Respiratory System Flashcards
2 essential things for efficient gas exchange
Diffusion distance btwn air and blood must be small
Surface area over which exchange takes place must be laege
What’s external respiration
Process in lungs by which oxygen is absorbed from atmosphere into blood within pulmonary capillaries and CO2 is excreted
Internal respiration
Exchange of gases btwn blood in systemic capillaries and tissue fluid and cells that surround them
Cellular respiration
Cells gain energy by breaking down molecules like glucose. Occurs in mitochondria consumes O2 and generates CO2
Pulmonary ventilation
Describes bulk movement of air in and out of lungs. Ventilatory pump comprises rib cage and it’s associated muscles and diaphragm
Conducting part
Cavities and thick wall tubes that conduct air btwn nose and lungs (warms humidifies and cleans air). Airways are nasal cavities, pharynx, larynx, trachea, bronchi and bronchioles
Respiratory part
Thin walled airways wheee gases exchange between air and blood. Airways ate respiratory bronchioles, alveolar ducts and sacs, alveoli
Main components bronchus
Goblet cells, cartilage plates, mucous glands, pseudostratified ciliated columnar epithelium
Main components bronchiole
Club cells, relatively more smooth muscle, simple columnar/cuboidal ciliated epithelium
Which airway is mostly affected during asthma attack
Bronchiole because the smooth muscle constricts due to bronchoconstriction
3 cells alveolus
Type 1 pneumocyte- squamous (surface area)
type 2 pneumocyte- secretes surfactant to reduce surface tension, prevent alveolar collapse
Alveolar macrophage - inject particles
Path of oxygen to reach rbc
Diaghram
How is inspiration produced
By contraction of external intercostal muscles, moving ribcage up and out and contraction of diaphragm
What happens to volume when the contractions occur
Increases volume of thoracic cavity
what would the outcome of gas exchange give
clean air
warmed air (room temp -> 37 degrees C)
saturated
whats conchae
bony structure surrounded by mucous membranes that helps with air conditioning, filtration and regulation
what heats air
rich blood supply under epithelium (heat from blood goes into air)
what saturates air
glands under epithelium (mucous and serous)
whats respiratory epithelium
pseudostratified ciliated columnar epithelium + goblet cells + basal cells
why does respiratory epithelium have basal cells
acts as stem cells for re-gen and growth
what adds resonance to voice
sinuses (air spaces in skull)
which region does infection risk go from moderate to high
near terminal bronchioles (generation 16-19)
what keeps trachea open
C shaped cartilage. Free end of cartilage are connected by trachealis sm muscle
whats trachea lined with
pseudostratified columnar ciliated
How does epithelial lining change from trachea to alveolus
Psudostratified columnar ciliated> columnar ciliated > cuboidal ciliated > squamous pneumocyte and surfactant cells
Where are mucous glands located
Trachea bronchus and bronchiole
Goblet secretes mucous in large airways
Club cells secretes watery secretion in bronchioles
Smooth muscle in the airways
Small airways have more than larger ones but smooth muscle doesn’t continue to alveolis
What part of bronchi supplies lobes
Secondary bronchi (2 to left, 3 to right)
What part of bronchi supplies segments of lungs
Tertiary bronchi (8 to left 10 to right)
What does the diaphragm form the roof and floor of
Floor of thorax and roof of abdomen
What increases volume of thorax causing inspiration
Contraction of diaphragmatic muscle (flattens the dome)
whats olfactory epithelium and where is it located
roof of sinus cavity near conchae. has receptors for smell
cribriform plate
separates the nasal cavity from the brain
what closes nasopharynx
soft palette
whats surfactant
comprised of lipids to decrease surface tension at the air-liquid interface within the alveoli.
What’s hilum
Area on medial surface where bronchi pulm arteries and veins enter and exit
Inspiration and expiration process
Is active and requires contraction of external inter coastal muscles
Expiration is passive and ribcage returns to resting position
What’s phrenic nerve
Nerve to send signals to diaphragm to move up ad down
Definition of respiration
Extract oxygen from air for aerobic metabolism and remove CO2 from tissues and put it into atmosphere inspiration (active),expirations (passive)
what adheres lungs to chest walls and keeps them from collapsing
negative intrapleural pressure relative to intrapulmonary pressure
what motor outflow does cervical area innervate
phrenic motor nucleus for diaphragm (C3 - C5) inspiratory
what motor outflow does thoracic area innervate
external intercostals (inspiratory)
internal intercostals (expiratory) T1-L1
what motor outflow does lumbar area innervate
abdominal motor neurons (T7-L1) expiratory
what happens to pressures during ventilation
inspiration = chest volume increases meaning lungs expand
this leads to more negative pleural pressure (pressure btwn lungs and wall).
as lungs expand the pulmonary pressure decreases.
whats tidal volume
volume of air moving into lungs at rest (0.5L for average human) can be measured with spirometer
whats vital capacity
total amount of air that can be exhaled after a maximal inhalation
equation for residual volume
residual volume = total lung capacity - vital capacity
what are lungs comprised of
elastic and collagen so can stretch and return to original shape
elastin and collagen forms matrix to support what
airways, blood vessels and lymphatic system
whats compliance
High compliance indicates that the lungs can easily expand with minimal pressure changes, while low compliance means that more pressure is needed to achieve the same volume change.
