity absorbed leading to a partial vacuum

-rich in blood & mucous glands

-air is warmed as it flows through

-traps incoming bacteria & other foreign debris

-contaminated mucus pushed toward pharynx by ciliated cells & swallowed

*extreme cold: cilia sluggish; runny nose

-muscular passageway

-5 inches long

-commonly called throat

-passageway for air & food

-tonils found in pharynx

1)pharyngeal tonsils

2)Palantine tonsils

3)lingual tonsils

-air enters in nasopharynx

-descends through the oropharynx

-goes through laryngopharynx to enter larynx

*auditory tubes that drian into middle ear open into the nasopharynx

-adenoids

-located high in nasopharynx

-"voicebox"

-formed by 8 rigid hyaline cartilages & a flap of elastic cartilage called Epiglottis

-Largest cartilage

-commonly called "Adams Apple"

-protects superior opening of larynx

-when we swallow the epiglottis forms a lid over opening of larynx

*anything other than air enters the larynx triggers the cough reflex

-"True Vocal Cords"

-vibrate with expelled air

-"windpipe"

-fairly rigid; reinforced w/ hyaline cartilage

-lined with ciliated mucosa, propel mucus

-keeps dust particles & other debris away from lungs; to throat where it is swallowed or spit out

-smoking: inhibits ciliary activity; ultimately destroying them

-coughing is their only means of preventing mucus accumulation in lungs

tracheal obstruction = life threatening

-Heimlich maneuver: air in person's lungs used to pop out any obstucting piece of food etc.

-right & left

*subdivision of the trachea

-right is larger & straighter than left

-subdivide after entering lungs

-finally ending in smallest conduction passageways = bronchioles

-bronchioles lead to alveoli

-occupy entire thoracic cavity except for most central area

-apex: just under collarbone

-base: rest upon diaphragm

-surface covered with visceral pleura & walls of thoracic cavity lined w/ parietal pleura

*produce pleural fluid which allows lungs to move freely during breathing

-air sacs

-millions of them

-resemble clusters of grapes

-make up bulk of lung

-final line of defense is in alveoli: macrophages (dust cells) wander in & out of alveoli & pick up bacteria & other debris

composed of:

-squamous epithelium which composes walls of alveoli (single layer)

-cobweb of pulmonary capillaries which cover external surfaces

-scattered among epithelial cells

-form surfactant

-coats gas-exposed alveolar surfaces

-lowers surace tension of film of water coating alveolar cells & keeps alveoli from collapsing during each breath

***premature infants (before 28 weeks) inadequate amount of surfactant = Infant Respiratory Distress Syndrom (IRDS)

-alveoli collapse after each breath

-use huge amounts of energy to reinflate every time

1)Pulmonary ventilation

2)External respiration

3)respiratory gas transport

4)internal respiration

air moving into & out of the lungs

*breathing

-completely mechanical

volume changes lead to pressure changes which lead to flow of gases to equalize the pressure

-large volume: molecules far apart, pressure exerted by the molecules hitting each other & the walls of the container is low, reduce volume

*molecules closer together & the pressure will rise

inspiratory muscles:

1)diaphragm (flattens out)

2)external intercostals contract

*size of thoracic cavity increases

-lungs stretch alos because they are adhered to thoracic walls

-molecues move further apart & pressure drops, creating a cavuum which suchs air into lungs until the pressure is = atmospheric pressure

-Largely a passive process in healthy people

-inspiratory muscles relax & lungs recoil therefore thoracic volume decreases & gases forced closer together causing pressure to rise inside lungs & gases to flow out until equilibrium is reached

Lung collapse

-seen when air enters the pleural space through a chest wound of from rupture of visceral pleura

-presence of air referred to as pneumothorax

-result from relex activity

-includes:

1)coughs

2)sneezes

3)laughing

4)crying/sobbing

5)yawning

6)hic cups

*coughs/sneezes cleans out airways

factors that affect respiratory capacity:

1)persons size

2)sex

3)age

4)physical condition

-normal breathing moves about 500 ml of air (~1 pint) into & out of lungs

*tidal volume (TV)

amount of air taken in forcibly over the tidal volume

-between 2100 ml & 3100 ml

amount of air forcibly exhaled after tidal expiration

*vital capacity: ~ 4500 ml

amount of exchangeable air is about 4500 ml

= TV + IRV + ERV

amount of air that remains in the conducting passageways & never reaches alveoli; amounts 150 ml during a normal breath

