The respiratory The respiratory systemsystem

Dhruvit KalathiyaVishal MangukiyaSuvik PatelRuchit ParmarSunil Prasad

The respiratory systemThe respiratory system

Learning objectivesLearning objectivesWhat we will learn in this presentation:

The structures of the respiratory system and their functions

The mechanisms of breathing

How gases are exchanged during breathing

The composition of inhaled and exhaled air

The different measurements of lung capacity and breathing

The effects of exercise on the respiratory system

What is meant by aerobic and anaerobic respiration

The nasal passages and The nasal passages and lungslungs

Air is drawn into the body via the nose or mouth. There are advantages to breathing through your nose:

Air then travels through the larynx, trachea (windpipe), bronchi (one bronchus to each lung) and bronchioles to the alveoli, where oxygen passes into the bloodstream.

the air is warmed so that it is closer to body temperature

tiny hairs and mucus in the nose filter the air, preventing larger dust and pollen particles reaching the alveoli

mucus moistens the air, making it easier for the alveoli to absorb.

PharynxPharynx Common space used by both the respiratory and digestive

systems. Commonly called the throat. Originates posterior to the nasal and oral cavities and extends

inferiorly near the level of the bifurcation of the larynx and esophagus.

Walls are lined by a mucosa and contain skeletal muscles that are primarily used for swallowing.

Partitioned into three adjoining regions: nasopharynx oropharynx

laryngopharynx

LarynxLarynx

Voice box is a short, somewhat cylindrical airway ends in the trachea.

Prevents swallowed materials from entering the lower respiratory tract.

Conducts air into the lower respiratory tract. Produces sounds. Muscular walls aid in voice production and the swallowing

reflex Glottis – the superior opening of the larynx Epiglottis – prevents food and drink from entering airway

when swallowing pseudostratified ciliated columnar epithelium

When you breathe in:

intercostal muscles between the ribs contract, pulling the chest walls up and out

the diaphragm muscle below the lungs contracts and flattens, increasing the size of the chest

the lungs increase in size, so the pressure inside them falls. This causes air to rush in through the nose or mouth.

Mechanisms of breathing – Mechanisms of breathing – inspirationinspiration

Diaphragm contracts

and moves down

Intercostal muscles pull

ribs up and out

Mechanisms of breathing – Mechanisms of breathing – inspirationinspiration

Mechanisms of breathing – Mechanisms of breathing – expirationexpiration When you breathe out:

Intercostal muscles between the ribs relax so that the chest walls move in and down.

The diaphragm muscle below the lungs relaxes and bulges up, reducing the size of the chest.

The lungs decrease in size, so the pressure inside increases and air is pushed up the trachea and out through the nose or mouth.

Diaphragm relaxes and bulges up

Ribs move in and down

Mechanisms of breathing – Mechanisms of breathing – expirationexpiration

Gas exchange at the Gas exchange at the alveolialveoli

The alveoli are bunches of tiny air sacks inside the lungs.

Each individual sack is called an alveolus.

When you breathe in, they fill with air.

The alveoli are covered in tiny capillaries (blood vessels).

Gases can pass through the thin walls of each alveolus and capillary, and into the blood stream.

Gases can also pass from the blood stream, into the alveolus.

Gas exchange at the Gas exchange at the alveolialveoli

Composition of inhaled and Composition of inhaled and exhaled airexhaled air

GasAmount in inhaled air

Amount in exhaled air

Oxygen 17%

Carbon dioxide 3%

Nitrogen 79%

Water vapour Small amount Large amount

17%

21%

Very small amount

79%

Measuring breathingMeasuring breathingTidal volume is the amount you breathe in and

out in one normal breath.

Residual volume is the amount of air left in your lungs after you have breathed out as hard as you can.

Minute volume is the volume of air you breathe in one minute.

Respiratory rate is how many breaths you take per minute.

Vital capacity is the maximum volume of air you can breathe out after breathing in as much as you can.

Breathing during exerciseBreathing during exercise

During exercise the muscle cells use up more oxygen and produce increased amounts of carbon dioxide.

Your lungs and heart have to work harder to supply the extra oxygen and remove the carbon dioxide.

Your breathing rate increases and you breathe more deeply.

Heart rate also increases in order to transport the oxygenated blood to the muscles.

Breathing during exerciseBreathing during exerciseMuscle cell respiration increases – more oxygen is used up and levels of CO2 rise.

