Test 2 Flashcards
What does it mean to say that a cell is electrically excitable?
neurons and muscle cells are electrically excitable. It means that they have action potentials, which are physiological electrical currents
What happens to membrane potential during an action potential?
The action potential is an explosion of electrical activity that is created by a depolarizing current. This means that some event (a stimulus) causes the resting potential to move toward 0 mV. When the depolarization reaches about -55 mV a neuron will fire an action potential. This is the threshold. If the neuron does not reach this critical threshold level, then no action potential will fire.
What is the general function/purpose of muscle tissue?
To generate force or movement: movement of organs or movement of the entire body
Describe four properties (characteristics) of muscle tissue.
1) Electrically excitable = conduct action potentials
2) Contractile = temporarily shorten
3) Extensible = stretch without tearing
4) Elastic = return to normal length following stretch
Muscle tissue both receives signals from the CNS via neurons and sends signals to the CNS via neurons. Describe afferent and efferent signals as they pertain to skeletal muscle cells
Afferent signals → travel to the CNS (send, travel from outside the CNS to in)
Efferent signals → travel from the CNS (receive).
What are proprioceptors and how do they contribute to homeostasis?
Incoming sensory information from joints and muscles that help provide a mental map of your body regarding joint angle, muscle lengths, tension. Input from proprioceptors ensures that motor neurons generate the right amount of output to muscle cells. During body movements, proprioceptor input influences motor neuron output, often at subconscious levels. Allows us to move in fluid and safe ways.
What are T-tubules and what role do they play in excitation-contraction coupling?
Tranverse tubules are extensions/tunnels of sarcolemma (the PM of a muscle cell). AP needs to reach interior of cell for contraction and T-tubules help achieve this. AP travels along sarcolemma and down T-tubules, to reach the cell’s interior.
What is the sarcoplasmic reticulum? What is it made of? What is its function or purpose?
Specialized type of smooth endoplasmic reticulum, membrane bound tubules. Stores calcium ions (Ca2+) in response to an action potential in a T-tubule, the SR quickly releases calcium, which floods the cytosol (this leads to contraction)
