Lecture 3 Flashcards Preview

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Flashcards in Lecture 3 Deck (23)
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1

Calcium Excitation-Contraction Coupling

In the 1960s Calcium Was Found to be the Intracellular Messenger That Activates Contraction in Response to Excitation of the Plasma Membrane

2

Calcium Excitation-Contraction Coupling

In the 1960s Calcium Was Found to be the Intracellular Messenger That Activates Contraction in Response to Excitation of the Plasma Membrane

3

Ionized Ca2+ concentration in extracellular space and intracellular stores is...

> 1 mM

4

Ionized Ca2+ concentration in cytosol of resting monocytes is...

5

The heart contracts when calcium...

enters the cytosol from the extracellular space and intracellular stores by passive diffusion down this >1,000 fold gradient

6

The heart relaxes when calcium...

is removed from the cytosol by active transport

7

Chemical signals: Ca2+ influx across the plasma membrane...

initiates a chemical signal when the cation binds to intracellular high affinity Ca2+ binding (E-F Hand) proteins

8

Electrical signals: Ca2+ influx across the plasma membrane generates...

an "inward" (depolarizing) current because the cation carries positive charge into the cell

9

Primitive monocytes

*Contractions are weak, tension develops slowly *only a small amount of calcium is needed to activate contraction *diffusion of Ca from the extracellular fluid into the cytosol is sufficiently rapid examples: embryonic muscle and adult smooth muscle

10

Adult skeletal and cardiac myocytes

*contractions are strong, tension develops rapidly *a large amount of calcium is needed to activate contraction *diffusion of calcium from the extracellular fluid is much too slow example: striated muscle

11

T-tubules

these tubules open to communicate freely with the extra cellular space, filled with calcium that can enter the cytosol when the calcium channels open. Rapidly propagate action potentials into the cell interior

12

Ionized Ca2+ concentration in extracellular space and intracellular stores is...

> 1 mM

13

Ionized Ca2+ concentration in cytosol of resting monocytes is...

14

The heart contracts when calcium...

enters the cytosol from the extracellular space and intracellular stores by passive diffusion down this >1,000 fold gradient

15

The heart relaxes when calcium...

is removed from the cytosol by active transport

16

Chemical signals: Ca2+ influx across the plasma membrane...

initiates a chemical signal when the cation binds to intracellular high affinity Ca2+ binding (E-F Hand) proteins

17

Electrical signals: Ca2+ influx across the plasma membrane generates...

an "inward" (depolarizing) current because the cation carries positive charge into the cell

18

Primitive monocytes

*Contractions are weak, tension develops slowly *only a small amount of calcium is needed to activate contraction *diffusion of Ca from the extracellular fluid into the cytosol is sufficiently rapid examples: embryonic muscle and adult smooth muscle

19

Sarcotubular network

Pumps calcium out of the cytosol into the SR

20

Adult skeletal and cardiac myocytes

*contractions are strong, tension develops rapidly *a large amount of calcium is needed to activate contraction *diffusion of calcium from the extracellular fluid is much too slow example: striated muscle

21

Subsarcolemmal cisternae

Contains structures that release calcium into the cytosol

22

T-tubules

these tubules open to communicate freely with the extra cellular space, filled with caliu

23

Dyad

Composite structures formed by the membranes of the t-tubules and the subsarcolemmal cisternae of the SR

Mediate the ability of an action potential at the cell surface to trigger the release of activator calcium from the sarcotubular network within the cell