Muscular And Nervous Flashcards
What is happening when a muscle contracts?
Thin actin filaments slide along the thick myosin filaments toward center of sarcomere.
They slide by the myosin head, binding to actin and the head region catalysis the hydrolysis of ATP into ADP and a phosphate group -suggests that myosin is the site of active movement
What is happening when a muscle relaxes from contraction ?
Tropomyosin and troponin (proteins in filaments) work together to block the myosin binding sites on actin, inhibiting them from sliding past each other.
Calcium ions are reeled from their bonds to troponin and the troponin-tropomyosin complex moves in a way that blocks the myosin binding sites-on actin
What type of control are skeletal muscles under, and what is its function?
Voluntary- moves our skeleton and some internal organs (tongues)
It is also found in the throat/pharynx and around the bus to control. The passage of materials
Describe skeletal muscle bundles
Numerous muscle fibres bound together by connective tissue
Describe skeletal muscle fibres
One long cell with several nuclei and many mitochondria. Can be very long
What are skeletal muscle fibres made of?
Myofibrils
What are myofibrils made of?
Myofilaments of contractile proteins
What are chief myofilament proteins
Actin and myosin
What is the pattern of banding of myofilaments a result of
Regular arrangement of thick myosin and think actin filaments
Where are smooth muscles found and what do they control?
Walls of the gastrointestinal tract and uterus and in blood vessels. they are under involuntary control of the peripheral or autonomic nervous system
What is the function of smooth muscles in GI tract and uterus?
Blood vessels?
Flow of materials
Control blood flow
Describe structure of smooth muscles
Spindle shaped, lack banded pattern of skeletal muscles and contain a single nucleus per cell
Where would you fin cardiac muscle and what control is it under?
Walls of heart where cells must contract simultaneously to efficiently pump blood and it is under involuntary control of peripheral nervous system
Cardiac muscles
A banded like appearance - they are sort and may be branches with usually one nucleus per cell
How do cardiac muscle cells communicate with each other ?
Electrical synapse which appear as dark lines - intercalated discs in longitudinal sections of cardiac muscle
When given a model of a neuron, point out all locations where information I received, carried and transmitted.
Dendrites - receives signals
Axon - Signals/action potential carried through axon in one direction
Synaptic terminals - transmits signals to other neurons
Explain where action potentials originate from, and which direction they travel
Action potential is created by signals received by the dendrites, once the sum of the signals is large enough, and action potential is created in the soma and is sent out to travel through the axon towards synaptic terminals.
Explain how a neuron produces resting potential, in terms of active transport and selective permeability to specific ions
For a neuron to produce resting potential, no stimulus will make Na+ ion gates closed, having its default charge of more positive on the outside of cell.
Explain how a neuron produces and action potential, in terms of voltage gate channels, diffusion, depolarizations and repolarization.
Starting with Na+ gates closed during resting potential, Na+ gates open from stimulus during depolarization, flooding the inside of the cell with Na+ through diffusion (positive charges), causing a spike in membrane voltage that results in an action potential. During action potential, Na+ gates close and K+ gates open, causing a decrease in membrane voltage which results in the repolarization phase.
Describe the cellular structures and processes that underlie the change in voltages associated with an action potential
Starting with Na+ gates closed during resting potential, Na+ gates open from stimulus during depolarization, flooding the inside of the cell with Na+ through diffusion (positive charges), causing a spike in membrane voltage that results in an action potential. During action potential, Na+ gates close and K+ gates open, causing a decrease in membrane voltage which results in the repolarization phase.
Once K+ h
0as been diffused, hyperpolarization causes the Na+ gates to open and K+ gates to close, spiking back up resting potential where Na+ gates close
Explain in detail how voltage gated Na+ and K+ channels in an axon produce a nerve impulse that travels in one direction along an axon
The sodium-potassium pump provides energy in the system where the outside of the cell is more positive than the inside fueled by ATP
1) 3 Na+ from inside bind to “pump”
2) ATP > ADP + PI plus energy to change pump shape
3) sodium get released outside of cell
4) 2 K+ ions bind to activated/changed pump, which then changes shape to original pump
5) 2 K+ released inside of cell
Resting cell membrane is highly permeable to K+ and only slightly permeable to Na+ ions.
Explain how a neuron prevents nerve impulses from traveling in the wrong direction
Depolarization - Once Na+ gates open and create an action potential, then Na+ gates close and K+ gates open, causing membrane voltage to drop back down during repolarization. And then K+ channels close for hyper polarization and back to resting potential. It occurs in one direction cause it occurs at the start of the action and the impulses can only travel towards the synaptic terminals.
Describe the relative importance of ATP and osmotic balance to muscle contraction
ATP binds to the myosin head during its low energy configuration, then hydrolyzes the ATP into ADP +Pi going from a low to high energy configuration, which results in myosin binding to actin, then releasing the ADP to slide the actin filament.
Compare and contrast unmyelinated and myelinated neurons
A meylinated neuron increases conduction speed of information, reducing the ability of current to leak out of the axon
