Chapter_8_Cardiomyocytes__1_slide_per_page

Chapter_8_Cardiomyocytes__1_slide_per_page - Chapter 8...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 8 Cardiomyocytes BME 501 T. K. Hsiai
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
1. General Cellular Morphology
Background image of page 2
Muscles Cardiac muscle is only in the heart and makes up the atria and ventricles (heart walls). Like skeletal muscle, cardiac muscle contains striated fibers . Cardiac muscle is called involuntary muscle because conscious thought does not control its contractions. Specialized cardiac muscle cells maintain a consistent heart rate. Over 600 skeletal muscles function for body movement through contraction and relaxation of voluntary, striated muscle fibers . These muscles are attached to bones, and are typically under conscious control for locomotion, facial expressions, posture, and other body movements. Muscles account for approximately 40 percent of body weight . The metabolism that occurs in this large mass- produces heat essential for the maintenance of body temperature.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2. Cardiac Cell Muscle
Background image of page 4
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Myocardial fibers are separated from adjacent fibers by their respective sarcolemmas, the end of each fiber is separated by dense structures (intercalated discs), that are continuous with the sarcolemma. anatomic syncytium .
Background image of page 6
Adherens Junctions Adherens junctions provide strong mechanical attachments between adjacent cells. •They hold cardiac muscle cells tightly together as the heart expands and contracts. •They hold epithelial cells together. •They seem to be responsible for contact inhibition . •Some adherens junctions are present in narrow bands connecting adjacent cells. •Others are present in discrete patches holding the cells together. Adherens junctions are built from: cadherins — transmembrane proteins (shown in red) whose •extracellular segments bind to each other and •whose intracellular segments bind to catenins (yellow). Catenins are connected to actin filaments
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Gap Junctions Gap junctions are intercellular channels some 1.5–2 nm in diameter . These permit the free passage between the cells of ions and small molecules (up to a molecular weight of about 1000 daltons). They are constructed from 4 (sometimes 6) copies of one of a family of a transmembrane proteins called connexins . Because ions can flow through them, gap junctions permit changes in membrane potential to pass from cell to cell. Example: The action potential in heart (cardiac) muscle flows from cell to cell through the heart providing the rhythmic contraction of the heartbeat. Cardiac muscle functions as a syncytium as a wave of depolarization followed by contraction of the entire myoardium in Concert (an all-or-none response occurs when suprathreshold stimulus is applied to any one focus).
Background image of page 8
Sacrolemmal invaginations at the Z- lines are connected with the bulk interstitial fluid, important for excitation- contraction coupling. Mitochondria
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/27/2008 for the course BME 501 taught by Professor Yamashiro,hsiai during the Fall '07 term at USC.

Page1 / 33

Chapter_8_Cardiomyocytes__1_slide_per_page - Chapter 8...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online