The brain detects increasing levels of CO2 – a signal is sent to the lungs to increase breathing.Breathing rate and the volume of air in

each breath increase. This means that more gaseous exchange takes place.

The brain also tells the heart to beat faster so that more blood is

pumped to the lungs for gaseous exchange.

More oxygenated blood gets to the muscles and more CO2 is removed.

Breathing changes Breathing changes during exerciseduring exercise

During rest During exercise

Respiratory rate 14 breaths/ minute 32 breaths/ minute

Volume per breath

0.4 litres 2.4 litres

Look at these statistics for a 16 year-old athlete:

RespirationRespiration

Glucose from food is used to fuel exercise.

Respiration is the process that takes place in living cells which releases energy from food molecules.

Waste products, including carbon dioxide, are produced as a result of the chemical reactions. These must be removed and excreted.

glucoseoxygen

energy

respirationOxygen is required to ‘break down’ the glucose to produce energy. This energy is used to make muscles contract.

Aerobic respirationAerobic respiration

Aerobic exercise can be maintained for long periods without the performer getting breathless or suffering muscle cramps. Moderate activities like walking, jogging, cycling and swimming use aerobic respiration.

There are two different types of respiration.

When you exercise at a steady, comfortable rate, the cardiovascular system is able to supply the muscles with all the oxygen they need.

Under these conditions, aerobic respiration takes place.

glucose + oxygen energycarbon dioxide+ + water

Anaerobic respirationAnaerobic respiration

When you exercise at a high intensity, the cardiovascular system cannot supply enough oxygen to the muscles.

Under these conditions, anaerobic respiration takes place.

With no oxygen available, glucose is burned to produce energy and lactic acid.

Lactic acid is a mild poison. As it builds up, it causes muscle pain and eventually cramp.

Short, intense activities like sprinting, weightlifting, jumping and throwing use anaerobic respiration.

glucose energy + lactic acid

21

you might want to think twice about you might want to think twice about smoking….smoking….

Respiratory Respiratory diseasesdiseases

ObjectivesObjectives

1. Antihistamines2. Decongestants3. Antitussives4. Expectorants5. Bronchodilators

DecongestantsDecongestants

Nasal CongestionNasal Congestion

Excessive nasal secretions

Inflamed and swollen nasal

mucosa

Primary causes

◦Allergies

◦Upper respiratory infections

(common cold)

Decongestants: Types Decongestants: Types (cont’d)(cont’d)

Two dosage forms

Oral

Inhaled/topically applied to the nasal

membranes

Oral DecongestantsOral DecongestantsProlonged decongestant effects,

but delayed onsetEffect less potent than topical No rebound congestionExclusively adrenergicsExample: pseudoephedrine,

Sinutab, Dristan, Tylenol cold, Sudafed

Topical Nasal Topical Nasal DecongestantsDecongestantsTopical adrenergics

◦ Prompt onset◦ Potent◦ Sustained use over several days causes

rebound congestion, making the condition worse

◦ Eg:

Topical Nasal Topical Nasal Decongestants (cont’d)Decongestants (cont’d)Adrenergics

◦desoxyephedrine◦phenylephrine

Intranasal steroids◦beclomethasone dipropionate ◦flunisolide ◦fluticasone

Nasal Decongestants:Nasal Decongestants:Mechanism of ActionMechanism of ActionSite of action: blood vessels surrounding nasal sinuses Adrenergics

◦ Constrict small blood vessels that supply URI structures

◦ As a result these tissues shrink, and nasal secretions in the swollen mucous membranes are better able to drain

◦ Nasal stuffiness is relieved

Nasal Decongestants:Nasal Decongestants:Mechanism of Action (cont’d)Mechanism of Action (cont’d)Site of action: blood vessels surrounding nasal sinuses Nasal steroids

◦ Anti-inflammatory effect◦ Work to turn off the immune system cells

involved in the inflammatory response◦ Decreased inflammation results in

decreased congestion◦ Nasal stuffiness is relieved

Nasal Decongestants: Nasal Decongestants: IndicationsIndicationsRelief of nasal congestion associated with: Acute or chronic rhinitis Common cold Sinusitis Hay fever Other allergies

Nasal Decongestants: Nasal Decongestants: Indications (cont’d)Indications (cont’d)

May also be used to reduce swelling

of the nasal passage and facilitate

visualization of the nasal/pharyngeal

membranes before surgery or

diagnostic procedures

Nasal Decongestants: Nasal Decongestants: Side EffectsSide Effects

Adrenergics SteroidsNervousness Local mucosal drynessInsomnia and irritationPalpitationsTremors(systemic effects due to adrenergic stimulation of theheart, blood vessels, and CNS)

AntitussivesAntitussives

Antitussives: DefinitionAntitussives: Definition

Drugs used to stop or reduce

coughing

Opioid and nonopioid

(narcotic and nonnarcotic)

Used only for nonproductive

coughs!

