Autorhythmic cell starts out at resting membrane potential (--60 mV), positive out, negative in. Cell begins depolarizing due to a slow continuous influx of sodium When the membrane potential gets to -40 millivolts, it has reached threshold for initiating an action potential.

What is the 2nd step in an action potential within an autorhythmic cell.

Calcium channels open and positively-charged calcium ions rush in. Calcium influx produces the rapidly rising phase of the action potential (depolarization), which results in the reversal of membrane potential from negative to positive inside the cell. Depolarization peaks at about +10 mV.

What is the 3rd step in an action potential within an autorhythmic cell.

Membrane potential goes from +10 mV to resting membrane potential (-60 mV). Potassium channels open, resulting in potassium rapidly leaving the cell.

What is the first step in an action potential within an contractile cell.

Contractile cells start with a resting membrane potential of about -90'mV. Neighboring cells (either autorhythmic or contractile cells) depolarize. Gap junctions are open and positive ions (Ca*2 and Na*) move in to the contractile cells through gap junctions and trigger a threshold.

What is the 2nd step in an action potential within an contractile cell.

The entry of positive ions brings the membrane potential to threshold, triggering voltage-gated channels and initiates depolarization. Rapid influx of sodium results in depolarization, resulting in a reversal of charge (depolarization) (to about +25 mV) as sodium moves into the cell.

What is the 3rd step in an action potential within an contractile cell.

Depolarization also causes opening of slow calcium channels, allowing calcium entry from the extracellular space. This calcium influx triggers additional calcium release from the sarcomplasmic reticulum. Intracellular calcium initiates cell contraction.

What is the last step in an action potential within an contractile cell.

The calcium channels close while more potassium channels open, allowing potassium to quickly leave the cell, resulting in repolarization.

9. Repolarization

10. Depolarization

11. Plateau

12. Repolarization (autorhythmic cells)

13. Pacemaker Potential (autorhythmic cells)

14. Depolarization and reversal of the membrane potential (autorhythmic)

15. Repolarization (event in autorhythmic cell)

due to efflux of potassium

16.) pacemaker potential (autorhythmic)

due to influx of sodium

17.) Depolarization and reversal of the membrane potential (autorhythmic cells event)

due to influx of calcium

23.)

Na+ leak channel

24.)

fast ca++ channels

25.)

k+ channel

26.)

Phospholipid membrane

27.)

gap junction

28.)

gap junction

29.)

fast na++ channel

30.)

slow ca++ channel

31.)

k+ channel

32.)

Sarcoplasmic reticulum

Initiates the depolarization impulse that generates an action potential, setting the overall pace of the heartbeat.

sa node

50.) Fast CA++ channels open

51. K+ Channels open

52. Na+ leak Channels

53. Pacemaker potential

54. Depolarization

55. Repolarization

56. Reversal of membrane potential

57. Ca++ channels and potassium channels both open

58. Ions flow across gap junctions to cause early threshold

59. K+ channels stay open

60. Fast Na+ channels open

61. Depolarization

62. Plateau

63. Repolarization

70. Ventricular systole- second phase: As ventricular pressure rises and exceeds pressure in the arteries the semilunar valves open and blood is ejected

71. Ventricular diastole- late: All chambers are relaxed; Ventricles fill passively

72. Atrial systole begins: atrial contraction forces a small amount of additional blood into relaxed ventricles

73. Ventricular diastole- early: As ventricles relax, pressure in ventricles drops; blood flows back against cusps of semilunar valves and forces them closed. Blood flows into relaxed atria

74. Ventricular systole- first phase: Ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves.

75. Isovolumetric contraction

76. Isovolumetric relaxation

80. The plasma of the blood is mostly made of what molecule?

water

Which part of the hemoglobin molecule does the O, bond to?

Fe * from the Heme group

The amount of Erythrocytes found in the blood is known as its

Hematocrit

82. Which chemical is partially responsible for Erythrocyte development?

EPO

Which type of cell fragments and becomes platelets?

B. Megakaryocyte