Nerve Cells and Excitability: Resting Membrane Potential

Question 1

Not All Neurones Are The Same

Answer 1

Neurons are the basic unit of the nervous system. We have around 1 billion neurons in our body. Most of them are in the central nervous system which is form by the brain and the spinal cord.
Many cells in the human body can divide and reproduce, making healing possible. Neurons, however, are post mitotic cells. A postmitotic cell is a cell which is fully differentiated and unable to dividing. which makes diseases affecting the brain particularly debilitating.
Neurons have differentsize and shape; most neurons have structural characteristics like the spinal cord neuron as shown hire the second neuron.

Question 2

Nerve Fiber

Answer 2

Some axon in our body can be very long. Therefore, for the information to travel fast up and down ourbody we need to cover the axon with a myelin sheath. Schwann cells will produce myelin
When the axon is covered with a myelin sheath is known as nerve fiber.

Question 3

Neurons communicate

Answer 3

Neurons communicate between each other through the dendrites and axon.
Incoming signalling are received at the dendrites and outgoing signals travels along the axon to the synaptic terminals.

Question 4

Structural Classification Of Neurons

Answer 4

• Multipolar Neuron: A neuron with one axon and multiple dendrites, commonly found in the central nervous system.
• Bipolar Neuron: A neuron with one axon and one dendrite, typically involved in sensory pathways such as those of the retina and olfactory system.
• Unipolar Neuron: A neuron with a single process extending from the cell body, which splits into two branches functioning as a combined axon and dendrite, often seen in sensory neurons of the peripheral nervous system.
• Anaxonic Neuron: A neuron without a distinct axon, primarily found in the brain and retina, where they are involved in local interneuronal communication.

Question 5

Classification of Neurons on the Basis of Function

Answer 5

Afferent neuron
Efferent neuron
Interneuron

Due to their functional and cellular specialization, neurons have lost the ability to mitotically divide.

Neurons are elongated cells with dendrites and axons. Axon can have myelin.

Neurons can be classified by the function or their shape.

Question 6

What is an Excitable Cell?

Answer 6

Refers to the ability of some cells to be electrically excited resulting in the generation of action potentials.

The main examples of excitable cell are neurons, musclecellsand some endocrine cells

All cells(not justexcitable cells) have a resting membrane potential (RMP): an electrical charge acrosstheplasma membrane, withtheinterior ofthe cellnegative with respect totheexterior.

In an excitable cell the resting membrane potential can change (graded or action potentials) in response to stimulation.

Excitable cellshave resting membrane potentials that range from -50mV to -85mV, whilenon-excitable cellshave potentials that range from -5 mV to -10 mV.

Question 7

Selective Permeability of Lipid Membranes

Answer 7

Lipid bilayer membranes are poorly permeable to charged molecules no matter how small they are

Question 8

Chemical gradient

Answer 8

gradient base on concentration

Question 9

Electrical gradient

Answer 9

Gradient base on charge

Question 10

Resting Membrane Potential

Answer 10

A sharp electrode in the soma records the electrical potential across neuronal membrane.

~-70 mV in most neurons.

Potential in physics is a separation of charge across lipid bilayer membrane.

Charge resides on ions inside and outside cell (Na+ and K+).

By pumping 3Na+ for 2K+ the Na+/K+ pumps establish not only the chemical gradient but also electrical one. The cell membrane serves as an insulator between inside and outside of the cell. As the concentration of Na+ and K+ changes within the cell several mechanisms work to establish and maintain a resting potential.

more sodium outside of the nerve than inside the nerve
more potassium inside the cell than outside the cell