Respiratory Lectures (8) Flashcards
4 primary functions of respiratory system?
L1
- Exchange of gases b/n atm and blood
- homeostatic regulation of body pH
- protection from inhaled pathogens and irritating substances
- vocalization
Air exchange occurs via ____.
L1
Bulk Flow
- blood flows from high to low pressures
- muscular pumps create pressure gradient (heart)
- resistance influenced most by diameter of tube that air is flowing through (length same, viscosity rarely changes in blood)
Why is it hard to breathe in a sauna?
L1
Air is more viscous (more water in it)
External Respiration
L1
movement of gases (mostly O2 and CO2) b/n enviro and cells
External Respiration steps
L1
- inhalation and exhalation -> exchange of air from atm to lungs & vice versa (ventilation)
- exchanging fresh O2 with CO2 into and out of body (lungs to blood) @ alveoli
- transport of gases in blood
- exchange of blood into the cells
Respiration requires coordination b/n ____.
L1
Respiratory and cardiovascular systems
:when you breathe slower your heart rate slows
Structures involved in ventilation and gas exchange
L1
→ conducting airways (upper and lower respiratory system)
→ alveoli
→ bones and muscles of thorax cavity (create force to move air)
Order the upper and lower respiratory system structures in order
L1
Nasal cavity pharynx larynx trachea (first of lower) L and R bronchi bronchioles alveoli
Where is the site of gas exchange in lungs?
L1
Alveoli
Bones and muscles in the thorax cavity
L1
Walls = spine, ribs, sternum, muscles Floor = diaphragm
What are the muscles of inspiration?
L1
Thorax cavity
-sternocleidomastoids, scalenes, external intercostals, diaphragm
What are the muscles of expiration?
L1
Thorax cavity
-internal intercostals, abdominals
Lungs composed of?
L1
light spongy tissue filled mostly by air-filled sacs (ALVEOLI)
- right lung slightly bigger than left (3 lobes)
- left has 2 lobes = cardiac notch
- each lung surrounded by pleural sac
Composition of pleural sac
L1
double-walled
- one layer connected to surface of LUNGS = visceral pleura, or wall of lungs (inside)
- other one connects to surface of thoracic CAVITY and DIAPHRAGM at bottom = parietal pleura (outside)
What’s the point of the pleural sac?
L1
- create moist slippery surface and prevent lungs from rubbing on walls during inhalation/exhalation (can move a bit)
- hold lungs to thoracic wall so they stay in an OPEN state since they are muscle tissue and naturally want to recoil (collapsed lungs)
How much fluid is inside the pleural sac?
L1
~10-20ml of fluid in entire lung since very small space b/n visceral and parietal layer
path air travels b/n coming into nasal cavity/mouth and ending in the alveoli
L1
nasal cavity → pharynx → larynx (vocal cords) → trachea (windpipe, semiflexible tube held open with ~20 cartilage rings) →L and R bronchi (going to L and R lungs) → smaller bronchi → bronchioles (no more cartilage on them, only smooth muscle, control amount of air coming to alveoli) → alveoli (air exchange)
Velocity of air ___ as it goes down the respiratory system.
L1
Decreases → important for alveoli to be able to properly do airflow exchange
- branching imc total cross sectional area
- velocity of air flow inversely proportional to total cross sectional area, V = Q/A
- only bronchioles and alveoli are exchange surfaces. All others are part of conducting system
Upper airways and bronchi play important role in _____.
i.e. Jobs?
L1
→ warm air to body (so body temp doesn’t fluctuate)
→ adding water vapor (alveoli need to be moist so gases can diffuse across → SALINE)
→ filter out foreign materials (traps them)
the 3 processes of upper airways and bronchi are more efficient with ___.
L1
Nose breathing:
→ nasal cavity has bigger SA, rich in blood supply and hair
→ shape of it allows air to come in fast so particles embed in mucus in back of pharynx and slide down to esophagus
Air is filtered in the ___.
Describe mucocillary escalator.
