Nerve Cell

What are the types of synapses?

1. Axosomatic 2. Neuroeffector synapses 3. Axodendritic 4. Axoaxonic

3 parts of the Nervous System

1. Central Nervous System (CNS): brain and spinal cord. 2.Peripheral Nervous System (PNS): nerves of the body 3.Autonomic Nervous System (ANS): has parts of the CNS and PNS.

What three characteristics do all neurons share?

1. Longevity - can live and function for a lifetime 2. Do not divide - fetal neurons lose their ability to undergo mitosis (the y lose their centrioles); neural stem cells are an exception 3. High metabolic rate - require abundant oxygen and glucose

What are 4 types of glia cells?

1. Oligodendrocyte 2. Schwann Cell 3. Astrocyte 4. Microglia

Photo of two of the 4 types of glial cells

1. Oligodendrocytes 2. Schwann Cell

What are the 3 functions of an ASTROCYTE?

1. Physically supports the neurons 2.Transmits materials from capillaries to neurons 3.Forms blood-brain barrier (BBB), which keeps out harmful substances and many medicines

What three things do all neurons do?

1. Receive a signal. Can be any type of stimulus (change in environment, signal from another neuron, etc). 2.Transmit a signal to another location. E.g. finger touching something → signal to spinal cord or brain. 3. Stimulate another cell a. Another neuron → transmit signal b. Muscle → contraction c. Gland → secretion

Why does sidedness exist (inside of cell negative, outside positive)?

1. The cell membrane has different permeabilities to each ion. 2.Pumps exist which force particular ions into or out of the cell 3.Channels made out of protein selectively allow particular ions into or out of the cell.

For a substance to diffuse across a semipermiable membrane, what two conditions must be met?

1. The membrane must be permeable to the substance. 2.The substance must have a concentration gradient

What are the three structural classifications of neurons?

1. Unipolar 2. Bipolar 3. Multipolar

What has the function of transmitting signals from the cell body to the area with neurotransmitters?

AXON

What is an action potential?

Action Potential = depolarization + repolarization

Describe the correct path an impulse takes across a synapse.

Axon of presynaptic neuron → SYNAPTIC CLEFT → dendrite of post synaptic neuron

What is movement of nutrients, wastes, and organelles between the cell body and axon terminals

Axoplasmic transport

What are the two parts of the CNS?

Brain and Spinal cord

41. What are ependymal cells?

Cells that line the ventricles of the brain and produce cerebral spinal fluid (CSF)

What does the Autonomic Nervous System control and what are its 2 divisions?

Controls autonomic function (blood pressure, digestion, etc). Sympathetic division Parasympathetic division

What receives the signal and carries the nerve conduction toward the cell body?

DENDRITES

When does Depolarization occur?

Depolarization: Enough sodium ions flow into the cell to make the membrane potential become positive

What sheath covers the axon (not referring to myelin)?

Endoneurium

What sheath covers a bunch of fascicles?

Epineurium

What are the supporting cells of the nervous system?

GLIA

42. What is the portion of the CNS that is unmyelinated (cell bodies of neurons, glia, and dendrites)?

GREY MATTER

What is a collection of cell bodies in the PNS?

Ganglion

What is a small neuron found only in the CNS?

INTERNEURON

Where are the cell bodies of motor neurons and interneurons located?

In gray matter

At resting membrane potential, is the inside of the cell membrane positive or negative? What about the outside of the cell membrane?

Inside is negative, outside is positive

What happens if a neuron's supply of neurotransmitters is exhausted?

It might be temporarily unable to transmit an impulse to another cell

Why does potassium want to get back into a cell?

It wants to get back into a cell because it is attracted to the negative charges on the protein inside the cell

Why does potassium constantly want to leave a cell?

It wants to leave to diffuse down its concentration gradient

What are the neurons that leave the CNS to effect a muscle or gland?

MOTOR NEURONS

What is an autoimmune disease where the oligodendrocytes (the myelin sheaths) are destroyed, interfering with the neuron functions in the CNS and brain?

MULTIPLE SCLEROSIS

What is the most common neurological disease of young adults?

MULTIPLE SCLEROSIS

Where do most tumors originate from?

Most tumors of the brain originate from glial cells.

What is myelin made of?

