Respiratory System rev 12-09 Performs 2 basic functions: Air distribution

Respiratory System BIO 006 1

Respiratory System rev 12-09

• Performs 2 basic functions:• Air distribution• Gas exchange—oxygen and carbon dioxide

Process of respiration is another important homeostatic mechanism; it enables our cells to function effectively

• Respiratory system filters, warms and humidifies the air we breathe


Upper respiratory tract—• nose, pharynx, and larynx

Lower respiratory tract—• trachea, bronchial tree, and lungs

including the alveoli


• Specialized membrane that lines the air distribution tubes in the respiratory tree• Covered with mucus and ciliated cells

• More than 125 ml of mucus produced each day forms a “mucous blanket” over much of the respiratory system• Helps to clean, warm and humidify air we breathe• Mucus moves only toward the pharynx except in

smokers• Cigarette smoke paralyzes the cilia and this

causes smoker’s cough

Respiratory MucosaRespiratory Mucosa


Nose or External NaresNose or External NaresStructure Nasal septum separates interior of nose into two

nasal cavities which are lined by mucous membrane Nerve endings responsible for the sense of smell

are located in the nasal mucosa Functions: Warms and moistens inhaled air

Frontal, maxillary, sphenoidal, and ethmoidal sinuses drain into nose Nasal mucosa also lines the sinuses and sinusitis

can often develop from colds• 2 ducts from the lacrimal sacs drain into the nasal

cavity


PharynxPharynx

Structure Also called the throat Both nasal cavities, the mouth, the esophagus, the

larynx, and the auditory (Eustachian) tubes open into the pharynx Pharyngeal tonsils are also in the pharynx

Functions Passageway for food and liquids Air distribution; passageway for air


LarynxLarynx

• Also called voice box• Structure

Several pieces of cartilage form framework Thyroid cartilage (Adam’s apple) is largest Epiglottis partially covers opening into larynx

and partially closes the larynx during swallowing Mucous lining Vocal cords stretch across interior of larynx

The space between these is called the glottisFunctions:

• Air distribution for air to move to and from lungs• Voice production


TracheaTrachea

Structure Also called windpipe Tube which extends from larynx into the thoracic

cavity Mucous lining C-shaped rings of cartilage hold trachea open

Function—passageway for air to move to and from lungs

If the trachea is blocked, the blockage can occlude the airway and if complete causes death in minutes

Heimlich maneuver is a lifesaving technique used to free the trachea of obstruction


Bronchi, Bronchioles, and AlveoliBronchi, Bronchioles, and Alveoli

Structure Trachea branches into right and left bronchi Each bronchus branches into smaller and smaller

tubes eventually leading to bronchioles which contain only muscle in their walls (no cartilage)

Bronchioles end in clusters of microscopic tubes called alveolar ducts. Each of these ducts ends in many alveolar sacs, the walls of which are made up of alveoli


Function Bronchi and bronchioles—air distribution;

passageway for air to move to and from alveoli Alveoli—exchange of gases between air and

blood Walls are made up of a single layer of cells as

are the capillaries which surround them The surface of the respiratory membrane

inside the alveolus is covered by a surfactant which helps reduce surface tension in the alveoli so they do not collapse as air moves in and out during respiration


Lungs and PleuraLungs and Pleura

Structure Fills the chest cavity, except for middle

space occupied by heart and large blood vessels

Pleura—moist, smooth, slippery membrane that lines chest cavity and covers outer surface of lungs; reduces friction between the lungs and chest wall during breathing


• Mechanics of breathing (respiration or pulmonary ventilation) Includes two phases: inspiration or

inhalation(movement of air into lungs) and expiration or exhalation (movement of air out of lungs)

Changes in size and shape of thorax cause changes in air pressure within this cavity and in the lungs

Air pressure differences actually cause air to move into and out of the lungs


Inspiration or Inhalation: Air moves into lungs Inspiratory muscles include diaphragm and

external intercostals Diaphragm flattens during inspiration External intercostal contraction elevates the

ribs The increase in the size of the chest cavity

reduces pressure and air enters the lungs


Expiration or Exhalation Quiet expiration is ordinarily a passive process During expiration, thorax returns to its smaller size

