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A & P I* > Heart > Flashcards

Heart Flashcards

1
Q

Endocardium

A

Inner epithelial lining of the heart, in contact with “chamber blood”

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2
Q

Epicardium

A

Outer serous membrane in contact with the myocardium and continuous with the inner layer of the pericardium (superficial to myocardium)

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3
Q

Pericardium

A

Continuation of the epicardium as an invagination of serous membrane, creating a thin space of enveloping serous fluid around the heart.
The outer aspect of the pericardium serves as an attachment point to surrounding structures in the thoracic cavity.
[aids against friction]

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4
Q

Myocardial tissue

Cardiac Muscle: voluntary or involuntary?

A

Cardiac muscle that is found only in the heart
Cardiac muscle is INVOLUNTARY – all muscle is excitable, contracts, and returns to resting membrane. Cardiac muscle contraction is INVOLUNTARY.

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5
Q

What lines closed cavities and produces serous fluid that AIDS in reducing friction upon organ movement?

A

Serous membranes (epithelial tissue)

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6
Q

Cardiac Myocyte

Similar to skeletal muscle in what ways? (4)

A

Is a cell type that makes up the myocardium
Similar to skeletal muscle:
- membrane and cytoplasm are referred to as sarcolemma and sarcoplasm, and it’s sarcoplasmic reticulum is a storage site for Ca
- it as T tubules that carry an action potential transversely across each cell
- actin and myosin are the contractile proteins of the cell (thus, striated)
- mitochondria and myoglobin are abundant to meet energy demands

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7
Q

Cardiac Myocyte

Differs from skeletal muscle how?

A
  • anatomically cardiac myocytes contain only one nucleus, and are interwoven and interconnected with adjacent myocytes to allow for a rapid spread of action potentials resulting in a unified contraction
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8
Q

Physiologically, how are cardiac myocytes unique?

A

They do not require innervation to initiate an action potential, though innervation may override this self-regulation

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9
Q

What are the 2 variants of heart muscle cells?

Where does the difference lie?

A

Pacemaker Cells & Contractile Cells

Difference lies in their resting membrane potential and length of action potential

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10
Q

Pacemaker Cells

A

Make up the nodes, bundles, and fibers

[smaller threshold to overcome e.g. -60 to -50]

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11
Q

Contractile Cells

A

Make up the atria and ventricles

[larger threshold to overcome e.g. -80 to -50]

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12
Q

What element plays a much bigger role in cardiac muscle than in skeletal muscle?

A

Calcium

  • rapid influx of Ca ions causes depolarization initiating action potential
  • slower continual influx of Ca (different pump) produces a prolonged action potential in the contractile cells of the atria and ventricles
  • Ca triggers Ca release from Sarco Reticulum
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13
Q

What are the chambers and valves lined with?

What do the conduction units carry?

A
  • endocardium

- carry action potentials within the myocardium

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14
Q

Passageways of Note:

A
  • Superior/Inferior Vena Cava
  • Right Atrium
  • Tricuspid Valve
  • Right Ventricle
  • Pulmonary Valve
  • Pulmonary Arteries
  • Pulmonary Veins
  • Left Atrium
  • Mitral Valve
  • Left Ventricle
  • Aortic Valve
  • Aorta
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15
Q

Blood moves through the organ because of?

The circulation of blood as it relates to the heart can be divided into:

A
  • pressure differences and the pump action of muscle tissue
  • Pulmonary Circulation
  • Systemic Circulation
  • Coronary Circulation
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16
Q

Pulmonary Circulation

A

Heart –> Lungs –> Heart

RV to LA

17
Q

Systemic Circulation

A

LV –> tissues –> RA

Aorta to Vena Cava

18
Q

Coronary Circulation

A

To and from myocardium

Aorta?

19
Q

Conduction Units of note (4)

A

Sinoatrial node: natural, inborn pacemaker (Ac starts)
Atrioventricular node: slows down Ac
Atrioventricular Bundle
Purkinje fibers

20
Q

Auscultation of the heart
What does it provide?
Under normal conditions, what is the rhythm maintained by?
What is the term for the sequence of events from the beginning of one heartbeat to the next?

A

(Palpation of the pulse)

  • provides a window into the rhythm of the heartbeat
  • maintained by the heart’s own conduction system
  • sequence termed: CARDIAC CYCLE (begins with SA node with a spontaneous action potential)
21
Q

Since myocytes do not require nerve innervation to contract, what allows for this automaticity?
What happens after depolarization?

A
  • constant motion of Na+, K+, and Ca++ in and out of the cell
  • after depolarization, the speed of the return back to resting potential differs among heart cells and thus creates a hierarchy of control over the rate of contractions
  • –SA node at top of hierarchy; “the pacemaker”, depolarizing 60-100x per min
22
Q

What is the propagation of the action potential of each cardiac cycle?
What is the result?

A

SA node –> through both atria –> AV node –> AV bundle –> left and right bundle branches continue through the ventricles via the Purkinje fibers from the apex to the base of the heart
- result is bilateral atrial contraction followed by bilateral ventricular contraction

23
Q

What are the heart sounds of a normal cardiac cycle?

A

LUB: atrioventricular valves closing – [TV and MV snapping shut simultaneously]
[allows atriums to fill and “get their stretch on”]
Dub: aortic and pulmonary valves closing
[ventricles filling when these are open]

24
Q

Frank Starling Mechanism

A
  • as venous return increases, so does the stretch of the atrial chambers’ this results in an increased force and rate of contraction
    [venous return determines cardiac output]
25
Q

EKG

What does the big picture show? (3 waves)

A

[Measure in change of membrane potentials]**
- recall that membrane/action potential is measured in milli lots. Voltage generated by the heart diffuses to the surface of the body and may be measured and recorded using electrocardiography

BIG picture of EKG show:

  • P wave: measure of atrial depolarization
  • QRS wave: measure of ventricular depolarization
  • T wave: measure of ventricular repolarization
26
Q

Though the myocardium is capable of regulating its own contraction rate, it is still innervated just in case. This allows the heart to be a part of what?

A
  • any coordinated sympathetic or parasympathetic adaptation
27
Q

Afferent fibers carry sensory information from ______ to _______.

A

Heart to the medulla

28
Q

Vagus Nerve
Cervical & Thoracic Nerves

Ach
NE

A

(Parasympathetic/Ach) - [inhibits action]
- the medulla can alter the heart function via the Vagus Nerve, or the cervical and thoracic sympathetic nerves (Sympathetic/NE)
ACh – decreased atrial contraction reducing the heart rate
NE – increases HR, contractility, speed of relaxation, and conduction velocity

29
Q

What MAY modify the actions of the medulla in response to stressors such as heat, dehydration, exercise, and emotions?

A

Hypothalamus

30
Q

Endocrine modifiers include?

What else will also affect contractility?

A

NE released from the adrenals, and thyroid hormone from the thyroid gland will have a direct stimulators effect on the cardiac myocytes
- abnormal extra cellular ion concentrations will also affect contractility

31
Q

Myocardium

A

The contractile, functional layer of the heart making up the bulk of the organ

A & P I* (10 decks)

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