Mostly lipid

What kind of neurons leave the CNS?

Motor (efferent) signals are carried away from the CNS. They innervate muscles and glands

What conducts impulses faster - myelinated or unmyelinated axon?

Myelinated

What is a network of nerves called?

NERVE PLEXUS

What is a collection of axons in the PNS?

NERVE; No cell bodies, dendrites, or synapses; just axons.

What are the BARE regions of axonal membranes found only in myelinated axons called?

NODES OF RANVIER

Gray matter in the CNS contains what structures?

Neuroglia, neuron cell bodies, dendrites. Everything except myelinated neurons

Where are unmyelinated axons found?

Neuron cell bodies, dendrites, and unmyelinated axons in the PNS and CNS.

Does potassium leave the cell because of neuron stimulation?

No, it can leave anytime because its channel is leaky.

Do glia cells process information in the nervous system?

No, the interneurons do that.

Do glia cells carry nerve impulses?

No. The impulses jump over the oligodendrocytes and Schwann cells, and astrocytes and microglia are not involved in nerve impuses at all.

Which cells provide the myelin sheath for neurons in the CNS?

OLIGODENDROCYTES

What is the neurolemma?

Outermost covering of a neuron (plasma membrane

What sheath covers a fascicle (bundle of neurons)

Perineurium

What makes the inside of a cell membrane negatively charged?

Proteins inside the cell make it negative

What does the word "innervates" mean?

Refers to a nerve supplying a muscle or organ. For example, "The phrenic nerve innervates the diaphragm muscle".

When does Repolarization occur?

Repolarization: Enough sodium ions flow out of the cell to make the membrane potential become negative

Which cells provide the myelin sheath for neurons in the PNS?

SCHWANN CELLS

What neurons go from body to CNS, carrying sensory information?

SENSORY NEURON

Where is most information processed?

SYNAPSES in the CNS

What part of a neuron stimulates another cell?

SYNAPTIC KNOBS

What are the two differences between SCHWANN CELLS and OLIGODENDRICYTES?

Schwann cells are in PNS and each cell only forms one myelin sheath. Oligodendricytes are in CNS and each cell can form more than one myelin sheaths.

What kinds of neurons enter the CNS?

Sensory (afferent) signals picked up by sensor receptors. They are carried by nerve fibers of PNS to the CNS

When a cell is at resting membrane potential and is then stimulated by a neuron, what is the first thing that happens to start the change in the overall charge on the inside of the cell?

Sodium channels open and sodium enters the cell.

What is a collection of axons in the CNS

TRACT

Where are the nucleus, ribosomes, and most organelles located?

The CELL BODY

What changes the overall charge on the inside and outside of the cell membrane?

The charges change when sodium channels open during neuron stimulation

What makes the CNS complex?

The large number of interneurons in the CNS

What is the correct sequence of events at a synapse?

The nerve impulse arrives at the synaptic knob of the presynaptic cell, then the neurotransmitter is released. The NT binds to receptors on the postsynaptic cell, generating an action potential in the postsynaptic cell axon. Then the NT is removed from the receptors of the postsynaptic cell, either by an enzyme, or they are taken back up into the presynaptic terminal knob and recycled.

What is the only function of the blood-brain barrier BBB?

The only function of the blood-brain barrier is to help protect the central nervous system.

What is the resting membrane potential of a cell? Why does potassium constantly want to leave a cell?

The resting membrane potential is how negative or positive the charge of the cell membrane is when it is not being stimulated by a neuron. The resting membrane potential is Minus 70-minus 90 mV

What are synaptic knobs filled with?

The synaptic knob has vesicles filled with a neurotransmitter that carries the signal.

Define MICROGLIA and their function

They are macrophages. They pick up bacteria and debris.

What is the function of glia cells?

They support the neurons

Are unmyelinated axons thinner or thicker than myelinated?

Unmyelinated axons are thinner.

What is the portion of the CNS with myelin (axons)

WHITE MATTER

What is the function of interneuron?

it connects two other neurons in the spinal cord

What is Wallerian Degeneration?

macrophages remove the debris of damaged axons

What are the structural classification of neurons based on ?

the number of processes that project from the cell body.

What is the function of MYELIN SHEATHS

to speed up the rate of nerve impulse conduction.