Respiration Flashcards
What is respiration?
The process in which nutrients are converted into useful energy in the cell
Roles of the respiratory system
- Gas exchange
- regulation of blood (tissue) pH: changing the amount of blood carbon dioxide levels (7.35-7.45 blood plasma is normal)
- Voice production: movement of air past vocal folds makes sound
- Olfaction: smell occurs when airborne molecules drawn into nasal cavity
- Protection: against particles by preventing entry and removing them from deep in chest
What includes in the upper respiratory system?
Pharynx, vocal cords, esophagus, larynx, trachea.
Conducting tissue (allows air to come in and out)
What includes in the lower respiratory system?
Left lung, right, right and left bronchus, diaphram
Conducting (allowing air to come in and out) and Transfer of gases into circulatory system
What are the nasal conchae (look at diagram in ON for more info)
Causes turbulence
3 series of bones
Have mucous membrane
help humidify the air breathed in
This is why snot builds up.
What are the 3 main sinuses? And what are their functions?
Frontal, Maxillary, Ethmoid
Lightens skull
Probably area for protection of the skull. Act as a heat buffer (heat transfer like ice cream, that isn’t transferred to brain which would do damage)
Don’t know which is the most important
Turbinates
Tissue in this is made out erectile tissue.
What does the Larynx do?
Maintains an open passageway
Epiglottis and ventricular folds prevent swallowed
Why do u feel stiches in lung after running and then breathing hard through mouth?
Because the mucosa lower in the chest is becoming dry and cold, triggering pain sensations
What the main areas to know in the larynx? And what are their functions?
Epiglottis and ventricular folds prevent swallowed material from moving into larynx and trachea
Vocal fold - 6 muscles which change tension on the tissue. As air passes, it causes vibrations
Tracheobronchial tree
a system of airways that allow passage of air into the lungs, where gas exchange occurs.
For correct function, need limited resistance (turbulence) and minimal dead space
What does Cartilage, smooth muscle, and smaller bronchioles do in the tracheobronchial tree?
Cartilage holds tube system open
Smooth muscle controls diameter and smaller bronchioles length
What does pseudostratified mean?
Look as if it’s stratisfied (more layers) but it isn’t
Tracheobronchial tree features
- pseudosstratified mucociliary epithelium lined down the conducting part of the respiratory tract
Why is turbulence an advantage?
Particles will tend to be pushed to one side to maybe interact with the mucous layer. However, particles lower than 1 micron can reach the alveoli
What is in the conducting zone?
Upper respiratory tract and tracheobronchial Tree
What is in the respiratory zone?
Respiratory bronchioles to alveoli and site for gas exchange
Describe the features of the lungs that make gas exchange efficient
Has a large surface area provided by large number of alveoli.
Surface is only one cell thick - providing short diffusion pathway
Supplied with blood by very dense capillary network
What are the two types of alveolus cells?
Type 1 cells - alveola lining cells, help with gas exchange because theyre so thin
Type 2 cells producing surfactant (reduces water surface tension in the alveoli)
Each cluster of alveoli is surrounded by…
Elastic fibers and a network of capillaries
What is the thin layer around the lung floating in the thoracic cavity called?
Pleural fluid (1-3mls). The lung isn’t directly attached to any muscle
What is the intrapleural space?
Negative pressure in the intrapleural space causing a partial vaccum which holds the lungs in place.
What is pleural fluid
A fine membrane that lines the lung and lines the walls of the chest (inside of rib cage and diaphragm)
What happens when inspiration of air happens? (diagram in ON)
Diaphram and external intercostals contract (muscles of the lungs)
Forces down abdominal contents
What happens in expiration?
Gentle breathing (not forced) -
Elastic recoil of the lung tissue, the diaphragm and ribs, and action of surfactant (which tries to close down the alveoli)
Forced expiration:
Abdominal assistance (internal intercost
Ventilation
air through lungs induced by volume changes - pressure changes in lung compartments
Air moves from high pressure to low
What is pleural pressure?
Pressure in the interpleural space
Always slightly negative because at the end of inspiration, lungs are pulling stronger on chest wall, similarly to expiration
How do u work out transpulmonary pressure?
