Functions of the Respiratory System

1. Constantly supplies adequate O2 to cells(it is an Air Distributor)

2. Removes CO2 from the body's cells(it is a Gas Exchanger)

3. Warms4. Filters5. Humidifies

air we breathe

6. Influences speech & sense of smell

-- the Respiratory System has 2 divisions

A. Upper Respiratory Tract (URT)-- located outside the thoracic

cavity & contains:

B. Lower Respiratory Tract (LRT)-- located in the thoracic cavity

& contains: trachea

lungsbronchial tree

nosepharynx

larynx

Respiratory Mucosa

-- covered with mucus& hair-like cilia

-- lines the air distributiontubes in the system

-- this mucus is themost importantair purification mechanism

-- traps foreignsubstances & moves

them up & out

-- area wheregas exchangeoccurs

from the blood

-- separates the air in the alveoli

capillary

alveolirespiratorymembrane

Respiratory Membrane

NoseNose

-- External nares (nostril)

-- mainly a passageway for air

-- warms & moistens inhaled air

-- contains nerve endings for sense of smell

NoseNose

-- also contains 4 paranasal sinuses:

Frontal

MaxillaryEthmoid

Ethmoid

Sphenoid

-- inflammation of the mucosa is called:

Sinusitis

-- mucosa that lines the sinuses is continuous with the mucosa that lines the nose

PharynxPharynx-- Also called the Throat

-- divided into 3 parts:

Nasopharynx

Oropharynx

Laryngopharynx

opening Eustachian tube-- opening to the Eustachian

tubes are located in the Nasopharynx

(allows for equalization of air pressures)

-- why it is easy for a URI to turn into a middle ear infection

Larynx

-- composed of pieces of cartilage (largest piece called the Thyroid cartilage or "Adam's Apple")

Epiglottis

-- a tissue that covers the larynx while eating is the:

Vocal Cords

-- 2 short fibrous bands that stretch across the interior of the Larynx

-- if tensed, voice is high-pitched-- if relaxed, voice if low-pitched

Both Thyroid cartilage& vocal cords grow faster & larger in males at puberty

Trachea

-- extends from the larynx to the bronchi

-- is made of 15 - 20 C-shaped rings of cartilage

-- these rings are almost non-collapsible

-- also contains mucus glands

TRACHEA

TRACHEA

-- even with the safeguard of non-collapsible rings, the trachea can be closed off due to:

a. tumors or infections

b. aspiration of food or other objects

-- complete obstruction can lead to death in minutes

-- 5,000 people in the U.S. are killed each year

Bronchi

-- contains 2 branches

-- Right bronchus straighter than left, so aspirated foreign object tend to end up in right lung

-- also contain rings of cartilage

AlveoliBronchioles

-- What 2 gases are involved here? O2 CO2

-- alveolar sacs are very thinned walled & lie close to thin walled blood capillaries

(sacs that resemble grape clusters)

-- this is where gas exchange occurs

-- do not contain rings of cartilage (made up of smooth muscle)

Rule: The Shorter the Distance through which Diffusion must take place, the Greater the Rate of Diffusion.

Alveoli

VenousCapillaryInterstitial Space

Interstitial Space

Alveoli

Rule: The Greater the Surface Area which Diffusion Takes place, the Greater the Rate of Diffusion.

--There are 300 Million Alveoli in the lungs

surrounded by Capillaries.

-- the alveoli walls are lined with a lipoprotein called: Surfactant

Surfactant

-- it reduces the surface tension in the alveoli

-- reduces the lungs tendency to recoil

-- Premature infants may not have surfactant yet, so develop: Respiratory

Distress Syndrome

LungsLungs -- Right lung contains 3 lobes-- Left lung only 2

Why?

