Nervous System

Endocrine System

* Chemicals (hormones)
* Slow and is carried by the bloodstream

Nervous System

* A series of electrical impulses
* Rapid and is carried by nerves

What is the purpose of the endocrine and nervous system?

Increase/decrease body activities to maintain homeostasis

Central Nervous System (CNS)

Brain and Spinal Cord

Peripheral Nervous System (PNS)

Nerves connecting CNS to other body parts

Autonomic Nervous System

Division of the PNS that controls automatic body functions

Somatic Nervous System

Division of the PNS that control voluntary body functions

Dendrites

* Branches of the neuron that receive input (stimulus)
* “__________ Listen”
* Can be hundreds per neuron
* Send nerve impulses __toward cell body__

Cell Body (Soma)

* Contains nucleus and organelles
* Cytoplasm, mitochondria, etc.

Nissl Bodies

* Make proteins
* repair/maintain neuron
* neurotransmitters
* Neuroglobin (stores O2)

Axon

* Send impulses __away from cell body__
* “________ Speak”
* One axon per neuron
* Terminal Branches

Myelin Sheath

* White matter surrounding parts of axon (not the dendrites or cell body)
* Consists of lipids, proteins, water
* Insulates axon and increases impulse speed

When does myelination begin in human?

During the third trimester

Nodes of Ranvier

* Gaps in myelin sheath
* Allows impulse to travel faster
* Impulse “jumps” from node to node

Neurons

* Nerve cells
* Transmit impulses

Sensory/Afferent Neurons

* Impulses to the CNS
* **“**__**A**__rriving at the CNS”

Motor/Efferent Neurons

* Impulse away from the CNS
* “__**E**__xiting the CNS”

Interneurons

Neurons found in CNS that connect two sections of the brain

Glia Cells

* “Glue”
* Don’t transmit impulses
* Provide structural support and nutrient

Microglia

A type of glia cells that are the immune system of the CNS (microbe eater)

What causes Multiple Sclerosis?

* Microglia eat away at myelin causing a bumpy transmission of impulse
* Driving on a road with potholes

Oligodendrocytes

* Glia cell that produces myelin in the CNS
* One cell that branches out to myelinate many axons

Schwann Cells

* Produce myelin in PNS
* Only found on individual axons
* Not branched

Astrocytes

* Star Cells
* Keep neurons near blood supply (access to nutrients)
* Make up the Blood Brain Barrier

Glioma

* Most common type of brain tumor
* Tumor of a glia cell

Action Potential

* Nerve impulse that travels along the axon

When a neuron is at rest it is…

* Positive outside and negative inside
* Polarized
* Excess of Na+ on the outside

Explain a nerve impulse

* Stimulus at dendrites triggers the opening of Na+ channels
* Na+ rushes in and depolarizes the membrane (inside is more positive than the outside at stimulated point)
* This then travels down the neuron and the impulse is complete

Saltatory Conduction

* Impulse jumps from one Node of Ranvier to the next
* Latin for jump
* Much faster than impulse in non-myelinated section

Synapse

The place where impulses are transmitted from one neuron to another