Elastic recoil of lung tissues aids in expiration Reduction in the size of the thoracic cavity

increases the pressure and air is forced out of the lungs


Exchange of Gases in the Lungs• Blood flow route

– Right atriumright ventriclepulmonary arterylungsgas exchangepulmonary veinleft atriumleft ventricleaorta

• Because of the thinness of the capillary wall, gases can be exchanged– Oxygen into the bloodstream to be distributed

throughout the body– Carbon dioxide into the alveoli and then into exhaled

air


• In the lungs, oxygen moves into the capillaries and combines with hemoglobin. It is transported in the bloodstream as oxyhemoglobin

• Oxyhemoglobin breaks down into oxygen and hemoglobin and the oxygen moves out of the arterial capillary blood into tissue cells

• Carbon dioxide moves from tissue cells into venous capillary bloodstream

• Hemoglobin combines with carbon dioxide, forming carbaminohemoglobin. This will also travel to the lungs to be exhaled.


Amount (volume) of Air Exchanges in RespirationAmount (volume) of Air Exchanges in Respiration• A spirometer can measure the volume of air

exchanged in breathing • Tidal volume--amount normally breathed in or out

with each breath• Inspiratory reserve volume—amount of air that can

be forcibly inhaled after a normal inspiration• Expiratory reserve volume —amount of air that can

be forcibly exhaled after expiring the tidal volume• Vital capacity —maximal volume you can exhale after

a maximal inspiration• Residual volume—air that remains in the lungs after

the most forceful expiration• Rate—usually about 12 to 18 breaths per minute;

much faster during exercise


Regulation of RespirationRegulation of Respiration

• Regulation of respiration permits the body to adjust to varying demands for oxygen supply and carbon dioxide removal

• Respiratory control centers are located in the medulla and the pons. Centers in the pons have a modifying function.

• Most important central regulatory centers are in the medulla; are called the inspiratory center and expiratory center Under resting conditions, nervous activity in the

respiratory control centers produces a normal rate and depth of respirations


• Respiratory control centers in the medulla are influenced by “inputs” from receptors located in other body areas: Cerebral cortex—voluntary (but limited)

control of respiratory activity Chemoreceptors respond to changes in

carbon dioxide, oxygen, and blood acid levels—located in carotid and aortic bodies

Pulmonary stretch receptors—respond to the stretch in lungs, thus protecting respiratory organs from overinflation


Types of BreathingTypes of Breathing

• Eupnea—normal breathing • Hyperventilation—rapid and deep

respirations• Hypoventilation—slow and shallow

respirations• Dyspnea—labored or difficult respirations• Apnea—stopped respirations• Respiratory arrest—failure to resume

breathing after a period of apnea

Respiratory System 20

Disorders of Respiratory System

Reduced air flow: – Asthma: causes partial closure of the bronchi and

increased production of mucus. – Emphysema is caused by damage to the alveoli

due to damage in the connective tissue in the bronchioles. The airways tend to collapse and this causes increased pressure in the lungs which eventually damage the alveoli.

– Bronchitis is an inflammation of the bronchi which causes increased mucus which causes increased coughing.

Respiratory System 21

Infections: – Pneumonia is an infection which causes

inflammation of the lungs. The alveoli secrete excess fluid so gas exchange is impaired.

– Tuberculosis is a bacterial infection which scars the lungs.

– Botulism is a poisoning by bacterial toxin. The toxin blocks the transmission of nerve signals to the respiratory muscles.

• Lung cancer• Congestive heart failure impairs lung functioning.• Cystic fibrosis is an inherited condition which

causes mucus producing cells in the lungs to produce a very thick, sticky mucus which causes frequent infections. Other organs of the body are also involved.


• Structure-Pharynx Also called the throat Divided into nasopharynx (portion behind the nose), oropharynx

(portion behind the mouth), and laryngopharynx (portion behind the larynx)

Both nasal cavities, the mouth, the esophagus, the larynx, and the auditory (Eustachian) tubes open into the pharynx Pharyngeal tonsils and openings of auditory tubes

are into pharynx


• Diffusion is the process which is involved in gas exchange (passive movement from an area of high concentration to low concentration)


Date post:	30-Dec-2015
Category:	Documents
Upload:	idona-armstrong
View:	15 times
Download:	1 times

Respiratory System rev 12-09 Performs 2 basic functions: Air distribution

Documents