A&P: Chapter 10 (Part 1)

Functions of Nervous System

1.) Sensory Input
2.) Integration
3.) Control of muscles and glands
4.) Homeostasis
5.)Mental Activity

Central Nervous System

Brain and spinal cord.

Peripheral Nervous System

Sensory receptors and nerves

Sensory Division

(Afferent Division) Sends action potentials from sensory receptors to CNS.

Motor Division

(Efferent Division) Sends action potentials from CNS to muscles, organs, or glands.

Somatic Motor

Sends action potentials from CNS to skeletal muscles (voluntary).

Autonomic NS

Sends action potentials from CNS to cardiac muscle, smooth muscle, and glands (involuntary).

Sympathetic Division

Active during physical activity, "fight or flight" NS during emergencies.

Parasympathetic Division

Active during resting, regulates some digestion and other "vegetative" functions.

Enteric Division

Located in digestive tract, runs most of digestion independent of the CNS.

Neuron

(Nerve cells) Cells that actually receive and transmit action potentials.

Neuroglia

(Glial Cells) Cells that support the neurons. They do NOT transmit and receive APs, they have functions to help the neurons transmit and receive APs.

Yes

Can you label this picture?

Soma

Main cell body

Trigger Zone

Beginning of axon and place where a new action potential originates.

Dendrites

Extensions of the cell membrane which have dendrite spines.

Dendrite Spines

Allow axons from other cells to form synapses.

Axon

Long tail of cell, often called the nerve fiber.

Synapse

Any connection point between an axon and another cell.

Presynaptic Terminal

An ending of an axon at the synapse.

Bipolar

1 dendrite & 1 axon
Found in retina of eye and in nasal cavity.

Unipolar

Has axon but the other end is not actually dendrites.
Often has a receptor instead of the dendrite, most sensory neurons are like this.

Multipolar

Many dendrites and 1 axon.
Most CNS and motor neurons are like this.

Types of CNS Glial Cells

1.) Astrocytes
2.) Ependymal Cells
3.) Microglial
4.) Oligodendrocytes

Types of PNS Glial Cells

1.) Schwann Cells
2.) Satellite Cells

Astrocytes

Forms link between blood vessel & neuron, can dilate or contract nearby blood vessels, help form synapses, regulate amount of ions available (needed for APs), and produces lactic acid for "back up energy" when glucose is low for neurons.

Reactive Astrocytes

Production of many astrocytes after a CNS injury. They wall of injury sites and limits inflammation, and limits regeneration of the damaged axons.

Ependymal Cells

Line ventricles of brain and spinal cord, (with blood vessels) form choroid plexus.

Choroid Plexus

Produces cerebrospinal fluid.

Microglia

The CNS's version of white blood cells, breaks down dead cells and invading microoganisms.

Oligodendrocytes

Wrap around axons and form myelin sheaths, only in the CNS.

Schwann Cells

Form myelin sheaths of PNS.

Satellite Cells

Surround soma (cell body), also helps gen nutrients to cell and absorb poisons away from it.

Functions of Myelin

1.) Insulates the signal (prevents signal from jumping to nearby axons).
2.) Encourages faster action potential propagation.

surrounded

Myelinated and unmyelinated axons are different based on how they are ____________ by Schwann cells or oligodendrocytes.

Myelinated Axons

Schwann cells or oligodendrocytes wrap around axon.

Unmyelinated Axons

Axons are "buried" within Schwann cells or oligodendrocytes but are not individually wrapped.

Action Potential

The electrical signal of the body.

Ligand-gated ion channels

Opens only for a specific ligand (molecule).

Voltage-gated ion channels

Opens only when a specific membrane potential is reached.

Leak channels

Always open and slowly leak one type of ion.

Sodium-Potassium Pump

Uses energy (ATP) to force K+ inside the cell and force Na+ outside the cell.

Resting Membrane Potential

The membrane potential in a normal or unstimulated cell.

Membrane Potential

Difference in charges between the sides of the membrane.

Polarized

When one side of the membrane is + and the other is -, the membrane is said to be _________.

-70 mV

The resting membrane potential of neurons.

Items Affecting Membrane Potential

1.) Ions
2.) Depolarization
3.)Hyperpolarization

Ions Affecting Membrane Potential

Na+, K+, Ca+2, Cl-

Depolarization

Decrease in the membrane potential, charges difference is becoming closer to 0 mV.

Hyperpolarization

Increase in the membrane potential, charge difference is becoming further from 0 mV.

Graded Potential

Any change in the resting membrane potential, or any stimulus that can affect an ion pump or channel.
Ex.) ligand binding to receptor, voltage change, mechanically opening a gate, temperature change, pH change

Summation

The adding up effect of multiple graded potentials.

proportional

Graded potential strength is ___________ to the stimulus.

Threshold

The level of voltage that must be reached for the change in membrane potential to spread to nearby parts of the cell membrane.