IMED1001 Study Guide - Final Guide: Endoplasmic Reticulum, Sarcomere, Myosin
IMED1001 Revision Tutorial 8
Basic Structure of Muscle Tissue:
-Muscle cells have sliding protein filaments!
-Striated cells are when the units are organised into the units!
-1 unit has:!
1. 2 sets of thin filaments!
2. 1 set of thick filament!
-Smooth cells are when the units are not organised into the units!
-= no striations!
Types of Muscle Cells:
-2 types:!
1. Striated (skeletal and cardiac)!
- structurally and functionally different although both are striated in appearance!
2. Smooth!
Skeletal Muscle Type:
-Mostly attached to bones!
-Purpose is to move bones!
Structure of Unit:
-A unit between 2 Z lines/discs is called sarcomere!
-Under LM - filaments cannot be seen!
-Only under EM with very high magnification!
-Sarcomeres when stacked end to end, forms MYOFIBRIL!
Myofibril:
-Thick myosin filaments form dark bands!
-Think actin filaments form light bands!
-In the middle of the light band = Z disc!
-Myosin filaments where there is no overlap = H zone!
*When myofibril stacked up, Z discs, dark bands, and light bands are lined up!
Skeletal Muscle Cell:
-It has fast contractions (functional difference from the rest)!
-eg. Contraction and relaxation can occur in a fraction of second!
-Important characteristic: multiple nuclei that are peripheral!!
-“peripheral multi-nucleated”!
-Each cell is formed when many skeletal cells fuse = that is why it is multi nucleated!
-There is striations!
-Striations: seen in longitudinal and oblique section!
Document Summary
Striated cells are when the units are organised into the units. 1 unit has: 2 sets of thin laments, 1 set of thick lament. Smooth cells are when the units are not organised into the units. 2 types: striated (skeletal and cardiac) Structurally and functionally di erent although both are striated in appearance: smooth. A unit between 2 z lines/discs is called sarcomere. Under lm - laments cannot be seen. Only under em with very high magni cation. Sarcomeres when stacked end to end, forms myofibril. In the middle of the light band = z disc. Myosin laments where there is no overlap = h zone. * when myo bril stacked up, z discs, dark bands, and light bands are lined up! It has fast contractions (functional di erence from the rest) Eg. contraction and relaxation can occur in a fraction of second. Important characteristic: multiple nuclei that are peripheral!
