2 - cardiac phys HR and contractility

Question 1

diastole

Answer 1

cardiac muscle at rest

Question 2

systole

Answer 2

cardiac muscle during contraction

Question 3

isovolumic ventricular contraction

Answer 3

first phase of ventricular contraction when AV valves are pushed closed by pressure within ventricles; semilunar valves remain open

Question 4

ventricular ejection

Answer 4

pressure within ventricles increases forcing semilunar valves open (leaving the heart), allows ejection of blood into the pulmonary or aortic circuit

Question 5

s1 sound

Answer 5

sound due to closure of the AV valves

Question 6

s2 sound

Answer 6

second heart sound due to the closure of the semilunar valves

Question 7

late diastole

Answer 7

both chambers are relaxed and ventricles fill passively

Question 8

atrial systole

Answer 8

atrial contraction forces a small amount of additional blood into the ventricles

Question 9

isovolumic ventricular relaxation

Answer 9

a ventricles relax, pressure in ventricles falls, blood flows back into the cusps of semilunar valves and snaps them closed

Question 10

Preload

Answer 10

myocardial stretch before contraction, preload is a volume = EDV

Question 11

afterload

Answer 11

a pressure, pressure in the aorta or pulmonary artery + EDP

Question 12

contractility

Answer 12

cardiac muscle fibers contract at given fiber length

Question 13

increase in stretch

Answer 13

increase in stretch exposes additional sites for Ca2+ binding and for actin-myosin interaction, increased stretch also effects greater release of Ca2+ from the SR

Question 14

normal SV number

Answer 14

55-100mL

Question 15

normal ESV number

Answer 15

50 mL

Question 16

normal EDV number

Answer 16

120 mL

Question 17

SV =

Answer 17

ESV - EDV

Question 18

ESV

Answer 18

volume of blood in a ventricle at the end of contraction, or systole, and the beginning of filling, or diastole. ESV is the lowest volume of blood in the ventricle at any point in the cardiac cycle

Question 19

EDV

Answer 19

volume of blood in the right and/or left ventricle at end load or filling in (diastole) or the amount of blood in the ventricles just before systole

varies with venous return aided by skeletal muscle and respiratory pump and increases with sympathetic innervation and epinephrine

Question 20

SV

Answer 20

volume of blood in millilitres ejected from the each ventricle due to the contraction of the heart muscle

Question 21

Factors affecting EDV (4)

Answer 21

1. skeletal muscle pump - goes against gravity
2. respiratory pump- helps blood return to the heart - makes pressure gradient less so draws air in and increases the abdominal pressure
3. sympathetic nervous system innervation of veins - increases sympathetic nerve firing on veins - contracts - goes back to the heart

Question 22

how does diuretic affect blood volume

Answer 22

causes blood volume to decrease

Question 23

force of contraction in ventricular myocardium is influenced by

Answer 23

contractility and EDV

Question 24

how does SNS increase contractility (NE and EPI)

Answer 24

increases the ability of the heart to contract at any EDV
NE is a positive inotropic agent

binds to b1 receptors and activates cAMP - phosphorylating VGCC so calcium entry increases as open time increases

phosphorylating phospholamban reducing inhibiting on Ca-ATPase on SR - increasing stores of Ca in SR which makes a more forceful contraction and removing Ca2+ from the cytosol faster so that Ca and troponin binding time shortens which causes a shorter duration of contraction

Question 25

phospholamban

Answer 25

inhibits ca2+ atpase (SERCA - delivers Ca2+ into the ER. Inhibited by PKA to cause an increase in heart rate. Epi is an inhibitor of PKA

Question 26

elevation of cAMP in cardiac myocytes results in

Answer 26

PKA activation and phosphorylation of 1. VGCC that increase Ca2+ induced Ca2+ release from the SR 2. phospholamban, removes inhibitory effect on SR Ca2+ ATPase (SRCA)

Question 27

verapamil

Answer 27

negative ionotropic agent and negative chronotropic agent. inhibits VGCC

Question 28

mirlinone is a phosphodiesterase inhibitor - phosphodiesterase breaks down cAMP

Answer 28

makes a more forceful contraction - positive ionotrope- this will increase cAMP which will increase

Question 29

how does afterload affect CO

Answer 29

L heart: pulmonary pressure | R heart: aortic pressure

Question 30

Afterload effects on the Frank-Starling Curve

Answer 30

Vasoconstriction increases: makes the curve go down, as SV will decrease relaxes smooth muscle: curve will increase as the SV will also increase but the EDV will decrease

Question 31

signs/symptoms of low cardiac output - heart failure

Answer 31

fatigue, weakness rapid or irregular heart beat ( body is trying to compensate for not enough oxygen getting to the blood) reduced ability to exercise difficulty concentrating or decreased alertness chest pain if your heart failure is caused by a heart attack

Question 32

signs/symptoms of high end diastolic pressure

Answer 32

(left ventricle is stiff and impaired relaxation) shortness of breath (dyspnea) when you exert yourself when you lie down swelling (edema) in your legs, ankles and feet persistent cough or wheezing with white or pink blood-tinged phlegm increased need to urinate at night (antidiuretic - releasing pressure) swelling of your abdomen (ascites) very rapid weight gain from fluid retention sudden, severe shortness of breath and coughing up pink, foamy mucus

Question 33

diuretic effect on the Frank-Starling curve

Answer 33

lowers the edv down and to the left - moves pt to a lower cardiac filling pressure along the same ventricular curve- not as much preload to increase SV

Question 34

positive inotropic effect on the frank-starling curve

Answer 34

digoxin or dobutamine - straight up - moves patients to a higher ventricular function curve

Question 35

negative inotropic effect on the frank-starling curve

Answer 35

straight down

Question 36

vasodilator effect on the frank-starling curve

Answer 36

Angiotensin converting enzymes (ACE) inhibitors or nitroprusside - up and left - reduces cardiac filling pressures - decreases afterload, increases sv, decreases edv

Question 37

how does digoxin affect contractility

Answer 37

Na/K Atpase provides a conc gradient so that Ca levels can be maintained - maintains a conc gradient - no RMP - narrow TI - more Ca can get pumped into the SR