L1
Trachea and bronchi
→ saline produced by epithelial cells. Overtop saline is layer of mucus produced by goblet cells. Mucus contains immunoglobulins to neutralize pathogens
→ mucociliary escalator: cilia in epithelial cells beat, push saline up so it pushes mucus with pathogens into pharynx and down to stomach
What is necessary for the mucociliary escalator to function?
L1
Saline
→ without saline layer, cilia become embedded in thick mucus and unable to move which can lead to infections, scarring of airways, inability to breath
Describe the CFTR channel
L1
Model of saline secretion by epithelial cells
→ A NKCC channel brings 2 Cl into epithelial cell from ECF
→ As 2 Cl- enter the epithelial cell, creates -ve charge
→ Na+ moves from ECF to cell paracellularly
→ this Na and Cl movement creates [ ] gradient for water to move from ECF to cell
→ anion channel on apical membrane allows Cl to enter lumen
*K that enters epithelial cell is removed by K channel
Cystic Fibrosis
L1
Autosomal recessive mutation in gene making CFTR (cystic fibrosis transmembrane conductance regulator)
→ less saline production: less Cl transport
→ mucus can’t be cleared properly, bacteria colonizes airways: recurrent lung infections
→ life expectancy ~40 yrs
→ affects pancreas (name: formation of cysts and fibrosis of pancreas)
Alveoli general facts (6)
L2
→ bulk of lung tissue
→ clustered at ends of bronchioles
→ heavy vascularized (covered in capillaries for gas exchange)
→ huge surface area
→ connective tissue tethers alveoli together
→ thin barrier where gases have to diffuse across: short distance = max diffusion
Types of alveoli
L2
Pneumocytes → bulk of wall of alveoli, for gas exchange. Make up 95% of SA
type 2 → 5% of epithelial cells. Make surfactant
resident alveolar macrophages → filter pathogens
Pulmonary Circulation
-why low pressure?
L2
High flow, low pressure
→ 0.5L (10%) of blood vol (75ml in capillaries)
→ rate of blood flow in lungs is high
→ low pressure circuit even w high flow: all blood goes through 10x/min i.e. 5L/min: bp of 25/8
→ low pressure bc of low resistance (short circuit, less gravity battle bc it mostly moves down, more distensible and more total CS area of arterioles (less smooth muscle)
Pulmonary Circulation: Low pressure means ___ out of capillaries but _____.
L2
minimal filtration of fluid out of capillaries but there’s lymphatic fluid to remove unfiltered fluid in lungs and keep min. diffusion distance
Both blood pressure and atm pressure are reported in ___.
What about respiratory pressure?
L2
→ mmHg
→ respiratory pressure: cmH2O
→ 1 mmHg = 1.36 cmH2O
→OR kPa: 760 mmHg = 101.325kPa
*normal sea level atm pressure is 760 mmHg but usually set to 0 cmH2O since we want to know pressure diff from enviro to inside body
Dalton’s Law
L2
total P exerted by gas mixture (atm air) is sum of P exerted by each gas (partial pressures)
→ depends on humidity of air
Partial pressure of gas =
Pgas in humid air =
L2
*partial P of gas = Patm x % of gas in atm
→ look at O2 and CO2 since their P drive diffusion
→ take account of water vapor P: in 100% humidity in 25 C, PH2O is 24 mmHg
*Pgas in humid air = (Patm - PH2O) x % of gas
Bulk flow described by:
P of inspiration and expiration?
L2
F = ΔP / P
→ ΔP: b/n alveoli and in atm (set to 0)
→if P in atm > alveoli = -F = inspiration
→ if P in alveoli > atm = +F = expiration
*control flow direction by changing lung size
Boyle’s Law
inc vol =
dec vol =
L2
P1V1 = P2V2 (inversely related)
→ helps to explain how change in lung vol creates change in lung P driving bulk flow
→ Alter P by changing V since gas exerts P on walls of alveoli/lungs
→ inc V = less bumping = dec P
→ dec V =more bumping = inc P
Inspiration and boyle’s law
L2
Lung V inc = alveoli V inc = P drop below atm = -F = P gradient = bulk flow of air into alveoli from atm
How is ventilation measured? What machine?
