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• Basic functions of the respiratory system– Supplies body with oxygen– Disposes of carbon dioxide

• Four processes involved respiration– Pulmonary ventilation– External respiration– Transport of respiratory gases– Internal respiration

Name the Four processes involved in respiration?

conducting zone + respiratory zone = respiratory tract (airway)•The conducting zone :

– Nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles;

•The respiratory zone : – Respiratory bronchioles, alveolar duct and alveoli

Divided into Conducting zone & Respiratory zone

Give the function of respiratory zone? Give the function of

conducting zone?

Olfactory receptors are located in the mucosa on the superior surface

The rest of the cavity is lined with respiratory mucosa

Moistens air

Traps incoming foreign particles

Lateral walls have projections called conchae Increases surface area Increases air turbulence in

the air so as to trap small particulates in mucus.

play the greatest role in warming and humidifying air

The nasal cavity is separated from the oral cavity by the palate Anterior hard palate (bone)

Posterior soft palate (muscle)

• Funnel-shaped passageway• Connects nasal cavity and mouth• Divided into three sections by location

– Nasopharynx – superior region behind nasal cavity– Oropharynx – middle region behind mouth– Laryngopharynx – inferior region attached to larynx

• Type of mucosal lining changes along its length • Two types of tonsils in the oropharynx

– Palatine tonsils – in the lateral walls of the fauces – Lingual tonsils – covers the posterior surface of the tongue

• The oropharynx and laryngopharynx are common passageways for air and food

• Three functions– Voice production– Provides an open airway– Routes air and food into the proper channels

• Superior opening is– Closed during swallowing– Open during breathing

• Descends into the mediastinum• C-shaped cartilage rings keep airway open• Carina

– Marks where trachea divides into two primary bronchi

– Epithelium• Pseudostratified ciliated columnar

Right lungs divided into 3 lobes; Left lungs divided into 2 lobesTrachea divide into 2 primary bronchiTotal 5 secondary bronchi

Respiratory Tree Respiratory Tree DivisionsDivisions Primary bronchi

Secondary bronchi Tertiary bronchi Bronchiole Terminal bronchiole

• Consists of air-exchanging structures• Respiratory bronchioles – branch from terminal

bronchioles– Lead to alveolar ducts

• Lead to alveolar sacs• Alveolus• Gas exchange

Alveoli is functional unit of respiration that has the greatest surface area for exchangeIn an average adult lung there are 300,000,000 alveoli

Thin squamous epithelial layer lining alveolar walls

Pulmonary capillaries cover external surfaces of alveoli

Gas crosses the respiratory membrane by diffusion Oxygen enters the blood Carbon dioxide enters the alveoli

Macrophages add protection Surfactant coats gas-exposed alveolar surfaces

Type I Pneumocytes (epithelial cells)

Type II Pneumocytes (surfactant cells) Secrete surfactant Most important component

of surfactant is Phospholipid The phospholipid known as

surfactant reduces surface tension within the alveoli so they do not collapse during exhalation.

• Pleurae help divide the thoracic cavity – Central mediastinum – Two lateral pleural compartments

• A double-layered sac surrounding each lung– Parietal pleura– Visceral pleura

• Pleural cavity – Potential space between the

visceral and parietal pleuraeThe main function of the pleural membranes is to reduce friction

• Pulmonary arteries– Deliver oxygen-poor blood to the lungs

• Pulmonary veins– Carry oxygenated blood to the heart

• Innervation– Sympathetic, parasympathetic, and visceral

sensory fibers• Parasympathetic – constrict airways• Sympathetic – dilate airways

Pulmonary ventilation – moving air in and out of the lungs

External respiration – gas exchange between pulmonary blood and alveoli

Transport of Respiratory gas – Transport of oxygen and carbon dioxide via the bloodstream

Internal respiration – gas exchange between blood and tissue cells in systemic capillaries

The exchange of gases between alveolar air and the blood is external respiration

The exchange of gases between blood and tissue or cells is internal respiration

• Two phases of pulmonary ventilation– Inspiration – inhalation – Expiration – exhalation

• Volume of thoracic cavity increases– Action of the diaphragm

• Diaphragm contracts and flattens

– Action of intercostal muscles• Contraction raises the ribs

– Increases the lung volume– Decreases internal gas pressure

• Deep inspiration requires – Scalenes– Sternocleidomastoid– Pectoralis minor– Erector spinae – extends the back

Anatomy of the respiratory muscles

• Quiet expiration – chiefly a passive process– Inspiratory muscles relax– Diaphragm moves superiorly– Volume of thoracic cavity decreases– Pressure increases

• Forced expiration – an active process– Produced by contraction of

• Internal and external oblique muscles• Transverse abdominis muscles

Relaxation of the diaphragm causes thoracic volume to decrease and intrapulmonary pressure to increase

Contraction of the diaphragm causes thoracic volume to increase and intrapulmonary pressure to decrease

Characters Inspiration ExpirationAction of the diaphragm:

Diaphragm flattens Diaphragm dome-shaped

Action of intercostal muscles:

Contraction raises the ribs Relaxations lowers the ribs

Lung volume Increases the lung volume Decreases the lung volume

Internal gas pressure

Decreases Increases

What is the difference between inspiration and expiration?

