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BIO 212 Class > Unit 6 Study Guide > Flashcards

Unit 6 Study Guide Flashcards

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Biology 101 flashcards
1
Q

Epicardium

A
  • outermost layer
  • also called the visceral layer of serous pericardium
  • composed of simple squamous epithelium and an underlying layer of areolar connective tissue
  • as we age, the epicardium thickens as it becomes more invested with adipose connective tissue
  • Heart receives nutrients from coronary vessels
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2
Q

Myocardium

A
  • middle layer of the hart
  • composed of cardiac muscle tissue
  • thickest of the three layers
  • contraction of this muscle generates the force necessary to pump blood
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3
Q

Endocardium

A
  • covers the internal surface of the heart and external surface of the heart valves
  • composed of simple squamous epithelium and an underlying layer of areolar connective tissue
  • Epithelial layer of the endocardium is continuous with the epithelial layer of the endothelium - lines blood vessels
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4
Q

Atrioventricular Valves

A

Right:

  • covers the right atrioventricular opening
  • has three cusps (tricuspid)

Left:

  • covers the left atrioventricular opening
  • has two cusps (bicuspid)
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5
Q

When the cusps are open

A

allows blood to move from an atrium into the ventricle

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6
Q

when the ventricles contract

A
  • blood is force superiorly as ventricular pressure rises, which causes AV valves to close.
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7
Q

AV valves

A

prevent blood flow back into the atrium

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8
Q

Semilunar valves

A
  • pulmonary semilunar valve

- aortic semilunar valve

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9
Q

pulmonary semilunar valve

A
  • located between the right ventricle and pulmonary trunk
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10
Q

aortic semilunar valve

A
  • located between the left ventricle and the ascending aorta
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11
Q

The semilunar valves open when

A
  • the ventricles contract and the force of blood pushes the semilunar valves open and blood enters the arterial trunks.
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12
Q

the semilunar valves close when

A
  • the ventricles relax and the pressure in the ventricles becomes less than the pressure in an arterial trunk
  • prevents back flow into the ventricle
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13
Q

function of the fibrous skeleton of the heart

A
  • provides structural support at the boundary between the atria and the ventricles
  • forms supportive fibrous rings to anchor the heart valves
  • provides a rigid framework for the attachment of cardiac muscle tissue
  • acts as an electrical insulator because it does not conduct action potentials and thus prevents the ventricle chambers from contracting at the same time as the atrial chambers.
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14
Q

sarcolemma

A
  • invaginate to form T-tubules that extend to the SR.
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15
Q

T-tubules

A
  • invaginate one per sarcomere and overlie Z discs.
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16
Q

sarcoplasmic reticulum

A
  • surrounds bundles of myofilaments called myofibrils in cardiac muscle, but is less extensive than the SR in skeletal muscle and lacks both terminal cistern and a tight association with T-tubules.
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17
Q

myofilaments

A
  • arranged in sarcomeres and appear striated.
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18
Q

Overlap of thick and thin filaments

A
  • does not occur when cardiac muscles are at rest.

- occurs when cardiac muscle is stretched as blood is added to the chamber.

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19
Q

intercalated discs

A

link cardiac muscle cells mechanically and electrically.

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20
Q

desmosomes

A
  • act as mechanical junctions to prevent cardiac muscle cells from pulling apart in times of stress/friction.
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21
Q

gap junctions

A
  • provide a low-resistance pathway for the flow of ions between the cardiac cells. Allow an action potential to move continuously along the sarcolemma of cardiac muscle cells, resulting in synchronous contraction of that chamber - functional synctyium
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22
Q

conduction system

A
  • electrical activity is initiated at the SA node, and an action potential is then transmitted through the conduction system
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23
Q

cardiac muscle cells

A
  • the action potential spreads across the sarcolemma of the cardiac muscle cells, causing sarcomeres within cardiac muscle cells to contract.
  • these events occur twice in cardiac muscle cells of the atria and then again in the ventricles
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24
Q

Nodal cells

A
  • located in the SA node
  • pacemaker cells
  • initiate a heartbeat by spontaneously depolarizing to generate an AP
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25
Q

resting membrane potenital

A

-60 mV

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26
Q

autorhythmicity

A
  • capable of depolarizing and firing an AP spontaneously without any external influence.
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27
Q

reaching threshold

A
  • slow voltage-gated Na+ channels open (repolarization from previous cycle).
  • Na+ flows into nodal cells, changing RMP from -60 mV to -40 mV which is threshold value
  • without outside stimulation
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28
Q

depolarization

A
  • changing of the membrane potential to threshold potential triggers opening of fast voltage-gated Ca2+ channels
  • Ca2+ entry into nodal cells cause a change in the membrane potential from -40 mV to a slightly positive value (just above 0 mV)
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29
Q

repolarization

A
  • calcium channels close and voltage-gated K+ channels open
  • K+ flows out to change the membrane potential back to -60 mV.
  • depolarization triggers the reopening of slow voltage-gated Na+ channels
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30
Q

sinoatrial node

A
  • located in posterior wall of the atrium
  • adjacent to the entrance of the vena cava
  • initiate heartbeat
  • pacemaker of the heart
31
Q

atrioventricular node

A
  • located on floor of the right atrium

- between right AV valve and opening for coronary sinus

32
Q

atrioventricular bundle

A
  • extends from the AV node into and through the interventricular septum
  • divides into let and right bundles
33
Q

