Muscle Flashcards
Describe the organisation of skeletal muscles
- Skeletal muscles each have a basement membrane called the external lamina
- Around the external lamina there is a supporting reticular fibre network called the endomysium this carries the smallest capillaries and neuronal processes
- Muscle fibres that work in small groups called fascicles are surrounded by thicker connective tissue layer which is the perimysium
- Fasciles are organised into whole muscles by the epimysium, this is a sheath of dense connective tissue which surrounds it
describe the basic organisation of skeletal muscles
Inidividual cells are called muscle fibres these are surrounded by the endomysium the perimysium surrounds the fasicle, and the epimysium surrouns the msucles
what do the tendons do
attach muscle to bone
what do the ligaments do
attach bone to bone
connective tissues in muscles are…
continuous with the tendosn and muscle attachments that direct the force of movement to the bone
describe the characteristics of muscle cells
- Dervied from mesoderm
- Have basement membranes and are supported and organised by connective tissues
- Rely on the interaction of actin and myosin myofilaments for contraction
- Have elasticity in that they can stretch beyond their normal resting length without damage and return to this legnth
- They are able to increase in size (hypertrophy) and number (hyperplasia)
How do you stain muscle cells
- Stain with H and E due to large amounts of myofilament proteins in their cytoplams
- Cytoplasm takes on a dark pink stianing
- nuclei stained blue
What are the three muscle cell types
- Skeletal muscle- voluntary
- Cardiac muscle
- Smooth muscle – involuntary
Name the properties that all 3 muscle types have
- All are contractile
- contain myofilaments
- are composed of actin and mysoin
- they have basement membranes called external laminae
what is the sacromere
A sarcomere is the functional unit of contraction within the muscle
Describe what a picture of skeletal muscle looks like
- Nuclei are on the outside and sit underneath the plasma membrane
- Straited
- Many nuclei per cell
- Many cells merge together to become one big cell
Describe the structure of skeletal muscles
- Muscle fibre = 1 cell with many peripheral nuclei to 10cm in length max
- 1 muscle fibre = 1 cell
- In development individual cells fuse
- Actin and myosin myofilaments are arranged in a regular lattice;
- They have sarcomeres
- Long cylindrical
- Multinucleate
- Straiations
What is the function of skeletal muscles
- voluntary movement
- Locomotion
- Manipulation of the environmnet
- Facial expression
- Voluntary control
where is skeletal muscle located
- In skeletal msucles attached to the bones or skin
what are the cells present in skeletal muscle
- Satellite cells - this is a population of stem cell that can add to the muscle fibre to aid its growth or to form a new muscle cell after damage, found under the muscle fibres and external lamelalle
- fibroblast - help produce the endomysium
- endothelial cells - line the capillaries
Name the bands and lines in the sarcomere and what they are
- M line where myosin is attached
- Z line where actin is attached and defines the limits of the sacromere
- I base is where actin is only found and therefore it does not overlap with myosin
- A band where myosin is located
- H bands are where only myosin filaments are found