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Bio40b > The Heart Concepts > Flashcards

The Heart Concepts Flashcards

1
Q

Where is the apex of the heart located? Does the heart angle anteriorly or posteriorly? To the left or to the right?

A

The apex of the heart is located at the most inferior aspect of the heart and is the pointed part. It is oriented “left-ward” and anteriorly

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2
Q

What are some structures the heart is anterior to? Posterior to? Inferior to? Superior to?

A
  • Anterior to the esophagus, aorta, pulmonary arteries, and thoracic vertebrae
  • Posterior to the sternum
  • Inferior to the first rib
  • Superior to the diaphragm
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3
Q

What type of membrane is the Pericardium? Which layer of serous pericardium is part of the cardiac wall? Which layer is part of the pericardium? What are the two parts of the pericardium? What is the function of the pericardium?

A

The pericardium is a serous membrane, that acts as mechanical protection for the heart and big vessels, and lubrication to reduce friction between the heart and the surrounding structures.

Visceral pericardium: wraps the actual organ

Parietal pericardium: lines the cavity

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4
Q

What fluid is located between the parietal and the visceral pericardial serous membranes?

A

Serous fluid

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5
Q

Which are the parts of the cardiac wall from superficial to deep?

A

Pericardium
Epicardium
Myocardium
Endocardium

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6
Q

What type of tissue makes up the endocardium?

A

Epithelial tissue

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7
Q

What are the functions and structure of the fibrous skeleton of the heart?

A

Functions:
- C.T. strength (the backbone of the heart)
- Origin and insertion of cardiac muscles
- Non-conductive. Electrically insulates chambers of the heart from one another

Structure:
- Dense irregular C.T.
- Two main rings in between the ventricles inferiorly and atrium superiorly
- Rings connected on a transverse plane

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8
Q

Which cardiac structures are continuous with the fibrous skeleton of the heart?

A

Interventricular septum

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9
Q

What are the 4 valves of the heart, their locations, and their functions? What 2 structures does each valve “connect”

A

Valves allow only a one-way flow

Atrioventricular valves (bicuspid and tricuspid):
- The Bicuspid connects the left atrium to the left ventricle
- The Tricuspid connects the right atrium to the right ventricle

Semilunar Valves (Pulmonary and aortic):
- The Pulmonary connects the right ventricle and the lungs
- The Aortic connects the left ventricle and the aorta

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10
Q

How is backflow prevention in AV valves different, mechanistically, from backflow prevention in semilunar valves?

A

Atrioventricular Valves:
- The pressure of blood from the sending chamber pushes open the cusps and allows flow into the receiving chamber. When the receiving chamber contracts, it pushes the cusps up to seal against backflow
- The papillary muscles also contract, pulling the chordae tendinae and sealing the cusps of the valve tight to prevent eversion of the cusps up into the sending chamber

Semilunar Valves:
- When the artery fills with blood, the backflow fills the valve cusps and pushes the free edges against each other to seal the valve and prevent backflow

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11
Q

Which 2 structures do the interatrial septum separate? The interventricular septum?

A

The interatrial septum separates the left atrium from the right atrium.
The interventricular septum separates the left ventricle from the right ventricle

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12
Q

Where are the right and left atria located, where do they receive blood from, and what are their roles?

A

Right Atrium= receives deoxygenated blood from the inferior and superior vena cava (and some coronary veins)
- Pumps deoxygenated blood and pump to the right ventricle through the tricuspid valve

Left Atrium= receives oxygenated blood from the lungs
- Collects oxygenated blood from the pulmonary veins and feeds blood through the bicuspid (mitral) valve into the left ventricle

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13
Q

Where are the atrial auricles located, and what is their function?

A
  • The right atrium auricle is like a folded pouch that projects anteriorly and can expand to collect more blood if needed
  • Left atrium auricle projects anterior to increase blood-holding capacity
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14
Q

What type of muscle makes the anterior surface of the atria “bumpy”?

A

Pectinate muscles

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15
Q

How are the Right and Left ventricles related to the systemic and pulmonary circulations? Which is part of a low-pressure system, with thinner ventricular walls, and which is part of a high-pressure system, with thicker ventricular walls?

A

The pump for the pulmonary circuit, which circulates blood through the lungs, is the right ventricle. The left ventricle is the pump for the systemic circuit, which provides the blood supply for the tissue cells of the body.

The right ventricle is part of a low-pressure system with thinner ventricular walls
The left ventricle is part of a high-pressure system with thicker ventricular walls

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16
Q

What are papillary muscles and chordae tendineae (and trabeculae carneae), where are they located, and what are their function during ventricular ejection?

A

Papillary muscles= project into the ventricle to hold the chordae tendineae. Contracts to pull the chordae tendineae shut and seal the valve to prevent eversion of the cusps up into the sending chamber

Chordae tendineae=dense regular C.T. (tendon-like) extensions of the tricuspid valve. Prevents the backflow of blood.

