Cardiovascular System - Cardiac cycle, sounds and rhythms

Question 1

Systole

Answer 1

• Heart contaction

Question 2

Diastole

Answer 2

Relaxation of heart

Question 3

Atria contraction

Answer 3

• Diastole initial when the atrium is filling with blood
• then Atrium in systole when contracting and pushing blood to ventricle

Question 4

Ventrical contraction

Answer 4

• Initially diastole when the ventricle is being filled with blood from atrium
• Systole when ventricle contracts until all blood enters either aorta or pulmonary vein then returns to diastole

Question 5

Sino Atrial node

Answer 5

• Specialised electrically active Myocardial tissue of atrium
• Intrinsic unstable spontaneous depolarisation
• Generates electrical activity-Impulse

Question 6

Atria ventricular node

Answer 6

• Specialised electrically active Myocardial tissue ventricular midline
• Intrinsic unstable spontaneous depolarisation
• Generates electrical activity-Impulse

Question 7

Inter nodal tracks

Answer 7

• Conduction pathways (Anterior, Middle & Posterior)
• Carry pulse, depolarise and contract atria (right and left)
• Converge at AV node

Question 8

Fibrous mid-line

Answer 8

No electical conductivity

Question 9

Bundle of HIS (AV bundle)

Answer 9

• Collect and carry to higher and lower part of the ventricles

Question 10

Purkinge Fibres

Answer 10

Specialised myocardium for electrical conduction towards contractile myocytes

Question 11

Vagus innervation

Answer 11

Suppress the heart rate

Question 12

Sympathetic Innervention

Answer 12

-Stimulates the AV and SA node this increases the heart rate

Question 13

Cardiac muscle

Answer 13

• Striated branched muscle fibre containing single nucleus with many mitochondria
• Gap junctions so depolarisation between cells
• Desmosomes hold the fibres close together in contractions

Question 14

Properties of Cardiac muscle

Auto-rhythmicity

Answer 14

Ability to initiate heart rate consistent and continuous at regular pace without any external stimuli (autonomic)

Question 15

Properties of Cardiac muscle

Excitability

Answer 15

• Ability to respond to stimuli of adequate strength and duration (threshold or more)
• Ability to generate and process action potential

Question 16

Properties of Cardiac muscle

Conductivity

Answer 16

Ability to conduct and transmit impulse through the cardiac tissue

Question 17

Properties of Cardiac muscle

Contractility

Answer 17

Ability to contract in response to stimulation (mechanical)

Question 18

Exitation-Contraction Coupling in Contractile Myocytes

Step 1 - Action Potential arrival

Answer 18

Action Potential from adjacent cell excites myocytes and trigger membrane depolarisation in T-tubules

Question 19

Exitation-Contraction Coupling in Contractile Myocytes

Step 2 - Calcium enters cell

Answer 19

Calcium enters the cell via voltage gated channel open the calcium enters cell

Question 20

Exitation-Contraction Coupling in Contractile Myocytes

Step 3 - Calcium binding

Answer 20

Calcium binds to Ryanodine receptor (RYR) and induce Calcium release from SR

Question 21

Exitation-Contraction Coupling in Contractile Myocytes

Step 4 - Trigger myosin

Answer 21

Calcium binds to troponin and triggers acting-myosin complex and contraction

Question 22

Exitation-Contraction Coupling in Contractile Myocytes

Step 5 - Calcium unbind

Answer 22

Calcium unbind from troponin and pumped back into SR

Question 23

Exitation-Contraction Coupling in Contractile Myocytes

Step 6 - Calcium causing relaxing

Answer 23

Calcium unbinding cause relaxation and excess Ca2+ exchanged with Na+

Question 24

Exitation-Contraction Coupling in Contractile Myocytes

Step 7 - Maintainance of Na+ gradient

Answer 24

Na+ gradient is maintained by sodium-potassium- ATPase pump.

Question 25

P wave

Answer 25

Atria depolarlisation contraction (systole)

Question 26

QRS complex

Answer 26

- Isovolumetric contraction when ventricle is filling - Ventricle depolarisation

Question 27

T wave

Answer 27

Ventricle repolarisation

Question 28

Atrial Systole

Answer 28

- Atrial myocardium contraction for 0.1 sec

Question 29

Ventricle Systole

Answer 29

Ventricular myocardium contraction at 0.3s

Question 30

Synus Rhythums

Answer 30

- Calculate by observing the R-R intervals - Calculate if there is Sinus bradycardia less beats per minute - Sinus tachycardia heart beat too fast

Question 31

ECG readings

Answer 31

1mV = 10mm high 5 boxes across is 1s

Question 32

Sinus bradycardia

Answer 32

- Rate is less than 60bpm - Usually asymptomatic beta blockers and calcium channel blockers my be the cause

Question 33

Sinus tachycardia

Answer 33

- rate greater than 100bpm - Occours in exercise and stress - Asymptomatic could by hypervolemea