Introduction to Muscle Flashcards
(33 cards)
Syncytium
Multinucleate cell
What forms myobfibrils
Myofibrils are formed by thousands of sarcomeres lined up at their Z lines
Why is SkM Striated
The regular arrangement of thick myosin, thin actin and Z-lines
Describe the Length-Tension relationship of skeletal muscle
An inverted U relationship between sarcomere length and tension
If the sarcomere is shortened too much, there will be no tension as the myosin heads are far from the ends of actin which bind to the heads, and if it is too extended, the distance between myosin heads and actin is too far. There is an ideal optimal resting length where the tension is maximised as the myosin heads fit well into the actin
Label this cross section of a SkM fibre
**Fat is needed to be burnt for energy
What is the name of heart muscle cells
Cardiomyocytes
Why are muscles in the heart wall arranged in spiral like structures
The wringing motion empties out the chambers more effectively, similarly to drying a dish cloth
How are cardiac muscle cells arranged
Single mono or di-nucleated cells with limb like extensions that connect to neighbouring cells and form fibre-like networks that produce force in a certain direction
**Like members of a human puramid
Are cardiomyocytes mono-nucleate or syncytial
Mono-nucleate
**Can bi bi-nucleate but generally not considered syncytial
What is the role of intercalated disks
Connecting neighbouring cardiomyocytes
Discuss the cross-striative properties of cardiomyocytes
They have centrally located nuclei and extensions which serve to connect them to neighbouring cells via intercalated disks
Does a cross section of the ventricular wall show longitudinal or cross sectioned cells?
Both lol get bamboozled
Does the heart have fibres?
It does not have fibres, instead the cells are linked to one another
Cardiac Muscle
Discuss the relationship of cardiomyocytes to basement membranes
Each cardiac muscle cell
has a basement membrane
How is information transmitted through intercalated disks
Gap junctions which allow the transfer of action potentials along cardiomyocytes
Role of Desmosomes on Intercalated disks in cardiomyocytes
Desmosomes allow longitudinal force transfer by creating strong adherence between cells
Why are intercalated disks very bumpy
Expanded surface area
Compare the length of cardiomyocytes to skeletal muscle fibres
Cardiomyocytes are much shorter
Do Cardiomyocytes have myofibrils and where are the nuclei
Cardiomyocytes are filled with shorter myofibrils that have nuclei in the middle of the cells
Discuss the amount of mitochondria and degree of capillarisation in Heart Cells
Heart cells have more mitochondria than smooth muscle cells or skeletal muscle fibres and are better capillarised
How are myosin heads arranged in smooth muscle
They are arranged in an antiparallel manner at opposite sides of the filament in smooth muscle
Describe the alternative of sarcomeres used in smooth muscles
3D networks of Actin filaments linked to myosin, held together by dense bodies that are attached to other actomyosin groups and also intermediate filaments
Effect of SM contraction on length and diameter
SM contraction shortens the cell to a fraction of its relaxed length while extending its diameter
