What does it mean when a nerve fiber is polarized?
polarization is due to unequal distribution of positive and negative ions between sides of the membrane and it is particularly important in the conduction of muscle and nerve impulses. Two kinds of nerve fibers, dendrites and axons extend from cell bodies.
When a nerve fiber is polarized at rest the concentration of?
A resting nerve fiber is “polarized” partly because the concentration of: Na+ is higher on the outside and K+ is higher on the inside. Which of the following ions pass through (leak through) the resting neuronal cell membrane most easily?
What happens when a nerve is polarized?
When a neuron is not stimulated — it’s just sitting with no impulse to carry or transmit — its membrane is polarized. Polarized. Being polarized means that the electrical charge on the outside of the membrane is positive while the electrical charge on the inside of the membrane is negative.
How do nerve fiber become polarized?
Nerves. A cell membrane is usually polarized as a result of unequal ion distribution.
What tissue is not one of the meninges?
What are the steps of nerve impulse?
The following four steps describe the initiation of an impulse to the “resetting” of a neuron to prepare for a second stimulation:
- Action potential. Unlike a graded potential, an action potential is capable of traveling long distances.
- Refractory period.
What produces myelin in the brain and spinal cord?
Myelin is made by two different types of support cells. In the central nervous system (CNS) — the brain and spinal cord — cells called oligodendrocytes wrap their branch-like extensions around axons to create a myelin sheath. In the nerves outside of the spinal cord, Schwann cells produce myelin.
What do reflexes help to control?
In a simple reflex, a neuron brings information about a stimulus to the brain or spinal cord and connects with a motor neuron. Reflexes allow you to react automatically to a stimulus. Although reflexes are the simplest way your nervous system controls your behavior, all reflexes are not simple.
Which ions pass through the resting neuronal cell membrane most easily?
In other words, it allows some charged molecules, known as ions, to pass through more easily than others. Among these ions that play an important role in the nervous system, potassium (K+), which is positively charged, is the one that passes most easily through a neural membrane in its resting state.
What part of the nerve is stimulated to invoke a nervous stimulus action potential?
The arrival of the nerve impulse at the presynaptic terminal stimulates the release of neurotransmitter into the synaptic gap. The binding of the neurotransmitter to receptors on the postsynaptic membrane stimulates the regeneration of the action potential in the postsynaptic neuron.
Why do nerve impulses move faster along myelinated neurons?
By acting as an electrical insulator, myelin greatly speeds up action potential conduction (Figure 3.14). For example, whereas unmyelinated axon conduction velocities range from about 0.5 to 10 m/s, myelinated axons can conduct at velocities up to 150 m/s.
What happens when potassium channels are blocked?
The primary role of potassium channels in cardiac action potentials is cell repolarization. Therefore, blocking these channels slows (delays) repolarization, which leads to an increase in action potential duration and an increase in the effective refractory period (ERP).
What are the simplest nerve pathways in the body?
So reflexes are the simplest nerve pathway. And reflexes are an automatic movement as a result of a stimulus, so it doesn’t take conscious effort for a reflex to occur. And reflexes can involve interneurons, or sometimes a motor neuron will synapse directly with a sensory neuron.
What does nerve mean?
(Entry 1 of 2) 1: sinew, tendon strain every nerve. 2: any of the filamentous bands of nervous tissue that connect parts of the nervous system with the other organs, conduct nerve impulses, and are made up of axons and dendrites together with protective and supportive structures.
Does myelination increase resistance?
The main purpose of myelin is to increase the speed at which electrical impulses propagate along the myelinated fiber. Myelin decreases capacitance and increases electrical resistance across the axonal membrane (the axolemma).