Chapter One - Respiratory Structure and Function Flashcards
What composes the respiratory system? Name the main structures.
Lungs
Pulmonary circulation
Muscles and ventilations
Gas exchange
Bronchioles (part of the lower respiratory tracts)
What’s the structural difference between the lower and upper respiratory tracks?
Upper: nose, mouth, trachea, anything above the vocal cords
Lower: Everything below the vocal cords
We are going to focus on the lower respiratory tract in this course.
What are the roles of the bony thorax (rib cage)?
Role is to protect the lungs
It also protects the heart
Expansion of the rib cage allows the ventilation, change of pressures to get air into the lungs. The framework upon which the muscles work
What are some ways you can impair respiratory function, regarding the bony thorax?
Rib fracture might impair respiratory function
Scoliosis = definition from the book
Through a birth defect or a growth defect, change in the bony rib cage shape.
Lung can get compressed and won’t be able to expand as well
It may be following some trauma, like surgery.. Therefore the rib cage might not be able to expand.
Neurological diseases
Example : High spinal cord injury
Which view of the bony thorax is this?
Anterior view
Which view of the bony thorax is this?
Posterior view
What are the two rib cage actions during breathing? Be precise.
Two movements (actions) that have a 3D effect on increasing the volume:
Bucket handle: increase of the lateral diameter of the rib cage
Pump handle action: up and out.
What are the muscles of ventilation?
Diaphragme = primary muscle of ventilation - 85% of the work of breathing when we are sitting
When we do hard work : other muscles get called in : abdominals, sternum mastoids, scalenes, rectus and obliques, traps,
If someone is just sitting there and you can see that most of the accessory muscles are being used.. That is an indication of something is wrong…
And we have to be asking WHY?
Ex: why are these muscles hypertrophied?
Ex: seeing a client that is rounded in the shoulder and has hypertrophied sternomastoids
External intercostals: help with inspiration
Internal intercostals: help with expiration
What are the primary and accessory muscles responsible for inspiration?
Primary :
Diaphragm
External intercostals
Accessory :
Scalenes
Pects (Major and minor)
Lats - serratus anterior
Taps - trapezius
Sternocleidomastoid
Erector spinae
Abdominals
They are critical muscles in inspiration!
Book = The essential muscles to achieve the active process of inspiration at rest are the diaphragm and internal intercostals.
What are the muscles responsible for expiration?
Internal intercostals
Abdominals
What is the innervation of the diaphragm?
The challenge of the diaphragm muscle is that it is 3D muscle, large dome shaped muscles and it is not easy to visualize
Imaging using ultrasound : visualise the diaphragm
Nerve supply to the diaphragm: phrenic nerve from C3, 4 and 5 = keep the diaphragm alive
What are the main functions of the upper respiratory system? What is the hilum?
Warms the air that we breathe
Filters out the dirt
Trachea splits into the two main stem bronchi
Sometimes you can see that the trachea will move from side to side and then you know that something would be wrong, and it could be because of the lungs.
Airway tree
Hilum (at the start of the main bronchi, see next slide): where the blood vessels, the nerve supply and the lymphatics all enter the lungs
Tumor in that area : NOT a good thing
We want to always know the location of the injury because it can indicate some things
What composes the hilum of the lung? Where is it located?
Pulmonary artery = it is the only artery in the body that carries deoxygenated blood
Veins = red: oxygenated blood
Veins = purple : deoxygenated blood
Describe the macroanatomy of the lungs, and name the differences between the right and left lungs.
Tree-like structure
Main stem bronchi, left and right, right is a little straighter and wider than the left. If you accidentally inhale something in your lungs, chances are in goes in the right lung.
Notice the difference between the right and left lung:
Right lung: upper, middle and lower lobe
Left lung: large upper lobe, smaller lower lobe
Bronchioles and terminal bronchioles, they have alveoli attached to them : conducting airways : where there is gas exchange, in the periphery of the lung
Describe the anatomy of the pleural membranes and cavities of the lung.
