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Biology (A&P 2) > Heart Exam1 > Flashcards

Heart Exam1 Flashcards

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1
Q

What are the two main divisions of the cardiovascular system? Also, what do they do?

A

Pulmonary Circuit - Pumps to lungs

Systemic Circuit- Pumps to body tissues

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2
Q

What are some aspects of the heart as well as the position?

A
  • Base-broad superior surface where vessels enter and leave
  • Apex-inferior surface (the point)
  • the heart is slightly left of central largely under the sternum
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3
Q

What are the dimensions and weight of the heart as well as the location?

A

-The heart resides within the mediastinum

The Adult Heart

  • 9cm (3.5in) wide at the base
  • 13cm (5in) from base to apex
  • 6cm (2.5in) from anterior to posterior (at thickest)
  • 300g (10oz) weight
  • Roughly the size of ones fist
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4
Q

Does the Mediastinum contain the heart?

A

Mediastinum- The thick median partition of the thoracic cavity that separates one pleural cavity for the other and contains the heart, great blood vessels, and thymus. The mediastinum is everything between right and left parietal pleuras.

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5
Q

describe the superficial anatomy of the heart and their actions?

A
  • Atria (atrium)-top chambers (receive blood)
  • Ventricles-bottom chambers
  • Aorta-takes blood from left ventricle to tissues
  • Vena Cavae (vena cava)-brings blood back to right atrium
  • Pulmonary trunk-takes blood from right ventricles to lungs
  • Pulmonary veins-brings blood back to left atrium
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6
Q

What do the Coronary Blood Vessels do and where are they located?

A

The Coronary Blood Vessels supply the myocardium with about 250 mL of blood per minute.

-5% of the circulating blood goes to meet the metabolic needs of the heart.

The Coronary Blood Vessels lie on the outside of the heart posterior and anterior

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7
Q

describe in order the pathway of blood through the heart.

A
  1. blood enters right atrium from superior and inferior venae cavae
  2. blood in right atrium flows through right AV valve into right ventricle
  3. contraction of right ventricle forces pulmonary valve open
  4. blood flows through pulmonary trunk
  5. blood is distributed by right and left pulmonary arteries to the lungs, where it unloads CO2 and loads O2
  6. blood returns from lungs via pulmonary veins to left atrium
  7. blood in left atrium flows through left AV valve into left ventricle
  8. contraction of left ventricle (simultaneous with step 3) forces aortic valve open
  9. blood flows through aortic valve into ascending aorta
  10. blood in aorta is distributed to every organ in the body where it unloads O2 and loads CO2
  11. blood returns to heart via venae cavae
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8
Q

Explain the function and terminology for the heart valves

A

Atrioventricular Valves- divides the aorta from the ventricles

  • Right AV valve=tricuspid valve
  • Left AV valve=bicuspid valve=mitral

Semilunar Valves-divide the ventricles from the blood vessels
*Aortic semilunar valve-controls blood flow from Left ventricle to aorta

Pulmonary semilunar- valve controls blood flow from R ventricle to pulmonary trunk

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9
Q

what is the importance of the chordae tendinae and the papillary muscles? what are their functions?

A

the chordae tendineae (tendinous cords) holding ends of AV valves to papillary muscles in the heart wall. these one way flap-type valves are seen throughout the cardiovascular system and help to maintain one-way-flow. Pressure will open them but shut them from the “flap” side. Pressure difference will either open or shut the valve depending on which side of the valve has higher pressure. the pressure in the left ventricle is so great during ventricular contraction that the tendinous cords and contraction of the papillary muscles are needed to prevent the valve flaps from being blown upwards into the atria

*if such and event occurs it is called mitral valve prolapes

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10
Q

why is the fibrous skeleton critical?

A

The fibrous skeleton of the heart is critical for helping to maintain electrical isolation of the upper and lower chambers so that they contract and relax in turn during a single heartbeat

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11
Q

are the valves and fibrous structure all part of the same skeleton? is there an electrical connection through the skeleton?

