Animal Muscles

This makes heart transplantations possible video 47

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ntations possible ! Video-47-04.mpg! Gap Junctions •  Cardiac and smooth muscle cells are arranged in sheets. •  Cells in the sheet are in electrical contact via gap junctions. •  An action potential in one cell can spread to all others in the sheet. ! Figure 5.7 Junctions Link Animal Cells Together (C)! GAP GAP junctions: junctions •  Connect the cytoplasm of two neighboring cells. •  Allows direct electrical communication between cells. •  Allows direct chemical communication between cells (small second messengers, such as IP3 and Ca2+) •  Allows passage of molecules smaller than ~1,000 Daltons. •  Allow cardiac and smooth muscle cells to contract simultaneously. ! Gap junctions allow communication ! Video-47-04.mpg! ! Tissue Layers of the Vertebrate Gut! Smooth Muscle Smooth muscle: •  Are the simplest muscle cells structurally. •  Single nucleus/cell. •  “Smooth” because actin/myosin are not as regularly arranged. •  Present in most internal organs (e.g. GI-tract, bladder, blood vessels) •  Under autonomic nervous system control. ! Smooth muscle cell and endothelial cell surrounding blood vessel and smooth muscle cell ! Jejunum ! 47.1 How Do Muscles Contract? What is a “twitch”? Skeletal muscle: minimum unit of contraction = a twitch. A twitch is measured in terms of tension, or force it generates. A single action potential generates a single twitch. ! 47.1 How Do Muscles Contract? Single twitch: if action potentials are close together in time, the twitches are summed, tension increases. Twitches sum because Ca2+ pumps can not clear Ca2+ from sarcoplasm before the next action potential arrives. Tetanus: when action potentials are so frequent there is always Ca2+ in the sarcoplasm. ! Twitches and Tetanus How Do Muscles Contract? How long muscle fiber can sustain tetanic co...
View Full Document

This note was uploaded on 02/13/2014 for the course MCDB 1B taught by Professor Weimbs during the Winter '08 term at UCSB.

Ask a homework question - tutors are online