Muscles 1 Flashcards
What are the 3 different types of muscles?
Smooth
Cardiac
Skeletal
What is the sarcolemma?
Cell membrane of a muscle cell
What 8s the sarcoplasmic reticulum?
Endoplasmic reticulum of muscle cells
What is epimysium?
Outermost covering (also referred to as deep fascia )
What is perimysium?
Intermediate covering
What is endonysium?
Innermost covering (single cell)
The structure of each muscle type is different based on its function with the body :
- produce movement
- maintain pressure
- generates heat
- stores minerals
- provide protection
- produces peristalsis
- constrict blood vessels
Describe smooth muscle
- spindle shaped cells (thick middle with tapered edges)
- thin diameter (3-8um)
- variable intermediate length
- single, centrally placed nucleus
- Only endomysium
- One cell= one fiber
- gap junctions are found in some areas
- has capacity to regenerate
- slow contraction
- involuntary
Where is smooth muscle found?
Found in walls of vessels and found in some organs
Describe cardiac muscle
- branched cylindrical shaped cells
- large diameter (10-20um)
- long length
- single, centrally placed nucleus
- endomysium and perimysium
- one cell= one fiber
- attached to each other by intercalated discs
- Gap junctions and desmosomes
- has limited capacity to regenerate
- slow contraction
- involuntary
Describe skeletal muscle
- elongated cylindrical cells
- large diameter (10-100um)
- long length
- multiple, peripheral nuclei
- endomysium, perimysium and epimysium
- one fiber consist of one fused elongated multinucleated cell
- no junctions
- has limited capacity to regenerate
- fast contractions
- different types of fibers
-voluntary
What types of nerves innervate skeletal muscles? Why?
Sensory and motor neurons
motor nerves cause them to contract
-Sensory nerves give information of what position the muscle is in (proprioception)
Describe neuromuscular junctions
The nerve fiber branches and attaches to muscle fibers at the neuromuscular junction
1 fiber= 1 neuromuscular
1 nerve may serve up to 100 fibers
- The lower the ratio of muscle fibers to nerve fibers the higher the specificity of movement
- E.g. muscles of the hand few muscle fibers to a nerve therefore very intricate movements possible
Explain muscle contraction
- Myosin heads break down ATP and become reoriented and energized
- Myosin heads bind to actin, forming cross-bridges
- Myosin cross-bridges rotate toward center of the sacromere (power strike)
- As myosin heads bind ATP, the cross-bridges detach from actin
What is hypertrophy?
Increase in the size of existing muscle cells as a response to stress
