respiratory physiology 1 - 3

Question 1

what is external respiration?

Answer 1

movement of gases between air and the body’s cells

Question 2

what are the two types of external respiration?

Answer 2

pulmonary circulation - takes CO2 to the lungs and collects 02 from the lungs

systemic circulation - delivers 02 to peripheral tissues and collects CO2 from peripheral tissues

Question 3

how do bronchioles maintain patency?

Answer 3

by forces from the thorax

Question 4

what are the additional functions of the RS?

Answer 4

Acid-base balance, protection from infection (epithelia and cilia), and communication via speech (we always exhale when we speak)

Question 5

what are the two types cellular respiration?

Answer 5

glycolysis (from glucose) and oxidative phosphorylation (the important one, which needs external respiration as it relies on burning oxygen)

Question 6

the systemic vein and pulmonary artery carry deoxygenated blood?

Answer 6

yes

Question 7

in the steady state, what is the net vol. of gas exchanged in the lungs per unit time?

Answer 7

250ml/min 02 and 200ml/min CO2

Question 8

Why is it important for for net volume exchanged in LUNGS to be equal to gas exchanged in PERIPHERAL TISSUES?

Answer 8

to prevent gas build up in circulation which would affect gas exchange. if supply doesn’t meet demand, then concentration gradients are disrupted so makes it harder to access oxygen or carbon dioxide. partial pressure of CO2 in cells only slightly higher in cells than arterial blood so very fine conc. gradient

Question 9

what is the respiration rate for adults at rest?

Answer 9

12 - 18 breaths per minute, but 40 - 45 max

Question 10

what is tidal vol?

Answer 10

the volume of air breathed in and out at rest (500ml)

Question 11

what is functional residual capacity?

Answer 11

the volume of air left in the lungs after a normal, relaxed expiration

Question 12

what is the inspiratory reserve volume?

Answer 12

the extra air that we can breathe in if we make a really big effort (used in exercise)

Question 13

what is the importance of residual volume?

Answer 13

stop alveoli collapsing therefore less energy required to inflate the alveoli on the next breath AND provides a volume of air so that gas exchange can occur between breaths

Question 14

what is the importance of the pleural fluid?

Answer 14

stops the chest wall expanding as it wished and stops the lungs recoiling as it wishes

Question 15

what is boyles law?

Answer 15

the pressure exerted by a gas is inversely proportional to its volume, so the bigger the volume, less pressure and vice versa

gases always move from high to low pressure so this is important in breathing. on expiration, chest wall expands, then that causes increase in vol and decrease in pressure, so flows in. and vice versa for expiration

Question 16

what is Henry’s law?

Answer 16

states the amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in the liquid

Question 17

what muscles does inspiration use?

Answer 17

external intercostal muscles, sternocleidomastoid, scalene’s, and diaphragm

sternocleidomastoids and scalene’s are only really used under increased inspiratory load

Question 18

what muscles are used in expiration?

Answer 18

as we know, expiration is a passive process at rest, but during severe respiratory load or if we want to forcefully exhale, we use muscles

internal intercostal muscles and abdominal muscles

Question 19

what happens to the airways during inspiration and expiration and how is this linked to asthma?

Answer 19

during inspiration, airways pulled open by the physical forces of inspiration

during expiration, airways are compressed by physical forces. normally, in healthy lungs, we do not feel this but in asthmatics the airways are already narrowed so this makes them worse which causes the wheeze sound heard on expiration

Question 20

what are the pressures of the lungs and compare them to atmospheric pressure?

Answer 20

alveolar pressure: pressure inside the thoracic cavity (positive or negative compared to atmosphere and changes between during breathing cycle)

intra-pleural pressure is the pressure inside pleural cavity (typically negative)

transpulmonary pressure: difference between alveolar and pleural pressure (should always be positive)

Question 21

what is the importance of surfactant?

Answer 21

detergent-like fluid produced by type-2 cells

reduces surface tension of alveoli (surface tension occurs anywhere where air and water mix), so reduces the tendency for the alveoli to collapse

since water molecules are attracted, if they all build up round the outside they will pull inward toward each other and collapse the alveoli which isn’t good!

so surfactant gets between the molecules to they cant join together

Question 22

why is surfactant more effective in small, rather than large, alveoli?

Answer 22

because surfactant molecules are more concentrated in small alveoli (look over law of LaPlace)

Question 23

when does the surfactant production begin to be increased in humans?

Answer 23

at the end of pregnancy, by production of thyroid and cortisol hormones that stimulates activity of type-2 cells

this is a risk for premature babies, as they have not developed this fully. further risk the younger the baby is born (production starts around 25 weeks gestation)

Question 24

what is anatomical dead space and what is its volume?

Answer 24

gas that occupies the conducting airways and does not take part in gas exchange

150ml

Question 25

what is the 2 types of ventilation?

Answer 25

Pulmonary (Minute) ventilation = total air movement into/out of lungs (relatively insignificant in functional terms)

Alveolar ventilation = fresh air getting to alveoli and therefore available for gas exchange (functionally much more significant!)

Question 26

what is the fate of the fresh air we inhale?

Answer 26

we inhale and exhale 500ml (tidal volume) but 150ml of that becomes dead space and only 350ml reaches alveoli. next inspiration after, first 150 ml we inhale is the dead space that has been sitting and this keeps going

refer to figure 17.12 silverthorn textbook

Question 27

what does increasing tidal volume do to alveolar ventilation?

Answer 27

increases it

calculated using (TV - dead space) x respiratory rate

Question 28

what is partial pressure?

Answer 28

the pressure of a gas in a mixture of gases is equivalent to percentage of that particular gas in the entire mixture multiplied by the pressure of the whole gaseous mixture

all gas molecules exert the same pressure so PP increases with increasing gas

Question 29

In hypoventilation, why does PP of oxygen fall?

Answer 29

because the oxygen being metabolised by the peripheral tissues is happening quicker than it is being replenished in alveoli