Lung structure + function
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Role of respiratory system
Ensure adequate intake of oxygen and removal of carbon dioxide
Name each structure of the lung
Name each part of an epithelial cell
Name each neurotransmitter + post-synaptic receptor for each nervous system
Alpha adrenoceptor subtypes
alpha1 alpha2
Beta adrenoceptor subtypes
beta1 beta2 beta3
Role of Alpha1 adrenoceptor
Vascular smooth muscle contraction
Role of Alpha2 adrenoceptor
Vascular smooth muscle contraction Prejunctional regulation of NA release
Role of Beta1 adrenoceptor
Sino-atrial node + ventricles in heart-rate Force of contraction
Role of Beta2 adrenoceptor
Airway smooth muscle relaxation
Role of Beta3 adrenoceptor
Skeletal muscle + adipose tissue
What are the muscarinic receptor subtypes?
M1, M2, M3, M4, M5
Role of M1 receptor
CNS Salivary glands Gastric glands
Role of M2 receptor
Heart - the rate of contraction GI smooth muscle contraction CNS
Role of M3 receptor
Salivary glands Smooth muscle (GI, airways)
Role of M4 receptor
CNS
Role of M5 receptor
CNS
Innervation of the airways
Sympathetic Parasympathetic Sensory nerves
How does the sympathetic nervous system affect airways?
Circulating adrenaline Act on Beta2-adrenoceptors on bronchial smooth muscle for relaxation Inhibitor of mediator release from mast cells Beta2-adrenoceptors on mucus glands to inhibit mucus secretion Increased clearance of mucus
How does the parasympathetic nervous system affect airways?
Release acetylcholine Activates muscarinic M3 receptors • causes bronchoconstriction • increase mucus secretion
How does sensory nerves affect airways?
local reflexes respond to irritants Causes: • coughing • bronchoconstriction • increased mucus secretion
Role of sensory nerves in exercise-induced asthma
What are cold receptors?
Other local control e.g. sensory nerves Detect changes in temperature On mast cells + airway epthelium + sensory nerves Involved in cold-induced asthma through activation of mast cells + mucus production
Causes of Breathlessness
congenital conditions e.g. cystic fibrosis infection inflammation cancer psychological lung degeneration cardiac e.g. heart failure pulmonary embolism pregnancy, obesity, altitude drug side effects (beta-blockers)