A

the heart valves and white fibrous structures supporting those valves are all part of the skeleton. the only electrical connection through the fibrous skeleton is via the AV node and the AV bundle.

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12
Q

what is the principle function of the principle coronary blood vessels?

A

the principle coronary blood vessels supply the myocardium with energy sources (glucose, fatty acids or keto acids) and the oxygen that it needs as well as removing carbon dioxide and wastes.

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13
Q

are coronary blood vessels what cardiologists and heart surgeons usually operate on?

A

yes these are the vessels that cardiologists put stents into and heart surgeons bypass if they become narrowed or clogged.

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14
Q

what does the special conducting system of the heart do and what does it include?

A

Coordinates and conducts electrical activity through the hear, thus coordinating sequence and timing of contraction for arterial and ventricular muscle cells.

  • includes:
  • Pace maker cells- sinoatrial (SA) node, atrioventricular node and atrioventricular bundle (bundle of his)
  • other conducting cells and fibers -right and left bundle branches and purkinje fibers
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15
Q

Explain the difference in the action potentials of the conducting system and pace maker cells

A

there are 2 types of action potentials generated in different cell types within this system

the first type is seen in specialized cells that are called pacemaker cells. they are modified muscle cells in specific locations. their action potential has a different shape from the other action potentials in the heart because the initial rising phase is generated by a voltage gated calcium channel rather than by voltage gated sodium channels.

*pacemaker cells do not have a membrane potential. they have pacemaker potentials

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16
Q

what is a pacemaker potential?

A

the pacemaker potential is slowly depolarizing baseline membrane potential that eventually reaches threshold triggering an action potential

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17
Q

What is the combination of gates that work sequentially to produce a drifting baseline membrane potential (pacemaker potential)?

A

It is generated by a combination of calcium sodium and potassium channels that work sequentially to generate this drifting baseline membrane potential know as the pacemaker potential.

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18
Q

where are pacemaker cells located?

A

pacemaker cells are located in the (SA) node the AV node and the uppermost part of the bundle of his (AV bundle)

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19
Q

do the bundle branches and purkinje fibers have a resting membrane potential?

A

Yes they exhibit resting membrane potentials seen in cardiac muscle cells

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20
Q

do the resting membrane potentials of purkinje fibers and bundle branches still differ from conventional action/resting potentials?

A

these are still different from the action potentials involved with skeletal muscles and neurons because it involves a voltage gated calcium channel in addition to the normal voltage-gated sodium channel and voltage-gated potassium channel.

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21
Q

what is the sequence of excitation of cells? How many steps are there and name them.

A 
The cells of the heart are electrically connected via gap junctions such tat the cells will fire AP's in a specific sequence.
1. SA node
2 Atrial muscle cells
3. AV node
4. AV bundle (bundle of his)
5. R and L bundle branches
6. Purkinje fibers
7. ventricular muscle fibers
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22
Q

Are pacemakers different from myoblasts?

A

Pacemaker cells and the other cells of the cardiac conduction system are cells that differentiate from other myoblasts in specific locations as heart develops.

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23
Q

what makes them different?

A

They express channels that are not found in other cells making them able to produce a pacemaker potential, depolarizing baseline that triggers the action potentials

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24
Q

What makes pacemaker cells unusual?

A

Some of the conducting cells are pacemaker cells
-capable of spontaneously depolarizing over threshold (pacemaker potential)

-action potentials generated by different currents and channels than cardiac muscle cells

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25
Q

what does permeability mean?

A

a decrease in permeability means a channel closed

an increase in permeability means a channel opened.

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26
Q

Explain in detail and sequential order the action potential of a ventricular cardiocyte (myocyte).

