Ch. 20 Flashcards

Question

Papillary muscles How do they work?

Answer 1

muscles that attach to cusps of the atrioventricular valves by thin strong connective tissue strings called chordae tendineae (heart strings) These muscles contract when ventricles contract and prevent valves from opening into atria

Answer 2

Aortic semilunar valve Pulmonary semilunar valve Purpose is to prevent blood flow back into ventricles

Answer 3

fibrous connective tissue between artia and ventricles. Forms a fibrous ridge around the atrioventricular and semilunar valves which provides solid support fibrous connective tissue plate also serves as a electrical insulation and provides attachment of cardiac muscle

Answer 4

elongated branching cells one or occasionally two centrally located nuceli Contain actin and myosin to form sarcomeres - gives striated apparence smooth sarcoplasmic reticulum which stores Ca2 T tubules near Z disc rich in mitochondria organized in spiral bundles or sheets bound by intercalated disc's

Answer 5

``` Sinoatrial node (SA) Atrioventricular node (AV) ``` Atrioventricular bundle

Answer 6

Passed through small opening in fibrous skeleton to reach interventricular septum where it divides to form R and L bundle branches. These extend beneath the endocardium on each side of interventricular septum they descend to the apex then are carried by Purkinje fibers to ventricular walls and papillary muscles

Answer 7

Sinoatria node (the pacemaker) SA NODE

Answer 8

1. Depolarization phase - membrane potential quickly becomes more postive. ***Na2+ channels open, K+ channels close, Ca2+ begin to open*** 2. Early repolarization phase - rapid & partial * **Na+ begin to close, some K+ open, Ca2+ open*** 3. Plateau phase - prolonged period of slow repolarization * **Ca2+ close, many K+ open*** 4. Final repolarization phase - membrane potential returns to resting level * **Cardiac muscl contracts and relaxes almost completely during refractory period***

Answer 9

When an action potential occurs, Ca2 enters the cell and binds to receptors resulting in the opening of Ca2+ channels on the membrane of the sarcoplasmic reticulum, Ca2 then moves out of sarcoplasmic reticulum and activates interactions between action and myosin producing a contraction

Answer 10

Ectopic focus - any part of the heart other than SA node that generates a heartbeat Causes are: \*SA node doesnt function properly \*Blockage of conducting pathways between SA node and other parts of heart \*When rate of AP outside of SA becomes enhanced - when cells are injured (inflammation or lack of blood supply, or certain drugs)

Answer 11

SA node spontaneously produces an action potential. SA NODE and neighboring cardiac cells are joined by gap junctions AP goes into contractile cell and down T tubule - opening a Ca2 channel allowing EXTRACELLULAR Ca2 to rush inside the cell. Ca2+ then binds to SR ca2 channels which let more calcium out (Calcium induced calcium channels) Ca2 flows out from SR and binds to tropomyosin. Allowing myosin to bind to actin and contract

Answer 12

Electrocardiogram record of electrical activity of the heart can reveal abnormal conduction pathways, hypertrophy, atrophy and approx location of cardiac muscle damage

Answer 13

P wave is result of AP that cause depolarization of atrial myocardium, signals the onset of atrial contraction QRS are 3 separate waves and signal ventricular depolarization and contraction T wave signals ventricular repolarization and relaxation

Answer 14

PQ interval represents time from begining of P wave (onset of atrial contraction to begining of their relaxation) to begining of QRS complex and last about 16 sec QT interval is beginging of QRS wave (onset of ventricular contraction) to end of T wave (ventricular relaxation). Last about 36 sec PQ - atrium contraction-relax 16 sec QT - ventricular contraction-relax - 36 sec

Answer 15

Ischemia is obstruction of blood supply to the walls of the heart

Answer 16

Bacteria cause the blood vessles to deposit the bacteria into the cardiac muscle where they release a toxin called pneumolysin which kills cardiac muscle cells. This causes microlesions and scar tissue which damages the functioning of the heart. Normal antibiotic for bacteria cannot be used here because it causes the bacteria cell walls to burst which in this case would cause more realease of pneumolysin causing more damage

Answer 17

repetitive pumping process that begins with onset of cardiac muscle contraction and ends with beginging of next contraction

Answer 18

1. ***ACTIVE VENTRICULAR FILLING*** - SA node generates AP -\> atrial contraction, forces blood to ventricles 2. ***PERIOD OF ISOVOLUMETRIC CONTRACTION***- AP passed to AV node -\> bundle -\>purkjne fibers producing ventricular contraction causing blood to flow toward atria and close AV valves. 3. ***PERIOD OF EJECTION*** - Pressure in ventricles increases until overcomes pressure in aorta and pulmonary trunk - valves open and blood is pushed to arteries 4. ***PERIOD OF ISOVOLUMETRIC RELAXATION*** - Ventricles relax, blood begins to flow down aorta and trunk causing valves to close.

Answer 19

