the respiratory system

The Respiratory System

B. Pimentel, M.D.

University Of Makati – College of Nursing

Functions

1. Gas exchange

2. Regulation of blood ph

3. Voice phonation

4. Olfaction

5. Innate immunity

Anatomy

Upper Respiratory tract

Nose, nasal cavity, pharynx and associated structures

Lower Respiratory tract

Larynx, trachea, bronchi, and lungs

Upper Respiratory Tract

Anatomy

Upper Respiratory Tract Nose and Nasal Cavity

Epithelial lining Stratified squamous epithelium with coarse hair,

traps dust particles and humidifies air.

Pseudostratified ciliated columnar epithelium with goblet cells


Nares (nostrils), external opening Choane, openings into the pharynx Nasal septum, divides the cavity in to left and

right halves Hard palate, floor of the nasal cavity Conchae, prominent bony ridges on the lateral

wall of each nasal cavity– Increase surface area

Upper Respiratory Tract Paranasal Sinuses

Paranasal sinuses, air filled spaces with in the bone (skull)

Maxillary, frontal, ethmoidal and sphenoidal– Open into the nasal cavity

– Reduce weight, produce mucus and act as resonating chambers

– Susceptible to infection and inflammation

Nasolacrimal duct


1.Sinus frontalis2.Cellulae ethmoidales3.Septum nasi4.Concha nasalis inferior5.Processus alveolaris

mandibulae with teeth6.Sinus maxillaris7.Margo infraorbitalis8.Linea innominata9.Lamina orbitalis ossis

ethmoidalis10.Margo supraorbitalis

Upper Respiratory Tract Pharynx

Common passageway for air and solid particles.

Leads to the respiratory and digestive systems.

3 regions: 1. Nasopharynx

2. Oropharynx

3. Laryngopharynx

Upper Respiratory Tract Pharynx (Nasopharynx)

Superior part of the pharynx, from the choane to the level of the uvula.

Soft palate, floor of the nasopharynx

Auditory tubes opens into the nasopharynx

Pharyngeal tonsils

Upper Respiratory Tract Pharynx (Oropharynx)

From the uvula to the epiglottis

Palatine tonsils, lateral walls near the border oral cavity and oropharynx

Lingual tonsils, surface on the posterior part of the tongue

Upper Respiratory Tract Pharynx (Laryngopharynx)

Posterior to the larynx and extend from the tip of the epiglottis to the esophagus

Lower Respiratory Tract

Lower Respiratory Tract Larynx

Connected superiorly to the pharynx and inferiorly to the trachea.

Consist of 3 unpaired and 6 pair cartilages

Lower Respiratory Tract Larynx (Function)

Open passageway, prevent swallowed material from the larynx

Primary source of sound production.

Lower Respiratory Tract Larynx (Function)

Air moving past vocal cords causes vibration. The greater the amplitude (greater force of air) of

vibrations the louder the sound. The frequency of vibrations determines pitch.

– Higher pitched tones are produced only when the anterior portions vibrate and progressively lower tones as the length of the involved cords increases

Lower Respiratory Tract Larynx (Unpaired Cartilages)

Thyroid cartilage (Adams apple), superiorly attached to the hyoid bone

Cricoid cartilage, base of the larynx Epiglottis, made of elastic cartilage. Its inferior

margin is attached to the thyroid cartilage anteriorly and it superior part projects freely toward the tongue

Lower Respiratory Tract Larynx (Unpaired Cartilages)

Lower Respiratory Tract Larynx (Epiglottis)

During swallowing, the larynx elevates and the epiglottis moves posteriorly to cover the opening of the pharynx

Lower Respiratory Tract Larynx (Epiglottis)

Lower Respiratory Tract Larynx (Paired Cartilages)

Posterior side of the pharynx Cuneiform cartilage, superiorly located Corniculate cartilage, middle Arythenoid cartilage, inferiorly located and

articulated with the cricoid cartilage

Lower Respiratory Tract Larynx (Vocal Cords)

Ligaments Vestibular folds (false

vocal cords) Vocal cords (true vocal

cords)

Lower Respiratory Tract Larynx (Vocal Cords)

Lower Respiratory Tract Trachea

Membranous tube that consists of dense connective tissue and smooth muscle reinforced with “C” shaped cartilage

Trachealis muscle – contraction of this smooth muscle narrows the diameter of the trachea


Primary bronchi – trachea divides to form two smaller tubes.