Antitussives: Antitussives: Mechanism of ActionMechanism of ActionOpioidsSuppress the cough reflex by direct

action on the cough centre in the medullaExamples:◦ codeine ◦ hydrocodone

Antitussives: Antitussives: Mechanism of Action (cont’d)Mechanism of Action (cont’d)NonopioidsSuppress the cough reflex by

numbing the stretch receptors in the respiratory tract and preventing the cough reflex from being stimulatedExamples:◦Dextromethorphan, Nyquil,

Robitussin

Antitussives: IndicationsAntitussives: Indications

Used to stop the cough reflex when the cough is nonproductive and/or harmful

Antitussives: Side EffectsAntitussives: Side Effects

DextromethorphanDizziness, drowsiness, nausea

OpioidsSedation, nausea, vomiting,

lightheadedness, constipation

ExpectorantsExpectorants

Expectorants: DefinitionExpectorants: Definition

Drugs that aid in the

expectoration

(removal) of mucus

Reduce the viscosity of

secretions

Disintegrate and thin secretions

Expectorants: Expectorants: Mechanisms of ActionMechanisms of ActionDirect stimulationReflex stimulation

Final result: thinner mucus that is easier to remove

Expectorants: Expectorants: Mechanism of Action (cont’d)Mechanism of Action (cont’d)Reflex stimulationAgent causes irritation of the GI tractLoosening and thinning of respiratory tract

secretions occur in response to this irritation◦ Example: guaifenesin

Expectorants: Expectorants: Mechanism of Action (cont’d)Mechanism of Action (cont’d)Direct stimulationThe secretory glands are stimulated directly

to increase their production of respiratory tract fluids◦ Examples: iodine-containing products such

as iodinated glycerol and potassium iodide

Expectorants: IndicationsExpectorants: Indications

Used for the relief of nonproductive coughs associated with:

Common coldBronchitisLaryngitisPharyngitisCoughs caused by chronic paranasal sinusitis

PertussisInfluenzaMeasles

Bronchial AsthmaBronchial AsthmaRecurrent and reversible shortness of breath

that occurs when the bronchi and bronchioles become narrow as a result of bronchospasm, inflammation, and edema of the bronchial mucosa, and the production of viscid (sticky) mucous.

Symptoms• wheezing, • shortness of breath, • chest tightness, • coughing.Asthma is caused by inflammation in the

airways. When an asthma attack occurs, the muscles surrounding the airways become tight and the lining of the air passages swells. This reduces the amount of air that can pass by.

AsthmaAsthmaMay be triggered by virusesIrritantsAllergensCan develop at any ageSeen more often in children who

are exposed to airway irritants during infancy

AsthmaAsthmaBronchoconstrictionInflammationMucosal edemaExcessive mucous

ClassificationClassification1.BronchodilatorsA . β2 Sympathomimetics : Salbutamol,Terbutaline,Bambuterol,Salmetrol,Formoterol,Ephedrine.

B . Methylxanthines : Theophylline, Aminophylline, Choline theophyllinate, Hydroxyethyl theophylline, Theophylline ethanolate of piperazine,Doxophylline

C . Anticholinergics :

Ipratropium bromide, Tiotropium bromide.

ClassificationClassification2.Leukotriene antagonists : Montelukast, Zafirlukast.3.Mast cell stabilizersSodium cromoglycate, Ketotifen4.Corticosteroidsa.Systemic : Hydrocortisone,Prednisolone and

others.b.Inhalational : Beclomethasone dipropionate,

Budesonide, Fluticasone propionate, Flunisolide, Ciclesonide.