Alveolar pressure - Pleural pressure
Force that tends to swell (distend) the alveoli
Alveolar volume can change by altering…what pressure?
Pleural pressure. It should always be negative to keep the lung in contact with the ribs.
What does a compliant lung mean?
A lung that’ll expand or contract, inflate or deflate with little force required. The ease at which the lung moves.
What is the normal adult transpulmonary pressure change numbers?
per (___) of air there is (___) H2O
per ~200mls of air there is 1cm H2O
Why would there be a decrease in compliance of the lung?
- Change in airway bringing air in e.g asthma
- Fibrosis of alveola region of lung so lose the elastic fibres (replaced by collagen which takes a lot more force)
- pulmonary oedema - lots of fluid
What effects in the lung alters inhalation compliance?
- Elastic fibres in lung
- surface tension in alveoli
Law of LaPlace
P = 2T/r
P = pressure
T = surface tension
r = radius
What are surfactant?
A surface active agent in water which reduces the surface tension of water (TYPE 2 alveolar cells make surfactant).
These break the semi-crystalline bonds between the water molecules to reduce surface tension
Stabilises alveoli
Prevents water from being brought into alveoli so reduces pulmonary oedema
Crucial for expansion of lungs at birth (don’t have many alveoli at birth and surfactant only made late in pregnancy)
How to work out alveolar ventilation rate and what is it on average?
(Tidal volume - Anatomical dead space) x Respiration rate = 4.2l/min
(TV-ADS)xRR
What does an increase in dead space mean?
Reduces alveolar ventilation (normal 6L/min)
What alters the amount of a specific gas in the alveolus and the rate of gas exchange?
partial pressure
what is daltons law of pressure
Total pressure = sum of partial pressures
Partial pressure of N2, O2, and CO2 in humidified air
N2: 563.4 (74.09%)
O2: 149.3 (19.67%)
CO2: 0.3 (0.04%)
Total: 760.0 (100%)
Partial pressure of N2, O2, and CO2 in Alveolar air (mm Hg)
N2: 569.0 (74.9%)
O2: 104.0 (13.6%)
CO2: 40.0 (5.3%)
Total: 760.0 (100%)
How can the partial pressures of O2 and CO2 change in the alveolus?
- Alveolar ventilation rate
- During periods of high metabolic activity (e.g., exercise), the body’s demand for O₂ increases and CO₂ production rises. This increases the uptake of O₂ and the release of CO₂ in the alveoli, decreasing P_O₂ and increasing P_CO₂.
- Atmospheric pO2 and pCO2 alter with atmospheric pressure (altitude) - e.g how high ure on a mountain
How fast does the gas exchange over the membrane in the lung? Ficks law?
Diffusion of gases - Fick’s law
Equation in ON
Wh
- solubility of gases in lipids is high but not in water so want to minimise the amount of water it has to go through before reaching blood cell carrier. Want the distance to be limited (so want the respiratory membrane to be as thin as possible)
- Rate transfer from alveolar air to plasma depends upon area of alveolus (if large then quicker bc provides large area for diffusion to occur)
How ;long does it take for blood to equilibrate with alveolar gases in the normal lung?
Within 0.2 seconds
What is pulmonary lung perfusion?
Increase of blood flow
What does increasing pulmonary arterial blood pressure cause?
- Increase speed of blood transition through pulmonary capillaries
- Collapsed vessels in the lung open so alveolar perfusion increases (normal resting lung, vessels are collapsed so by increasing blood pressure, they open up)
- Vessels dilate (they are compliant - respond to small changes) so alveolar perfusion increases
Perfusion means blood flow
What is physiological dead space?
The portion of the tidal volume not participating in gas exchange with pulmonary capillary blood.
Like anatomical dead space but inclusion of parts of alveolus that aren’t functioning bc of plugs of mucous in that region or smth like that (a blockage)
What does hypoxic mean?
Low oxygen
What does henry’s law say?
The amount of gas dissolved in the blood depends on the partial pressure of the gas surface it’s interacting with, and the solubility
How many mls of O2 does 1g of haemoglobin carry when saturated?
1.3 mls
What is allosteric activation? Link it to Oxygen and Hb
Binding of one ligand alters the interaction between substrate and ligand at other binding sites.