Carina – the most inferior tracheal cartilage, which separates the opening into the two primary bronchi. It is very sensitive to mechanical stimulation and foreign objects reaching it will produce a powerful cough.

Lower Respiratory Tract Tracheobronchial Tree

Beginning with the trachea, all respiratory passageways– Main bronchi → lobar bronchi (2 left, 3 right) →

segmental bronchi (bronchopulmonary segments) → bronchioles → terminal bronchiole → respiratory bronchioles → alveolar duct → alveoli

Conducting zone: From the trachea to the terminal bronchioles

Respiratory zone: Extends from terminal bronchioles to alveoli

Lower Respiratory Tract Tracheobronchial Tree

Lower Respiratory Tract Tracheobronchial Tree (Alveoli)

The tissue surrounding the alveoli contain elastic fibers that allow the alveoli to expand and recoil.

Type I pneumocytes – form 90% of alveolar wall, gas exchange

Type II pneumocytes – secretory cells that produce surfactant


Respiratory membrane – of the lungs is where gas exchange between air and blood takes place.

To facilitate the diffusion of gases – Thin layer of fluid lining the alveolus – Alveolar epithelium simple squamous epithelium – Basement membrane of the alveolar epithelium – Thin interstitial space – Basement membrane of capillary endothelium – Capillary endothelium simple squamous epithelium


a = alveoli, with thin interalveolar septa between them

b = smooth muscle in its wall

c = blood vessel, filled with r.b.c.'s

d = bronchiole

Lower Respiratory TractLungs

Principal organs of respiration Hilum – region on the medial surface for entry and

exit of blood vessels, lymphatic vessels, nerves, and primary bronchus

Root of the lung – all structures passing through the hilum

Right lung has three lobes. Left lung has 2 lobes.

Lower Respiratory TractLungs

Muscles of Respiration

Diaphragm – dome shaped, attaches to the inner circumference of the inferior thoracic wall.

Inspiration – diaphragm, external intercostals pectoralis minor, and scalenes.

Expiration – diaphragm, abdominal muscles and internal intercostals.

Muscles of Respiration

Respiratory Physiology (Ventilation)

The process of moving air into and out of the lungs. The flow of air into the lungs requires a pressure

gradient from the outside of the body to the alveoli.

Airflow from the lungs requires a pressure gradient in the opposite direction. – Movement of air into and out of the lungs results from

changes in thoracic volume, which causes changes in alveolar pressure


Atmospheric Pressure (Patm) - pressure exerted by the air surrounding the body. At sea level its equal to 760mmHg. For our purposes, we'll assume it to be constant and assign it a value of 0mmHg.


Intrapulmonary Pressure (Palv) - pressure exerted by the air within the alveoli. It rises and falls during inspiration and expiration, but it always equalizes with atmospheric pressure.


Intrapleural Pressure (Pip) - pressure within the pleural cavity. It is always lower than both atmopsheric pressure and intrapulmonary pressure.

Respiratory Physiology

Lung recoil - causes the alveoli to collapse and it results from

1. Elastic recoil caused by the elastic fibers in alveolar walls.

2. Surface tension of the film of fluid that lines the alveoli.

Respiratory Physiology

Surfactant - mixture of lipoprotein molecules form a layer over the surface of the fluid within the alveoli to reduce surface tension. – Significantly reduces the tendency of the lungs to

collapse.

Respiratory Physiology (Gas Exchange)

The factors that influence the rate of gas diffusion across the respiratory membrane include

1. Thickness of the membrane. Increasing membrane thickness decreases

diffusion– Ex. Pulmonary edema, TB, Pneumonia

Respiratory Physiology (Gas Exchange) Pulmonary edema

Respiratory Physiology (Gas Exchange) Pulmonary edema

CXR 51 year old male with

shortness of breath. bilateral parahilar

infiltrates


2. Surface area Healthy normal individuals 70 square meters Decreases in area caused by diseases

– Ex. Emphysema, lung ca.

