3.10.3 Biological Measurement

Question 1

What side of the heart is responsible for pumping deoxygenated blood to the lungs?

Answer 1

Right

Question 2

What side of the heart is responsible for pumping oxygenated blood around the body?

Answer 2

Left

Question 3

What directions do veins go?

Answer 3

veINs go INto the heart

Question 4

What direction do arteries go?

Answer 4

Go away from the heart, out to the body.

Question 5

What is the purpose of valves?

Answer 5

Stop backflow of blood

Question 6

Why do muscles contract?

Answer 6

They are stimulated by electrical signals

Question 7

What does the sinoatrial (SA) node control?

Answer 7

Controls the contraction of the atria.

Question 8

What does the atrioventricular (AV) node control?

Answer 8

Controls the contraction of the ventricles.

Question 9

How many electrical pulses does the SA produce per minute?

Answer 9

70

Question 10

What do nerve cells do?

Answer 10

Carry impulses (electrical signals) around the body.

Question 11

What do dendrites do?

Answer 11

Carry signals to other cells.

Question 12

What does the nerve fibre consist of?

Answer 12

Aton and Myelin Sheath

Question 13

What does the nerve fibre do?

Answer 13

Passes the signal along to contract the muscle.

Question 14

What do the signals (that the nerve cell carries) depend on?

Answer 14

The concentration of K+ and Na+ ions inside and outside the cell membrane.

Question 15

What happens during Resting (no signal)?

Answer 15

There is a large conc. of K+ inside, and Na+ outside.
The Na+ concentration is bigger, so there is p.d. across the membrane - cell is polarised.
- membrane is not permeable.

Question 16

What happens during Action (cell stimulated)?

Answer 16

Cell membrane is permeable to Na+, and they diffuse through due to a concentration gradient and negative ions inside.

Question 17

What happens if the stimulus is big enough?

Answer 17

The threshold potential (around -55mV) is reached.
The flow of ions increases rapidly, decreasing the p.d
[depolarisation]

Question 18

What happens when the p.d reaches 0V?

Answer 18

It’s depolarised

Question 19

What value(s) does the p.d continue to flow to?

Answer 19

+30mV
(+40mV for the heart)

Question 20

What happens to the cell membrane when it’s reversed polarised?

Answer 20

Membrane is impermeable to Na+ ions.

Question 21

What happens during repolarisation?

Answer 21

Membrane now permeable to K+ ions, which diffuse through and restore the original p.d balance.

Question 22

What happens before the p.d goes back to its resting position?

Answer 22

It gets an ‘overshoot’

Question 23

How long does the process (of stimulus causing depolarisation and repolarisation) take?

Answer 23

2 ms

Question 24

What is contraction in the heart controlled by?

Answer 24

SA and AV nodes

Question 25

How long does the contraction in the heart take?

Answer 25

0.2 s

Question 26

What is depolarisation?

Answer 26

The contraction of muscle

Question 27

What is repolarisation?

Answer 27

The muscle relaxing

Question 28

What does ECG stand for?

Answer 28

Electrocardiography

Question 29

Why are electrodes placed on the certain parts of the skin surface for an ECG?

Answer 29

Needs to be where arteries are close to the surface.

Question 30

How is contact conductivity improved during an ECG?

Answer 30

Clearing/ removing hair Removing dead skin cells (exfoliating) Use of electrolyte gel

Question 31

What does an electrolyte gel do?

Answer 31

Removed air gap so there is better contact conductivity.

Question 32

Why do signals received from an ECG need amplifying?

Answer 32

Signals at the surface are weak.

Question 33

What parts of the body are used in an ECG?

Answer 33

Limbs Chest

Question 34

Why isn't right leg used in an ECG?

Answer 34

Too far away from heart (arteries)

Question 35

How many electrodes are used during an ECG?

Answer 35

3

Question 36

How are the electrodes used in an ECG?

Answer 36

2 held at 0 potential + connected to 2 diff. limbs. Other attached to remaining limb. [it is possible to record the difference in potential between one limb and the average of the other two]

Question 37

What does trace depend on?

Answer 37

Where the electrodes are put.

Question 38

What is a P-wave?

Answer 38

The depolarisation and contraction of the atria.

Question 39

What is the QRS-wave?

Answer 39

The depolarisation and contraction of the ventricles.

Question 40

What is a T-wave?

Answer 40

The repolarisation and relaxation of the ventricles.