structure and function of the respiratory system

componentss of urt

• nasal cavity

• oral cavity

• nasopharynx

• pharynx

• oropharynx

• epiglottis

• larynx trachea

• oesophagus

what is the diaphragm innervatd by

phrenic nerve- which is a somatic motor nerve

what are the external intercostal muscls innervated by

intercostal nerve

respiration in horses

• biphasic ventilation

• locomotion ventilation coupling

layers of the blood gas barrier

• surfactant

• tpe 1 alveolar epithelial cell

• basal laminar of epithelial cell

• connective tissue

• basal lamina of endothelial cell

• endothelial cell

• plasms

• rbc membrane

• 0.2-0.6 um thick

• large surface ae to volume

ficks law

rate of transfer of gas through a sheet of tissue is proportional to the tissue area and the difference in partial pressur ebetween the two sides and inversely proportional to the tissue thickness

oxygen transport in the blood

• most carried by haemoglobin in red blood cells

• 3 percent dissolved in plasma

• reversible binding o2 to heme- high po2 is binding, low po2 is release

anatomy of urt

• oesophagus lies dorsal to larynx

• trachea lies ventral to oesophagus

what is the blood gas barrier

• surfactant

• type 1 alveolar epithelial cell

• basal laminar of epithelial cell

• connective tissue

• basal lamina of endothelial cell

• endothelial cell

• plasma

• rbc membrane

• 0.2-0.6um thick

• large surface area to volume

diffusion of oxygen and carbon dioxide in the lung

• lower partial pressure in venous end compared to arterial end for oxygen

• vice versa for carbon dioxide

• move from an area of low to high partial pressure

diffusion of oxygen from capillary into tissue

• systemic arterial blood partial pressure 95mmHg

• Interstitial fluid 40mmHg

• large pressure difference meaning rapid diffusion

• partial pressure of blood leaving the capillaries drop

oxygen carriage in blood

• most carried by haemoglobin, some dissolved in plasma

• reversible binding oxygen to haem

• high po2 is binding, low po2 is release

carbon dioxide carriage in blood

• most as bicarbonate ion which is important for acid base balance

• some carried by Hb

• some dissolved in plasma

• reversible binding of carbon dioxide to amine radicals of Hb- carboaminohaemoglobin

importance of ventilation and perfusion

• to maintain proper concentrations of oxygen, carbon dioxide and hydrogen ion concentration in tissues

features of the upper respiratory system

• respiratory epithelium- nose to terminal bronchioles, lined by mucus which keeps epithelium moist and traps small particles

• cilia beats mucus towards the pharynx

• nasal cavity warms, humidifies and filters air, turbulent precipitation

features of the lower respiratory tract

• CONDUCTING ZONE

• structural support (cartilage which decreases as descend to lower levels)

• modulation of airway diameter (smooth muscle)

• defence ( mucociliary escalator, mucus production by goblet cells and glands, ciliated epithelium

• RESPIRATORY ZONE

• gas exchange (type 1 pneumocytes- very thin, and capillaries in intimate contact with air spaces)

• redistribution of ventilation (limited smooth muscle)

• maintain open alveoli (type 2 pneumocytes- produce surfactant)

pleural cavity

• is a potential space between the paritiel and visceral pleura

• contains small volume of serous fluid which helps lubrication

• surrounds lungs in the thoracic cavity

• is a vaccum

• negative pressure essential to pull lungs out when ribcage and diaphragm expand thoracic cavity

the pleura

visceral plura

• attached to surface of lung inc fissures

• elastic fibres

• continuous with paritiel at the hilium

parietal pleura

• covers internal suface of thoracic cavity

• mediastinal- lines mediastinum

• costal- lateral wall of rib cage

• cervical- extension of pleural cavity into neck

• diaphragmic- lines cranial surface of diaphraghm