Heart

Question 1

What are the four key anatomical features of the heart?

Answer 1

4 chambers, 4 vessels, 4 valves.

Question 2

What type of flow does the heart maintain?

Answer 2

: Unidirectional flow with high pressure, thanks to valves.

Question 3

What’s the structural difference between arteries and veins?

Answer 3

Arteries = high pressure; veins = low pressure reservoir, containing most of the blood at rest.

Question 4

Why is lung pressure lower than systemic pressure?

Answer 4

Prevents fluid leakage into alveoli; pulmonary pressure ~20 mmHg.

Question 5

When did hearts first appear in evolution?

Answer 5

Very early—seen even in worms; evolved as closed systems in many organisms.

Question 6

Which animals have 4-chambered hearts?

Answer 6

Only birds and mammals.

Question 7

What video example shows a simple heart system?

Answer 7

Daphnia – has an open circulatory system but still needs a heart.

Question 8

Why is haemoglobin evolution critical?

Answer 8

Enables efficient oxygen transport → ATP production → supports larger, more active organisms.

Question 9

Why has synthetic blood development failed?

Answer 9

Complexity of mimicking haemoglobin’s function has not yet been successfully replicated.

Question 10

Why is the heart considered the primary organ?

Answer 10

It’s the first organ to develop in embryos; essential for distributing nutrients and oxygen.

Question 12

How is the heart protected and positioned in the body?

Answer 12

: It’s behind the sternum, surrounded by ribs and vertebrae; the descending aorta runs down next to the spine, making it highly protected. The heart is slightly off-center but deeply shielded.

Question 13

What are the basic physical characteristics of the heart?

Answer 13

Weighs ~300g (about 0.66 lbs), ~12cm long (varies by sex), female hearts are generally smaller. Surrounded by fat, especially in older individuals. Enclosed in a sac called the pericardium.

Question 14

What is the memory rule for heart anatomy?

Answer 14

4 Chambers (2 atria, 2 ventricles), 4 Vessels (vena cava, pulmonary artery, pulmonary veins, aorta), 4 Valves (2 atrioventricular: tricuspid & mitral; 2 semilunar: pulmonary & aortic).

Question 15

What is the function of the heart valves?

Answer 15

Atrioventricular valves (tricuspid, mitral) prevent backflow into atria; semilunar valves (pulmonary, aortic) prevent backflow from arteries. Valve dysfunction, like mitral valve disease (e.g., in King Charles Spaniels), can lead to serious issues like pulmonary congestion.

Question 16

How does blood flow through the atria and ventricles?

Answer 16

Blood flows directly from veins into atria and through to ventricles during diastole. Atrial contraction “tops off” the ventricles (~15%). Atria look small but are crucial during exercise and aging.

Question 17

Which part of the heart is the most muscular and why?

Answer 17

The left ventricle—because it must pump blood to the whole body against high resistance. It is the thickest and largest chamber.

Question 18

What is coronary circulation and how is it visualized?

Answer 18

Coronary arteries originate at the base of the aorta and supply the heart muscle. Angiograms (imaging with contrast) show these vessels. Blockages here lead to heart attacks.

Question 19

What is the typical human blood pressure and why does it matter?

Answer 19

120/80 mmHg is normal. This high pressure requires strong valves and muscle to maintain one-way flow and efficient circulation.

Question 20

What happens when coronary arteries are blocked?

Answer 20

The heart muscle (myocardium) is starved of oxygen, and cells die quickly—this is a heart attack. Coronary arteries must remain patent for decades to keep the heart alive and functioning.

Question 21

Why is it important to stay active and maintain cardiovascular health?

Answer 21

A healthy lifestyle supports coronary artery function, which supplies the heart muscle. Inactivity and poor diet increase the risk of artery blockage and heart disease.

Question 22

What are the atrioventricular valves and their supporting structures?

Answer 22

The tricuspid and mitral valves prevent backflow into the atria. They’re supported by chordae tendineae (“heart strings”) and papillary muscles that prevent valve prolapse during contraction.

Question 23

What are heart valves made of, and how durable are they?

Answer 23

Valves are delicate, gossamer-like structures embedded in a tough fibrous collagen ring. Despite their fragility, they function efficiently for decades unless diseased.

Question 24

What can happen if heart valves fail?

Answer 24

Valve disease (e.g., mitral valve disease) causes improper closure, leading to backflow, inefficient pumping, and sometimes valve replacement. The flaps may become thickened or deformed.

Question 25

What is the fibrous ring in the heart?

Answer 25

A dense, collagen-rich structure anchoring the valves; very strong—requires a hacksaw to cut in large hearts (e.g., ox hearts). It keeps the valves securely in place.

Question 26

What makes cardiac muscle unique compared to other muscles?

Answer 26

It's striated like skeletal muscle but made of short cells connected by gap junctions—allowing fast electrical transmission for synchronized contraction.

Question 27

Why are gap junctions essential in heart muscle?

