Topic 7 Flashcards
Skeletal mm is formed from a fusion of hundreds of embryonic cells called _________?
Myoblasts
Plasma membrane of skeletal mm is called the __________?
Sarcolemma
The cytoplasm of skeletal mm cell is ka _________ and it contains structures that allow the cell to generate the ____ needed for contraction.
Sarcoplasm
ATP
Structures found in sarcoplasm
Glycogen (glucose polymer)
Mitochondria
Myoglobin (O2 storing protein)
The majority of the sarcoplasm contain myofibrils - rod like cylinders.
Each myofibril is composed of __________ and consist of a repeating orderly arrangement of units ka sarcomeres.
What are the proteins they are made from?
Myofilaments
Made from the proteins actin and myosin
Is referred to as the thick filament
Myosin
Is referred to as the thin filament
Actin
The _______ consist of the following pattern; a region of just thin filaments followed by region of thin and thick filaments that overlap
Myofibril
This region of thin filament appears light and is referred to as the ___ band
I band
This region of overlap appears dark and is referred to as the ____ band
A band
The dark A band has a small lighter area in the midsection known as the ___ zone which is vertically bisected by the dark line called the ___ line
H zone
M line
The ___ zone contains thick filament only and has no overlap
H zone
Each I band is also bisected vertically by a dark line known as the _________
Z disk
The basic functional unit of the muscle cell.
___________ is a defined segment of a myofibril.
Sarcomere
The linkage between actin and myosin is known as
A cross bridge
During the act of muscle contraction, what gets smaller?
The muscle fiber, the myofibrils within the muscle fiber, sarcomeres, distance between the Z discs, I band, H zone
Note: that the A band move closer together but they do not decrease in size
What tissue types are found in skeletal muscle?
Skeletal muscle tissue, nervous tissue, epithelial tissue, and connective tissue
What tissue surrounds the skeletal muscle? (Epimysium)
Dense irregular CT
Within the muscle there are bundles of skeletal muscle fibers known as _________.
Fascicles
Each fascicle is surrounded by layer of fibrous CT ka _________
Perimysium
What is comprised of the endomysium?
A loose sheath of CT
The attachment of a skeletal mm to a bone is usually classified as an ________ (the bone that does not move) or an _______ (the bone that moves)
Origin and insertion
The arrival of an action potential at the axon terminal will promote the release of ______________ into the synaptic cleft
Acetylcholine (ACh)
ACh Will diffuse across the synaptic cleft and bind to the __________ _________ on the motor and plate
Cholinergic receptors
These cholinergic receptors are chemical gated ion channels. The binding of acetylcholine causes these channels to open. This results in the influx of ________ and membrane depolarization known as a graded potential. If it is strong enough it will cause an action potential.
Na+ (sodium)
The stimulation of the motor endplate by the acetylcholine is short live it since the synaptic cleft contains the enzyme _________________________ which quickly breaks down acetylcholine.
Acetylcholinesterase
The endoplasmic reticulum of the muscle cell is known as
The sarcoplasmic reticulum
The action potential will spread down the membrane of the
T tubules
The rise in sacroplasmic _______ levels will begin the process of contraction
Ca2+ (calcium)
Under resting conditions, myosin cannot latch onto actin and form cross bridges because the myosin-binding sites on actin are blocked by a protein called
Tropomyosin
The position of tropomyosin is determined by a protein attached to tropomyosin called
Troponin
The calcium that enters the sarcoplasm from the terminal cisternae will bind to
Troponin
When calcium binds to troponin it ________ ______. This causes tropomyosin to change positions and exposes the myosin-binding sites on the actin filaments
Changes shape
The calcium levels in the sarcoplasm do not stay elevated for long. The membrane of the sarcoplasmic reticulum contains a pump that _______ ____________ calcium back into the sarcoplasmic reticulum
Actively transports
What covers the myosin binding sites on actin?
Tropomyosin