L2
1 respiratory cycle = inspiration and expiration
→ Spirometer measures lung V
→ inhale = bell sinks, water raises. Exhale = bell raises, water drops.
Spirometer tracing shows? (6)
L2
Tidal Volume Inspiratory reserve volume Expiratory reserve volume Total lung capacity Functional residual capacity Inspiratory capacity
Tidal Volume
L2
TV ~500ml
→ amount of air entering and exiting lungs during quiet respiration
→ total pulm ventilation = TV x freq of breaths
Inspiratory reserve volume
L2
IRV ~300ml
→ air that could be inspired beyond quiet inspiration
expiratory reserve volume
L2
ERV ~1100ml
→ air remaining within lungs that could be expired after quiet expiration
residual volume
L2
RV ~1200ml
→ can’t be measured with spirometer
→ amount of air left in lungs even with max expiratory (after you expire even your ERV)
→ prevents airway collapse since it takes LARGE P to re-inflate lungs → allows continuous gas exchange & prevents wasted energy of transporting useless blood
Total lung capacity
L2
sum of all 4 volumes
= TV + ERV + IRV + RV
= 3100 ml
functional residual capacity
L2
amount of air left in lungs after quiet expiration
→ ERV + RV (~2300ml)
inspiratory capacity & vital capacity
L2
max amount of air that can be inspired
→ IRV + TV (~800)
*vital capacity is max achievable (forced) tidal volume = IRV + TV + ERV (~1900ml)
Pulmonary function test
L2
someone’s forced vital capacity (FVC) compared to forced expired volume in 1 second (FEV1)
→ FEV1 is ~80% of VC (1520ml). Any lower: obstructive pulmonary disease (inc. resistance) **asthma
→ FVC ~3-4L. Any lower: restrictive pulmonary disease (dec lung compliance so harder to bring in/out enough air) ex, pulmonary fibrosis
*in these diseases, other one is a normal value
*inspiration occurs when alveolar pressure decreases so… how do we change alveolar pressure?
L3
Use skeletal muscle pump to increase vol of lungs/alveoli creating P dec
→ ~70% of inspiratory volume change is DIAPHRAGM (main muscle of quiet ventilation)
→ ~30% of vol change is rib cage movement (external intercostals and scalenes)
Diaphragm positioning
L3
sheet of skel muscle at thoracic cavity base
resting position → curved up
contracting → flattens downwards and inc thoracic cavity volume by pulling lungs downward
External Intercostals and scalene movement
L3
external UPPER intercostals and scalenes contract in a “pump handle” motion, so they move out
→ scalenes move from neck to upper ribs and moves sternum outwards
external LOWER intercostals create “bucket handle” motion, so they move up
→ imagine each rib as handle of bucket: contraction causes them to lift upward and out so increases vol
Since expiration occurs when alveolar pressure increases… how do we do this?
L3
→ quiet expiration: passive relaxation of inspiratory muscles (external muscles and scalenes)
→ as everything relaxes: vol decreases in thoracic cavity = lung vol dec = alveoli pressure increases above atm = air flows out (follows pressure gradient)
Muscles involved in forced expiration?
L3
→ abs (contraction inc pressure in abdominal cavity, pushes diaphragm upward in its curved state, dec lung vol, inc pressure)
→ internal intercostals and triangularis sterni (depress sternum more, dec thoracic vol)
→ neck/back muscles (curl over, dec thoracic vol)
Muscles involved in forced inspiration?
L3
→ sternocleidomastoids (neck to front of sternum, lift sternum out, contribute to pump handle effect)
→ neck/back muscles (lift head, inc thoracic volume and extend back)
→ upper respiratory tract muscles (dec airway resistance; open larynx to let more air in)
