Respiratory 1 Flashcards by Anjlie Tulshi

What is the function of the respiratory system?

-exchange O2 & CO2 between the environment & tissues

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What does the respiratory system include?

lungs & series of airways that connect lung to external environment
1. Conducting zone:
-air in & out of lungs
2. Respiratory zone:
-lined w alveoli = gas exchange location

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Describe what the conducting zone includes.

-nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles
>bring air in & out of respiratory zone for gas exchange
>humidify, warm, filter air before gas exchange
>known as anatomic dead space

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What is the conducting airway lined with?

-mucus secreting ciliated cells
>remove inhaled particles
>LG = filtered out in nose
>SM = enter airway, captured by mucus, swept up by cilia

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What type of muscle is in the walls of the conducting airways?

-smooth muscle
>sympathetic & parasympathetic
>changes in diameter of conducting airways = changes resistance = changes airflow

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Describe the sympathetic system in the conducting zone.

-via circulating EPI = activates B2
-Gs
-dilation of airway

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Describe the parasympathetic system of the conducting zone.

-activates M3
-Gq
-constriction of airways

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Describe the respiratory zone.

-where gas exchange occurs
-respiratory bronchioles, alveolar ducts, alveolar sacs

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Describe respiratory bronchioles.

-transitional
-cilia
-sm muscle
-alveoli bud off walls

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Describe alveolar ducts.

-lined w alveoli
-NO CILIA
-little sm muscle
-terminate in alveolar sacs (lined with alveoli)

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Describe alveoli.

-pouch-like invaginations of walls of respiratory bronchioles, alveolar ducts, & alveolar sacs
>alveoli walls = thin, lg surface for diffusion of gases & covered by capillaries
alveoli poorly perfused w blood = dead space

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Describe alveolar cells.

-alveolar walls = elastic w epithelial cells (alveolar cells)
>also called Type I & Type II pneumocytes

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Describe type I alveolar cells.

-95% of alveolar surface
-form tight epithelial barrier w type II cells
-keeps alveoli dry
-thin = efficient gas exchange between alveolus & pulmonary capillaries

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Describe type II alveolar cells.

-5% of alveolar surface
-synthesize pulmonary surfactants
>reduce surface tension of alveoli
>prevent alveoli from collapsing at the end of expiration
-secrete cytokines
>recruit inflammatory cells
-regen for type I & II

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Describe alveolar macrophages.

-keep alveoli free of debris (since they have no cilia)
-migrate to bronchioles
>cilia go to upper airways & pharynx = swelled/expectorated

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Describe the respiratory cycle.

-inspiratory phase -> expiratory phase
>inspiration = more effort than expiration (passive) except in horses

Describe inspiration.

-enlargement of thorax & lungs (inflow of air)
>enlargement due to diaphragm & external intercostal m
>diaphragm = caudal
>external intercostal m = cranial & outward

Describe expiration.

-passive (can be active during accelerated breathing or impediments to outflow of air)
-internal intercostal m

Describe abdominal breathing.

-predominates
-visible movement of abdomen

Describe costal breathing.

-rib movement
-painful conditions = predominate

IMP TERMS.

Eupnea = normal breathing
Dyspnea = difficult
Hyperpnea = increased depth/freq
Polypnea = rapid/shallow (panting/hyperpnea similar)
Apnea = cessation
Tachypnea = excessive rapidity
Bradypnea = abnormal slowness

Describe pulmonary ventilation.

-lung = elastic
-thin layer of pleural fluid (lube)
-suction of excess fluids into lymphatic channels = slight neg pressure between visceral & parietal surface

Describe barometric pressure.

-aka atmospheric pressure
>mixture of gases (79% N2 & 21% O2)
>gases = total atmosphere pressure of 760 mmHg @sealevel
*respiratory pressures = expressed relative to atmospheric pressure (neg or pos)
*relative pressures = atmospheric pressure is 0

What is the pressure in the lungs?

-since barometric pressure (Pb) is constant = pressure in lungs must be high or lower than Pb for air to flow
1. Pleural pressure
2. Alveolar pressure
3. Trans pulmonary pressure
*boyles law = volume & pressure inversely proportional

Describe pleural pressure.

‘Intra-pleural pressure’ -pressure exerted outside lungs (pleural cavity) -less than atmospheric pressure (-5 to -7) -neg pressure increases during inspiration w the increase in volume [pressure in pleural cavity increases when volume decreases] >during expiration its reversed *doesnt equilibrate w atmospheric pressure or alveolar pressure bc no communication*

Describe alveolar pressure.

‘Intra-pulmonary pressure’ -pressure in alveoli that increases & decreases w each breath >when the volume increases, alveolar pressure decreases -always equal to atmospheric pressure at the end of inspiration & expiration = rest period *inward flow of air into alveoli during inspiration = pressure in alveoli falls slightly neg*

Describe transpulmonary pressure.

-pressure diff between alveolar pressure & pleural pressure in lungs -measures elastic force in lungs that collapse during respiration = recoil pressure >at a lung volume, the transpulmonary pressure is equal & opposite to the elastic recoil pressure >if transpulmonary pressure is 0 (alveolar pressure = pleural pressure) the lungs collapse *pneumothorax*

What is the transpulmonary pressure under normal conditions?

-always pos -intrapleural always neg -alveolar pressure from neg to pos

What causes the lungs to collapse (recoil pressure)?

1. Stretching of elastin & collagen by lung inflation 2. Surface tension of fluid lining the alveoli *surface tension = force between water in the liquid that lines each alveoli*

Describe surfactants.

-surface active substances where water molecules have less attraction -lipoprotein complex = 30% protein & 70% lipid >produced by type II pneumocytes -accumulate at surface of alveoli & displace water = decrease surface tension (T) >prevent collapse of lung at end of expiration >increases pulmonary compliance —reduces work of inflating lungs

What needs to happen for inspiration to occur?

-lungs must expand when stretched = compliance >lung expansion for each increase in transpulmonary pressure (Palv - Pip) >factors that affect compliance = —destroy lung tissue —fibrotic —edematous —impede lung expansion *lack of surfactant = decreased compliance*

What needs to happen in order for expiration to occur?

-lungs get smaller when stretching force is released = elasticity (return to normal when distended) -elastic tension increases during inspiration when lungs are stretched & reduced by elastic recoil during expiration *elasticity = aids in pushing air out*