CH:20 - Heart

Question 1

Histology of Cardiac Muscle

Answer 1

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

Question 2

physiology of cardiac cells

Answer 2

RMP of contractile fibers is -90 mV

Question 3

Depolarization

Answer 3

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

Question 4

Plateau

Answer 4

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

Question 5

Repolarization

Answer 5

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

Question 6

Conduction System

Answer 6

the route used to propagate action potentials throughout the Heart muscle

Question 7

The Sinoatrial (SA) Node

Answer 7

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

Question 8

Atrioventricular (AV) Node

Answer 8

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

Question 9

Atrioventricular (AV) bundle

Answer 9

Bundle of HIS, carries impulses towards ventricles

Question 10

Right and Left Bundle Branches

Answer 10

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

Question 11

Purkinje fibers

Answer 11

branches that carry the impulses throughout the myocardium

Question 12

Ectopic Pacemaker

Answer 12

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

Question 13

Artificial Pacemaker

Answer 13

Surgical devise that artificially initiates the electrical impulse

Question 14

Electrocardiogram (ECG or EKG)

Answer 14

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

Question 15

P wave

Answer 15

Atrial depolarization, is a slight lag before atrial systole occurs

Question 16

QRS complex

Answer 16

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

Question 17

T wave

Answer 17

ventricular repolarization

Question 18

P-Q Interval

Answer 18

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

Question 19

ST segment

Answer 19

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

Question 20

Systole

Answer 20

Cardiac contraction

Question 21

Diastole

Answer 21

Relaxtion

Question 22

Atrial systole

Answer 22

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

Question 23

End diastolic volume (EDV)

Answer 23

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

Question 24

Ventricular Systole

Answer 24

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

Question 25

Relaxation period

Answer 25

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

Question 26

Auscultation

Answer 26

The act of listening to the sounds of the body

Question 27

S1 = lub

Answer 27

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

Question 28

S2 = dupp

Answer 28

Closing of the semilunar valves at the beginning of ventricular diastole

Question 29

Murmur

Answer 29

abnormal heart sound, often associated with a valve disorder

Question 30

Cardiac Output (CO)

Answer 30

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

Question 31

Stroke volume

Answer 31

Volume of blood ejected by the ventricle

Question 32

Cardiac reserve

Answer 32

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

Question 33

Frank-Starling (law of the heart)

Answer 33

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

Question 34

Contractility

Answer 34

strength of the Heartbeat

Question 35

afterload

Answer 35

pressure that must overcome before semilunar valve can open

Question 36

Automatic Nervous system (ANS)

Answer 36

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

Question 37

Proprioceptors

Answer 37

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

Question 38

Chemoreceptors

Answer 38

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

Question 39

Baroreceptors, or baroceptors (pressure receptors)

Answer 39

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

Question 40

Chemical Regulation

Answer 40

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

Question 41

Other influences

Answer 41

temperature, emotion, sex, age

Question 42

Myocardial Infarction = MI = Heart attack

Answer 42

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

Question 43

Congestive Heart Failure

Answer 43

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

Question 44

Coronary Artery Disease

Answer 44

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)

Question 45

Arteriosclerosis

Answer 45

hardening of the arteries

Question 46

Atherosclerosis

Answer 46

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