Cardiac contraction

1. An ______ _________ arrives at the __ __ node and causes _____________

2. There is an influx of ____ ions, which causes ______ ________ ______ ______ to open slowly in the ___ _______ of cardiac myocyte membranes. This is called the _______ ________

3. Underneath the __ ______ is the _________ _________. Ca++ binds to _________ _________ on its surface and causes ______ __________ ________ _________.

4. ___ ions bind to ________ on cardiac muscle fibres, exposing the _______ binding site and allowing _______ ______ to form and contraction to occur.

At rest, myocytes do not fully ______, so that if needed, a higher influx of ___ will give stronger _________.

Once the myocyte is _______, there is no more ___ influx and the __ __ __ __ are closed.

During _________ _________:
1. __ __ __ __ from sarcoplasmic reticulum stops
2. __ ions leave the cell by __/__ exchanger
3. __ ions leave the cell via an ______ pump
4. _______ pumps __ back into sarcoplasmic reticulum
5. ___ ions enter mitochondria

There is no longer any __ ions available for _______ so _______ occurs

What are positive inotropes?

When might drugs be given which are positive inotropes?

Name 2 classes of positive inotropes?

Name 2 sympathomimetics

What do they do?

How does that increase contractility?

Despite quicker APs, the time for _______ remains similar so __ __ is maintained. However if HR is excessively increased, ________ will be too short to sustain __ __.

What does amrinone do?

Name a cardiac glycoside

How do they work?

How do they do this?

What else can digoxin be used for?

What is the disadvantage?