Purkinje fibers

A
  • extend from the left and right bundles beginning at the apex of the heart and continue through walls of the ventricles
34
Q

cardiac cycle

A
  • inclusive changes within the heart from the initiation of one heartbeat to the start of the next
35
Q

systole

A
  • contraction of a heart chamber
36
Q

diastole

A
  • relaxation of a heart chamber
37
Q

Atrial systole

A
  • atrial contraction and ventricular flying
  • atria contract
  • ventricles relax
  • ventricular pressure less than atrial pressure
  • ventricular pressure less than arterial trunk pressure
  • AV valves open
  • semilunar valves closed
38
Q

Early ventricular systole

A
  • atria relax
  • ventricles contract
  • ventricular pressure is greater than atrial pressure
  • ventricular pressure is less than arterial trunk pressure
  • AV valves closed
  • semilunar valves closed
39
Q

late ventricular systole

A
  • atria relax
  • ventricles
  • ventricular pressure is greater than atrial pressure
  • ventricular pressure is greater than arterial trunk pressure
  • AV valves closed
  • semilunar valves open
40
Q

Early ventricular diastole

A
  • atria relax
  • ventricles relax
  • ventricular pressure is greater than atrial pressure
  • ventricular pressure is less than arterial trunk pressure
  • AV valves closed
  • semilunar valves closed
41
Q

Late ventricular diastole

A
  • atria relax
  • ventricles relax
  • ventricular pressure is less than atrial pressure
  • ventricular pressure is less than arterial trunk pressure
  • AV valves open
  • semilunar valves closed
42
Q

AV valves open because

A
  • pressure exerted by blood filling the atria is greater than the pressure exerted by blood remaining in resting ventricles
43
Q

Semilunar valves closed because

A
  • the pressure exerted by the blood remaining in the filling ventricles is less than the pressure exerted by the blood in arterial trunks
44
Q

AV valves remain closed because

A
  • pressure exerted by blood remaining in filling ventricles is lower than pressure exerted by blood in arterial trunks
45
Q

cardiac output

A
  • the amount of blood that is pumped by a single ventricle is 1 minute
  • liters per minute
  • measure of effectiveness of cardiovascular system
46
Q

cardiac output formula

A

Heart Rate X stroke volume

47
Q

heart rate

A

number of beats per minute

48
Q

stroke volume

A

volume of blood ejected during one beat

49
Q

chronotropic agents

A

factors that change heart rate

50
Q

positive chronotopic agents

A
  • cause an increase in heart rate

- include sympathetic nerve stimulation and certain types of hormonal stimulation

51
Q

thyroid hormone

A
  • increase number of beta 1 adrenergic receptors

- makes nodal cells more responsive to epinephrine and norepinephrine

52
Q

caffeine

A
  • increases cAMP and heart rate
53
Q

nicotine

A
  • stimulates norepinephrine
54
Q

cocaine

A
  • inhibits reuptake of norepinephrine
  • increase heart rate
  • can lead to fast and erratic heart beat, possibly fatal
55
Q

negative chronotopic agents

A
  • decrease heart rate
56
Q

parasympathetic innervation

A
  • most importnat
  • axons releasing Ach binds ot M2 muscarinic receptor
  • binds voltage-gated K+ channels
  • causes hyper polarization as K+ exits
  • longer times for cells to reach threshold
  • heart rate slowed
57
Q

beta blocker drugs

A
  • interfere with NE and Epi binding to beta receptors

- used to treat high blood pressure

58
Q

stroke volume

A
  • the volume of blood ejected per heartbeat

- dependent upon the volume of blood that enters that heart and the end of heart contraction

59
Q

end diastolic volume

A

the volume of blood that enters that heart and the end of heart contraction

60
Q

end systolic volume

A
  • the blood remaining in the ventricle at the end of ventricular contraction
61
Q

SV =

A

EDV-ESV

62
Q

venous return

A
  • volume of blood returned to heart via great veins
  • increased venous return occurs with greater pressure of slower heart rate
  • increases stretch of heart wall (preload), which results in greater overlap of thick and thin filaments within the sarcomeres
  • additional cross bridges formed, and ventricles contract with greater force
  • stroke volume increases
63
Q

inotropic agents

A
  • substances that act on myocardium to alter contractility

- alter the force of contraction at any given stretch of the cardiac cells.

64
Q

positive inotropic agents

A
  • increases Ca2+ concentration in sarcoplasm
  • greater binding of Ca2+ to troponin of thin filaments within sarcomeres of myocardium, results in formation of additional cross bridges and ventricles contract with greater force.
  • stimulation by sympathetic nervous system
65
Q

negative inotropic agents

A
  • decreases contractility by decreasing available Ca2+ and fewer numbers of cross bridges are formed
66
Q

afterload

A
  • resistance in arteries to the ejection of blood by ventricles
  • pressure that must be exceeded before blood is ejected from the chamber
67
Q

Right atrium and left atrium separated by

A

interatrial septum

68
Q

right ventricles and left ventricles separated by

A

inter ventricular septum

69
Q

right atrium

A
  • takes in deoxygenated blood from tissues through the vena cava
70
Q

coronary sinus

A

drains deoxygenated blood from the heart wall

71
Q

right ventricle

A
  • pumps deoxygenated blood through pulmonary trunk to pulmonary artery to the lungs
72
Q

left atrium

A
  • receives oxygenated blood through pulmonary vein
73
Q

left ventricle

A
  • pumps oxygenated blood through aorta to the rest of the body
  • aortic semilunar valve positioned at the boundary of left ventricle and ascending aorta
74
Q

spread of action potential through heart’s conductive system

A
  • distributed through both atria and relayed to AV node
  • delayed at AV node so atria contract before ventricles do
  • travels from AV node through AV bundle to purkinje fibers
  • spreads through ventricles via gap junctions

BIO 212 Class (12 decks)

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