CGIER 27 - Respiratory system: Pathways and Mechanism Flashcards
What is the function of aerobic respiration and what does it require?
Aerobic respiration is highly effective at producing ATP from glucose but requires a steady supply of O2
what is the product of glycolysis?
pyruvic acid
requires 2 ATP
What is produced after glycolysis if oxygen is not present and what process occurs?
lactic acid
ethanol
fermentation (fermentation)
What is process occurs when oxygen is present after glycolysis?
krebs cycle use 36 ATP
oxidative phosphorylation
Three distinct stages of respiratory system?
External respiration
Internal respiration
Gas transport
External respiration
transfer oxygen into blood from atmosphere
Internal respiration
cellular respiration O2 uptake and CO2 production within cell
gas transport
transport of O2 and CO2 in the blood. (through blood stream through capillary beds in cells)
homiotherms
- warm blooded animals, can maintain their own body temperature
- have high oxygen requirements
Function of respiratory system
supply oxygen to body
remove CO2 from body
Level of respiration depends on…
metabolic activity - oxygen requirement
phayrnx
The back of the nasal cavities is continuous with the pharynx.
-An opening in the floor of the pharynx leads to the larynx
what does larynx contain?
contains the vocal cords, cartilage embedded in its wall prevents the larynx from collapsing
what is the epiglottis and what is its function?
flap that automatically closes off the larynx during swallowing so that food and liquid enter the oesophagus rather than the lower airway
constituents of the pharynx
nasopharynx(top)
oropharynx (middle)
laryngopharynx (bottom)
common infections in upper respiratory system
Common Cold Sore throat Earache Blocked sinuses Nasal Congestion
what type of infection is commonly found in upper respiratory tract
viral but can be bacterial
viruses that infect upper respiratory tract
rhinovirus
influenza
bocavirus
lower respiratory tract
starts at trachea bronchus bronchioles terminal bronchioles alveolar sacs
where can we find hyaline cartilage in the lower respiratory system and why is it present
in trachea and bronchi
used to prevent it from closing in on itself
what kind of cells are found in the inner lining of epithelium of bronchus
mucous secreting goblet cells
what kind of epithelium is in the trachea, bronchi and bronchioles
ciliated epithelium - pushes the mucous secreted by goblet cells to assist in cough reflex
type of lining in the alveolus and its purpose
is lined by an extremely thin, single layer of epithelial cells. Allows gases to diffuse freely through the walls of the alveolus and into the capillaries that surround it.
what are the 2 thin cell layers between alveolus and capillary
epithelium of alveolar wall and endothelium of capillary wall
2 cell types of alveolar walls
Type I pneumocyte
Type II pneumocyte
Type I pneumocyte
pulmonary epithelium. These cells are extremely thin to allow for gas exchange, endothelium thickness = 0.5µm
Type II pneumocyte
secretes surfactant.
Surfactant = a phospholipid acts as detergent and reduces surface tension - allows alveolus to open and prevents it from collapsing
respiratory distress syndrome in premature babies
premature babies (under 32 weeks) have not fully developed type II pneumocytes lung expansion is difficult insufficient surfactant - surface tension won't allow alveoli to expand
causes of respiratory distress syndromw
baby is delivered early
lungs are one of the last organs to fully develop as they are not needed until birth
how is respiratory distress syndrome in premature babies treated?
put on a mechanical ventilator - forced expansion
oxygen therapy - increased conc. of oxygen
synthetic or natural surfactants are given
how many lobes do the left and right lung both have
left - 2 lobes
right - 3 lobes
why is the left lung smaller than the right lung
left lung is smaller to make space for heart - left lung has cardiac notch
components of thoracic cage
anterior sternum
posterior spinal column
rib cage
diaphragm
what are the lungs covered by?
by visceral pleura (inner)
parietal pleura
contains fluid inbetween linings
what do pleural walls secrete
secrete serous membrane
infection of serous membrane in pleural walls is called
pleurisy
pressure in intrapleural space in lungs
-4 mm Hg
less than atmospheric pressure and alveolar pressure
acts as suction to keep lungs inflated
what causes the lungs to collapse?
when the intrapleural pressure in lungs is 0 - no suction
allows lungs to contract
- a lot of elastic tissue in the lungs
pneumothorax - intrapleural pressure during expiration and inspiration
exp. = -2 mm Hg
insp. = -6 mm Hg
3 processes during inspiration
(active) The diaphragm contracts - less convex, flat and low the intercostal muscles - short muscles that lie between the ribs
external intercostal muscles - contract - ribs go outward and upwards - push sternum out - increase volume
processes of expiration
passive - elastic recoil
diaphragm and intercostal muscle relax
diaphragm - rises and becomes convex again
chest wall falls inward
reduced volume in chest cavity - raise in pressure
respiratory centre in the brain
medulla and pons
respiratory centre - medulla
dorsal respiratory group - stimulates inspiratory movements
ventral respiratory groups - stimulates expiratory movements
3 respiratory groups of neurons in respiratory centre
dorsal respiratory group(medulla)
ventral respiratory group(medulla)
pontine respiratory group (pons)
pons - respiratory centre
pontine respiratory group has 2 groups
- pneumatoxic centre - sends inhibitory signals to inspiratory centre of medulla
- apneustic centre - stimulates the inspiratory neurons of dorsal and ventral groups
chemical regulation - chemosensory area
in medulla sensitive to CO2 and H+ conc. - drop in pH
high levels cause excitation of inspiratory area
chemoreceptors - chemical regulation
in carotid and aortic bodies
sensitive to PO2 conc. - oxygen conc
decreased PO2 send impulse to inspiratory via vagus X and glossopharyngeal IX
Basic rhythm generated by …
neuronal oscillatory circuit in inspiratory area
Hering- Breuer reflex
stretch receptors in lung tissue, bronchi, bronchioles may on activation transmit inhibitory signal via the vagus nerve (X) to the inspiratory area; prevents over-inflation of the lung
path of inspiration
inspiratory circuit fires(2 seconds)
nerve impulse
diaphragm and external intercostal muscle contract
inspiration
path of expiration
inspiratory circuit dormant 3 seconds
expiratory area dormant
expiration by default
