week 9 Flashcards
pulmonary ventilation refers to:
the mechanical mvmt of air in and out of the body
what is eupnea and describe muscles involved
eupnea is quiet breathing
inspiration is active and expiration is passive
muscles involved are the diaphragm and the external intercostals
what is hyperpnea and describe muscles involved
increased Ve that matches metabolic demands
Inspiration is active and expiration is also active
Muscles involved in inspiration: diaphragm, external intercostals, scalenes and sternocleidomastoid
Muscles involved in expiration: abdominals and internal intercostals
What is minute ventilation
The total volume of air that we inspire or expire every minute - what we can easily measure
Define tidal volume
The volume of each breath (VT)
Define breathing frequency or respiratory rate
Number of breaths per min (fB)
Define alveolar ventilation
Amount of air that reaches the alveoli and can participate in gas exchange - effective ventilation (what we care about)
Define dead space (VD)
Portion of each breath that gets wasted
Define anatomical dead space
Air that never reaches the alveoli
Always there
Assumed to be 150 mL
Define physiological dead space
Air that never reaches the alveoli with no/poor perfusion (blood flow)
What is the formula for calculating minute ventilation
VE = VT x fB
What is the formula for alveolar ventilation
VA = (VT - VD (assumed 150 mL)) x FB
Outline the three phases associated with the VE response to dynamic exercise
Phase 1: immediate increase - fast component ~ 10 s
Phase 2: exponential increase - slow component ~ 1 min (more at high intensity)
Phase 3: steady state - appropriate for MR unless intensity is too high to be supported aerobically - steady state never attained
VE plateaus within 1-2 mins
Review pages 5 6 and 7 of respiratory I
What are early VE responses driven by
VT and then FB
What does reducing VD/VT mean
You have to move less air to meet gas exchange needs - saves energy
Why is breathing tightly controlled
- to match metabolic demands (VO2 and VCO2)
- to maintain acid-base balance (pH)
- to clear airways
- to communicate (phonation + emotional expression)
What is the term used for under ventilation
Hypoventilation
Insufficient supply
- can’t meet metabolic demands
- reduced energy capacity
- serious consequences - death blah
Insufficient clearance
- CO2 accumulates
- causes problems on its own
What is the term used for over ventilation
Hyperventilation
Waste of energy
Slight oversupply of O2 (not harmful)
Excessive clearance of CO2:
- CO2 levels drop
- causes problems on its own
Where is the central control of breathing and what triggers inspiration
In the brainstem - pons and medulla
Nerves trigger inspiration
Describe volitional control of breathing
- how we can voluntarily override our breathing control centers
- involves higher brain centers - cerebral cortex
Describe chemical control of breathing
Uses central chemoreceptors in the medulla and peripheral chemoreceptors in the aorta and carotid artery
- together, they sense CO2, pH, and O2 of arterial blood
What is ventilation stimulated by
- increased CO2
- decreased pH -> increased H+
- decreased O2
What is the influence of body temp on the breathing control centers
Temp directly excites the breathing control centers - increased VE
What is the contribution of proprioceptors on the breathing control centers
Sensory input from muscles, joints and tendons provide input that the body is moving - increased VE
What is the influence of higher centers on the breathing control center
Cortical control
- includes volitional control
- non-volitional influences include:
- thinking about/planning/controlling mvmt
- central command
Hypothalamic control
- strong emotion
- perception of pain and intense effort
describe what O2 and CO2 look like in the following conditions:
1. inspired air
2. alveolar air
3. arterial blood
4. venous blood
- PIO2 and PICO2
- PAO2 and PACO2
- PaO2 and PaCO2
- PVO2 and PVCO2
in exercise induced hyperpnea, what factors are responsible for:
- initial jump to phase I
- gradual climb and settling in at steady state
- ventilatory drift that happens after ~30 mins
- brain involvement in generating mvmt (anticipatory response)
- brain involvement in generating mvmt, mvmt of muscles and joints, perception of mvmt and effort
- increased body temp
what is the ACSM classification and what are its pros and cons
all possible intensities from rest to max divided into 5 categories
pro: very simple to apply to anyone
con: doesnt make much sense physiologically or metabolically
define domains
domains (the categories) are defined by metabolic processes that occur at that intensity
define boundaries
boundaries between domains are defined by physiological events - we figure out the lower/upper limits of each domain by determining the boundaries
what do we determine boundaries/domains based on and what is a pro and a con of this
we determine boundaries and domains based on: HR, power, and speed
pro: based on individual physiology rather than guesses
con: technically demanding and resource intensive to determine
what is determination useful for
- assessing/monitoring subtle changes in fitness
- determining precise training intensities to elicit specific metabolic adaptations
- predicting endurance performance
describe the extreme intensity domain
steady state: not attainable
sustainability: less than 2 mins
anaerobic contribution: significant
fatigue mechanisms: accumulation of metabolites, central fatigue
describe the severe intensity domain
steady state: not attainable
sustainability: several minutes
anaerobic contribution: substantial
fatigue mechanisms: accumulation of metabolites, central fatigue
example: VO2 max
describe the heavy intensity domain
steady state: reached within 10-20 mins
sustainability: multiple hours
anaerobic contribution: obvious
fatigue mechanisms: glycogen depletion, central fatigue
example: maximum sustainable intensity
describe the moderate intensity domain
steady state: reached within 2-3 mins
sustainability: indefinitely
anaerobic contribution: negligible
fatigue mechanisms: central fatigue
example: measurable anaerobiosis
describe metabolic thresholds
they represent physiologically significant events
1st metabolic threshold
- when anaerobic glycolysis rises above the baseline
- boundary between moderate and heavy domains
2nd metabolic threshold
- when the rate of anaerobic glycolysis makes exercise unsustainable
- boundary between heavy/severe domains
how can we identify thresholds
we can identify thresholds using data from incremental tests to maximum
lactate data -> lactate thresholds (LT1/LT2)
ventilatory data -> ventilatory thresholds (VT1/VT2)
describe LT1
intensity where [La-] first increases more than or equal to 1 mmol/L above baseline
- [La-] is now spilling into the blood because rate of La production exceeds rate of La clearance by the cell
describe LT2
intensity where [La-] vs WL curve starts to increase more steeply
- La is now accumulating in the blood because the rate of La production exceeds the rate of La clearance from the blood (skeletal muscle, heart, liver)
