Overview of Heart
Why is myocardium important?
Creates structural support for heart, allows for contractions, and insulates electrical activity
What happens in the atria during the QRS complex?
What signals cardiac muscle cells to contract? Do these nerve signals come from the CNS or PNS?
Action potentials; no! they originate in specialized pacemaker cells
They bury themselves at the bottom of lake and ponds and slowly leach minerals from their shells into their blood to counteract the accumulation of acidic CO2 until its warm enough to emerge
What are the two circuits of the heart?
Pulmonary and systemic
What does the pericardium do?
Structure that surrounds heart to anchor it, reduce friction as it pumps, and protect it from changing shape or overfilling
What unique structures are found in cardiomyocytes? What feature allows signals to be sent so quickly?
What is atypical about purkinje fibers?
They are the slowest conducting cells of the heart that rely on ion channels for carrying action potentials
Rocks! During mechanical digestion the rocks hit hard materials (Bones?) and break them down
What differentiates pulmonary and systemic circulation besides their areas of blood flow?
Pressure; pulmonary circuit is low-pressure while systemic circuit is high-pressure
What causes coronary artery disease? Why is it problematic?
The time that an action potential spreads throughout the heart (tells us our heart rate)
What does sinus rhythm mean?
The pacemaker cell (SA node) sets and maintains the heart's normal contractile rhythm
Why do none of the alligator handlers ever get their hands bit off?
Rate and force of heart contractions
Why is there no need for valves between the atria and the venous blood that flows into them?
Atria are under very low pressure, meaning majority of blood flows into atria via gravity and the pressure in veins
What extrinsic factors can influence the rate of SA node signaling?
Sympathetic and parasympathetic nervous sysetms
Ectopic pacemakers
Why do a cat's lungs predispose it to dying if it gets hit by a car?
Cats don't have separate lung cavities, so if one lung collapses, both lungs will give out, and it will be sad for the cat
Compare pulmonary gas exchange and systemic gas exchange.
Pulmonary capillaries facilitate exchange of carbon dioxide and oxygen at alveoli; systemic capillaries do the reverse at tissues
1) What feature encases both the left and right atriums? 2) What is its job? 3) Does it differ at all between right and left atrium?
Auricle; it expands to provide the atria with more space to hold blood; yes, the auricle of the right atrium is much larger
What might happen if cardiac muscles cells did not contract in a coordinated manner?
How does the electrical signal change in speed as it travels through the heart?
It is at its fastest right after SA node generation and decreases considerably in impulse speed as it travels through the AV node
Why have none of the biggest loser contestants ever been able to keep off the weight they lost?
Each person's body has a fat mass set point that it will religiously defend. People can temporarily lose weight, but their body will subconsciously up and down regulate metabolic processes to keep that fat mass set point. Only bariatric surgery has been shown through research to permanently reset this point.