whats elasticity
ability of lung tissue to return to its original shape after being stretched or deformed
changing compliance to reduce it does what
increases elasticity as elasticity is reciprocal of compliance
how does surface area relate to alveolus
It directly affects the efficiency of gas exchange in the lungs
whats Laplaces law
describes the relationship between the pressure inside a spherical structure (like an alveolus) and its surface tension and radius
P=2T/r
Whats COPD
factors like smoking reduce elastic components in lungs so more compliant and easy to inflate. less deep breaths?
whats fibrosis
factors like contaminated environment causing inflammatory response which decreases compliance and so effort to inflate lungs is greater
diff btwen COPD and fibrosis
massively expanded lungs/deflated lungs
flattened diaphragm/fluffy areas fibrotic tissue
mid sternal space reduced/ mid sternal space wide
whats funnel effect
high to low resistence as generations occur. airflow is fastest at high resistence then slow at low resistence to allow for gas exchange to occur
factors affecting airflow
- residual volume
- functional residual capacity
- total lung capacity
what happens to resistence to airflow as you inhale
decreases as air ways open up
parasympathetic pathway of air
vagus releases Ach to act on muscarinic receptor to constrict bronchioles
sympathetic pathway of air
sympathetic nerves come out from thoracic spinal segment and release noradrenaline to act on beta-adrenoceptors to relax smooth muscle and dilate it.
whats hering-breuer reflex
helps regulate breathing and prevent over-inflation of the lungs. Reflex involves stretch receptors located in the smooth muscle of the airways and lungs. When the lungs inflate to a certain extent, these stretch receptors are activated. Once activated, the stretch receptors send signals via the vagus nerve to the respiratory centers in the brain (particularly the medulla oblongata and pons).This signal inhibits further inhalation and initiates exhalation.
whats sheet blood flow around alveoli
arrangement of capillaries ensures close contact of blood and alveolar surface for efficient gas exchange.
Sheet flow is laminar means blood moves in parallel layers = efficient gas exchange
whats oedema and whats its causes
abnormal accumulation of fluid in the interstitial spaces.
Increased Hydrostatic Pressure
whats distension and recruitment
where some capillaries open due to high pressure
what causes right heart failure
low O2 = pulm art, pressure up = pulmonary hypertension due to hypoxia=vasoconstriction
how does hypoxia cause right heart failure
This increases resistance in the pulmonary arteries, making it harder for the right ventricle to pump blood into the lungs.
how does hypoxia cause left heart failure
In response to low oxygen levels, the body may increase heart rate and contractility to maintain adequate oxygen delivery. This increased workload can strain the left ventricle, especially if it is already compromised.
what factors regulate movement of gas across respiratory surface
area, thickness of tissue, partial pressure differential across tissue
(constant factors - solubility and molecular weight)
thickness
as theres a small distance of 0.5micrometres so more prone to infection
2 factors controlling blood flow into lungs
physical- as pulmonary artery pressure increases, pulmonary vascular resistence decreases due to distention and recruitment of vessels
hypoxia- decreased O2 causes vasoconstriction limitting blood to poorly ventilated alveoli
what happens when blood flows poorly through ventilated alveoli
forms a shunt reducing PO2 levels in pulmonary vein
zones in lungs
top HP is lowest (PA>Pa>Pv) poorly perfused
middle (Pa>PA>Pv)
base HP is greatest (Pa>Pv>PA) greatly perfused
ideal ratio VA/Q = 1. why is it under 1 usually
things like gravity
when does internal and external intercostals contract
internal only contracts during forceful exhalation and external contracts during inspiration to lift up ribcage
how is o2 transported in blood
binds with haemoglobin and dissolves in solution (plasma)
how does o2 bind to hb
binds to fe2+ which reveals another site for binding. this increases in speed of binding. Hb consists of polypeptide chain (globin) and 4 haem molecules, binds to o2 with salt bridge
what does blood o2 levels depend on
both saturation of hb and PO2
how does hb affinity for o2 change
in acidic environments - less affinity for o2
at tissues = more co2, less ph = o2 released
at lungs = less co2, more ph = o2 taken up
3 ways co2 is transported
dissolved in solution (20x more soluble than o2)
combines with proteins to make carboamino compounds
in rbc
how does cl- shift occur
hco3- moves out of cells down conc. gradient so cl- moves in to maintain electroneutrality
2 types of chemoreceptors
peripheral and central
peripheral chemoreceptor (fast response)
at aortic arch and at carotid artery which connects to brainstem via vagal and glossopharyngal nerves. very sensitive to hypoxia, protons, co2 and when activated increases rate and depth of breathing (minute volume inc)
central chemoreceptors (slow response due to time taken to make H+)
controls ventilation via co2. in neurons or astrocytes. sensitive to H+ ions. CO2 diffuse across BBB and dissolves in CSF to form carbonic anhydrase which dissociates into H+ (this takes time) relex is increasing minute volume by inc in PaCO2
