RESPIRATORY SYSTEM

Respiratory system Molecules of oxygen

and carbon dioxide are passively exchanged, by diffusion, between the gaseous external environment and the blood.

This exchange process occurs in the alveolar region of the lungs

Respiratory Control Ventilation occurs under the control of the

autonomic nervous system from parts of the brain stem, the medulla oblongata and the pons.

This area of the brain forms the respiration regulatory center, a series of interconnected brain cells within the lower and middle brain stem which coordinate respiratory movements.

This section is especially sensitive during infancy, and the neurons can be destroyed if the infant is dropped and/or shaken violently. The result can be death due to "shaken baby syndrome”

Control of Breathing

Breathing is regulated by the rhythmicity center in the medulla of brain

Medulla stimulates inspiratory muscles (diaphragm & external intercostal muscles)

rhytmicity center

Control of Breathing

Human Respiration

Works together with the circulatory system Exchange of gases between atmosphere,

blood, and cells If respiratory system and/or circulatory

system fails, death will occur Cells need O2 for work; release CO2 as a

waste product Accumulation of excess CO2 is toxic to

cells and MUST be removed

Respiratory SystemIntakes oxygenReleases carbon dioxide waste

Circulatory system Transports

gases in blood between lungs and cells

Respiratory Structures and Organs

Respiratory Structures and Organs Nose – made of cartilage and bone and

is designed to warm, moisten, and filter air as it comes into the system

Pharynx – (throat) conducts food and air; exchanges air with Eustachian tube to equalize pressure

Respiratory Structures and Organs Larynx – (voice box)

connects the pharynx and the trachea; made of cartilage; contains vocal cords

Epiglottis – flap of tissue that covers trachea; ensures food travels down the esophagus

Trachea – (windpipe) tubular passage way for air; carries air to the lungs

Bronchi – pair of tubes that branch from trachea and enter lungs; have cartilage plates; lining is ciliated & secretes mucus

larynx

trachea

bronchi

bronchioles

Respiratory Structures and Organs Bronchioles – tiny tubes lacking

cartilage and cilia; possess smooth muscle

bronchiolesmooth muscle

Respiratory Structures and Organs Alveoli – cup shaped structures at

the end of the bronchioles that resemble bunches of grapes; are in direct contact with capillaries (gas exchange);

Alveoli

Lungs – paired, cone-shaped organs that are surrounded by a pleural membrane, made of elastic tissue, and divided into lobes

Mechanics of Breathing

Inhaling (active process) – Air moves in. Why??Gases move from an area of high pressure

to low pressureDuring inspiration – diaphragm pulls down

and lungs expandWhen lungs expand, it INCREASES the

VOLUME, which DECREASES the PRESSURE inside lungs

Lung pressure is lower than outside pressure, so air moves in

Mechanics of Breathing

Exhaling (passive process) – breathing outDiaphragm and muscles relaxVolume in lungs and chest cavity

decreases, so now pressure inside increases

Air moves out because pressure inside is HIGHER than OUTSIDE atmosphere

Respiration

What is respiration?External respiration – exchange of

O2 and CO2 between respiratory surfaces and the blood (breathing)

Internal respiration – exchange of O2 and CO2 between the blood and cells

Cellular respiration – process by which cells use O2 to produce ATP

External Respiration

Exchange of O2 and CO2 between alveoli and blood

Partial pressure of O2 higher in alveoli than blood so O2 diffuses into blood

Partial pressure of CO2 higher in blood than alveoli, so CO2 moves into alveoli in opposite direction and gets exhaled out

Internal Respiration

Exchange of O2 and CO2 between blood and tissues

Pressure of O2 higher in blood than tissues so O2 gets release into tissues.

Pressure of CO2 higher in tissue than in blood so CO2 diffused in opposite direction into blood.

CO2 Is a waste product O2 Is used in cellular respiration

Gas Exchange

Earth’s atmosphere is about 78% Nitrogen and about 21% O2

What happens to the air when we inhale?

300 million alveoli in a healthy lung Hemoglobin can hold four O2 molecules

GAS INHALED EXHALED

O2 20.71% 14.6%

CO2 .004% 4.0%

H2O 1.25% 5.9%

Gas Transport in Blood

Carbon dioxide70% as bicarbonate ion (HCO3

-) dissolved in plasma

23% bound to hemoglobin7% as CO2 dissolved in plasma

Oxygen99% bound to hemoglobin1% as O2 dissolved in plasma

Carbon monoxide poisoning occurs because CO binds to hemoglobin more readily than O2

Lung Defense systems Airway epithelial cells can secrete a variety of

molecules that aid in lung defense. Secretory mmunoglobulins (IgA), collectins (including Surfactant A and D), defensins and other peptides and proteases, reactive oxygen species, and reactive nitrogen species are all generated by airway epithelial cells.

These secretions can act directly as antimicrobials to help keep the airway free of infection. Airway epithelial cells also secrete a variety of chemokines and cytokines that recruit the traditional immune cells and others to site of infections.

Respiratory during pregnancy The respiratory system lies dormant in the human

fetus during pregnancy. At birth, the respiratory system becomes fully functional upon exposure to air, although some lung development and growth continues throughout childhood.

The lungs of pre-term infants may not function well because the lack of surfactant leads to increased surface tension within the alveoli. Thus, many alveoli collapse such that no gas exchange can occur within some or most regions of an infant's lungs, a condition termed respiratory distress syndrome.

Infectious respiratory diseases Infectious, environmental and other

"diseases" (e.g., pneumonia, tuberculosis, asbestosis, particulate pollutants)

Coughing is of major importance, as it is the body's main method to remove dust, mucus, saliva, and other debris from the lungs.

Sleep apnea is a sleep disorder

characterized by abnormal pauses in breathing or instances of abnormally low breathing, during sleep.

Each pause in breathing, called an apnea, can last from a few seconds to minutes, and may occur 5 to 30 times or more an hour

Respiratory System Disorders Asthma – muscles of

bronchioles constrict, drastically reducing ventilation

Emphysema – destruction of alveoli

Tuberculosis – highly contagious bacterial infection

Lung cancer – 90% of lung cancer victims have a history of smoking

Facts about ETS Smoking causes 20% (or 1 in 5) of all

deaths in the United States each year. In 1988, the U.S. Surgeon General

reported that nicotine is just as addictive as heroin and cocaine. A "hit" of nicotine reaches the brain in seven seconds, twice as fast as heroin injected into the vein.

There are over 19 known carcinogens in cigarette smoke.

After quitting smoking

At 20 minutes after quitting:Blood pressure decreasesPulse rate dropsBody temperature of hands and feet

increases.

After quitting smoking

At 8 hours:Carbon monoxide level in blood drops to

normalOxygen level in blood increases to normal

After quitting smoking

At 24 hours: Chance of a heart attack decreases

After quitting smoking

At 48 hours:nerve endings begin regrow

After quitting smoking

Between 2 weeks and 3 months:Circulation improvesWalking becomes easierLung function increasesThe worst of nicotine withdrawal symptoms

subside within the first month. Following that, the focus shifts to learning how to decipher and reprogram the psychological tugs or urges to smoke that we've all built up over the years.

After quitting smoking

At One Year Smoke-Free:Your excess risk of coronary heart disease

is decreased to half that of a smoker after one year.

In class exercise

How is it that cigarette smoke can be linked to an increased incidence of many kinds of cancers?

Explain reason(s) why a person who has never smoked a day in their life can get lung cancer?