-measured w/ a spirometer

-Bronchial Sounds

-Vesicular Breathing Sounds

-Rales & Wheezing

-Occur as air fills the alveoli

-soft

-resemble sounds of muffled breeze

-rasping sound

-abnormal chest sounds

-a whistling sound

-abnormal chest sound

-gas exchanges are made according to the laws of diffusion:

movement occurs towards the are of lower concentration

-oxygen tends to move from the air into the capillaries of the pulmonary circulation

-CO2 will leave the blood and pass into the air in alveoli

-transported in the blood in two ways:

1)most attaches to hemoglobin molecules inside the rbcs to form oxyhemoglobin (HbO2) 

2)a very small amount is dissolved in plasma

-most transported in the plasma as the bicarbonate ion (HCO3-)

-to diffuse it must be released from bicarbonate ions

-bicarbonate ions combine with hydrogen ions to form carbonic acid (H2CO3) which then splits to form water and CO2

 -smaller amount 20-30% carried inside the rbcs bound to hemoglobin

-attatches to different site than oxygen therefore it does not interfere with oxygen transport

Hypoxia

&

Carbon Monoxide Poisoning

-fair skinned people appear to have bluish cast to their skin & mucous membranes (cyanosis)

-more difficult to ovserve in dark skinned people

-need to look at nail beds

-CO is odorless & colorless that binds to hemoglobin at the same sites as oxygen

-competes with oxygen

-Hb binds more readily with CO than oxygen

-leading cause of death from fire

-does not produce characteristic signs of hypoxia, instead the victim becomes confused & has  a throbbing headache. In rare cases skin becomes cherry red

-given 100% oxygen until CO is cleared from the body

-neural centers that control respiratory rhythm are located in the medulla and pons

-medulla contains the inspiratory and expiratory centers

-the pons contains the apneustic center:

provides the inspiratory drive & pneumotaxic center

-broncioles & alveoli have stretch receptors that respond to extreme overinflation as well as extreme deflation

-if medulla centers completely suppressed (an over dose of sleeping pills, morphine or alcohol) respiration stops completely & death occurs

a)physical factors

b)volition (conscious control)

c)emotional factors

d)chemical factors

-talking, coughing & exercise

-increased body temp. causes an increase in rate of breathing

(conscious control)

-voluntary control is limited & the respiratory centers will simply ignore messages when oxygen supply is getting low or the pH is falling

-most important factor modifying respiratory rate & depth

-increased levels of carbon dioxide & decrease in blood pH are the most important stimuli leading to an increase in the rate & depth of breathing

-changes in the oxygen concentration is detected by chemoreceptors in the aorta & carotid artery; send impulses to medulla

-people with chronic lung disease retain carbon dioxide & levels no longer trigger breathing; rely on oxygen levels instead

-carbonic acid increases during hypoventilation & decreases during hyperventilation

Chronic Obstructive Pulmonary Disease

(COPD)

-chronic bronchitis & emphysema major cause of death & disability in the U.S.

-Certain features in common:

1.almost always have history of smoking

2.coughing & frequent pulmonary infections

3.most are hypoxic, retain carbon dioxide & develop resipiratory failure

4.dyspnea

-alveoli enlarge as the walls of adjacent chambers break through & chronic inflammation promotes fibrosis in the lung

-lungs become less elastic & airways collapse during expiration

*use a lot of energy to exhale

-oxygen exchange is efficient until late in the disease

-Mucosa of lower respiratory passages becomes becomes severly inflammed & produces excessive amounts of mucus

-pooled mucus impairs gas exchange & ventilation & increases risk of lung infections

-cyanosis in common

-1/3 of all cancers in US

*over 90% of victims were smokers

-low cure rate

*5 year survival is 7%, average person suvives only 9 months after diagnosis

-metastasizes rapidly & widely

-most causes not diagnosed unti lthey are well advanced

3 most common types:

1. squamous cell carcinoma: 20-40% cases, epithelium in larger bronchi

2.adenocarcinoma: 25-35% cases, originates in peripheral ares of lung as solitary nodules that develop from mucous glands & alveolar epithelial cells

3. small cell carcinoma (oat cell cell carcinoma) 10-20% cases, orginate in primary bronchi & grow aggressively in cords

treatment: complete resection (removal) of diseased lung, due to spread most likely option is chemotherapy & radiation