Respiratory 1

Question 1

What is the function of the respiratory system?

Answer 1

-exchange O2 & CO2 between the environment & tissues

Question 2

What does the respiratory system include?

Answer 2

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

Question 3

Describe what the conducting zone includes.

Answer 3

-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

Question 4

What is the conducting airway lined with?

Answer 4

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

Question 5

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

Answer 5

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

Question 6

Describe the sympathetic system in the conducting zone.

Answer 6

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

Question 7

Describe the parasympathetic system of the conducting zone.

Answer 7

-activates M3
-Gq
-constriction of airways

Question 8

Describe the respiratory zone.

Answer 8

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

Question 9

Describe respiratory bronchioles.

Answer 9

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

Question 10

Describe alveolar ducts.

Answer 10

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

Question 11

Describe alveoli.

Answer 11

-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

Question 12

Describe alveolar cells.

Answer 12

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

Question 13

Describe type I alveolar cells.

Answer 13

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

Question 14

Describe type II alveolar cells.

Answer 14

-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

Question 15

Describe alveolar macrophages.

Answer 15

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

Question 16

Describe the respiratory cycle.

Answer 16

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

Question 17

Describe inspiration.

Answer 17

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

Question 18

Describe expiration.

Answer 18

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

Question 19

Describe abdominal breathing.

Answer 19

-predominates
-visible movement of abdomen

Question 20

Describe costal breathing.

Answer 20

-rib movement
-painful conditions = predominate

Question 21

IMP TERMS.

Answer 21

1. Eupnea = normal breathing
2. Dyspnea = difficult
3. Hyperpnea = increased depth/freq
4. Polypnea = rapid/shallow (panting/hyperpnea similar)
5. Apnea = cessation
6. Tachypnea = excessive rapidity
7. Bradypnea = abnormal slowness

Question 22

Describe pulmonary ventilation.

Answer 22

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

Question 23

Describe barometric pressure.

Answer 23

-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

Question 24

What is the pressure in the lungs?

Answer 24

-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

Question 25

Describe pleural pressure.

Answer 25

‘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

Question 26

Describe alveolar pressure.

Answer 26

‘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

Question 27

Describe transpulmonary pressure.

Answer 27

-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

Question 28

What is the transpulmonary pressure under normal conditions?

Answer 28

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

Question 29

What causes the lungs to collapse (recoil pressure)?

Answer 29

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

Question 30

Describe surfactants.

Answer 30

-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

Question 31

What needs to happen for inspiration to occur?

Answer 31

-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

Question 32

What needs to happen in order for expiration to occur?

Answer 32

-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