NERVOUS SYSTEM

Functions:
1. receives incoming signals
2. generates outgoing signals

nonexcitable cells that provide structural support of the serve impt physiological and immunological functions in the nervous system.also called GLIAL CELLS

an atom or small molecule with a positive or negative electrical charge

the brain and spinal cord

the portion of the nervous system that lies outside the brain and spinal cord; includes nerves and ganglia

refers to a cell that responds to stimuli by generating an electrical signal at the cell membrane. NEURONS AND MUSCLE CELLS ARE EXCITABLE

a cell that receives signals from a neuron or a hormone ; target cell communicate can be another neuron, muscle, glands.

a neuron with a central cell body that gives rise to multiple dendrites and a single axon. The most comon type of neuron in humans.

the portion of the neuron containing the nucleus and organelles, also called the SOMA

another word for BODY. In the nervous system, the soma refers to the cell body of a neuron.

a cytoplasmic process that extends from a neuron's cell body. Neuron typically have many dendrites, which are usually shorter and thicker than axons and highly branched. Dendrites receive signals from other neurons.

a long, thin cytoplasmic process that extends from a neurons cell body. The axon may be insulated with MYELIN. Each neuron has a single axon, which transmits ACTION POTENTIAL

3 CHARACTERISTICS STRUCTURAL FEATURES: 1. cell body 2. dendrites. 3. axons

receives signals coming in from other cells and send them toward the axon.

is the main nutritional and metabolic region of the neuron, also receives signals from other cells and sends them toward the axon.

-transmitting or conducting region of the neuron.
-generates an action potential, an outgoing signal also called nerve impulse, and conduct it to next cell.

a long distance regenerative electrical signal transmitted along axon. The action potential is the all or none event. also called a NERVE IMPULSE, SPIKE OR DISCHARGE.

another term for action potential

information flow is DIRECTIONAL
- path of information: dendrites(IN)-soma(IN)-axon(out)
-action potential is conducted along the axon toward the target cell.

junction between a neuron and its target cell (another neuron, muscle or gland). Signals between neuron and other cells are communicated across synapses.

the first portion or initial segment of the axon

a brach of an axon

the bulbous ending of a branch of an axon. also called synaptic ending or a synaptic bouton.

THE insulation surrounding axons. The myelin sheath is formed by support cells that wrap repeatedly around an axon, forming a thick layer of cell membrane.

- insulate the axon
one type of support cell in the nervous system. found in the peripheral nervous system, this forms myelin sheaths around axons

schwann cell wraps around and around the axon. so cytoplasm is squeezed out so the tightnes wound becomes the insulation

- gap between schwann cell.
tiny areas of bare axon between neighboring segments of myelin sheath; charge flows across the mebrane only at the nodes of ranvier so the action potential appears to jump along the axon.

1. dendrites 2. cell body

Axon-vary in length 1 or 2 mm more than 1 m.
-insulated with myelin sheath

control the movement of ions across the membrane.

an atom or small molecule with a positive or negative electrical charge.

proteins that are embedded in the lipid bilayer of the cell membrane.

integral proteins containing watery pores through which ion pass to cross the cell membrane.
- control the movement through the neuronal cell mebrane.

IOn channels are :
-selective(they select ions for passage based on the charge on the ion, size and how much water the ion attracts and holds around it.
-passive or active (ACTIVE have gates that open or close the channel. ) (PASSIVE - leakage channels that are always open, ion pass continuosly)
-regionaly located
-functionally unique

ion channels with gates that are open or close by changes in the membrane.

slightly more positive outside and slighlt negative inside.

- the difference produces a voltage across the cell mebrane. (-70 mv)
-electrical potential or voltage across a cell membrane that results from the separation of charged particles across the mebrane.
- at rest (volatage gated are closed) during action potential (voltage gated are open and close

a chemical that is release at the synapse

Gamma-aminobutyric acid (a neurotransmitter )

ion chanelss with gates that open or close when a neurotransmitter binds to them.

REGIONALLY LOCATION:
1. PASSIVE CHANNELS - located in dendrites, cell body, axon.
2. CHEMICALLY GATED CHANNELS - dendrites and cell body.
3. VOLTAGE GATED CHANNELS - axon hillock, unmyelinated axons and Nodes of Ranvier.

1. PASSIVE CHANNELS - responsible for resting membrane potential
2. CHEMICALLY GATED CHANNELS- responsible for synaptic potentials or incoming signal to neuron.
3. VOLTAGE-GATED CHANNELS - generation and propagation of action potential, the outgoing signal of neuron.

- incoming signal to neurons.
-a short distance electrical signal thatcary vary in amplitude.

-only potassium may pass through
-always open
-found on dendrites
found on cell body
found along axon
-essentialfor producing the resting membrane potential

-only sodium may pass through
-opened and closed gates
-gates are sensitive to mebrane voltage
-found along axon
-not found on dendrites or cell body
-essential for producing action potential

cause ions to move across cell membranesresults in separation across the membrane, then creates action potential or force.

electrical potential

the movement of molecules from one location to another because of random thermal motion. NET MOVEMENT is from a region of higher conct. to a region of lower conct.

an atom or small molecule with a positive or negative electric charge.

negatively charged ion

positively charged ion

integral proteins containing watery pores through which ion pass to cell membrane.

located outside the cell, includes interstitial fluid and plasma.

OUTSIDE/INSIDE THE CELL :
1. NA - 150 outside
2. K - 150 inside
3. Cl 10 inside

characteristics of cell membrane that permits some particles to cross it, but prevents other particles from crossing
- permeable to NA K Cl , impermeable to - charged and anions that are large.

very permeable to K and slightly to Na

the difference in the concentration of a particular substance between two adjacent areas.

an electrical force across a cell membrane that resulsta from separation of charged paricles across the mebrane.
-pulls K into cell.

- state of chemical stability in which no net change occurs. For ion in equilibrium across cell membrane, the amt moving out is equal to amt moving in .

the membrane potential at which the electrical and chemical forcs that drive that ion across the cell mebrane are equal and opposite.

resting neurons: very permeable to K and slight to Na

a membrane enzyme that uses the energy of ATP to transport Na and K ion against their respective electrochemical gradients.
- uses the energy of ATp to move Na and K against their electro chemical gradients.
- 3 Na pumps out and 3 K pumped in.