Chapter 4: Calcium & Power Stroke
How many sarcomeres are in a muscle?
zillions of sarcomere
There are 2 kinds of myosin cross bridges, what are they?
1) Cocked 2) Uncocked
In a sarcomere there are two myofilaments(proteins), what are they?
1) Myosin 2)Actin
When a sarcomere is contracted, how long it is?
2 mircometer
How long is a sarcomere when its relaxed?
2.5 mircometers
What is the purpose of a calcium pump?
The purpose is to take Calcium back up
If cocked myosin crossbridge interacts with actin , and what occurs?
A power stroke occurs
(ATP/ADP) is required to cock the myosin cross bridge.
ATP
What is always present in a muscle?
ATP is always present in a muscle
How is energy produced?
ATP-ADP +P=energy
Why are the cocked myosin crossbridges not allowed to interact with Myosin?
Because of Troponin
What is the function of the T- Tubule?
Brings action potential down to SR
What does calcium interacts with for muscle contraction?
Calcium interacts with Actin & Myosin Filaments
Describe the action of calcium in muscle contraction.
Calcium levels go up in a cell; increase of intracellular calcium causes muscle contraction
What stops tropomyosin and how does it stop?
Calcium stops tropomyosin and it moves it out of the way
What happens if you bring action potential down to the sarcoplasmic reticulum?
Calcium will release
Myosin crossbridges are (cocked/uncocked) in an uncontracting muscle
Cocked
T or F: Both the myofilaments, Actin and myosin shorten when contracted.
False
What does the uncocked myosin crossbridge do?
It binds and splits ATP and then becomes cocked
Describe the myofilament; Myosin
Large Filament
Who has T- Tubules?
Only skeletal muscles
Describe a cocked myosin crossbridge
Responsible for the sliding of filaments Connects to Actin and pushes it along
Where is calcium stored?
Sarcoplasmic Reticulum
Describe the myofilament; Actin
Smaller Filament
What is the boundary of every sarcomere called?
The boundary of every sarcomere is called z- lines
What happens when the muscle contracts?
The myofilaments do not contract but they slide "sliding filament mechanism, causing a degree of overlap increases
What is the functional unit of the muscle and what does it have the ability to do?
The sarcomere is the functional unit of the muscle and it has the ability to contract
If the Myofilaments in a sarcomere don't shorten when contracted, then what does?
The sarcomere itself.
What is the chemical inhibitor that stop contraction?
Tropomyosin
Describe the H-Zone in a sarcomere
no overlap (relax) overlaps (contracted)
Define Sarcomere
part of muscle that is responsible for muscle contraction; distance in a muscle between two z-lines.
What is Rigor Mortis?
state of stiffness; stops making ATP. YOU DEAD!
What is a power stroke?
when actin moves a little and then sliding of filaments (uncocks)
