DSA #3

Question 1

V/Q ratio of 0 indicates what?

Answer 1

no ventilation ie. peanut stuck in throat
arterial blood gas composition will equal venous blood
creates a physiological shunt

Question 2

what effect does hypoxic vasoconstriction have?

Answer 2

happens when the V/Q ratio is low, the V/Q raised and brings arterial blood gases closer to expected values

Question 3

what happens when the V/Q ratio is high?

Answer 3

bronchoconstriction, to INC resistance and DEC ventilation thus limiting alveolar dead space

Question 4

what is anoxia?

Answer 4

total absence of oxygen being delivered to the tissues

Question 5

describe hypoxic hypoxia

Answer 5

PaO2 is below normal bc alveolar PaO2 reduced

blood cannot fully equilibrate with alveolar air

Question 6

describe anemic hypoxia

Answer 6

O2 carry capacity of the blood is reduced

ex. CO

Question 7

describe circulatory hypoxia

Answer 7

tissue not receiving sufficient O2 bc the heart cannot pump blood to the tissue

ex. sickle cell,

Question 8

describe histotoxic hypoxia

Answer 8

cells poisoned, tissue unable to use O2

ex. Cyanide

Question 9

quickly describe what is fucked up with each type of hypoxia:
hypoxic
anemic
circulatory
histotoxic

Answer 9

lungs
blood
tissue
everything is working properly

Question 10

describe characteristics of CSF

Answer 10

very little protein
NO cholesterol
like plasma and absorbed in the blood
more HCO3-

Question 11

how is chronic hypercapnia fixed by choroid plexus?

chronic hyopcapnia?

Answer 11

HCO3- added to CSF, H+ moved into the blood

H+ added to CSF, HCO3- moved into blood

Question 12

oxygen content equation

Answer 12

oxygen content = oxygen capacity x %saturation

oxygen capacity = amt Hb in blood x 1.34

Question 13

describe the 3 steps in an acute response to altitude (hypoxia)

Answer 13

1. peripheral chemoreceptors INC firing rate at a PaCO2 of 70 mmHg and INC ventilation
2. Inc ventilation will INC PaO2 and DEC PaCO2
3. DEC PaCO2 will cause a DEC in the firing rate of central chemoreceptors

Question 14

name the 3 big adjustments of acclimatization

Answer 14

1. cells of choroid plexus have a CSF that is more basic, add H+ to it, but still maintain a PaCO2 lower than normal
2. INC EPO production –> INC Hb content of blood
3. INC # and size of mitochondria, more efficient O2 utilization

Question 15

what happens in altitude sickness?

Answer 15

cerebral vasculature will dilate in response to hypoxia

this causes INC perfusion pressure and filtration leading to mild edema

Question 16

pulmonary edema is a side effect of altitude, when does it occur and for what reason

Answer 16

rapidly ascend greater than 2500m and then do physical activity OR live at altitude, come down to sea level then go back up
edema due to INC pulmonary vascular permeability, pulmonary hypertension occurs but LA pressure is NORMAL

Question 17

total barometric pressure equation

descend 10m = INC 1 atm

Answer 17

pressure due to water + pressure due to air

ie. 4atm + 1atm

Question 18

what happens in hyperbaric conditions

how can it be used for treatment?

Answer 18

O2 toxicity leading to superoxide anion and peroxide production

CO poisoning

Question 19

what is nitrogen narcosis?

Answer 19

high [N2] exerts effects on neurons in CNS similar to alcohol

Question 20

what are bends or decompression sickness?

Answer 20

ascending too rapidly from underwater
N2 dissolves in plasma while submerged, when you ascend slowly it has time to get back to the lungs to convert to the gas state there, but if ascent is too rapid, it will convert to gas while in blood
this is painful

Question 21

what happens in an air embolism?

Answer 21

glottis is closed and air is not allowed to leave the lungs during ascent so it goes into the blood
PV may rupture creating an air embolus which can kill

Question 22

V/Q ratio of infinity indicates what?

Answer 22

pulmonary embolism which blocks blood flow

creates alveolar dead space