Respiratory System. Introduction The CV and Respiratory system cooperate to supply O2 and eliminate...

Respiratory SystemRespiratory System

IntroductionIntroduction

• The CV and Respiratory system cooperate to supply O2 and eliminate CO2


• The Resp. Sys. provides for gas exchange


• The CV transports respiratory gases


• Respiration is the exchange of gases between the atmosphere, blood, and cells


Consists of

1. Nose

2. Pharynx

3. Larynx

4. Trachea

5. Bronchi

6. Lungs


• The conducting system consists of a series of cavities and tubes –nose, pharynx, larynx, trachea, bronchi, bronchiole, and terminal bronchiole


• The conducting system conducts air into lungs


• The respiratory portion consists of the area where gas exchange occurs-respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli

NoseNose

• The external portion of the nose is made of cartilage and skin and is lined with mucous membrane.

NoseNose

• It is stratified squamous epithelium inside the nostrils

NoseNose

• It turns into pseudostratified columnar epithelium deeper inside

NoseNose

• The bony framework of the nose is formed by the frontal bone, nasal bones, and maxillae

NoseNose

• The internal structures of the nose are specialized for

1. warming

NoseNose

2. moistening

NoseNose

3. Filtering incoming air

NoseNose

4. Receiving olfactory stimuli

NoseNose

5. Serving as large, hollow resonating chambers to modify speech sounds

NoseNose

• The space within the internal nose is called the nasal cavity.

NoseNose

• It is divided into right and left sides by the nasal septum

NoseNose

• The anterior portion of the cavity (nostrils) is called the vestibule

PharynxPharynx

• Throat

PharynxPharynx

• Muscular tube lined by a mucous membrane

PharynxPharynx

• Anatomic regions

1. Nasopharynx

2. Oropharynx

3. laryngopharynx

PharynxPharynx

• Nasopharynx functions in respiration

PharynxPharynx

• The oropharynx and laryngopharynx function in digestion and in respiration

LarynxLarynx

• Voice box

LarynxLarynx

• Passageway that connects the pharynx with the trachea

LarynxLarynx

It contains

1. Thyroid cartilage (Adam’s apple)

LarynxLarynx

2. Epiglottis (prevents food from entering the larynx)

LarynxLarynx

3. Cricoid cartilage (connects the larynx and trachea)

SwallowingSwallowing

1. Larynx raises up


2. Epiglottis covers the entry into the glottis


3. The upper esophageal sphincter opens


4. Food is diverted into the esophagus

Voice ProductionVoice Production

• The larynx contains vocal folds (true vocal cords) which produces sound


• The true cords and the space between them make up the glottis


• In males, the true cords are thicker and longer


• The false cords close when we clear our throat

TracheaTrachea

• Windpipe

TracheaTrachea

• Extends from the larynx to the primary bronchi

TracheaTrachea

• Composed of smooth muscle and C-shaped rings of cartilage

TracheaTrachea

• Lined with pseudostratified ciliated columnar epithelium

TracheaTrachea

• The cartilage rings keep the airway open

TracheaTrachea

• Cilia sweep debris away from the lungs and back to the throat to be swallowed

BronchiBronchi

• The trachea divides into the right and left primary bronchi

BronchiBronchi

• The bronchiole tree consists of the

1. trachea

BronchiBronchi

2. Primary bronchi

BronchiBronchi

3. Secondary bronchi

BronchiBronchi

4. Tertiary bronchi

BronchiBronchi

5. Bronchioles

BronchiBronchi

6. Terminal bronchioles

BronchiBronchi

• Walls of bronchi contain rings of cartilage, which disappears distally

BronchiBronchi

• Walls of bronchioles contain smooth muscle only, without cartilage

BronchiBronchi

• The epithelium changes from ciliated pseudostratified columnar to non-ciliated simple cuboidal in the terminal bronchioles

BronchiBronchi

• Sympathetics release norepinephrine and epi. which stimulates beta two receptors causing bronchodilation

