Is the dorsal side lighter than the ventral side?
Usually, the dorsal surface is darker than the ventral surface (though sometimes this is obscured in the preservation process). Lightly rub your finger along the ventral side toward the posterior end of the worm. You should feel a roughness caused by tiny bristles called setae.
How does the dorsal surface of an earthworm differ from the ventral surface?
The dorsal surface of some species of earthworms is darker than its ventral surface. The bottom-side of an animal is called the ventral surface. In many animals, the ventral surface is a lighter colour or shade than the dorsal surface. The periproct is the last segment of an earthworm.
Why is the dorsal side of an earthworm darker?
The dorsal side of an earthworm is muddy brown in color and darker than the ventral side. The ventral side is hidden underneath and does not need to blend in. C) It acts as camouflage. The eartworm places its dorsal side up in the summer, when the dirt is brown.
What is the top side of the worm called?
Dorsal. The top of the earthworm running from the anterior to the posterior.
Are earthworm axons myelinated?
The median and lateral giant axons in the ventral nerve cord of the earthworm Lumbricus terrestris are ensheathed by extensive spiral glial cell wrappings which resemble vertebrate myelin. The other, smaller, axons are encompassed by attenuated glial processes, as is typical of invertebrates.
What is the ventral nerve cord in an earthworm?
Earthworms have a simple nervous system. The cerebral ganglion is connected to a ventral nerve cord that runs the length of the body. Each segment is connected to this cord, allowing earthworms to move and respond to light, touch, chemicals, vibrations and more.
Is this of physiological significance to the earthworm?
Is this of physiological significance to the earthworm? This behavior is called recruitment. Yes, it is of physiological importance to the earthworm.
What is Saltatory propagation?
Saltatory conduction (from the Latin saltare, to hop or leap) is the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.
Why is Saltatory propagation faster?
Saltatory conduction occurs in myelinated axons from one node of Ranvier to the next node. Therefore, the action potential is only generated at the neurofibrils in myelinated axons. Hence, it is faster than continuous conduction. Electrical signals travel faster in axons that are insulated with myelin.
What is the difference between hyperpolarization and depolarization?
Hyperpolarization is when the membrane potential becomes more negative at a particular spot on the neuron’s membrane, while depolarization is when the membrane potential becomes less negative (more positive). The opening of channels that let positive ions flow into the cell can cause depolarization.
What is the difference between continuous propagation and Saltatory propagation?
The key difference between saltatory and continuous conduction is that saltatory conduction is the propagation of action potential along myelinated axons while continuous conduction is the propagation of action potential along unmyelinated axons.
Is continuous propagation faster than Saltatory?
Continuous propagation – of action potentials along an unmyelinate axon and affects one segment of the axon at a time. Saltatory propagation – Action potential along myelinated axon and is faster and uses less energy than continuous propagation.
Is Saltatory conduction faster?
Electrical signals travel faster in axons that are insulated with myelin. This is called saltatory conduction which means “to leap.” Saltatory conduction is a faster way to travel down an axon than traveling in an axon without myelin.
How can propagation speed be increased for a neuron?
Describe how myelination of an axon increases the speed of propagation. A selective advantage of myelination is space efficiency. Explain saltatory conduction. the propagation of action potentials along myelinated axons from one node of Ranvier to the next, increasing the conduction velocity of action potentials.
Are nodes of Ranvier evenly spaced?
Yes the nodes of Ranvier are equally spaced along the axon.
How can you increase the speed of an action potential?
2. Diameter of the axon – the larger the diameter of an axon increases the rate and speed of conductance as there is less leakage of ions. 3. Temperature – The higher the temperature the faster the conductance.