Topic 4: The Respiration Flashcards
What is the primary function of the respiratory system?
obtain OXYGEN, eliminate CARBON DIOXIDE
What are other important functions besides respiration of the respiratory system? (5)
- filters, warms and moistens incoming air
- maintains blood pH
- produces sound
- assists in olfaction
- helps return blood to the heart
What is Dalton’s Law of Partial Pressures?
gases move independently down their partial pressure gradients, from higher to lower pressure
What is the expression for partial pressure?
partial pressure exerted by each gas in a mixture equals the total pressure times the fractional composition of that gas in the mixture
What is the partial pressures in atmosphere?
- nitrogen (597.4 mmHg)
- oxygen (158.8 mmHg)
- carbon dioxide (0.3 mmHg)
- other gases (3.5 mmHg)
Total: 760.0 mmHg
How do fish breathe underwater?
fish gills use a countercurrent exchange system, where blood flows in the opposite direction to water passing over the gils; blood is always less saturated with O2 than the water meets
What are the two aspects to respiration?
- external respiration
- internal respiration
What happens during external respiration? (3)
- ventilation or gas exchange between the atmosphere and alveoli in the lungs
- exchange of O2 and CO2 between air in the alveoli and the blood
- transport of O2 and Co2 between the lungs and the tissues
What happens during internal respiration?
exchange of O2 and CO2 between the blood and the tissues
What are the two anatomical (and functional) divisions of the respiratory system?
- upper respiratory tract
- lower respiratory tract
What organs makeup the upper respiratory tract?
- nose
- pharynx
- larynx
What is the function of the upper respiratory tract?
warms, moistens and filters air
What organs makeup the lower respiratory tract?
- trachea
- bronchi
- bronchioles
- lungs
What is the function of the lower respiratory tract?
allows oxygen to enter the blood and carbon dioxide to leave the blood
What is the structure of the trachea?
- 5 inch tube that connects the larynx to the bronchial tree
- muscular walls are embedded with 16 to 20 “C”-shaped pieces of cartilage
What happens during tracheotomy?
the trachea is opened between two “C” rings to bypass the larynx and allow access to the lungs
What is the bronchial tree?
- the trachea splits into two primary bronchi, which lead to each lung
- the primary bronchi(s) divide into secondary bronchi
- branching continues, leading to smaller and smaller tubes (tertiary, bronchioles, terminal)
How large are the lungs?
fill the rib cage, extending from the diaphragm to the collar bone
What is the difference between the right and left lung?
- the right lung is shorter and wider and has three lobes
- the left lung is thinner, has two lobes and the cardiac notch
What is the pleural sac?
a thin sac that allows the lungs to expand and contract without tearing the delicate respiratory tissues
What are the two types of pleural sacs?
- visceral pleura
- parietal pleura
What is the visceral pleura?
stuck to the lungs
What is the parietal pleura?
stuck to the thoracic wall (ribs)
What is intrapleural fluid?
secreted by surfaces of the pleura that lubricates pleural surfaces
What is pleurisy?
inflammation of the pleural sac
Where are the lungs locates?
in the fairly rigid thoracic cavity
What is the difference between the lungs and thoracic cavity?
lungs are smaller than the thoracic cavity but are very elastic and are slightly stretched under normal conditions
What happens to the lungs in slight negative pressure?
the intrapleural space “glues” the outside of the lung to the inside of the thoracic pressure
What is the pressure of the alveoli?
760 mmHg
What is the pressure of the thoracic cavity?
760 mmHg
What is the pressure of the pleural sac?
756 mm
Why are lungs stuck to visceral pleural?
the transmural pressure gradient across the lung wall
Why is the thoracic cavity stuck to the parietal pleura?
the transmural pressure gradient across the thoracic wall
What expands when the chest cavity expands?
the lungs
What is traumatic pneumothorax?
a puncture in the chest wall permits air from the atmosphere to flow down its pressure gradient and enter the pleural cavity abolishing the transmural pressure gradient (from the “outside”)
What is collapsed lung?
when the transmural pressure gradient is abolished, the lung collapses to its unstretched size, and the chest wall springs outward
What is spontaneous pneumothorax?
a whole in the lung wall permits air to move down its pressure gradient and enter the pleural cavity from the lungs, abolishing the transmural pressure gradient (form the “inside”). As with traumatic pneumothorax, the lung collapses to its unstretched size)
What do each terminal bronchiole branch into?
several respiratory bronchioles that end in a cluster of alveoli called an alveolar sac (a bit like cluster of grapes)
What supplies each cluster?
a pulmonary artery and pulmonary vein
What covers the surface of the alveolar sacs?
capillaries
How does gas exchange occurs?
by diffusion between the alveoli and the capillaries (oxygen enters, carbon dioxide exits)
Why does gas exchange occur?
- the alveoli have extremely thin membranes-one cell layer thick (like capillaries)
- the cell membranes are moist: allows good gas exchange, but tends to make alveoli collapse-wet balloon
What happens during gas exchange?
- elastic fibers are stretched
- septal cells produce surfactant
What is surfactant?
a detergen-like fluid that prevents the moist alveoli membranes sticking together
How do premature babies get surfactants?
supplied with artificial surfactant
What happens during alveolar interdependence?
- an alveolus in a group of interconnected alveoli starts to collapse
- the surrounding alveoli are stretched by the collapsing alveolus
- the surrounding alveoli are collapsing too. They then pull outward on the collapsing alveolus. Expanding force pulls the collapsing alveolus open.