Respiratory Physiology (Gas Exchange) Emphysema

CXR 65 y/o female with a

120 pack year history of tobacco use. – hyperaerated lungs

– flattened diaphragms

– narrow heart shadow

– widened rib spaces

– decreased vascular markings


3. Partial pressure difference The difference between the partial pressure of the

gas in the alveoli and the partial pressure of gas in the blood of the pulmonary capillaries.

Pressure gradient diffuses from high to low.

Respiratory Physiology (Gas Exchange) Partial Pressure Difference

Respiratory Physiology (Gas Transport)

1. Molecular oxygen is carried in blood– 98.5% bound to hemoglobin

– 1.5% in plasma.

Binds in a reversible fashion.

2. Carbon dioxide is transported in three major ways – 7% is transported dissolved in plasma.

– 23% transported in combination with blood proteins.

– 70% transported in the bicarbonate form.

Binds in a reversible fashion.


3.Haldane effect – hemoglobin that has released its oxygen binds more readily to carbon dioxide than hemoglobin that has oxygen bound to it.

4. Chloride shift – Bicarbonate ion concentration inside RBC’s are lowered by exchanging them for chloride ions. As bicarbonate ions are produced, carrier molecules in RBC membranes move bicarbonate ions out of the RBC’s and chloride ions into the cell.


4. Chloride shift – Bicarbonate ion concentration inside RBC’s are lowered by exchanging them for chloride ions. As bicarbonate ions are produced, carrier molecules in RBC membranes move bicarbonate ions out of the RBC’s and chloride ions into the cell.

Regulation of Respiration (CNS)

CNS Medullary respiratory system – dorsal

portion of medulla oblongota, and ventral portion. – Although the dorsal and ventral respiratory

groups are bilateral, cross communication does exist, so that respiratory movements are symmetrical


Dorsal respiratory system is most active during inspiration but is responsible for stimulation of the diaphragm.

Ventral respiratory group is active during both inspiration and expiration. Stimulate the external and internal intercostals, and abdominal muscles.

Pontine Respiratory group – neurons in the pons, some are active in expiration or inspiration and/or both.

Regulation of Respiration

(Cerebral and Limbic System Control) Possible to voluntarily or involuntarily to control

rate of breathing through the cerebral cortex.

Apnea – absence of breathing.

Voluntary apnea increases a greater and greater urge to breathe due to increasing PCO2 levels.

Regulation of Respiration (Chemical Control of Ventilation)

The Chemoreceptors involved with the regulation of respiration responds to changes in hydrogen ion concentration and PO2, or both.

Chemosensitive areas are located in the medulla oblongota.

Peripheral Chemoreceptors are found in the carotid and aortic bodies.

Regulation of Respiration (Effect of pH)

Chemosensitive area of the medulla oblongota is bathed in cerebrospinal fluid and is sensitive to changes in pH.

The chemosensitive area reacts indirectly to change in blood pH.

Carbon dioxide levels change pH. Respiratory system plays an important role in

acid-base balance.

Regulation of Respiration (Effect of Carbon Dioxide)

The major regulator of respiration.

Hypercapnia – greater than normal levels of carbon dioxide in the blood.

Hypocapnia – lower than normal carbon dioxide levels.

Regulation of Respiration (Effect of Carbon Dioxide)

Regulation of Respiration (Effect of Oxygen)

Hypoxia – decrease in oxygen levels below normal levels.

The effect of oxygen concentration in the blood has a small role in regulation of respiration.

O2-Hemoglobin Dissociation CurveDescribes the percentage of hemoglobin saturated with oxygen at any

given PO2

Revised ScheduleMaySat 20 - Respiratory System

- Digestive and GI System

Sun 21 - Urinary System & Acid Base Balance

Sat 27 Midterms!!!

- Reproductive System (Male and Female)- Endocrine System

Sun 28 - Nervous SystemsPreceptorials 2

JuneSat 3 Pre-final Review Sun 4 Finals!!! All schedules are subject to

changes

the respiratory system

Documents

partial pressure difference

nasal cavity

partial pressure

vocal cords

pressure gradient

carrier molecules

normal levels

carbon dioxide