The lung is surrounded with 2 pleural membranes who form the pleural sac:
Parietal pleura
Visceral pleura
In between them is the pleural fluid
Viscera: refers to organs
Parietal: the outer layer
Why do we have these two layers? What is the role of the sac?
The two layers create a sac around the lung: pleural sac filled with pleural fluid
Allows:
Movement of the lungs in the rib cage
Allows the lung to expand with very little friction
Pleural sac creates a pressure gradient around the lung (we’ll see that later)
Name and describe the first main possible dysfunction in the pleural space. Why can this be a problem?
Pneumo meaning? = air
Pneumothorax : tends to be at the top of the lungs (air floats)
Sometimes air gets in the pleural space : and that is called a pneumothorax
Why is that a problem?: changes the pressure gradient = sometimes the lung collapses
Air from the outside atmosphere is positive so the lung will collapse
The air is actually compressing the lung and the lung can’t expand as much
This could be life-threatening
PTs don’t treat pneumothoraces
Name and describe the second main possible dysfunction in the pleural space. Why can this be a problem?
Hemothorax : fluid in the pleural space
Tends to be at the bottom of the pleural space
What the problem with a pleural effusion/hemothorax ?
Impairs gas exchange because it too is compressing the lung so it may make your alveoli much smaller and it may cause them to collapse
We as PT’s might be trying to rehabilitate someone to reuse a alveoli that has collapsed
Where are the two pleural sac dysfunction located and how do they move with a change in position of the body?
Pneumothorax = is always at the top of the lung because it is air
Depends on what position the person is : lying on your left side, the air would be positioned laterally of the lung, on the top
Pleural Effusion hemothorax = fluid so it will be at the bottom of the lung
What are the two main zones of the airway tree?
Respiratory zone = have alveoli = so the gas exchange can happen
Conduction zone = no alveoli = no gas exchange
Describe the anatomy of the bronchus
Between cartilage: smooth muscles = we don’t have much control, it’s involuntary
Smooth muscle initially protects
Your larger airways have more cartilage
Airway : mucus lining, cilia
What is asthma? Describe its pathology.
Asma = is a common disease = when the smooth muscles constrict = makes it harder to breathe = medication directed to relax the smooth muscles
Uncontrolled bronchoconstriction after a long period of time.
Notice the cartilage rings.
Another thing is that asthma is an inflammatory disease = so it makes the airway smaller and the airway wall gets thick (inflammatory reaction)
Inflammation : bronchial wall, or airway smooth muscle
Normal responses to healing but if it’s persistent it becomes a problem
When can bronchoconstriction be a good thing?
Bronchoconstriction = good thing if there is a nasty or toxic substance in the air (ex: smoke from a wildfire)
Describe the anatomy of the periphery of the lung.
Action for gas exchange takes place
Things I want you to notice:
Periphery of the lung: alveoli = elastic fibres in the walls of the alveoli. Lungs are like a balloon, they are very elastic when they are healthy
You have a network of blood vessels that surround the alveoli
Where gas exchanges happen
VAN : vein, artery and nerve
What are the two actions necessary for gas exchange to take place?
Respiration = gas exchange
Ventilation = moving air in and out of the lungs
Why do we have these alveoli? Why not just one big balloon?
More surface area for gas exchange = estimated to 70 square meters (she tends not to ask incidental numbers like that)
What is the role of the lymphatic system? What is lymphoedema?
Lymphatics = it’s where fluid excess is picked up and re-enters the circulatory system (it drains the interstitial fluid)
The lymph system is part of your immune system, and it carries lymphocytes (it carries white blood cells but not red blood cells)
People with lymphoedema = refers to swelling that generally occurs in one of your arms or legs. Sometimes both arms or both legs swell. Lymphedemais most commonly caused by the removal of or damage to your lymph nodes as a part of cancer treatment.
