Unit 5- Muscles Flashcards
What are the functions and uses of smooth muscle?4.3.7.2
- Non striated
- Involuntary
- Contracts slow but fatigues slow
- Found in the gut and blood vessels
What are the function and uses of cardiac muscle? 4.3.7.2
- Found in the heart
- Never tire
- Intrinsic rhythm
- Contracts spontaneously
What are the functions and uses of Skeletal muscle? 4.3.7.2
- Striated
- Attached to the skeleton
- Voluntary nervous system
- Contracts fast and fatigues fast
- Made of myofibrils
How is myofibril composed?
4.3.7.2
- Myofibrils ly parralel to eachother
- Composed of the single unit ‘sarcomere’
- Actin and myosin proteins are found in the sarcomere
- Cytoplasm is the sarcoplasm (contains mitochondria)
- Network of membranes is the sarcoplasmic reticulum ( stores Calcium ions)
What are fast twitch fibres?
4.3.7.2
- Glycolytic/White muscle fibres
- Contract rapidly
- Sudden burst of energy
- Functions anaerobically due to fatiguing quick
- Fewer blood vessels
- Less mitochondria
- Lower levels of myoglobin hence a paler red colour
- More myofibrils
- High level of creatine phosphate ( converts ADP to ATP)
What are slow twitch fibres?
4.3.7.2
- Oxidative/red muscle fibres
- Slow release of energy
- Contracts slowly
- Rich blood supply
- Many mitochondria
- Plenty of myoglobin hence a red colour
- Rely on glucose
Recall some differences between fast and slow twitch fibres
4.3.7.2
- Fast twitch is a pale red while slow twitch is dark red
- Fast twitch is quick release of energy while slow twitch is over a long period of time
- Fast twitch faitgues quickly while slow twitch dont
- Fast twitch have fewer mitochondria compared to slow twitch
- Fast twitch have a lower level of myoglobin
What three zones are present on a sarcomere and what are they composed of ?
4.3.7.3
- I Band - Actin only
- A Band- Actin and myosin
- H Band- Myosin only
- Z line- A single unit of a sarcomere is between two z lines
What are the changes in the band during contraction?
4.3.7.3
- A bands remain same length
- I and H bands get shorter
What is the structure of actin and myosin?
4.3.7.3
Myosin-
- Two linear polypeptide chains wrapped around eachother
- Globular head containing ADP+Pi
- Globular head can act as ATPase
Actin-
- Two actin monomer chains joined together
- Myosin binding sites present
- Tropomyosin wrapped around the actin
- Troponin molecules bound on tropomyosin
Explain the sliding filament theory
4.3.7.3
- Release of calcium ions from the sarcoplasmic reticulum
- Calcium ions bind onto troponin causing the troponin to change shape
- Troponin changing shape pulls the tropomyosin exposing the myosin binding sites
- Myosin globular head attaches to the binding site forming an actin-myosin bridge
- ADP+Pi released from the globular head causing the head to change shape and move forward thus pulling on the actin molecule shortening the sarcomere
- Free ATP binds to the globular head breaking the actin-myosin bridge through the use of ATPase forming ADP+Pi
What joins muscle to bones?
4.3.7.4
Tendons
What joins bones to bone?
4.3.7.4
Ligaments
What are the properties of ligaments?
4.3.7.4
- Elastic to allow bone movement
- Composed of yellow elastic tissue
- Can vary in how tight they are due to the composition of collagen and white fibrous tissue
What are the properties of tendons?
4.3.7.4
- Relatively elastic
- Strong
- Provides shock absorption
