Physiology - Intro

Question 1

Define respiration.

Answer 1

Exchange of oxygen and carbon dioxide between the environment and tissues

Question 2

Describe what respiration can be divided into.

Answer 2

External - exchange of oxygen and carbon dioxide between the atmosphere and blood flowing through the lungs
Internal - transport of oxygen and CO2 between the tissues and lungs by the circulating blood. O2 consumption and CO2 production in tissues.

Question 3

Name the five steps of respiration.

Answer 3

Ventilation 
Gas Exchange 
Gas Transport
Gas Exchange 
Cellular Respiration

Question 4

Define ventilation.

Answer 4

Process of moving air in and out of the lungs in order to supply oxygen and remove carbon dioxide from the alveoli.
Process of BULK FLOW

Question 5

Define the first gas exchange in the process.

Answer 5

Describes how O2 and CO2 moves across the alveoli membrane down their partial pressure gradients.
Process of DIFFUSION

Question 6

Define gas transport.

Answer 6

Blood leaves the lungs high in O2 and low in CO2.

Pumped around the body by a process of BULK FLOW.

Question 7

Describe the second gas exchange.

Answer 7

At the interface between the capillaries and the cells there is exchange of O2 and CO2 down their partial pressure gradients.
Process of DIFFUSION

Question 8

Define cellular respiration.

Answer 8

Cells use O2 and produce CO2.

Question 9

What is Dalton’s Law of Partial Pressures?

Answer 9

Pgas = Fgas x Ptotal
Need to know the % of concentration of each gas and the atmospheric pressure.
Normally use 760mmHg
** see lecture slides and make a note to paste on wall

Question 10

What does water vapour do in the trachea?

Answer 10

Reduces the PO2 in the trachea by about 10mmHg

Question 11

How do we calculate the pressure of inspired O2? (PIO2)

Answer 11

PIO2 = FIO2 x (barometric pressure - 47)

Question 12

How do we calculate the ventilation?

Answer 12

VE= f x VT

Question 13

Why do we calculate alveolar ventilation?

Answer 13

Not all the inspired air reaches the alveoli - as fresh air is inhaled, it is mixed with air in the anatomical dead space.

Question 14

How do we calculate alveolar ventilation?

Answer 14

VA = f x (VT - D)

Question 15

What does alveolar ventilation measure?

Answer 15

Measures the flow of fresh gases into and out of the alveoli during a particular time

Question 16

What type of breathing increases/decreases alveolar ventilation?

Answer 16

Slow deep breathing increases VA

Rapid shallow breathing decreases VA

Question 17

What is the primary principle of ventilation?

Answer 17

Air moves from an area of higher pressure to an area of lower pressure.

Question 18

Describe the pressures causing inspiration.

Answer 18

Lower pressure inside lungs

Higher pressure outside lungs

Question 19

Describe the pressures causing expiration.

Answer 19

Higher pressure inside lungs

Lower pressure outside lungs

Question 20

Describe what happens on inspiration/expiration.

Answer 20

Volume changes
Pressure changes
Gas flow and pressure equalization

Question 21

What does Fick’s Law of Diffusion explain?

Answer 21

Explains gas exchange through the membranes.

Question 22

How does pulmonary disease impair gas transfer capacity?

Answer 22

Thickening of the alveolar membrane e.g. pulmonary fibrosis

Reduction in SA e.g. emphysema (destruction of alveoli = reduced SA)

Question 23

Name the five mechanisms causing arterial hypoxaemia.

Answer 23

Reduced PB or FIO2 
Hypoventilation 
Impaired diffusion
Shunt 
V/Q mismatch (ventilation, perfusion)

Question 24

What two forms is oxygen carried in the blood?

Answer 24

Dissolved and combined with Hb

Question 25

What is the O2 capacity?

Answer 25

Maximal amount of O2 that can be combined with Hb

Question 26

Describe the oxygen Hb combination.

Answer 26

Easily reversible to give oxyhaemoglobin

O2 + Hb HbO2

Question 27

How much oxygen can one gram of Hb combine to?

Answer 27

1.34ml O2

Question 28

How many grams of Hb does a normal litre of blood have?

Answer 28

150g of Hb

Question 29

How do we calculate the O2 capacity?

Answer 29

Grams of Hb x 1.34ml O2

Question 30

How is CO2 transported?

Answer 30

Dissolved in plasma - 10%
Transported as HbCO2 (20%)
Transported as HCO3- (bicarbonate dissolved in plasma - 70%)

Question 31

What is the central controller of respiration?

Answer 31

Pons, medulla and other parts of the brain

Question 32

What are the effectors of respiration?

Answer 32

Respiratory muscles

Question 33

What are the sensors of respiration?

Answer 33

Chemoreceptors, Lung and other receptors (stretch)