What is the role of cilia? Can they be damaged? Give an example of when this happens. What is the significance of this damage?
Air = up over the goblet cells and ciliated epithelial cells
Cilia = help clear the lungs with their wavelike movements = the role of this is that they move particles and mucus of some sort … they will push the particles and mucus into a larger area so that we can be able to cough it out.
Can the cilia be damaged? Yes.
Ex: smoking = chronic lung disease: the epithelial cells change and the cilia may not beat properly or even disappear from the surface.. Also causing inflammation and infection
The implication is that the lungs won’t be able to move the mucus and obstructs the airways. It can generate a chronic inflammatory response.
What do the fibroblasts do? What is IPF?
Fibroblast = it produces new cells which are support cells that act as a fibrous structure
IPF = Idiopathic pulmonary fibrosis (IPF) causes scar tissue to grow inside your lungs. Usually, when you breathe in, oxygen moves through tiny air sacs in your lungs into your bloodstream. From there, it travels to organs in your body
What is the alveolar wall structure?
Capillaries in the alveolar wall
Black dots = red blood cells that are carried in the capillaries = capillary networks in between alveoli
Name the three cell types that compose the alveolar cell wall structure. What are their roles and their distribution? What kind of fiber do we find in the alveoli?
Pneumocyte type 1 cell = they are the most common (about 90% of the cells) = these give structure to the lung
Other 10% = type II pneumocytes = they make surfactant (What is the importance of surfactant? It decreases surface tension, and essentially allows us to breathe)
Lungs have elastic fibres, they are very elastic, like a balloon
Alveolar macrophage: it is part of the immune system. They roam around doing surveillance in your lungs, and they can become more active and call more cell types to the affected area.
The lung has a huge surface which is responsible to filter the air we breathe, the air we breathe is not really clean and the alveolar macrophage will try to protect the alveoli.
What is the interstitium? What happens when the lymphatic system doesn’t function properly?
Interstitium = everything that is not really a cell = that is the interstitium which is a loose accumulation of tissue
Pink around the dark red blood cells : the interstitium, it is the fine tissue part of this very fine alveolar wall.
The lung becomes boggy when fluid isn’t taken up by the lymphatic system or because it changes the pressure in the vascular system: the fluid is being pushed out, into the lungs = makes it harder to breathe (boggy: viscous, stiffer, like a sponge that fills up with fluid (a term that we will hear again))
As a PT = we can’t fix this. Most often they need medication to help with that.
What kind of system is the pulmonary circulation?
Really important thing to know is that the pulmonary circulation is a closed-loop system as part of the larger circulatory system
Name one difference between the pulmonary and systemic circulation. Why is that?
Lower blood pressure in the pulmonary vascular system
Pulmonary: 4 mm Hg
Systemic: 60 mm Hg (numbers not important)
Just know that there is a BIG difference.
This is to prevent damage to the lung, essentially to alveoli
The entire cardiac output from the right ventricle goes to the lung: into a relatively small space = pulmonary capillaries are fine, delicate structures that can’t tolerate a high pressure
On the left side of the heart, the entire cardiac output gets distributed into a much larger system, it goes into arms, legs, etc.
When we come to look at pediatric issues = children may be born with birth defects = sometimes blood from the left ventricle goes into the right ventricle = and so there is some blood in the right ventricle that never went through gas exchange, which is decreasing the function
What are the two types of afferent input that control the ventilation? What is the difference between a pacemaker for the control of ventilation versus one for the heartbeat?
Afferent input (the signal) to the brain may be neural (passed to the brain by the nerves), or humoral (the signal travels in the blood)
Because breathing is so essential to life, we would want to know everything about it, but the reality is that we don’t know everything about it.
Like heart, breathing has an automatic rate, it happens automatically.
Pacemaker for control of ventilation, compared to the heart’s, is not in one specific site, it depends of neural networks (or groups of cells)
Ocillation circuits is the inspiration and expiration.