5.anti-IgE antibodyOmalizumab

Salbutamol(Salbutamol(ββ2 2 sympathomimetics)sympathomimetics)Machanism of action :A highly selective β2 agonistCause bronchodilation through β2 receptor

stimulationIncreased cAMP formation in bronchial

muscle cellRalaxationIn addition,increased cAMP in the mast cells

and other inflammatory cells decreases mediator release

SulbutamolSulbutamolSelectivity is further incresed by inhaling the

drugInhaled salbutamol produces bronchodilation

within 5 min and action lasts for 2-4 hours…therefor it is used to abort and terminate attacks of asthma,but not suitable for the round the clock prophylaxis.

Side effectSide effect

Muscle tremorsPalpitationRestlessnessNervousnessThroat irritationAnkle edema

Dose2-4 mg oral,0.25-0.5 mg i.m./s.c., 100-200 µg by inhalation

Theophylline(methylxanthTheophylline(methylxanthines)ines)Mechanism of action :Increase levels of energy-producing cAMP*This is done competitively inhibiting

phosphodiesterase (PDE), the enzyme that breaks down cAMP

Result: smooth muscle relaxation, bronchodilation, and increased airflow

*cAMP = cyclic adenosine monophosphate

Side effectSide effect

Nausea, vomiting, anorexiaGastroesophageal reflux during sleepSinus tachycardia, extrasystole,

palpitations, ventricular dysrhythmiasTransient increased urination

Dose

100-300 mg TDS (15 mg/kg/day)

Anticholinergics: Anticholinergics: Mechanism of ActionMechanism of ActionAcetylcholine (ACh) causes bronchial

constriction and narrowing of the airways.Anticholinergics bind to the ACh

receptors, preventing ACh from binding.Result: bronchoconstriction is prevented,

airways dilate.

Side EffectsSide Effects

Dry mouth or throat

Gastrointestinal distress

Headache

Coughing

Anxiety

AntileukotrienesAntileukotrienes

Currently available agents:montelukast (Singulair)zafirlukast (Accolate)zileuton (Zyflo)

Antileukotrienes: Antileukotrienes: Mechanism of ActionMechanism of ActionLeukotrienes are substances released

when a trigger, such as cat hair or dust, starts a series of chemical reactions in the body.

Leukotrienes cause inflammation, bronchoconstriction, and mucus production.

Result: coughing, wheezing, shortnessof breath

Antileukotriene agents Antileukotriene agents preventprevent leukotrienes leukotrienes from attaching to receptors on cells in the lungs from attaching to receptors on cells in the lungs and in circulation.and in circulation.

Inflammation in the lungs is Inflammation in the lungs is blockedblocked, and asthma , and asthma symptoms are relieved.symptoms are relieved.

Side Effects

HeadacheDyspepsiaNausea DiarrheaDizzinessInsomniaLiver dysfunction

Corticosteroids: Corticosteroids: Mechanism of ActionMechanism of ActionStabilize membranes of cells that

release harmful bronchoconstricting substances.

These cells are leukocytes, or white blood cells.

Also increase responsiveness of bronchial smooth muscle to beta-adrenergic stimulation.

Inhaled CorticosteroidsInhaled Corticosteroidsbeclomethasone dipropionate

(Beclovent, Vanceril)triamcinolone acetonide

(Azmacort)dexamethasone sodium

phosphate (Decadron Phosphate Respihaler)

flunisolide (AeroBid)

Side EffectsSide EffectsPharyngeal irritationCoughingDry mouthOral fungal infections

MucolyticsMucolytics

Agents which breakdown the mucus.

Examples:- Ambroxol, Bromhexine

Ambroxol Bromhexine

Amcold (Brand Name)Cipla Ltd (Company

Name)

Ascoril (Brand Name)Glenmark Ltd

(Company Name)

ExpectorantExpectorantDrugs Which helps in expelling out mucus.

Examples:- Guaifenesin, Potassium Iodide

Guainfenesin Potassium Iodide

Barkeit (Brand Name)Unisankyo Ltd

(Company Name)

Betadine (Brand Name)

Win Medicare Ltd (Company Name)

Cough Cough SuppressantSuppressant

Drugs used to suppress the cough specially used in dry cough.Examples:- Codeine phosphate, Dextromethorphan

Codeine Dextromethorphan

Corex (Brand Name)Pfizer Ltd (Company

Name)

Alex Lozenge (Brand Name)

Glenmark Ltd (Company Name)

Guided By:Mr. Prashant Pandey

Reference:Medical Pharmacology by K.D.TripathiEdition 6th.