Binding of O2 to one Hb subunit induces conformational changes in the remaining active sites, enhancing their affinity for O2.
The haem group is a phorphyrin ring which will release bile when broken down. It forms a ring with Iron 2 in it and there is a charge-Oxygen interaction which is stabilised by presence of histidine’s on the globulin chains around it
What happens when oxygen binds to haemoglobin?
Conformational changes that cause the molecules of haemoglobin rotate against each other.
Go from tense state (low affinity for O2) to relaxed (higher affinity)
What’s special about histidine
Can pick up protons so if the pH changes, Histidine can act like a buffer.
What does myoglobin do?
Act as an oxygen reservoir. It has a higher affinity for it than haemoglobin so when oxygen starvation happens (bc of exercise so capillaries tighten) then it is released from myoglobin.
It’s a monomer so no allosteric activity.
What does 2,3-bisphosphoglycerate do?
When hypoxia occurs, this increases.
Stabilises Hb tetrameter into tense form (less affinity for O2)
Means that once the molecule gets to the tissue, it’s more likely to drop the O2 into the tissues due to the low affinity
Blood stored in blood banks loses its normal content of 2,3-DPG (biphosphoglycerate). Is this good or bad? Explain
Bad, fresh blood better, could add 2,3 into it.
If ure chronically anaemic then u make more 2,3 anyways
4 things that change haemoglobin affinity for oxygen?
Hydrogen ion concentration (more = more affinity) - comes from CO2 or Lactic acid
Temperature (low temp = high affinity, high temp = low affinity, tense state)
2,3-DPG (more of it = less affinity)
Is carbon dioxide or oxygen more soluble?
Carbon dioxide (20x more soluble)
How is 6% of CO2 carried in the blood? (diagram in ON to help answer)
6% CO2 is carried in the interstitial fluid of the capillary
The rest goes into the red blood cell
How is 24% of CO2 carried in the blood? (diagram in ON to help answer)
24% binds to the amino groups on the proteins within the red blood cell (Hgb) forms a carb-amino group (carbon interacting with free amines at the N-terminal)
How is 70% of CO2 carried in the blood? (diagram in ON to help answer)
70% interacts with water to produce carbonic acid (H2CO3) which is catalysed by carbonic anhydrase. This breaks down the H2CO3 to produce bicarbonate ions (HCO3-) and H+.
Don’t want to reverse this reaction so to prevent this, separation of H+ and HCO3- occurs
Bi-carbonate-Chloride ion exchanger (Band 3) pushes out HCO3- from the red blood cell and brings in Cl- (Water transfers with the Cl- so the cell swells a bit)
Is haemoglobin a weak or strong acid?
Weak. It likes to bind to protons. whereas oxyglobin is stronger (tends to give up the proton)
What does plasma pH regulate?
Breathing (and vise versa)
The more carbon dioxide there is in the plasma…
The lower the pH because bicarbonate ion and H+ is produced afterwards.
When can u get metabolic acidosis?
- caused by lactic acid, doing lots of exercise and not fully breaking down carbohydrates or ketone bodies
- When u have kidney failure because can’t get proper buffering in the tissues
What is ventilation rate controlled by?
Blood levels of CO2 rather than O2
4 regulatory centers in the brain stem (Diagram in ON for hint)
Dorsal respiratory group - dorsal medulla - causes inspiration
Ventral respiratory group - ventrolateral medulla - modifies expiration and inspiration in response to heavy exercise.
Pneumotaxic center - modifies rate and depth of breathing. faster
Apneustic center - if it’s unchecked then it tries to cause continuous breathing in (inspiration) (last center to die when we die, apeneustic breathing)
Describe the Dorsal respiratory group cycle thing (diagram in ON)
Dorsal respiratory group inhibited > inspiratory muscle relax > passive expiration > dorsal respiratory group active > inspiratory muscles contract > inspiration occurs
What is the control of the central(medullary) chemoreceptors?
- Blood is brought to brain
- CO2 diffuses out of blood through blood brain barrier, into cerebrospinal fluid
- This induces the carbonic acid reaction to then dissociate into protons.
- Proton receptors on the surface of the medulla respond to this
- This stimulates the dorsal respiratory group and apeneustic center to increase breathing in.
