L10- Mucles Flashcards
What are the 3 types of muscle tissue?
Skeletal, cardiac and smooth muscle
Skeletal muscle location & function
Location = attaches bones across joints
Function = moves joints ➡️moves the body
Smooth muscle function and location
Location = around tubes and sacs
Function = open/ close tubes
Regulate diameter of tubes
Propel material through tubes
Cardiac muscle function and location
Function: create driving pressure to move blood thoughts vessels
Location= heart
What muscle tissues are striated?
Skeletal and cardiac muscle
What muscle types are voluntary and which are involuntary?
Skeletal muscle = voluntary
Cardiac and smooth = involuntary
What is the primary function of skeletal muscle?
Energy transducer
What happens in a skeletal muscle when it is contracted vs relaxed?
Contracted = active
- Motor neuron Ap releases Ach ➡️ binding to Nicotinic receptor ➡️ depolarization = contraction
Relaxation = passive
- no action potentials to motor neuron
Structural hierarchy of skeletal muscle
Muscle ➡️ fascicle ➡️ muscle cell (myofiber) ➡️ myofibril
Fascicle
Bundle of muscle cells
Muscle cell (myofiber)
Muscle fiber
Myofibril
Chain of sarcomeres
What is a sacromere
Made up of thick (myosin) and thin (actin) filaments
Sarcoplasm
Cytoplasm
Sarcolemma
Plasma membrane
Sarcoplasmic reticulum stores
Calcium ca+
What conducts Ap to the sacroplasmic reticulum?
Transverse (t) tubules
What is the flow of an action potential traveling down sarcolemma
Action potential down sarcolemma ➡️ t tubules ➡️ signals saroplasmic reticulum to release ca2+ ➡️ ca2+ bathes myofibers ➡️ initiating contraction
Sarcomere
Z disc to z disc
What are thick and thin filaments made out of?
Thick = myosin
Thin = actin
H zone
Thick filaments only
A band
Thick and thin filaments
I band
Thin filaments only ( from 2 sacromeres)
What causes striations in skeletal muscle?
Overlapping of thin and thick filaments
What happens when the sacromere shorten?
A band - stays the same
H zone- shrinks/ disappears
Z bands - shrink / get closer together
I bands - shrink
What are the binding sites on the thick filament?
Actin binding site & Myosin ATPase site
What is the binding site on thin (actin) filaments?
Myosin binding site
What are the two regulatory proteins found on thin filament?
Tropomyosin - covers myosin binding site
Troponin - holds tropomyosin in place
Cross bridge cycle
Myosin heads attach to thin filament
Mechanism of cross bridge cycle
Cross bridge forms b/w charged myosin head & actin
- Myosin head ratchets pulling actin
- Myosin heads releases from actin
- Myosin head recharged by ATP