L13 The Heart

Question 1

What is the pericardium?

Answer 1

Pericardium is a protective, fluid-filled sac that surrounds heart

Acts like a protective bubble for your heart. Reduces friction as it beats

Question 2

How many chambers are within the heart?

Answer 2

4 chambers

Question 3

What does the right atrium (RA) receive?

Answer 3

Deoxygenated systemtic venous return

Question 4

Where does the right ventricle (RV) push blood to?

Answer 4

Pushes blood to pulmonary circulation for oxygenation

Question 5

Where does the left atrium (LA) receive oxygenated blood from?

Answer 5

From pulmonary circulation

Question 6

Where does the left ventricle (LV) pump oxygenated blood to?

Answer 6

Pushes blood to head and body under high pressure

Question 7

What does the work pulmonary refer to?

Answer 7

Refers to anything related to lungs

Question 8

How many circulations are there within the heart?

Answer 8

Pulmonary and systemic circulation

Pulmonary ( between heart and lungs)
Systemic ( between heart and body)

Question 9

What do valves do?

Answer 9

Valves control unidirectional blood flow in cardiac cycle

Question 10

What are the two atrioventricular valves called?

Answer 10

Mitral and tricuspid

Question 11

What are the two semilunar valves called?

Answer 11

Aortic valve
Pulmonary valve

Question 12

What is chordae tendinae?

Answer 12

They are thin, strong cords of fibrous connective tissue

Question 13

What connects the atrioventricular valves to the cardiac walls?

Answer 13

Chordae tendinae and papillary muscles

Question 14

What is the heart wall made of?

Answer 14

Endocardium - outermost
Myocardium
Epicardium

Question 15

What are conducting cells?

Answer 15

They are a group of cells that are responsible for rapidly spreading action potentials (AP)

Specialised cardiac cells

Question 16

What are contractile cells?

Answer 16

They are responsible for contraction of the heart via action potentials (AP)

Question 17

What is the link between the electrical signals and contraction of the myocytes (excitation - contraction coupling)?

Answer 17

Calcium ion release

Question 18

Give me a structural property of the myocardium

Answer 18

Has extensively branched muscle fibre cell - connected by intercalated discs (ID)

Question 19

What do gap junctions (GJ) do?

Answer 19

They facilitate the depolarisation current flow from cell to cell

Question 20

What do Desmosomes do?

Answer 20

They act as strong anchoring points between the cells

anchor fibres together

Question 21

How does excitation - contraction coupling happen?

Answer 21

Action potential triggered in sarcolemma which spreads to the T tubules which releases calcium ions which binds the actin adn myosin together creating a large instantaneous force

Question 22

Where do electrical signals originate from ?

Answer 22

The sinoatrial node (SAN)

Question 23

What is the body’s natural pacemaker called? (The 1st pacemaker)

Answer 23

Sinoatrial node

Question 24

What is Action potential (AP) propagation?

Answer 24

It’s the process by which electrical signals, or nerve impulses, travel along the axon of a neuron

Question 25

What two ways can AP propogate?

Answer 25

Cell to cell via gap junctions Conduting pathways ## Footnote AP - action potential

Question 26

What is the atrioventricular (AV) node?

Answer 26

Acts as a secondary pacemaker ## Footnote Located in the right atrium

Question 27

Why is the atrioventricular node 0.1s delayed compared to the SA node?

Answer 27

It allows the atria to fully contract and empy their blood into the ventricles before the venctricles contract. ## Footnote Maximises efficiency of blood pumping

Question 28

What does the atrioventricular ring do?

Answer 28

It prevents the direct spread of electrical impulses from the atria to the ventricles

Question 29

What is the secondary (backup) pacekmaker?

Answer 29

AVN - atriovenventricular node

Question 30

What is the 'His- Purkinje fibre system'?

Answer 30

Specialised network of cells in the heart that rapidly conducts electrical impulses throughout the ventricles

Question 31

What are the average bpm of each pacemaker?

Answer 31

1st - 60-100/min 2nd - 40bpm 3rd - 20bpm

Question 32

What happens during atrial systole?

Answer 32

Atrial depolarisation Contraction of atrium, increases pressure

Question 33

What happens during isovolumentric ventricular contraction?

Answer 33

Purkinje fibre electrical activation causes ventricles to contract (systole), which increases pressure ## Footnote When AV close, ventricular has more pressure than atrial chamber

Question 34

What are the two AV valves?

Answer 34

Mitral and tricupsid valves

Question 35

What are the two semilunar valves called?

Answer 35

Pulmonary and aortic valves

Question 36

What happens during rapid ventricular ejection?

Answer 36

- Semi lunar valves (SLV) open and rapid blood ejection - Ventricular volume decreases

Question 37

What happens during reduced ventricular ejection?

Answer 37

- SLV still open - blood still ejected - Arterial volume decreases - Blood transfered to 'arterial tree' by elastic recoil

Question 38

What happens during isovolumetric ventricular relaxation?

Answer 38

- Begins after ventricles fully repolarised - Ventricles relaxed - pressure decreases - SLV close

Question 39

What happens during rapid ventricular filling?

Answer 39

- Ventricular pressure is greater than atrial pressure - Mitral and tricuspid valves open

Question 40

What happens during ventricular filling?

Answer 40

Longest phase of cardiac cycle and includes last portion of ventricular filling

Question 41

List the order of the sequence of how blood flows through the heart (7)

Answer 41

-Atrial systole -Isovolumetric ventricular contraction -Rapid ventricular ejection - Reduced ventricular ejection - Isovolumetric ventricular relaxation - Rapid ventricular filling - Reduced ventricular filling

Question 42

How do myocytes vary in anatomy and channels?

Answer 42

They have time dependent + voltage gated (VG) currents ## Footnote Ion channels open and close in response to changes in membrane voltage and time

Question 43

What does ECG stand for?

Answer 43

Electrocardiogram

Question 44

Are the IC and EC currents in the heart muscle cells equal and opposite?

Answer 44

Yes.

Question 45

What is 'sum of vectors'?

Answer 45

Refers to the collective electrical activity generated by millions of individual cells as they depolraise and repolarise

Question 46

What detects the sum of vectors?

Answer 46

By electrodes on the body's surface

Question 47

Why are electrodes measured in planes?

Answer 47

Electrodes measure in planes because they capture the electrical activity of the heart from different angles ## Footnote Can cause a positive or a negative deflection

Question 48

What does the P wave stand for?

Answer 48

Depolarisation of atria

Question 49

What does the QRS complex mean?

Answer 49

Depolarisation of ventricles

Question 50

What does the T wave stand for?

Answer 50

Repolarisation of ventricles