Respiratory System Physiology Flashcards
types of epithelium in the lungs
columnar epithelium —> stratified epithelium with mucosy material that traps small particles in microns
what types of particles get through the layers?
silica, bugs, and bacteria that are too small to be trapped go through the air space
functions of lung
-gas exchange- take in O2 for body to function and exhale CO2
-filter inspired air
-defends against inhaled particles
-immunological surveillance- lung is exposed to the outside environment
-peptide processing- produce and process peptides that regulate functions
what do we need to do to breathe?
-breathing is automatic but we can induce it consciously
-breathing center in brainstem and regulates ventilation
-circulation is automatic- transport O2 to the tissues and the CO2 away
-respiration is automatic and affected by the environment
breathing: the steps
-respiration is regulated by CO2 levels in the blood and is affected by low O2 levels but the primary is CO2 levels
-stimulus to start breathing
-lungs expand/muscle contracts and muscles are in the ribcage (intercostal muscle) and diaphragm (men use diaphragm more than women) —> creates negative pressure in chest and expands lung
-air comes in (higher in O2 than CO2)
-gets carried to alveoli and O2 gets diffused to capillaries
-O2 gets picked up by hemoglobin and CO2 will diffuse to alveolar space and when you exhale it gets removed
-pulmonary veins carry oxygen rich blood and carried to left ventricle and CO2 gets carried to lungs
-exhaled air with oxygen and CO2 goes out
-process begins again
anatomy
-respiratory bronchiole (last airway)- in the beginning they are lined by ciliated columnar epithelium then it flattens to cuboidal then flat
-in the alveolar duct you have flat epithelia, which branches into alveolar sacs that contain alveoli —> increases surface area
-capillaries are lined with endothelial cells that have a permeable cytoplasm and junctions between them
-permeability varies depending on conditions like if there is inflammation in the cytoplasm, the permeability will increase
how many cell types line aveolar spaces?
two types
type I pneumocytes
-flat cells in the cytoplasm that are difficult to see under a microscope and the nuclei are small
-basement membrane underneath
type II pneumocytes
-bigger and plumper so they are easier to spot and they produce surfactant, which decreases the tension of surfaces to keep them open
-basement membrane underneath
what are the layers air goes through?
air and cells travel through the cytoplasm —> basement membrane —> cytoplasm —> capillary space
what do macrophages do?
-air spaces have macrophages to clean up
-if one macrophage can’t do it, a bunch of them will fuse together to create one big macrophage
what are the types of giant cells?
osteoclasts, langerhan cells, and foreign body giant cells
arteriole wall
-airways, air spaces, and alveoli
-alveoli are composed of the alveolar wall, capillaries, and flat big cells called type I and type II pneumocytes
what do clinicians do for premature babies who do not produce enough surfactant?
-inject surfactant into them
-they can also give steroids to accelerate maturation of cells and supplemental O2 but have to be careful not to give too much O2 since that can be toxic
how does air travel from the terminal bronchioles?
respiratory bronchioles (lined by ciliated columnar epithelium) —> alveolar duct —> atrium —> alveolar sac (flat)
how do we decide to breathe?
central controller (brain stem) gives output to effectors (respiratory muscles), which send to sensors (chemoreceptors and stretch receptors) and they will give input back to the brainstem to increase/decrease breathing
central chemoreceptors
-from the capillaries, CO2, H+, and HCO3 will diffuse from the blood-brain barrier to the extracellular fluid and the chemoreceptors will react to the CO2 and pH environment
-receptors are located near the ventral surface of the medulla
-sensitive to the CO2 in the blood but not the O2
-chemoreceptors are based in CSF —> CO2 to get across to ECF then CSF to drop pH
CO2 and O2 stimulate ventilation
-as CO2 levels increase, they stimulate ventilation and the level of ventilation depends on the amount of O2 in the air
-in the presence of hypoxia, move in more air to get the same amount of O2 when there is less O2 in the air
-low pH can also mean that there is more CO2 in the blood
peripheral chemoreceptors
-located in the carotid and aortic bodies
-respond to decreased arterial PO2 and increased PCO2 and H+
-rapidly responding
-only receptors that respond to decreased arterial PCO2
-these will kick when you have high altitude or hypoxia since the central chemoreceptors are more sensitive to CO2
ventilatory response to hypoxia
-only the peripheral chemoreceptors are involved (not in the brain)
-there is neglible control during normoxic conditions
-control becomes important in chronic hypoxic situations like the Himalaya and long-term hypoxemia caused by chronic lung disease —> want to move in more air to get the same amount of O2
-brain allows you to have high CO2 and people need hypoxic drive to breathe
how do we move air into lungs?
-lung has airways and air spaces
-bronchus- areas with cartilage
-bronchioles- areas without cartilage
-peripheral lung has few bronchi
-terminal bronchioles split into respiratory bronchioles and into alveoli
how many layers are there to airways?
-23 levels
-go 16 branching to get to the terminal bronchiole
-go 6 or 7 levels of branching, each airway branches into 2-3 branches
-no respiration in the conduction zone —> dead space volume that is 150 mls vs the volume of the alveolar region being 2.5-3 liters
what does the space in airways do?
-does not participate in respiration
-conducts the air to alveolar space for respiration
-called the dead space
physiological dead space
-anatomical dead space- fairly constant and spans up to level 16
-alveolar dead space- varies and spans levels 17-19
-these together make up the physiological dead space