session 4

Question 1

action potential phases

Answer 1

• rapid depolarisation
• plateau
• repolarisation

Question 2

what occurs dueing depol of the heart

Answer 2

fast sodium Na+ channels open for rapid depol

Question 3

plateau pahse of the heart

Answer 3

• slow calcium channels open
  
  • calcium binds to troponin
• potassium channels open (K+)

Question 4

repolarisation of the heart

Answer 4

calcium channels close

potassium channels open

This then goes back to resting membrane potential

Question 5

refractory period

Answer 5

Long Period after a contraction which doesn’t allow a second contraction to occur

• Tetanic contraction therefore not allowed - this is when they just remain contracted
  *

Question 6

Question 7

electrocardiogram (ECG)

Answer 7

• electrical currents of the heart detected on skin surface
• is a sum of all action potentials of active cells

Question 8

Answer 8

• A - P-Q segment
• B - QRS complex
• C - S-T segment
• D - P-Q interval
• E - Q-T interval

Question 9

P wave represents

Answer 9

atrial depolarisation

• impulse from SA node over atria

Question 10

QRS complex represents

Answer 10

ventricular depol

• spread of impulse through ventricles

Question 11

T wave represents

Answer 11

ventricular repol

Question 12

As atrial fibers depolarise the P wave appears. After the P wave begins..

Answer 12

The atria contract

Question 13

pathway of electrical current

Answer 13

• SA node
• AV node
  
  • slight delay here to let atria contract
• bundle branches
• perkinje fibres

Question 14

three phases of cardiac cycle

Answer 14

• atrial systole
  
  • 0.1 sec
  • atria contract and blood through AV valves into ventricles
• ventricular systole
  
  • 0.3 sec
  • ventricles contract and AV valves close
  • ventricular ejection
• relaxation period
  
  • 0.4 sec
  • ventricular diastole
  • ventricular filling

Question 15

End diastolic volume is

Answer 15

the amount of blood in the ventricles at the end of diastole

Question 16

define isovolumetric contraction

Answer 16

• AV and SL valaves are all closed
• ventricular volume remains the same

Question 17

ventricular ejection

Answer 17

• pressure rises and SL valaves open = blood ejection from heart

Question 18

end systolic volume ESV

Answer 18

amount of blood in the left ventricle at the end of systole

Question 19

stoke volume

Answer 19

volume ejected per beat from each ventricle

Question 20

ventricular pressures

Answer 20

• maximum BP in aorta is 120mmHg
• max in pulmonary trunk 30mmHg

Question 21

why is left ventricular wall thicker

Answer 21

ejects same amount of blood with more force

Question 22

auscultation

Answer 22

• listening to sounds within body
• can hear heart sounds which result from turbulent blood flow and valve closure

Question 23

Four heart sounds

Answer 23

• S1 (lubb)
  
  • closing of AV valves
• S2 (dupp)
  
  • closing of SL valves
• S3
  
  • rapid ventricular filling
• S4
  
  • during atrial systole

Can only hear sound 1 and 2 in normal heart

Question 24

Heart murmur

Answer 24

Abnormal heart sound

• some can be from backward blood movement in the heart

Question 25

Cardiac output

Answer 25

* volume of blood from ventricle into aorta each minute * CO = SV x HR *

Question 26

what influences stroke volume

Answer 26

* preload * frank-starling law of the heart * increased filling = more muscle stretch = more blood pumped out * contractility * afterload * pressure heart has to overcome before semilunar valve can open

Question 27

regulation of heart rate

Answer 27

* neural factors * sympathetic impuses increse HR and contraction force * parasymp decresae HR * hormones and ions * eg adrenaline * other factrs * eg age, gender

Question 28

heart disease risk factors

Answer 28

* high cholesterol * high BP * smoking * diabetes * high fibrinogen levels

Question 29

clinical heart issues

Answer 29

* MI = myocardial infarction * death of heart muscle from low oxygen * replaced with scar tissue * blood clot * angina pectoris * heart pain from ischaemia

Question 30

coronary artery disease/ coronary heart disease

Answer 30

* heart receives inadewuate blood due to obstruction of its supply * eg * atherosclerosis * coronary artery spasm * clot

Question 31

congestive heart failure

Answer 31

* brought on by high BP, MI or CAD * heart begins to fail * **left ventricular failure = pulmonary oedema** * **right ventricular = peripheral oedema**