Nervous System SG

What is the purpose of the nervous system?

controls and integrates all body activities to maintain life.

• sensing

• interpreting

• reacting

What are the parts of the nervous system?

CNS, PNS

The central nervous system includes what parts of the nervous system?

spinal cord, brain

The peripheral nervous includes what parts of the nervous system?

everything else (sensors)

What is the somatic nervous system?

voluntary

• neurons from cutaneous and special sensory receptors to CNS

• motor neurons- skeletal muscle

What are neurons?

a specialized cell transmitting nerve impulses; a nerve cell.

how do neurons fire?

by generating an electrical impulse called an action potential when stimulation exceeds a specific threshold

What is a synapse? How does it relate to neural communication?

a specialized, minute junction between two neurons—or a neuron and a target cell—where signals are transmitted, typically via chemical neurotransmitters

List the three types of neurons

1. Multipolar: several; dendrites and one axon (common)

2. Bipolar: One main dendrite and one axon. sensory input

3. Pseudo unipolar: one process only

What is the general purpose of neuroglia?

act as the essential support system for neurons in the nervous system, providing structural, metabolic, and protective functions to maintain homeostasis

name all the neuroglia and their general function

astrocyte: form blood brain barrier by covering blood capillaries

oligodendrocytes: form myelin sheaths around axon in CNS

ependymal: produce cerebrospinal fluid lining cerebrospinal/cavities

satellite: flat cells support neurons w/metabolic functions (produce ATP, glucose)

Schwann: produce myelin sheath for axon and PNS

Which neuroglia cells produce myelin?

Schwann, oligodendrocyte

When and how do ions move across the plasma membrane of a neuron (think dendrite side)

through ligand-gated ion channels when neurotransmitters bind during synaptic transmission, or via pump mechanisms to maintain resting potential. Sodium and Calcium, flow into the dendrite for excitation

What is a graded potential and how does it happen?

electrical charge across a neurons membrane.

1. stimulus occurs

2. ion channels open

3. Ione move across membrane (Na enters K leaves)

4. local electrical change forms creating graded potential

What is an action potential and how does it happen

rapid electrical signal that travels along a neuron

1. threshold is reached (graded potential -55)

2. depolarization (Na opens)

3. repolarization (K opens)

4. hyper polarization (K opens)

5. resting state (closed)

If you inject KCL into a human body it breaks up into K and Cl. How would an excess of K change an action potential graph? Which way does the charge go? How could this influence a neurons from firing (more excitable or less)

extra K+ is outside neurons. In the action potential graph less K+ leaves the cell. The inside of the neuron becomes less negative (more positive). The resting membrane potential shifts upward. Large increase of K+ would make the neuron less excitable because sodium channels stop working properly.

What is the difference between saltatory and continuous conduction in nerves.

Saltatory: myelinated axons, jumps from node to node (faster, less energy)

Continous: unmyelinated axons, moves step-by-step along (slower)

What is a chemical synapse

a small gap between cells where neurons send signals using neurotransmitters.

A postsynaptic neuron receives a greater number and frequency of excitatory signals than inhibitory signals, but not enough excitatory signals to reach threshold level. What will develop in this neuron?

it will develop a graded potential and a EPSP

What is Acetylcholine and how is it used in the body

a neurotransmitter that causes muscles to contract by transmitting signals from motor neurons to muscle fibers

How and where do neurons repair/regenerate

PNS neurons can regenerate axons if the cell body is healthy, guided by Schwann cells

what is neuronal summation?

the process by which a postsynatpic neuron adds up all the incoming signals to decide whether to fire an action potential