Week 1 Respiratory Physiology Flashcards by Race Uy

Central Controller

Brainstem

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Effectors

receives info from central controllers and causes ventilation to occur

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Sensors

gathers info and provides feedback to the central controller to allow to adjust output (eg chemoreceptors and mechanoreceptors)

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Control of breathing - Sensors

breathing stimulated and regulated by CO2, H+, & O2 concentrations

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What are Chemoreceptors?

chemical sensors in the brain and blood vessels that identify changing levels of oxygen, carbon dioxide and H+

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What do Chemoreceptors - Central (medulla) detect?

detects change in pH (H+) caused by changes in PCO2

Note: Blood brain barrier impermeable to H+ (CO2 can diffuse through CSF combines with water to give off H+)

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What do Chemoreceptors - Peripheral (carotid sinus, aortic arch) detect?

detects changes in PO2, PCO2, pH

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Normal PaCO2

38-42 mmHg

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What happens when there is an increase of CO2 in blood?

increased breathing rate and depth of respiration (Increased ventilation

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What happens when there is a Decrease of CO2 in blood

reduced ventilation (less breathing)

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Normal PaO2

80-100 mmHg

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Ventilation is not stimulated by falling….

PaO2 until O2 reaches about 50mmHg

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Hypercapnia

excessive carbon dioxide in the blood

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deficiency in the amount of oxygen reaching the tissues

Hypoxia

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Factors that can affect/override central control

voluntary: eg. hyperventilation
Disease process: eg. brain injury, fractured ribs, thoracic injury

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Muscles acting on Thorax during NORMAL INSPIRATION

diaphragm

-parasternal intercostals

scalenes
quadratus lumborum

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Muscles acting on thorax during NORMAL EXPIRATION

mainly passive elastic recoil

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Movement of ribs 1-6

“pump handle” - moves up and down

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Movement of ribs 7-10

“bucket handle”

caused by contraction of the diaphragm
increase transverse (lateral diameter of the rib cage)

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Movement of ribs 10-12

“caliper” movement

non fixed ribs (11-12 floating, 8-10 - false ribs)
outwards and backwards swing of the ribs
also increases lateral diameter

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Breathing Inspiration and expiration Process - is it active or passive?

Inspiration - active
Expiration - passive (muscles relax, lungs recoil, compresses air, pressure in alveoli increases and gas moves outward)

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Tidal Volume (VT)

Amount of air that moves in and out of the lungs during a normal breath

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Minute ventilation

aka minute volume; amount of air moved in and out of the lungs in one minute

minute ventilation (MV) = tidal volume (Vt) x respiratory rate

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Dead space

Study These Flashcards

ventilation but no perfusion

What is Anatomic dead space

- gas in conducting airways

What is Alveolar dead space

- gas in respiratory zone where there is no perfusion

Physiological Dead space

anatomical dead space + alveolar dead space

Blood that enters the arterial system without going through ventilated lung is called

Shunt

Extrapulmonary shunt examples:

congenital heart defect, blood going from left side of the heart to the right side of the heart (septal defect)

Intrapulmonary shunt

blood that goes through the lungs but is not exposed to a ventilated lung - examples: lung collapse, consolidation - leads to reduction of PaO2

what is dead space?

- ventilation but no perfusion - High V/Q ratio >1

What is a shunt

- perfusion but no ventilation - Low V/Q ratio <1

What is the response of the pulmonary vasculature when PaO2 alveolar gas is reduced?

- Hypoxic vasoconstriction. Vasoconstriction (opposite to other mms) - acts to divert blood flow to other alveoli with better oxygen exchange

What is hypoxic vasoconstriction?

- the response of the pulmonary vasculature when there is a reduction in PaO2. - acts to divert the blood to alveoli with better oxygen exchange

what is Diffusion?

movement of gas molecules across the alveolar capillary membrane

What are factors that affect gas diffusion?

- surface area of the membrane - thickness and chemical composition - pressure gradient of gas across the membrane - solubility of the gas - molecular weight of the gas - Blood volume and Hb concentration - lung volume

3 means/forms in which CO2 is transported in the blood?

- Dissolved - Combines with Hemoglobin (Hb) - as Bicarbonate (HCO3-)

Does CO2 diffuse quicker than oxygen? True or False

True (CO2 is more soluble)

What is the measure of the resistance to gas flow through an airway?

Airway Resistance (Raw)

What are factors that influence airway resistance?

1. Length of tube 2. Radius of the tube 3. Driving pressure 4. Viscosity of gas

Expiratory flow

- dependent on lung volumes - the higher the lung volume, the greater the airflow For example: - you can cough harder if you inhale first (Try coughing without inhaling first)

How distensible or elastic the lung is? The elastic properties of the lungs?

Lung compliance

Compliance equation

Compliance = volume change per unit pressure

Reduced compliance means...

stiffer lungs

Increased compliance means...

floppy lung

Alveoli are supported by?

Surfactant and Interdependence

What is Interdependence?

- interdependence what we call the alveoli attached and are working together to support each other - if one of the alveoli collapses - the expansion of other alveoli exerts a pull on the collapsed ones which may assist in their re-expansion

What is Collateral Ventilation?

- alveoli are interconnected in which the alveoli can be ventilated through a different passage - alternate pathways of ventilation between adjacent alveoli

Amount of time it takes for an alveoli (or region of lung to distend? It is also related to lung stiffness (Compliance) and resistance to airflow

Time constants

For normal lungs at normal lung volume, the dependent lung receives?

- greater ventilation -Note: Dependent lung is lower lung region

When side lying, what is the dependent lung?

- the lung at the bottom

In upright sitting - the lungs dependent is the...

"bases" (lowest parts of middle and lower lobes)

For normal lungs at low volume which is a lot easier to expand? Non-dependent or dependent

Non dependent (it is more compliant and therefore is better ventilated

Is perfusion gravity dependent in the lung (true or false)

True - Ie more at the bottom At the top of the lungs - the capillaries may be squashed At the Bottom - capillaries may squash alveoli

What do you call when ventilation and perfusion does not match?

V/Q mismatch - V/Q mismatch results in a drop in PaO2

what is the perfect V/Q

V/Q match in the Apex of the lung

Better Ventilation (V) than Perfusion(Q) >1

V/Q match in the Middle of the lung

even ventilation (V) and Perfusion (Q) = 1

V/Q match in the Bottom of the lung

better perfusion (Q) than ventilation (V) <1

Week 1 Respiratory Physiology Flashcards

(59 cards)