A
  1. Voltage-gated Na+ channels open
  2. Na+ inflow depolarizes the membrane and triggers the opening of still more Na+ channels creating a positive feedback cycle and a rapidly rising membrane voltage.
  3. Na+ channels close when the cell depolarizes and the voltage peaks at nearly +30 mv
  4. Ca++ entering through slow Ca++ channels prolongs depolarization of membrane, creating a plateau. plateau falls slightly because some K+ leakage, but most K+ channels remain closed until end of plateau
  5. Ca++ channels close and Ca++ is transported out of cell. K+ channels open, and rapid K+ outflow returns membrane to its resting potential
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27
Q

what is important about a prolonged calcium influx during the plateau phase?

A

Calcium influx occurring during the plateau phase is needed to bind to troponin to allow muscle contraction in heart muscle cells, some calcium comes form the sarcoplasmic reticulum, but much of it comes in via these voltage-gated calcium channels. longer action potentials with more calcium influx can actually lead to stronger longer contractions of heart muscle.

*contraction starts a little after the action potential begins and stops about the same time the action potential ends

28
Q

what are some terms associated with stroke and contraction and relaxation of the heart?

A
  • systole-contraction
  • diastole-relaxation
  • End-diastolic volume (EDV) - start of systole
  • End-systolic volume (ESV) -end of systole
  • Stroke volume (SV)
  • Ejection Fraction
29
Q

when systole and diastole are used what are they assumed to mean?

A

When the terms systole and diastole are used they are assumed to refer to ventricular systole and diastole unless you specifically state atrial systole/diastole

30
Q

What does SV refer to ?

A

Stroke volume (SV)= end-diastolic volume-end systolic volume

31
Q

What does ejection fraction represent?

A

Ejection fraction is represented by dividing

SV/EDV* 100

32
Q

How long does a action potential usually last in a skeletal muscle and neuron? what causes it?

A

2-10 m sec, Na+=rising phase

K+=falling phase

33
Q

how long do the action potential of a pacemaker cell last and what electrolytes cause it?

A

5 m sec, Ca++=rising phase

K+=falling phase

34
Q

Is potassium always responsible for the falling phase?

A

K+ is always responsible for falling phase

35
Q

what are the basic physics of blood flow?

A
  • Flow (F)
  • Pressure at 2 points (P1 & P2), difference delta
  • Resistance (R)
  • F=deltaP/R
36
Q

What are the principles of volume?

A

Pressure and flow. fluid doesn’t change its volume under normal conditions found in the body

37
Q

When pressure is applied what happens

A

when pressure is applied that pressure is increased within the fluid causing it to generate force (pressure) on the walls of its container

38
Q

When pressure is present what are the actions that take place?

A

When pressure in one place (P1) is greater than pressure in (P2) the fluid will flow form point 1 to point 2

39
Q

The amount of flow is a function of what?

A

The amount of flow is a function of the difference between the pressures at each point (deltaP) and the resistance to flow inherent to the container or tube.

40
Q

other than a thick viscous fluid what else resists movement?

A

the sides of the chamber or tube create friction or turbulence that also adds to resistance

41
Q

What does the term cardiac cycle refer to ?

A

A term used to refer to everything occurring during on cycle of a heartbeat

42
Q

what does the cardiac cycle include?

A

includes:

  • ECG
  • heart sounds
  • pressure changes in atria, ventricles, pulmonary trunk and aorta
  • valves opening and closing
  • volume changes in atria and ventricles
43
Q

what are the cardiac phases?

A

*ventricular filling (diastole)
-passive
-active=atrial systole
*ventricular contraction (systole)
-isovolumetric contraction -ventricles contract
to raise pressure
-ejection- pressure high enough to open valves,
blood moves out
*isovolumetric relaxation (early part of diastole)
-ventricles relax after semilunar valve shuts (all
valves closed)
-pressure decreasing until AV valve opens
-volume in ventricle =end systole volume

44
Q

what happens to valves during the sounds 1-3?

A

S1=”lubb” closing of AV valves
S2=”dub” closing of semilunar valves
S3=heard during ventricular filling

45
Q

what are the determinants of cardiac output?