There is a lot that happens before the muscles of inspiration and expiration are activated.
What are the different types of neural control?
Different types of neural control: Motor cortex, limbic system, muscle afferents, lung receptors, right ventricle and peripheral chemoreceptors
What do the peripheral chemorecteptors do?
Peripheral chemoreceptors = aortic body receptors and carotid body receptors = they communicate through nerves to the respiratory system (they sense the chemical composition of the blood… they also have a humoral aspect )
What is the influence of the higher brain center and limbic system on the control of ventilation? Give some examples.
It is important to understand that the higher brain center and limbic system influence the control of the ventilation.
Because of that we are able to control our ventilation. Ex. when we want to dive underwater.
When you hold your breath, when you’re emotional (scared, excited, anxious), it affects your breathing through the limbic (or emotional) system.
When we are eating or drinking, it also affects our breathing (we are momentarily holding our breath)
How could a chroninc illness that makes them breathe too fast affect other aspects of the patients’ life?
Chronic illness where you breathe too fast = can make you not want to eat or drink, to focus on breathing, it affects your nutrition
What is the role of the hypothalamus? How is it related to the respiratory rate?
Hypothalamus = homeostasis, for example temperature regulation, just think that often when you are warm your breathing changes. If you think about animals, a dog will breathe much faster when they are warm.
Where are situated the main pacemaker groups for breathing? Name both of them and what their role is.
Main pacemaker groups are in the medulla of the brain. Two groups of cells: dorsal respiratory group (yellow), and ventral respiratory group (purple). Cells here have a role for inspiration, it sets the rhythm of your breathing
One is about inspiration (dorsal), but the other one is about inspiration AND expiration (ventral)
Give some examples of other organs that can help regulate breathing.
There are also many other organs in the body that help to regulate breathing. Ex. receptors in your lung which is going to tell information on breathing and then it will be adjusted consequently. Ex 2: green part: senses the chemical concentrations in the plasma.
Other influences can also come from higher in the brain. We need to understand as a PT that if there is a brain injury and that could lead to an abnormal breathing pattern
What is humoral control? Name the three different types of receptors, where they are situated and what is their mechanism of action.
HUMORAL CONTROL = signal travels through the blood (chemoreceptors can be peripheral or central)
Lung receptors:
Stretch receptors
Irritant receptors
J receptors
Ex: they make you cough when a particle is detected
Irritant receptors :
Tend to be found in the epithelium of small airways
Stimulate by toxic particles in lungs
Stimulate coughing and smooth muscle constriction
Can also increase RR to limit toxic particles from the lung
Stretch receptors:
Tend to be in smooth muscle
J receptors are in the interstitium beside the capillaries:
They are sensitive to changes in capillary blood pressure
They can cause shallow breathing
They tend to cause coughing or more rapid respiratory rate
What do the peripheral chemoreceptors do? Which factor gives us the strongest drive to breathe, and which are the other ones? What are central chemoreceptors not able to sense?
Peripheral chemoreceptors: negative feedback chain
Also the only one that senses oxygen concentration, compared to the central (that is their main difference)
CO2, PH and O2:
CO2 = our strongest drive to breath
Small changes in PCO2 drives your breathing
PO2 has to go below 60mm Hg to drive breathing, which is really low
Central chemoreceptors:
Do not sense oxygen concentration
What affects the central chemoreceptors, and why can’t hydrogens ions do that?
Hydrogen ion = H+ , the red block = does not pass through the cerebrospinal fluid. It is the PCO2 that is increased and that affects the central chemoreceptors
Give a brief recap on the control of ventilation.
Recap on control of ventilation:
We don’t understand a lot
Respiratory center is in the palm of the medulla
One group of cells, the dorsal, is the rhythm generator
Input from all the other receptors modulate that, the modulation is complex, we know about the stimulus but we don’t need to know about the connections in the brain
Stretch, irritant receptors… We have to know what they do but not where their input goes or how it works