What are the forces keeping the alveoli open?
- transmural pressure gradient
- pulmonary surfactant (which opposes alveolar surface tension)
- alveolar interdependence
What are the forces promoting alveolar collapse?
- elasticity of stretched pulmonary connective tissue fibers
- alveolar surface tension
What controls pulmonary ventilation?
controlled by muscles in the thoracic cavity system
Is inhalation an active or passive process?
active process
What happens during inhalation?
- the dome-shaped diaphragm contracts, causing the thoracic cavity to expand
- the lungs expand to fill the larger space resulting in a drop of air pressure inside the lungs
- air is drawn into the lungs to equalize the pressure
Is exhalation an active or passive process?
passive process
What happens during exhalation?
- the diaphragm relaxes returning the thoracic cavity to its original size resulting in an increase in air pressure in the lungs
- the lungs spring back to their original size
- air is pushed out of the lungs into the atmosphere
Is inspiration an active or passive process?
active process
What is inspiration?
the act of taking air into the lungs
What is the shape of the diaphragm muscle?
shaped like a dome, with the convex side upward
What happens during inspiration?
- the diaphragm and the external intercostal muscles located between the ribs expand the volume of the chest cavity
- when the diaphragm contracts, it moves downward toward the abdomen, so it acts like a piston and increases the vertical dimension of the thoracic cavity
- when the external intercostal muscle contract, the rib cage and sternum are raised up and outward. This expands the thoracic cavity in the horizontal dimension
- since the lungs are stuck to the ribs, they also expand and air is pulled in
What is the structure after inspiration?
- contractions of external intercostal muscles cause elevation of ribs, which increases side-to-side dimension of thoracic cavity
- lowering of diaphragm on contraction increases vertical dimension of thoracic cavity
- elevation of ribs causes sternum to move upward and outward, which increases front-to-back dimension of thoracic cavity
Is expiration an active or passive process?
usually passive process
What happens during passive expiration?
- the inspiratory relax and the inherent elasticity of the lung pulls the rib cage down and the diaphragm up, reducing the volume of the thorax and air is expelled
What happens during active expiration?
pushing out the air from your lungs (or coughing). enabled by contraction of internal intercostal and abdominal muscles
What is the structure after passive expiration?
return of diaphragm, ribs, and sternum to resting position on relaxation of inspiratory muscles restores thoracic cavity to preinspiratory size
What is the structure after active expiration?
- contraction of internal intercostal muscles flattens ribs and sternum, further reducing side-to-side and front-to-back dimensions of thoracic cavity
- contraction of abdominal muscles causes diaphragm to be pushed upward, further reducing vertical dimension of thoracic cavity
What controls the resting respiratory rate?
the medulla oblongata and the pons in the brain stem
How does the medulla oblongata and the pons control the resting respiratory rate?
- the respiratory center triggers the diaphragm to contract for two seconds and then relax for three seconds
- cycle repeats continuously unless overridden by higher brain function
What happens when you hold your breath?
the body senses the levels of CO2 and O2 in the blood through chemoreceptors in the carotid artery (neck) and aortic bodies (aorta); high CO2 levels immediately trigger an increase in the rate of respiration
What is SPIROGRAM?
recording
What is total volume?
volume of air moving in or out in each (resting) respiratory cycle
What is inspiratory reserve volume?
air inspired with maximal effort in excess of tidal volume-taking as deep a breath as you can
What is expiratory reserve volume?
air expired by maximal effort after passive expiration. Pushing out as much air as you can
What is residual volume?
air left in lungs after maximal expiratory effort; important even when “wind knocked out of you” still some air left for gas exchange, also easier to inflate a partially filled alveolus than one that is completely collapsed
What is total lung capacity?
maximum volume of air the lungs can hold
What is inspiratory capacity?
maximum volume of air that can be inspired after a normal expiry (IC=IRV+TV)
What is functional residual capacity?
volume of air in lungs at the end of a normal expiry (FRC=ERV+RV)
What is vital capacity?
maximum that can be breathed in after a maximum expiry (VC=IRV+TV+ERV)
In an oxygen hemoglobin dissociation curve, what is the plateau region?
- safety margin. PO2 drops from 100% to 80%: decrease of Hb saturation by only 5% (think bank vault)
- increasing P02 from 100 to 760…breathing pure oxygen…doesn’t increase the amount of oxygen carried by the blood
In an oxygen hemoglobin dissociation curve, what is the steep region?
- unloading. High metabolic activity (exercise): PO2 may drop from 40 to 20
- Hb saturation drops from 75% to 25%…a 45 percent drop. More oxygen available
What is the binding of oxygen by hemoglobin dependent on?
temperature, pH
What is function of hemoglobin?
- carries O2 in the blood
- as PO2 increases, more of it is bound to hemoglobin
What happens to hemoglobin when temperature is higher?
- less oxygen is bound to hemoglobin
- when then is a need to let go of oxygen, less of it binds to hemoglobin
What happens to hemoglobin when temperature is low?
- hemoglobin has a high affinity for O2 when the temperature is low. So for a given PO2, more of the oxygen is bound to hemoglobin
- so when there is a need to grab more oxygen, more of it binds to hemoglobin
What happens to hemoglobin when pH is high?
in the lungs, the pH of the blood is basic so hemoglobin grabs onto oxygen
What happens to hemoglobin when pH is low?
in the body, the pH of the blood is low so hemoglobin lets go of oxygen
