Muscle tissue Flashcards
What are the charasteristics of cardiac muscle tissue?
Involentary and intrisinacly controlled, striated, bransched and single nucleotided.
Describe smooth muscle tissue
Involentary controlled, not striated, not bransched and single nucleotide
Describe skeletal muscle
Cylindrical, multinucleotide, striated and under volentary control
What is the overall anatomy of the skeletal muscle and why?
Surronding the muscle there are the epimysium, then there are lots of faciles surronded by perimysium. The fasicles in turn are made out of muscle fibers that are surronded by endomysium. The muscle fibers are made out of myofribilis are are surronded by their membrane called the sacrolema. The epimysium, perimysium and endomysium are there to support the muscles so they don’t take damage.
What is the anatomy of the myofibrilis?
The myofibrilis are divided into sarcomeres. Sarcomeres are made out of myofilaments. Myofilaments are two types of proteins called actin and mysoin. The sarcomeres are seperated by z-lines. When relaxed the actin is covered by troponin and tropomyosin that blocks the myosin binding spots.
Describe the process of a muscle contraction
The brain sends a signal across the motor nerve when we want to use our skeletal muscles. The action potential travels along the nerve until it reaches the target muscle. The synapses release acetylcoline and the receptors at the muscle cells are voltage sensitive sodium channels and the acetylcoline trigger a release of sodium into the cell. If strong enough signal this will cause an action potential that will travel along the muscle cells triggering a release of sodium into the cells. The action potential traels until it reaches the membrane called the sarcolema which has T-tubes that go deep into the cell. The action potential travels down the T-tubules and triggers the voltage sensitive calciumion channels found in the cells sarcoplasmic reticulum. The channels open and the calcium travels along the rest of the cells causing the troponin to bind to the calciumions instead of the actin. This causes the tropomyosin to change shape revealing the binding sites of the actin for the myosin. Myosin then binds to ATP cleaving the molecule into ADP+P, releasing energy that it uses to bind to the actin binding spots. When it binds to the actin it will cause the muscle to contract. The process goes on causing a process called the sliding filament model which is when the filaments slide in different directions due to the myosin using up the energy from the ATP releasing then binding to new ATP and binding again. When this is synchronised this causes a slide of the filaments causing complete muscle contraction.
Describe the process of the muscle going from contraction to relaxation
The calcium pumps will start to restock the cell leading it to take back the calcium ions that the troponin is binding to causing it to start binding with the actin again. This changes the shape causin tropomyosin to once again block the binding spots and the myosin has to release the actin.
