Week 17

Question 1

What does A refer to?
What does a refer to?

Answer 1

A= alveolar
a=arteriole

Question 2

What should the ventilation (v) to perfusion (q) ratio be?

Answer 2

v/q= between 0.8 and 1

Question 3

What is it called when v/q>1 ?

Answer 3

Anatomical dead space

Question 4

What is it called when v/q=1 ?

Answer 4

Alveolar dead space (no Blood supply)

Question 5

What is it called when v/q<1 ?

Answer 5

Shunt (blood supply but no gas exchange)

Question 6

What disease cause shunt?

Answer 6

underventialted alveoli
airway obstruction
collapsed alveoli

Question 7

What disease cause dead space?

Answer 7

Pulmonary embolism
Emphysma

Question 8

define Atelectasis

Answer 8

collapsed alveoli

Question 9

define pulmonary embolism

Answer 9

blood clot

Question 10

define emhysema

Answer 10

destruction of pulmonary capillaries

Question 11

Why is pulmonary perfusion highest at the bottom of the lung?

Answer 11

Due to gravity acting on blood

Question 12

What should the difference in pressure be between A and a?

Answer 12

about 5 mmHg

Question 13

What does ARDS stand for?

Answer 13

Acute Respiratory Distress Syndrome

Question 14

Why is Po2 very low in the mitcohondria?

Answer 14

Oxygen is converted into water in mitochondria as it’s the final electron acceptor

Question 15

What kind of shunt does everyone have?

Answer 15

Right to left anatomical shunt
2% of deoxy CO is dumped into left ventricle

Question 16

What does right to left ventricle shunt partly explain?

Answer 16

PAo2> Pao2

Question 17

What is the unhealthy shunt called?

Answer 17

Physiological shunt
caused by normal perfusion/ limited gas exchange

Question 18

What equation gives the Rate of diffusion?

Answer 18

(pressure difference x SA x diff constant) / Thickness

Question 19

How is Co2 transported in blood?

Answer 19

mostly HCO3- form, or combined with Hb. Some dissolved in solution

Question 20

What is the chloride shift?

Answer 20

HCO3- formed in RBCs
(via carbonic anhydrase)
HCO3- goes to plasma in exhcange for chloride on hb
so charges cancel out

Question 21

What is the point of the chloride shift?

Answer 21

Increase blood’s ability to carry O2
Increases buffering ability of HCO3-

Question 22

What is the CO2 dissociation curve like?

Answer 22

Not sigmoidal, just upwards curve

Question 23

What is the haldane effect?

Answer 23

the difference between venous and arterial blood CO2 enhances the unloading of CO2 from tissues to blood. This means at lower PO2 Hb has greater affinity for CO2

Question 24

What does hypoventialtion do to blood PCO2?

Answer 24

increased CO2= acidosis

Question 25

What does hyperventialtion do to blood PCO2?

Answer 25

decreased CO2= alkalosis

Question 26

What is the only O2 sensor in the body?

Answer 26

Carotid body

Question 27

What drives breathing?

Answer 27

decreased arterial PO2 increased arterial PCO2 increased H+ conc

Question 28

Why can't CO2 cross the BBB?

Answer 28

small but non polar

Question 29

What is Hypocapnic braking?

Answer 29

Low Co2 levels reduce the drive to breathe so that more CO2 is not blown away

Question 30

What is the equation linking flow to blood pressure and resistance?

Answer 30

Flow= Change in Bp / resistance

Question 31

What is the exercise pressor reflex?

Answer 31

The body increases blood pressure when it recognises that exercise it taking place

Question 32

What are the two parts of the pressor reflex?

Answer 32

Mechanoreflex (how much the muscle deforms) Metaboreflex ( how chemically changes in muscle)

Question 33

What is sympatholysis?

Answer 33

Products made during exercise block effects of sympathetic ns eg. nitric oxide=vasodilator

Question 34

Why do people with hypertension have an exaggerated rise in blood pressure even if on medication?

Answer 34

Due to increased metaboreflex activity