BronchiBronchi

• Parasympathetic release ACh which stimulates muscarinic ACh receptors causing bronchoconstriction

LungsLungs

• Paired organs in the thoracic cavity

LungsLungs

• Enclosed and protected by the pleural membrane

LungsLungs

• Parietal pleura – outer layer which is attached to the wall of the thoracic cavity

LungsLungs

• Visceral pleura – inner layer, covering the lungs

LungsLungs

• Pleural cavity (space) – A small space between the pleurae that contains a lubricating fluid secreted by the membranes

LungsLungs

• Extend from the diaphragm to just slightly superior to the clavicles

LungsLungs

• Lie against the ribs anteriorly and posteriorly

LungsLungs

• Right lung has three lobes

LungsLungs

• The left lung has two lobes

LungsLungs

• Tertiary bronchi supply segments of lung tissue called bronchopulmonary segments

LungsLungs

• Each bronchopulmonary segment consists of many small compartments called lobules

LungsLungs

• Lobules contain

1. lymphatics

LungsLungs

2. arterioles

LungsLungs

3. venules

LungsLungs

4. Terminal bronchioles

LungsLungs

5. Respiratory bronchioles

LungsLungs

6. Alveolar ducts

LungsLungs

7. Alveolar sacs

LungsLungs

8. alveoli

AlveoliAlveoli

• Have a surface area of 70 square meters

AlveoliAlveoli

• Consists of

1. Type I alveolar cells (simple squamous)

2. Type II alveolar cells (septal)

3. Alveolar macrophages (dust cells)

AlveoliAlveoli

• Type II alveolar cells secrete alveolar fluid which keeps the alveolar moist

AlveoliAlveoli

• The alveolar fluid contains surfactant which prevents the collapse of alveoli with each expiration

AlveoliAlveoli

• Gas exchange occurs across the alveolar-capillary (respiratory) membrane

AlveoliAlveoli

• Respiratory membrane consists of the two layers of simple squamous cells and their basement membranes

Pulmonary VentilationPulmonary Ventilation

• Breathing

Pulmonary VentilationPulmonary Ventilation

• Process by which gases are exchanged between the atmosphere and lung alveoli.

InspirationInspiration

• Occurs when alveolar pressure fall below atm. pressure.


• Contraction of the diaphragm and external intercostal muscles increases the size of the thorax.


• Thus decreasing the intrathoracic pressure so that the lungs expand.


• Expansion of the lungs decreases alveolar pressure to 758 mmHg.


• Air moves along the pressure gradient from atm. 760 into the lungs.

ExpirationExpiration

• Occurs when alveolar pressure is higher than atm. pressure (760).


• Relaxtion of the diaphragm and external intercostals results in elastic recoil of the chest wall and lungs which…..


1. Increases intrathoracic pressure


2. Decreases lung volume


3. Increases alveolar pressure so that air moves from the lungs to the atmosphere

Alveolar Surface TensionAlveolar Surface Tension

• Causes the alveolar to assume the smallest diameter


• Surface tension must be overcome to expand the lungs during each inspiration


• It is the major component of elastic recoil, which acts to decrease the size of the alveoli during expiration


• Surfactant decreases surface tension of the alveoli and prevents their collapse following expiration

Lung Volumes and CapacitiesLung Volumes and Capacities

• Tidal volume - amount of air inhaled or exhaled with each breath under resting conditions (500ml)


• Inspiratory reserve volume – Amount of air that can be forcefully inhaled after a normal tidal volume inhalation (3100)


• During forced inspiration the muscles sternocleidomastoid and pectoralis minor are also used


• Expiratory reserve volume – Amount of air that can be forcefully exhaled after a normal tidal volume exhalation (1200ml)


• Forced expiration employs contraction of the internal intercostals and abdominal muscles


• Vital capacity – Maximum amount of air that can be exhaled after a maximal inspiration (4800ml)


• Residual volume – Air remaining in the lungs after the expiratory reserve volume is exhaled (1200)


• Minute Volume of Respiration – the total volume of air taken in during one minute


