Unit 2

Question 1

Gaseous exchange (alveoli)

Answer 1

Oxygen:
Diffuses from high partial pressure in air to low partial pressure in our blood. Concentration gradient causes gaseous exchange to occur.

Carbon dioxide:
Diffuses from high partial pressure in our blood to low partial pressure in the air. Concentration gradient causes gaseous exchange to occur.

Question 2

Gaseous exchange (muscle)

Answer 2

Oxygen:
Diffuses from high partial pressure in our blood to low partial pressure in our muscle tissue. Concentration gradient causes gaseous exchange to occur.

Carbon dioxide:
Diffuses from high partial pressure in our muscle tissue to low partial pressure in our blood. Concentration gradient causes gaseous exchange to occur.

Question 3

SV/HR/Q

Answer 3

Q = SV x HR

Stroke volume = volume of blood ejected from heart per beat.

Heart rate = number of beats per minute.

Cardiac output = volume of blood ejected from the heart every minute.

Question 4

Mechanisms of venous return

Answer 4

(Smooth muscle) around vessels contract to squeeze blood through.
(Pocket valves) prevent back flow helping blood flow in 1D only.
(Gravity) pulls blood above the heart back to the heart.

(Respiratory muscle pump) squeezes blood out of the thoracic cavity when breathing out.
(Skeletal muscle pump) when your muscles contract blood is squeezed through the blood vessels.

Question 5

Cardiac cycle

Answer 5

Diastole:

1) Atria relax, expanding drawing blood in.
2) Pressure in atria increases, opening AV valves.
3) Blood passively enters ventricles.

Systole:

4) Atria contract forcing remaining blood into ventricles.
5) Ventricles contract forcing open the SL valves ejecting blood into arteries.

Question 6

Cardiac conduction system

Answer 6

1) Cardiac impulse initiated in SA node.
2) Impulse travels through Atria walls causing them to contract.
3) Impulse activates SA node.
4) Impulse passes down bundle of His where it is split left and right.
5) Impulse reached Purkinje fibres causing ventricles to contract.

Question 7

Values of HR/SV/Q

Answer 7

Rest Sub-max Maximal
Heart 70bpm 100bpm 220-age
rate

Stroke 70ml 100ml 120ml
volume

Cardiac 5L/min 10L/min 20L/min
output

Question 8

VE/F/TV

Answer 8

VE = Minute ventilation
F = Breathing rate 
TV = Tidal volume

VE = F x TV

       Rest                    Max intensity VE      12breaths/min   50breaths/min TV      0.5L                    3L VE      6L/min                150L/min

Question 9

Mechanics of breathing at rest

Answer 9

Inspiration…

Diaphragm and external intercostals:
Contract

Ribs move:
Up and out

Volume thoracic cavity:
Increases

Lung air pressure:
Decreases

Air moves:
In

Expiration…

Diaphragm and external intercostals:
Relaxes

Ribs move:
Down and in

Volume thoracic cavity:
Decreases

Lung air pressure:
Increases

Air moves:
Out

Question 10

Mechanics of breathing during exercise

Answer 10

Inspiration…

Diaphragm and external intercostals:
Contract

Sternocleidomastoid and scalene:
Contract

Ribs move:
Up and out (forcefully)

Volume thoracic cavity:
Increases (further)

Lung air pressure:
Decreases (further)

Air moves:
In (even more)

Expiration…

Diaphragm and external intercostals:
Relaxes

Internal intercostals and obliques:
Contract

Ribs move:
Down and in (quicker)

Volume thoracic cavity:
Decreases (quicker)

Lung air pressure:
Increases (quicker)

Air moves:
Out (even more)

Question 11

Vascular shunt mechanism

Answer 11

Baroreceptors and Chemoreceptors

…send info to…

Vasomotor control centre

…sends increased/decreased…

Stimulation to sympathetic nervous system

…causes vasoconstriction/dilation…

Of pre capillary sphincters and arterioles in the muscles/organs

Increases/decreases blood flow (80/20%)

Question 12

Regulation of heart rate

Answer 12

Neural/Intrinsic control

…sends information to…

Cardiac control centre

…stimulates…

Accelerator/vagus Nerve

…increases/decreases impulses sent to…

SA Node

Hormonal control:

Adrenaline bypasses brain directly stimulates heart (SA node) instantly increasing HR.