Trabeculae carneae= muscle wall is ridge by traceulae carneae. The biggest is the papillary muscles that prevent the backflow of blood

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17
Q

Which structure do the right and left coronary arteries branch off of? What are some key branches of the right and left coronary arteries?

A

The right and left coronary arteries branch off of the most inferior portion of the ascending aorta

Right coronary arteries:
- Marginal branch

Left coronary arteries:
- Circumflex artery
- Anterior interventricular artery
- Inferior interventricular artery

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18
Q

What is the function of coronary arteries, and what is the importance of arterial anastomoses in coronary circulation?

A

The cardiac wall is too thick to allow for diffusion of nutrients to the superficial layers of the myocardium so coronary circulation feeds the cardiac muscle from the outside.

Arterial anastomoses are the intersection of the arteries which gives alternate paths for blood to reach every myocardial cell in case of blockage in an artery

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19
Q

Which sulci tend to be great places to find coronary blood vessels?

A

Coronary sulcus

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20
Q

Where do all coronary veins drain to?

A

Large coronary sinus on the anterior surface of the right ventricle

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21
Q

What is the correct order of structures in the sequence of whole body circulation – starting at the right atria, traveling through the whole body, and arriving back at the right atria? (should be 10 “structures” in your sequence)

A

Right Atria
Right ventricle
The pulmonary trunk and pulmonary arteries
Lungs (pulmonary capillaries)
Pulmonary veins
Left atrium
Left ventricle
Aorta and systemic arteries
Systemic capillaries
Superior and inferior vena cavae and coronary sinus

22
Q

What are the structural and functional differences between the Tricuspid and Bicuspid valves?

A

Tricuspid:
3 flaps
Connects the right atrium and ventricle

Bicuspid:
2 flaps
Connects the left atrium and ventricle

23
Q

What are the differences in innervation between cardiac and skeletal muscles?

A

Skeletal muscle is innervated by the somatic nervous system and cardiac muscles are innervated by the autonomic nervous system

Cardiac muscle innervated simultaneously through gap junctions. Skeletal muscles innervated separately.

24
Q

What is the correct order of the 5 common structures of the intrinsic cardiac conduction system?

A

SA Node and Bachmann’s bundle
AV Node
Bundle of His
Left and right bundle branch
Left and right Purkinje fibers

25
Q

How do nodal cells differ from contractile cells? Which is more prevalent in the heart?

A
  • Nodal cells connect together to travel to the entire heart bringing electric signals to all contractile cells (more prevalent in the heart)
  • Contractile cells contract when they get pinged by Nodal cells
26
Q

Where does the pacemaker potential originate, and how is it developed?

A
  • Leak channels in nodal cells are Na channels which cause a constant slight depolarization from -60 to -55 mV.
  • This triggers voltage-gated Ca channels to open, which depolarizes the inside of the cell to reach the threshold
  • The rush of cations depolarizing Nodal cells move through gap junctions of intercalated discs into the contractile cells via gap junctions triggers contractile cells to depolarize, contract, and beat the heart
27
Q

What 2 types of channels are responsible for depolarizing pacemaker cells to threshold?

A

Funny Na leak channels and voltage-gated Ca channels

28
Q

What 2 types of channels are responsible for the typical post-threshold massive depolarization and repolarization?

A

Depolarization: voltage-gated Na+ channel

Repolarization: voltage-gated K+ channel

29
Q

What is the resting potential of a pacemaker cell?

A

No resting potential

30
Q

What is the frequency of depolarizations in the SA Node (every 0.8 seconds)

A

They regularly depolarize to the threshold about once every 0.8 seconds

31
Q

Why do we want to slow down electrical signaling through the AV bundle?

A

The delay ensures that you can fill the ventricles with blood before you contract

32
Q

Which structure do the right and left bundle branches of the intrinsic cardiac conduction system split around when moving inferiorly?

A

Interventricular septum

33
Q

What is the role of ANS innervation and adrenergic hormones in heart rate?

A
  • The sympathetic arm of the ANS uses hormones (norepinephrine and epinephrine) from the chromaffin cells of the adrenal gland that bind to the membrane of Nodal cells to activate Ca channels to help depolarize the Nodal cell membrane FASTER than usual
  • So threshold (AP) is reached more quickly, so the heart rate increases
34
Q

Why is the “plateau” between depolarization (all the way up to +30 mV) and repolarization typically hundreds of times longer in cardiac contractile muscle cells, than in typical skeletal muscle cells? What’s so important that has to happen during this long plateau in cardiac muscle?

A

The “plateau” doesn’t rapidly repolarize immediately after rapid depolarization as in what’s seen in typical skeletal muscles. It maintains a steady rate of depolarization.

This plateau period in cardiac muscle is due to a perfect balance of some calcium (Ca) channels allowing calcium (Ca) to come in and some potassium (K) channels opening to allow potassium (K) out

35
Q

What is an EKG, what does it measure, and why is it so valuable a tool in cardiology?