Parietal Pleura

Visceral Pleura

Intrapleural space

-- lining of the walls of the thoracic cavity is called:

-- membrane that covers the lungs is called:

-- area between the 2 membranes is called:

Inflammation of the Pleura is called:

Pleurisy

Pneumothorax

-- pressure in the Intrapleural place should be less than atmospheric in order for lungs to remain inflatedLung compressed

Trachea

Diaphragm

Hole in lung

Chest wall

Heart

Air in Pleural Space

760

761

754

Breathing or Pulmonary Ventilation(exchange of gases between environment & alveoli)

(exchange of gases between the alveoli & the blood)

(exchange of gases between the blood & the cells)

External Respirations

Internal Respirations

Cellular Respiration

CO2O2

CO2

O2

O2

CO2

O2 + food CO2 + ATP

(using food & oxygen to make ATP)

Pulmonary ventilationPulmonary ventilation

-- includes 2 phases:

Inspiration (movement of air into the lungs)

Expiration (movement of air out of the lungs)

-- because the lungs are enclosed in the Thoracic cavity, if its shape is changed, the pressure within the cavity is changed

-- the difference in air pressure between the atmosphere & the lungs is what causes air to move in or out of the lungs

-- changing the shape of the thoracic cavity involves 2 muscles:

1. the Diaphragm

2. External Intercostals

-- the most important muscle of inspiration

When the diaphragm contracts, it flattens out & makes the chest cavity longer from top to bottom-- the nerve that stimulates the diaphragm is the:

Phrenic Nerve

-- the External Intercostals enlarges the thoracic cavity from front to back when contracted

(These muscles just relax)

-- Expiration is primarily a passive action

Atmospheric Pressure

Pressure in Lungs

Pressure in the Intrapleural Space

760

760

754

At Rest

INSPIRATION

Visceral Pleura

Parietal Pleura

760

754

AIR

Air moves from an area of higher pressure to an area of lower pressure

759

Atmospheric Pressure

Pressure in Lungs

Pressure in the Intrapleural Space 760

760

754

At Rest

EXPIRATION

760

754

Air moves from an area of higher pressure to an area of lower pressure761

-- During normal Expiration, the muscles of Inspiration relax

-- However, when speaking, doing heavy work, or singing,

-- the muscles involved here are the:1. Internal Intercostals

2. Abdominal Muscles

--Decreases thoracic cavity from front to back

-- push abdominal organs up against the diaphragm

-- decreasing chest cavity from top to bottom

-- this forces more air out past the vocal cords

we need a more forceful expiration.

Regulation of BreathingRegulation of Breathing

Respiratory Control Centers are locatedin the: Medulla

(with help from the Pons)

-- helps to maintainnormal breathing rate of:

14 to 20 breaths/minute

Cerebral Cortex

-- can voluntarily speed up or slow down respirations

-- we will resume normal breathing when body senses we need more O2 or CO2 levels are too high

-- children can hold their breath until they pass out

-- however, will start to breathe normally once they do

(temper tantrum)

Receptors that influence Receptors that influence respirationrespiration1. Chemoreceptors

-- located: Carotid arteriesArch of the Aorta

-- Stimulated by: O2

Change in pH

-- thus increasing rate & depthof respirations

CO2

2. Pulmonary Stretch Receptors

-- located throughout the pulmonaryairways & alveoli

-- prevent over-inflation of the lungs

-- when the right amount of air enters the lungs, the receptors send a message to the Medulla to inhibit the Inspiratory Center

Liters6

5

4

3

2.5

2

1

0Time

Spirometer -- measures amounts of air exchanged in breathing

Tidalvolume

Tidal Volume (TV)-- amount of air taken into & expelledin normal inspiration & expiration

-- about 500 cc

-- amount of air that can be forciblyinhaled over & above Tidal volume

-- about 3,000 cc

Liters6

5

4

3

2.5

2

1

0Time

Tidalvolume

Inspiratory reserve (IRV)

Inspiratoryreserve

Liters6

5

4

3

2.5

2

1

0Time

Tidalvolume

Inspiratoryreserve

Expiratoryreserve

Expiratory reserve (ERV)-- amount of air that can be forcibly

exhaled over & above Tidal volume

-- about 1000 cc

Liters6

5

4

3

2.5

2

1

0Time

Tidalvolume

Inspiratoryreserve

Expiratoryreserve

Totallung

capacity

Vitalcapacity

Vital Capacity (VC)-- largest amount of air that can be

forcibly exhaled after maximum inhalation

-- about 4500 cc

(VC = IRV + ERV + TV)

Liters6

5

4

3

2.5

2

1

0Time

Tidalvolume

Inspiratoryreserve

Expiratoryreserve

Totallung

capacity

Residual volume

Residual Volume

-- air that remains in lungs after forcible exhalation

-- about 1200 cc