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bio 242 > CH:20 - Heart > Flashcards

CH:20 - Heart Flashcards

1
Q

Histology of Cardiac Muscle

A

Length 50-100um, diameter 14um, cells branch off and are less round than skeletal muscle, one nucleus per cell, more mitochondria than skeletal muscle, contains intercalates disk between cells, and has several desmosomes and gap junctions

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2
Q

physiology of cardiac cells

A

RMP of contractile fibers is -90 mV

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3
Q

Depolarization

A

voltage gated fast Na+ channels open up at threshold stimulus causing rapid depolarization

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4
Q

Plateau

A

Depolarization is prolonged when voltage gated slow calcium channels open, calcium from the sarcoplasmic reticulum is also released into the sarcoplasm, this causes prolonged contraction in the cardiac muscle cell

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5
Q

Repolarization

A

recovery of RMP caused by closure of calcium channels, and potassium channels remaining open

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6
Q

Conduction System

A

the route used to propagate action potentials throughout the Heart muscle

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7
Q

The Sinoatrial (SA) Node

A

In RT Atrium, the pacemaker, consists of autorhythmic cells that spontaneously generate a nerve impulse (90 to 100 times/min), signal goes through both atria gap junctions located in intercalated discs

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8
Q

Atrioventricular (AV) Node

A

Located in lower interatrial septum (generates impulses rate of 40 to 50 times/minute), signals goes to ventricles

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9
Q

Atrioventricular (AV) bundle

A

Bundle of HIS, carries impulses towards ventricles

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10
Q

Right and Left Bundle Branches

A

The AV bundle bifurcates to form these branches, one for each ventricle, transmits impulses through interventricular septum, apex of the heart

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11
Q

Purkinje fibers

A

branches that carry the impulses throughout the myocardium

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12
Q

Ectopic Pacemaker

A

The site other than the SA node initiates an electrical impulse, results extra heart beats

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13
Q

Artificial Pacemaker

A

Surgical devise that artificially initiates the electrical impulse

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14
Q

Electrocardiogram (ECG or EKG)

A

A recording of electrical changes that accompany the heartbeat, lead 2 record is from right arm to left leg

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15
Q

P wave

A

Atrial depolarization, is a slight lag before atrial systole occurs

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16
Q

QRS complex

A

The onset of ventricular depolarization, atrial repolarization is hidden in this segment

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17
Q

T wave

A

ventricular repolarization

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18
Q

P-Q Interval

A

From the beginning of atrial excitation to the beginning of Ventricular excitation, the time required for the electrical impulse to travel from SA node through conduction systems

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19
Q

ST segment

A

Time when the ventricle is fully depolarized, this segment is lengthened during MI

20
Q

Systole

A

Cardiac contraction

21
Q

Diastole

A

Relaxtion

22
Q

Atrial systole

A

contraction of the atria forces blood past the AV valves into the ventricles

23
Q

End diastolic volume (EDV)

A

The amount of blood in the ventricle during diastole, 130 ml

24
Q

Ventricular Systole

A

Ventricular contraction increase intraventricular pressure causing the semilunar valve open, blood ejected from heart, causes ventricular depolarization

25
Q

Relaxation period

A

Decreases HR, pressure within ventricle decrease, the pressure in the aorta and pulmonary trunk causes semilunar valves to close, ventricles fill up, ventricles 3/4 full when the next atrial systole (P wave) occurs, associated with ventricular diastole

26
Q

Auscultation

A

The act of listening to the sounds of the body

27
Q

S1 = lub

A

First heart sound, with the closing of the AV Valves after the ventricular systole

28
Q

S2 = dupp

A

Closing of the semilunar valves at the beginning of ventricular diastole

29
Q

Murmur

A

abnormal heart sound, often associated with a valve disorder

30
Q

Cardiac Output (CO)

A

Volume of blood ejected by the left ventricle in 1 minute, stroke volume X HR (in BPM)

31
Q

Stroke volume

A

Volume of blood ejected by the ventricle

32
Q

Cardiac reserve

A

the ratio between a person max CO and CO at rest, usually 4 to 5 resting CO

33
Q

Frank-Starling (law of the heart)

A

The greater the stretch in cardiac fibers (during Diastole) will result in a greater contraction, this increase stroke volume and cardiac ouput

34
Q

Contractility

A

strength of the Heartbeat

35
Q

afterload

A

pressure that must overcome before semilunar valve can open

36
Q

Automatic Nervous system (ANS)

A

Cardiovascular center in Medullae oblongata is responsible for increasing or decreasing impulse in the heart, nerve receptors in body send info to nervous system

37
Q

Proprioceptors

A

monitor the position of body parts, i.e. increased movement increases heart rate

38
Q

Chemoreceptors

A

monitor chemical changes in the blood, i.e. increased carbon dioxide levels increases heart rate

39
Q

Baroreceptors, or baroceptors (pressure receptors)

A

that respond to changes in blood pressure. Chemoreceptor and baroceptors are located in the Aortic Arch and the Internal Carotid Arteries.

40
Q

Chemical Regulation

A

hormones like epinephrine, norepinephrine, T3 and T4 increase heart rate, ion imbalances effect membrane potentials (i.e. RMP)

41
Q

Other influences

A

temperature, emotion, sex, age

42
Q

Myocardial Infarction = MI = Heart attack

A

a complete obstruction of blood to par of the heart; death of heart muscle, results in varying degrees of damage, damage is repaired by fibrosis

43
Q

Congestive Heart Failure

A

results from a weakened heart that can’t pump blood adequately, results in a back-up (pooling) of blood which leads to edema

44
Q

Coronary Artery Disease

A

the effects of accumulation of atherosclerotic plaques in the Coronary arteries, this reduces blood flow to the myocardium, associated with diet, genetics, smoking, high BP, Diabetes, life style (i.e. too much fun stuff)

45
Q

Arteriosclerosis

A

hardening of the arteries

46
Q

Atherosclerosis

A

development of plaques in the endothelium of arteries, Lipids accumulate along with other material, may cause blockage of the vessel

bio 242 (3 decks)

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