A
  • Determinants of cardiac function/output
    - heart rate (HR) - measured in (BPM)
    - stroke volume (SV) - measured in mL/beat

*Cardiac Output= HR x SV

46
Q

does preload involve pressure?

A

pressure in the ventricle wall at the end of distole

47
Q

what does after load involve?

A

tension that the ventricular wall has to generate in order to cause ejection

48
Q

inotropic means what?

A

increasing contraction of muscle cells

49
Q

define chronotropic

A

increasing heart rate

50
Q

in healthy individuals changes in preload are generally caused by what?

A

in normal healthy individuals changes in preload are generally caused by increases or decreases in the volume of blood in the ventricles (venous return)

51
Q

Afterload is generally determined by pressure in what?

A

afterload is generally determined by the pressure in the aorta and systemic circuit that must be overcome for the heart to push more blood into the aorta

52
Q

what are some hormones that have an inotropic effect/ increased calcium influx

A

some hormones that have an inotropic effect include epinephrine, norepinephrine, thyroid hormone and glucagon

53
Q

what does the frank starling mechanism posit? (sterlings law of the heart)

A

increased venous return=increased stroke volume

*the increase in stroke volume is greater than the increase in venous return ( because of EDV-end diastolic volume)

54
Q

what are the events that lead to the starling law of the heart?

A

The increased force of contractithe frank starling principle is due to both increase in volume of blood returned to the heart (increased veous return and EDV) and due to increased force of contraction of the ventricle wall (decreased ESV)

on is a direct result of the increased stretch in the ventricular wall. The increased stretch leads an elastic recoil that helps increase force, and this stretch also leads to a more favorable length-tension relationship for cardiac muscle, which also helps increase force generated by ventricular myocyte.

55
Q

what does sympathetic activity and innervation dot to the heart? what are two hormones involved?

A

Sympathetic activity and innervation (norepinephrine, epinephrine) speeds up the heart and increases the force of contraction of the heart.

56
Q

what does the parasympathetic innervation do to the heart rate? name a hormone and receptor?

A

parasympathetic innervation (acetylcholine onto a muscarinic cholinergic receptor) will slow down the heart rate.

57
Q

how do alterations in the heart rate happen?

A

alterations in the heart rate happen by increasing the speed of the pacemaker potential or decreasing the speed of the pacemaker potential.

58
Q

what is the heart rate of a heart that doesn’t receive innervation?

A

the rate of a heart that does not receive innervation is about 100 bpm. the heart is said to have a parasympathetic tone (e.g. avg bpm 72)

59
Q

what are the layers and membranes of the heart in order from the outside in?

A

*Parietal Pericardium-lines pericardial cavity
*Parietal Cavity
*Visceral Pericardium- lines heart
*Myocardium-muscle
Endocardium-lines chambers
(Epicardium=visceral pericardium)

60
Q

is there a fluid that reduces friction that lies between the visceral pericardium and parietal pericardium?

A

yes, pericardial fluid fills the parietal cavity to reduce friction during contractions of the heart

61
Q

What makes up the heart wall specifically.

A
  • endocardium
  • myocardium
  • epicardium
62
Q

what is the description of the endocardium and it’s functions?

A
  • Lines chambers
  • helps prevent clotting
  • continuous with endothelium of blood vessels
63
Q

what is the description of the myocardium and it’s functions?

A
  • heart muscle
  • electrically connected muscle cells & some special fibers for conducting electrical current
  • contains connective tissue fiber skeleton (anchors reinforces, supports & electrically isolates in places)
64
Q

what is the description of the epicardium and it’s functions?

A
  • thin outer layer of mesothelium (membrane)
  • some adipocytes; simple squamous epithelium & areolar tissue (general term for connective, reticular, and adipose tissue)
65
Q

are there intercalated cardiac muscles that provide an electric connection?

A

yes, intercalated discs containing desmosomes & gap junctions which provide electrical connections between adjacent cells

Biology (A&P 2) (14 decks)

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