Systole - contract Dystole - to dilate Atrial systole - contraction of atrial myocardium Ventricular systole - contraction of ventricular myocardium

Answer 20

EDV -volume of blood in ventricles when they were relaxed

Answer 21

Intrinsic regulation - results from hearts normal functional characteristics - functions whether heart is in body or not

Answer 22

Sympthetic division can increase cardiac output by 50-100% over resting values, where para can cause only a 10-20% decrease These division help keep blood pressure, blood O2, blood CO2, and blood ph within their normal range Parasympathetic - Vagus nerve - has an inhibatory effect - decreasing heart rate Sympathetic - innervates heart by nerves in thoracic region of spinal cord innervate heart as cardiac nerves - increases heart rate and force of contraction

Answer 23

Secretion of epinephrine and norepinephrine is controlled by SYMPATHETIC division of the ADRENAL medulla. It occurs in response to ....... physical activity, emotional excitment, stressful situations

Answer 24

Detect changes in blood pressure Dectect this by stretch receptors in the walls of blood vessels and communicate with control center in medulla oblongata

Answer 25

Chemoreceptor reflexes help regulate hearts activity Sensitive to changes in CO2 levels, blood ph

Answer 26

Causes heart rate and stroke volume to decrease. Causes a heartblock- loss of AP conduction through heart

Answer 27

Autorythmic cells have no "resting potential" however, their starting point or PACEMAKE potential is APPROX (-60mv to -41mv) They spontaneously depolarize by FUNNY channels which leak Na2+. once enough Na2+ has leaked in they reach threshold of -40mv A influx of Ca2 comes in and they become more positive generating an AP They repolarize by closing Ca2+ channels and opening K+ channels

Answer 28

The resting membrane potential is -90 mv AP enters contractile cells via gap junctions via intercalated discs, causing Na2+ to open - Na2+ rushes out causing cell to repolarize to 20MV The K+ channels open, allowing K+ to leave - repolarizing the cell ALSO we have Ca2+ open causing Ca2+ to rush in DELAYING the repolarization process resulting in PLATEAU (refractory period - contract during this time) Slow K+ channels open which leads to repolarization

Answer 29

Cardioacceleratory center sends signals through sympathetic truck to increase rate and force. \*Stimulates SA, AV nodes, heart muscle and coronary arteries Cardioinhibiatory center sends signals via parasympathetic to decrease rate \*Inhibits SA & AV nodes via vagus nerve

Answer 30

1. May cause heart block - Few or no impulses reach ventricles Treatment: Artificial pacemaker 2. Ectopic focus - slower beats/min

Answer 31

Ausultation - listening to sounds made my body First lubb is made by closure of AV valves, turbulence in bloodstream and movements of heart wall Second dupp is made by closure of semilunar valves, turbulence of bloodstream and movement of the heart wall

Answer 32

Aortic valves can be heard in 2nd intercostal space at right sternal margin Pulmonary trunk valves heard in 2nd intercostal space at left sternal margin Bicuspid valves can be heard over heart apex in 5th intercostal space, in line with middle clavicle Tricuspid valve can be heard in right sternal margin of 5th intercostal space

Answer 33

Heart murmur - abnormal heart sounds when blood hits obstructions Usually indicates valve problems Incompetent valve - fails to close completely, allowing backflow of blood / swishing sound Stenoic valve - fails to open completely, restricting blood flow through valve / high pitched or clicking sounds

Answer 34

STROKE VOLUME is amount of blood pushed out of ventricles during a contraction SV = EDV - ESV ESV is END SYSTOLIC VOLUME - amount of blood in ventricles before they contract EDV - END DYSTOLIC VOLUME - amount of blood in ventricles after they contract

Answer 35

ACH - Hyperpolarized by opening K+ channels = slower HR (little or no effect on contractility) Norepinephrine - causes pacemaker to fire more rapidly - increases contractility

Answer 36

Epinephrine - increases HR and contractility Thyroxine - increases HR and enchances effects of epinephrine and norephinrine IONS - balance must be maintained, imbalances are very dangerous

Answer 37

Fetus has fastest HR Female has faster HR Increase with excersice Increase with temp

Answer 38

Tachycardia - Adult HR greater than 100 bpm Causes: stress, anxiety, drugs, heart disease, fever / loss of blood or damage to myocardium Bradycardia - Adult HR less than 60 bpm Causes: in sleep, low body temp, endurance trained athletes

Answer 39

Hypocalcemia (low Ca2+) - depresses heart Hypercalcemia (high Ca2+) - increases HR and contractility Hyperkalemia (high potassium) - alters electrical activity, lead to heart block or cardiac arrest Hypokalemia (low potassium) - results in feeble heart beat, arrhythmias

Answer 40

120ML (EDV) - 50 ML (ESV) - 70 ml/beat Preload, contractility, after load

Answer 41

Preload - degree of stretch of cardiac muscle cells before they contact

Answer 42

_Force_ Surface area units are mmhg (units of mercury pillar)

Ch. 20 Flashcards

(70 cards)