• Partial Pressure– Each gas in atmosphere contributes to the entire

atmospheric pressure, denoted as P• Gases in liquid

– Gas enters liquid and dissolves in proportion to its partial pressure

• O2 and CO2 Exchange by DIFFUSION– PO2 is 105 mmHg in alveoli and 40 in alveolar

capillaries (blood)– PCO2 is 45 in alveolar capillaries (blood) and 40 in

alveoli

• Oxygen is 21% of atmosphere• 760 mmHg x .21 = 160 mmHg PO2• This mixes with “old” air already in alveolus to

arrive at PO2 of 105 mmHg• So normal PO2 of the alveolar air 105 mmHg• Carbon dioxide is .04% of atmosphere• 760 mmHg x .0004 = 0.3 mm Hg PCO2• This mixes with high CO2 levels from residual

volume in the alveoli to arrive at PCO2 of 40 mmHg• normal PCO2 of the capillary blood is 40 mmHg

The partial pressure of oxygen in arterial blood is approximately 100 mmHg

• Oxygen transport– 1.5% dissolved in plasma

– 98.5% bound to hemoglobin (Hb)

• Oxyhemoglobin is produced in greater amounts in the pulmonary capillaries than in systemic capillaries

Oxyhemoglobin Saturation Curve :higher PO

2 results in greater Hb saturation

How is oxygen transported in blood?

• Carbon dioxide transport:– ~9% dissolved in plasma– ~13% as carbamino compounds

• Most combined with Haemoglobin

– ~78% as Bicarbonate

– bulk of carbon dioxide carried in blood• CO2 + H2O H2CO3 H+ + HCO3

- (Bicarbonate)

Describe the different forms in which carbon dioxide is transported

Haldane effectInverse relationship between amount of Hb-O2 and CO2 carrying capacity of blood

Lung volumes and vital capacity Total Lung Volume: (~6000ml) Measurement: Spirometer Tidal Volume (~500 ml): Volume of air inhaled and

exhaled in a single breath

Inspiratory Reserve Volume (~3100 ml): The amount of air that can be inhaled beyond the tidal volume

Expiratory reserve volume (~1200 ml): the amount of air that can be forcibly exhaled (forced ventilation) beyond the tidal volume

Differentiate between inspiratory and expiratory reserve volume

Vital Capacity (~4800 ml): The maximal volume that can be exhaled after maximal inhalationVital Capacity = Tidal volume+ IRV+ ERV

Total lung capacity = vital capacity + residual volume

Residual volume (~1200 ml): the amount of air remaining in the lungs, even after a forceful maximal expiration

Dead Space Volume (Physiologic): The total amount of air that cannot be exchanged either because of disease or because it cannot reach an exchange site

What is the difference between residual and dead space volume

Respiratory control centers are located in the PONS & MEDULLA

Chemoreceptors in the respiratory centre in the brain stem’s medulla detect an increase in blood CO2 levels

Additional chemoreceptors on aorta and carotid artery monitor oxygen & blood acidity

The intercostal and phrenic nerves stimulates the diaphragm to contract increase the rate and depth of breathing

Describe the location and function of chemoreceptors?

Characters External Respiration Internal RespirationSite of occurrence At the respiratory surface At the cellular level

Exchange of gases Oxygen of air or water and carbon dioxide of blood

Oxygen of blood and carbon dioxide of cells

Nature Physical Process Physico-chemical process

Energy Food is not oxidized so no energy is produced

Food is oxidized in the mitochondria and energy is produced

Enzymes Not involved Large number of enzymes involved

What is the difference between internal and external respiration?

• Newborns – 40 to 80 respirations per minute

• Infants – 30 respirations per minute

• Age 5 – 25 respirations per minute

• Adults – 12 to 18 respirations per minute

• Rate often increases somewhat with old age

1. What is the basic function of Respiratory system? 2. Name the 4 processes involved in respiration? 3. Write the name and function of upper and lower respiratory tract? 4. Where do you find olfactory receptors? Nostrils or Nose5. Name the types of tonsils in the oropharynx? 6. Write the function of larynx? 7. What is the other name for Adam’s apple? Larynx8. Name the type of cartilage present in the trachea? C-shaped cartilage9. How many lobes are present in human lungs? 3 lobes in the right lungs

and 2 lobes in left lungs10.Name the functional unit of lungs? Alveoli 11.Write short notes on Pleurae? A double-layered sac surrounding each

lung (a) Parietal pleura (b) Visceral pleura12.Write about the innervations of lungs?

1. Parasympathetic – constrict airways2. Sympathetic – dilate airways

13. Describe the mechanism of expiration? 14. How is oxygen transported in blood? 15. How is carbon dioxide transported in blood? 16. Write short notes on: Vital capacity, Tidal Volume, Inspiratory Reserve

volume, Expiratory Reserve volume17. What is the total lung volume? ~6000 ml18. Name the instrument used for measuring lung function? Spirometer19. Which part of brain controls respiratory? Pons and Medulla oblongata20. How does brain regulates respiration?

Phrenic nerve to diaphragmIntercostal nerve to external intercostal musclesChemoreceptors on aorta and carotid artery

13. Which reflex involves a spasmodic contraction of the diaphragm- Hiccup

14. Which reflex is caused by local alveolar decreases in oxygen content? Yawn