Answer 27

They allow electrical signals to pass quickly between cells without synaptic delay, ensuring nearly simultaneous ventricular contraction—crucial for efficient pumping.

Question 28

What is meant by the heart being a dual synchronous pump?

Answer 28

The heart has two pumps (right and left) working in sync—one sends blood to the lungs, the other to the body. Both rate and volume output are variable.

Question 29

What are systole and diastole?

Answer 29

Diastole is when the heart relaxes and fills; systole is when it contracts and ejects blood. Diastole lasts longer than systole in a typical cardiac cycle.

Question 30

How does the heart adapt to exercise and training?

Answer 30

Training increases stroke volume and can lower resting heart rate over time. Elite athletes may have resting rates <40 bpm due to larger, more efficient hearts.

Question 31

What is the “athlete’s heart”?

Answer 31

A larger heart (in volume or muscle mass) from training. Can include irregular rhythms, depending on the type of sport and conditioning. Not always pathological.

Question 32

What are the two main circulatory routes of the heart?

Answer 32

Pulmonary (to the lungs) and systemic (to the rest of the body).

Question 33

Why is the circulatory system considered parallel, not series?

Answer 33

So all organs receive oxygen and nutrients equally; organs like the brain can't wait for blood that's already been through another organ.

Question 34

What organ has a "series" circulation and why?

Answer 34

The liver, which receives blood from the gut via the portal vein before systemic circulation.

Question 35

What home system is used as an analogy for circulatory flow?

Answer 35

A two-pipe radiator system — all radiators (organs) heat up (receive blood) at the same time.

Question 36

Why can’t blood go from gut to brain in series?

Answer 36

Because the brain needs fresh, oxygenated, and nutrient-rich blood — not pre-filtered by other organs.

Question 37

What causes the "lub-dub" sound of the heart?

Answer 37

The snapping shut of valves — AV valves first, then semilunar valves.

Question 38

What are the atria and ventricles doing during each heart cycle?

Answer 38

Atria contract to fill the ventricles (priming); ventricles contract to pump blood to lungs/body.

Question 39

What is the primary pacemaker of the heart?

Answer 39

the sinoatrial (SA) node, located where the superior vena cava enters the right atrium.

Question 40

What happens if the SA node fails?

Answer 40

The AV node or Purkinje fibres can take over at a slower rate.

Question 41

What conducts signals through the ventricles?

Answer 41

The AV bundle, bundle branches, and Purkinje fibres.

Question 42

Are these conducting structures nerves?

Answer 42

No, they are specialized muscle cells, not nerves.

Question 43

Why is the fibrous ring important?

Answer 43

It electrically insulates atria from ventricles, forcing the signal to go through the AV bundle.

Question 44

What external systems regulate the heart rate?

Answer 44

The autonomic nervous system (parasympathetic and sympathetic) and circulating adrenaline.

Question 45

What unique motion does the heart perform during contraction?

Answer 45

A twisting or wringing motion due to muscular arrangement, enhancing blood ejection.

Question 46

Why is recreating a heart with engineering difficult?

Answer 46

The heart's motion is complex and evolved — not just a mechanical pump.

Question 47

What is cardiac output and how is it regulated?

Answer 47

Cardiac output (CO = heart rate × stroke volume) is the amount of blood pumped per minute; it increases with exercise via higher HR and stroke volume (initially), then mostly HR.

Question 48

How does exercise affect heart rate and stroke volume?

Answer 48

Heart rate rises rapidly (parasympathetic withdrawal, then sympathetic drive); stroke volume increases but may fall slightly at very high heart rates due to reduced filling time.

Question 49

What determines your maximum heart rate?

Answer 49

Roughly 220 minus age; elite athletes have lower resting HRs, allowing a greater increase during exertion.

Question 50

Which animals have superior cardiovascular performance?

Answer 50

Sled dogs (~300 bpm), racehorses, and greyhounds have exceptional heart and respiratory function compared to humans.

Question 51

What is the Frank-Starling mechanism?

Answer 51

Increased stretch of the ventricle leads to stronger contraction — an intrinsic way the heart adjusts output.

Question 52

How is the heart controlled extrinsically?

Answer 52

Autonomic nervous system (parasympathetic slows, sympathetic speeds up) and hormones like adrenaline increase HR and contractility.

Question 53

What is VO₂ max and why does it matter?

Answer 53

It’s the maximum oxygen your body can use during exercise; higher VO₂ max = better endurance and cardiac output.

Question 54

Where is heart rate regulated in the brain?

Answer 54

Brainstem centers integrate signals from the body (muscles, baroreceptors, chemoreceptors) and "Central Command" (anticipation of exercise).

Question 55

What’s the difference between intrinsic and extrinsic heart control?

Answer 55

Intrinsic: heart muscle responds to stretch (Starling’s Law). Extrinsic: nervous system and hormones alter rate and force.

Question 56

What are the key anatomical features of the heart to remember?

Answer 56

4 chambers, 4 valves, 4 major vessels, and a dual-pump system (pulmonary and systemic circuits) — all regulated by electrical conduction.