Introduction to Nervous System

For every 2 (potassium) K+ that move into the cell,

the pump moves 3 Na+ out of the cell to maintain a more positive charge on the outside of the neuron

Sodium- Potassium pump occurrences

works before action potential at resting potential and after an action potential to bring it back to resting potential.

How is the myelin sheath created?

-wrapped around axon like a coil; waxy insulation 1. made of specialized cells, really flat cells- called schwann cells which is a type of neuroglia 2. Outer layers of the schwann cell are called neurilemma Myelin helps nerve impulses travel more quickly myelin wrappings- myelin sheath 3. bc they are individual cells wrapped it creates spaces which are called Node of Ranvier

Nervous System Overview Summary The nervous system controls the body by receiving sensory _________ from the ___________ nervous system, integrating messages in the __________ nervous system, and responding through the ___________ nervous system. The PNS is divided into ____________ (voluntary) and __________ (involuntary) sections.

1- input 2- peripheral 3- central 4- peripheral 5- SNS (Somatic Nervous System) 6- ANS (Autonomic Nervous System)

Nervous Tissue Summary Neurons only make up______of the nervous system tissue, but they are the essential cells for carrying _______ around the body. The impulses pass through the processes and into the cell ______. Neurons can be classified by the _____ they have or by their _____.

1. 10% 2. impulses 3- body 4- number of processes 5-function

There are 2 major types of nerve cells:

1. Neurons responsible to conduct impulses around the body 10% of nerve cells 2. Neuroglia (nerve-glue) support, insulate and protect neurons 90% of nerve cells

What is resting potential?

At rest, a neuron's intracellular space is negatively charged due to more Cl- ions and the extracellular space is positively charged due to more Na+ ions.

What happens at repolarization?

As the impulse passes, potassium diffuses out of the neuron through voltage-gated potassium channels

What is the structure of a neuron?

all neurons have a main cell body ( contains nucleus, cytoplasm, other organelles) and have cell body with processes. Processes divide into DENDRITES (hair-like)- bring impulses into cell body AXON- send impulses away from cell body Branches off into AXON-TERMINALS where there are NEUROTRANSMITTERS that pass impulse to the next neuron

What is a nerve impulse?

•A nerve impulse is an electrical signal that travels along the neuron. It arises from the movement of ions causing a change in electrical charges.

Neurons can also be classified by functions

-afferent neurons : carry impulses toward the CNS -efferent neurons : carry impulses away from CNS -interneurons : connect afferent and efferent neurons

Nerve Protection and Support Summary Neurons pass ______ to or from the CNS. The ____ is covered by a myelin ___, which is formed by _____ cells. Neuroglia help to produce this insulation or support & ____ neurons, provide _______ response or secrete cerebrospinal fluid.

-impulses -axon -sheath -Schwann -anchor -immune

A Sodium- Potassium pump:

3 Na* out: 2 K* in membrane Potential to make sure there is more positive charge on the outside and more negative charges on the inside The sodium-potassium pump then restores the ion concentrations to normal and the resting potential returns.

What are the major functions of the nervous system?

NS is the master control center for the body. Works with the endocrine system. To do this it uses SENSORY INPUT- detects changes (stimuli) inside and outside the body INTEGRATION- processing and interpreting information RESPONSE- activation of muscles (motor output) or glands

What are the functions of neuroglia in the Central nervous system?

Neuroglial are found in either the CNS or the PNS In the CNS there are Astrocytes: Support & anchor neurons to astrocytes surrounding capillaries • Microglia: Provide immune response to central nervous system • Ependymal cells: Secrete and circulate cerebrospinal fluid • Oligodendrocytes: Generate and maintain the myelin sheath of neurons in the central nervous system and link neurons together (make electrical impulses go faster)

What are the types of neurons?

Neurons can be classified by the number of processes extending from the cell body -Unipolar neurons (1 processes) found spinal cord -Bipolar Neurons (2 processes) found in sense organs retina, olfactory epithelium, and ear -Multipolar neurons (many processes) found in most regions of CNS and PNS

How is the nervous system organized?

The nervous system is divided into: - central nervous system (CNS)- consists of the brain and spinal cord - Peripheral Nervous System (PNS)- other nerves 1. Cranial Nerves- originate from brain 2. Spinal Nerves- originate from spinal cord: info collected comes from spinal cord

what happens at depolarization?

When the neuron is stimulated, either by the environment or another neuron, sodium rushes into the neuron through 2. sodium voltage-gated channels and quickly reverses the charges

What is a synapse?

Where 2 neurons meet is called a synapse. The 2 neurons do not touch. The space between them is called the synaptic cleft.

What are the functions of neuroglia in the peripheral nervous system?

Within the peripheral nervous system: •Satellite cells: Support and anchor neurons in the peripheral nervous system (make sure neurons stay together) • Schwann cells: provide myelin insulation to neurons in the peripheral nervous system (stronger impulses, stronger way)

What two ions are positively charged located inside and outside?

sodium (Na+) and potassium (K+)

How is resting potential maintained?

sodium potassium pump

What events occur at the synapse?

•As the impulse reaches the axon terminal, it can not cross the gap. "The impulse stimulates an influx of calcium gated channels causing vesicles to release neurotransmitters across the synaptic cleft. •These neurotransmitters cause channels to open in the next neuron, continuing the action potential from one neuron to the next. •Neurotransmitters in the synaptic cleft are reabsorbed into the presynaptic cell through a re-uptake protein or broken down by enzymes