A

An EKG (electrocardiogram) is a composite recording of all the electrical activity (AP) of the entire heart over the course of one heartbeat.

An ECG can help identify an unusually fast heart rate (tachycardia) or an unusually slow heart rate (bradycardia).

36
Q

What is the typical range of scale (in mV) of an EKG from the typical highest point to the lowest point on the recording (remember that it’s about -90 to +30 mV in recordings from a typical muscle cell)?

A

-0.5 to 1.0 mV

37
Q

Generally speaking, what do deflections (up and down) in an EKG represent? What does flat (baseline) segments represent?

A

Up and down deflections represent depolarization and repolarization. Flat segments represent depolarization in the plateau phase

38
Q

What are Stroke Volume (SV), End Diastolic Volume (EDV), and End Systolic Volume (ESV), and how do they relate mathematically? How are SV and Heart Rate (HR), related to Cardiac Output (CO)?

A

SV= the actual volume of blood leaving the ventricles at each contraction

EDV= the full amount of blood the ventricles hold before contraction

ESV= the amount left in the ventricles after contraction

SV = EDV - ESV

CO = SV x HR

39
Q

If atrial pressure is less than ventricular, what will happen to the AV valves? If atrial pressure is greater than ventricular?

A

If the atrial pressure is less than the ventricular, the AV valves will stay closed

If atrial pressure is greater than the ventricular, the AV valves will pop open

40
Q

If ventricular pressure is less than arterial pressure, what will happen to the semilunar valves? If ventricular pressure is greater than arterial?

A

If ventricular pressure is less than arterial pressure, the semilunar valves will stay closed

If ventricular pressure is greater than arterial, the SLV will pop open

41
Q

If both intake and outtake valves are closed and ventricular contraction begins, what happens to the ventricular pressure? Which law helps us understand how pressure and volume are inversely related in a closed system?

A

Boyle’s law: P1V1 = P2V2
Ventricle needs to contract to build up pressure in the ventricles to open up SLV to send blood into the arteries. The ventricular pressure needs to be greater than arterial pressure, 80 mmHg, for the SLV valves to open

42
Q

When ventricular pressure is greater than atrial, but lower than arterial, what phase of the cardiac cycle are you in?

A

Isovolumetric contraction

43
Q

To hear valves closing, what do you need to do to the heart?

A

Lub= AV valves closing during isovolumetric contraction
Ventricular pressure is higher than atrial pressure
Dub= SL valves closing during isovolumetric relaxation
Arterial pressure is higher than ventricular pressure

44
Q

If EDV = 133 mL, ESV = 63 mL, HR = 71 beats per minute, what is CO? What unit do we use for CO?

A

SV= EDV-ESV
SV= 133ml - 63ml = 70ml
CO= SV x HR = 70 x 71 = 4970ml =4.97 L/min

Use liters for CO

45
Q

Will changes in SV change CO? Changes in HR? Changes in EDV? ESV?

A

Changes in the SV, HR, EDV, and ESV will change CO
Changes in the EDV and ESV will change SV, so changing CO

46
Q

What do we call agents that increase HR? Decrease HR? Increase the contractile force of the heart? Decrease contractile force of the heart?

A

Agents that increase HR= positive chronotropic agents

Agents that decrease HR= negative chronotropic agents

Agents that increase the contractile force of the heart= positive ionotropic agents

Agents that decrease the contractile force of the heart= negative ionotropic agents

47
Q

What is the role of the Cardiovascular center, of the Medulla oblongata, in regulating changes to SV and HR?

A

Sympathetic:
Increased contractility of atria and ventricles increases stroke volume
Increased rate of spontaneous depolarization in the SA node (and AV node) increases heart rate

Parasympathetic:
Decreased rate of spontaneous depolarization in the SA node (and AV node) decreases heart rate
No parasympathetic innervation for the contractility of the heart

48
Q

Mechanistically, how is Ca involved in positive ionotropism?

A

If you impact the heart with chemicals that increase the inflow of Ca, you’ll get a positive ionotropism. More Ca entering the cell joins Ca from the SR and more cross-bridge formation, more “power-stroking” and more force of contraction

49
Q

Which sensory inputs can be positively chronotropic? Positively ionotropic?

A

Positively chronotropic:
Bears (special sense input)
The limbic system (nervousness)
Proprioception
Chemoreceptors (aortic arch)
Baroreceptors

Positively ionotropic:
Norepinephrine and epinephrine

50
Q

Which type of ANS outflow will be positively chronotropic? Negatively chronotropic?

A

Sympathetic innervation= positively chronotropic
Parasympathetic innervioa= negatively chronotropic

51
Q

What is the clinical term for elevated HR? Depressed HR?

A

Elevated HR = Tachycardia
Depressed HR = Bradycardia

Bio40b (28 decks)

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