Q2-MB8/Muscle mechanics Flashcards
Explain the length tension relationship in sarcomeres.
Crossbridges can only form where thin and thick filaments overlap, so the length of the sarcomere has a direct influence on the tension produced when the sarcomere shortens.
https://www.youtube.com/watch?v=pjs7qke3L2I4
What is tetanus?
Tetanus is an infection caused by bacteria called Clostridium tetani. It causes uncontrollable spasms of skeletal muscles.
How does tetanus work?
The toxin blocks inhibitory synpases in the CNS, so there is inc. muscle activity of the motor nerves to the skeletal muscle.
What is opisthotonus and its relation to tetanus?
state of severe hyperextension and spasticity where a person’s head, neck, and spinal column enter into a complete bridging/arching position
What is summation and tetanus?
Since the AP of a skeletal muscle cell is abt 5 milliseconds long, the muscle can be activated over 200 times per second. The muscle can be activated to contract many times, even before it has had time to relax.
A muscle cell twitch can have a duration of how long?
a few hundred milliseconds
Is a muscle cell twitch refractor?
never
What is the staircase phenomenon/treppe?
When a muscle is stimulated repetitively at a frequency below the summation frequency, there is a progressive increase in the tension developed with each twitch until a maximum twitch is reached.
What are the 2 types of smooth muscle?
multiunit and visceral (single-unit)
Where are visceral/single-unit/unitary smooth muscle cells found?
Intestine
Uterus
Bladder
Ureters
Ducts of exocrine glands
Precapillary sphincters
Small blood vessels e.g. arterioles
Where are multiunit smooth muscle cells found?
Cilliary muscle
Iris
Piloerector muscles
Large arteries and veins
Arteriovenous shunt vessels
Bronchial smooth muscle