• Minute Volume of Respiration – tidal volume x 12 respirations per minute = 6000ml/min

Dalton’s lawDalton’s law

• Each gas in a mixture of gases exerts its own pressure as if all the other gases were not present


• Partial pressure of a gas – the pressure exerted by that gas in a mixture of gases


• Partial pressure of a gas = % of the mixture represented by the gas times the total pressure


• Total Pressure (P) = Add all the partial pressures

External RespirationExternal Respiration

• In internal and external respiration, O2 and CO2 diffuse from areas of their higher partial pressures to areas of their lower partial pressures

External RespirationExternal Respiration

• Results in the conversion of deoxygenated blood coming from the heart to oxygenated blood returning to the heart.

Internal RespirationInternal Respiration

• Tissue Respiration


• The exchange of gases between tissue blood capillaries and tissue cells.


• Results in the conversion of oxygenated blood into deoxygenated blood


• During exercise more O2 enters tissue cells than at rest

Respiratory CenterRespiratory Center

• Area of the brain from which nerve impulses are sent to resp. muscles

Respiratory CenterRespiratory Center

Consists of

1. Medullary rhythmicity area

2. Pneumotaxic area

3. Apneustic area

Medullary Rhythmicity AreaMedullary Rhythmicity Area

• Controls the basic rhythm of respiration


Consists of

1. Inspiratory area

2. Expiratory area


• The inspiratory area has autorhythmic neurons that set the basic rhythm of respiration


• Expiratory area remains inactive during most quiet respiration but active during forced expiration


• Inspiration last 2 seconds


• Expiration lasts 3 seconds

Pneumotaxic AreaPneumotaxic Area

• Coordinates the transition between inspiration and expiration

Apneustic AreaApneustic Area

• Sends impulses to the inspiratory area that activate it and prolong inspiration, inhibiting expiration

Cortical InfluencesCortical Influences

• Allow conscious control of respiration

Cortical InfluencesCortical Influences

• Needed to avoid inhaling noxious gasses or water

ChemoreceptorsChemoreceptors

• Monitor levels of CO2 and O2 and provide input to resp. center

Central ChemoreceptorsCentral Chemoreceptors

• Located in the medulla oblongota

Central ChemoreceptorsCentral Chemoreceptors

• Respond to change in H+ concentration or PCO2 or both in cerebrospinal fluid

Peripheral ChemoreceptorsPeripheral Chemoreceptors

• Located in the walls of systemic arteries

Peripheral ChemoreceptorsPeripheral Chemoreceptors

• Respond to changes in H+,PCO2, and PO2

HypercapniaHypercapnia

• A slight increase in PCO2 (and H+) stimulates central chemoreceptors

HypercapniaHypercapnia

• The inspiratory area is activated and hyperventilation occurs

HypocapniaHypocapnia

• PCO2 is lower than 40 mm Hg


• Chemoreceptors are not stimulated


• Inspiratory area sets its own pace until CO2 accumulates

HypoxiaHypoxia

• Oxygen deficiency at the tissue level

Hypoxix HypoxiaHypoxix Hypoxia

• Caused by low PO2 in arterial blood

Hypoxix HypoxiaHypoxix Hypoxia

• Caused by high altitude, airway obstruction, fluid in lungs

Anemic HypoxiaAnemic Hypoxia

• Too little functioning hemoglobin

Anemic HypoxiaAnemic Hypoxia

• Caused by hemorrhage, anemia, carbon monoxide poisoning

Stagnant hypoxiaStagnant hypoxia

• The inability of blood to carry oxygen to tissues fast enough to sustain their needs

Stagnant hypoxiaStagnant hypoxia

• Caused by heart failure, circulatory shock

Histotoxic hypoxiaHistotoxic hypoxia

• Blood delivers adequate oxygen to the tissues, but the tissues are unable to use it properly

Histotoxic hypoxiaHistotoxic hypoxia

• Caused by cyanide poisoning

Respiratory System. Introduction The CV and Respiratory system cooperate to supply O2 and eliminate...

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