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Description
Flashcards by Evian Chai, updated more than 1 year ago
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Created by Evian Chai
about 4 years ago
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| Question | Answer |
| Skeletal muscle cells are unique because | They are multinucleated |
| Place the following in order of formation: Myofibril Myotube Myoblasts Satellite Cells Myofiber | 1. Satellite cells (mitotically quiescent) 2. Myoblasts fuse 3. Myotube 4. Myofibril 5. Myofiber |
| A muscle is made of ... wrapped together to form a ... cell which then are wrapped to form a ... which then are grouped to form muscle | 1.myofibrils 2. Muscle fiber 3. fascicle |
| The endomysium wraps around what? What is it made of? | - Each muscle fiber cell (containing many myofibrils) - Blood vessel, nerves, fibroblast |
| The perimysium wraps around what? What is it made of? | - Each fascicle made up of many muscle fiber cells - Connective tissue |
| The epimysium wraps around what? What is it made of? | - Around skeletal muscle made of many fascicles - Fibrous connective tissue (irregular) |
| What is the myotendinous junction? | Where muscle fiber merges with dense collagenous connective tissue of the tendon |
| What do coastameres do? Where are they located? | Provide stability to the contractile apparatus Located on top of the sacrolemma at the Z lines |
| What is a muscle fiber innervated by? | Motor neuron |
| Where do the neuron and the muscle meet? This is the location of the neuromuscular junction | Motor end plate |
| What is a motor unit made of? What does smaller motor unit indicate? | All the muscle fibers a single motor neuron innervates Finer degree of muscle control |
| What are the four types of muscle cells? | 1. Skeletal muscle 2. Smooth muscle 3. Cardiac muscle 4. Myo-epithelial cells |
| Are cardiac myocytes multinucleated? | Sometimes- they are uni or bi nucleated The nuclei is centrally located |
| What is the structure of a cardiac myocyte? | - Striated with actin and myosin (but shorter than skeletal muscle) - many mitochondria |
| What joins cardiac myocytes together and allow them to function as a functional syncytium? | Intercalated discs |
| Why do cardiac myocytes have gap junctions in between them? | To allow for the transmission of action potentials |
| Can cardiac myocytes regenerate? | No, no satellite cells unlike in skeletal |
| What are the three junctions in an intercalated disc and their functions? | 1. Gap junction, to allow for waves of depolarisation to spread through heart 2. Adherans junction (actin-actin) to tether disc 3. Desmosome (IF-IF) between cardiac cells so they do not split during contraction |
| What is contraction of the heart caused by? What modulates it? | No neurons, generated involuntarily by SA/AV node Modulated by PNS/SNS |
| What are Purkinje fibers and what do they do? | Conductive myocytes that make sure atria contracts from top-->down/ventricles contract down-->up |
| Where is smooth muscle found? | 1. Gut walls 2. Blood vessels 3. Respiratory tract 4. Urinogenital tract |
| Is smooth muscle multinucleated? What is the structure? | - No, single nucleus - Cell surrounded by basal lamina - Gap junctions to allow for group contraction and Ca2+ to pass through |
| What do pericytes do? | Line small blood vessels and divide to form new SM cells |
| Is SM striated? | No, actin and myosin meshwork instead |
| What controls SM contraction? | Hormones PNS/SNS |
| Which muscle type does not contain troponin? How does it contract instead? | SM Calcium binds to calmodulin in smooth muscle. - It activates myosin light chain kinase which uses ATP to phosphorylate myosin-cross bridges - ATP —> ADP + Pi - Myosin binds to actin and forms cross bridges |
| Which muscle type cannot renew itself? | Cardiac myocytes |
| Which muscle type has no striations? | Smooth Muscle |
| Distinguish muscle types | 1. Skeletal 2. Smooth muscle 3. Cardiac myocytes |
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