Unit 6 - Nervous System (nervous tissue)

What is the nervous system divided into?

1. Central Nervous System - brain and spinal cord
2. Peripheral Nervous System - other nerves

How is the nervous system organized?

1. Sensory (afferent) Division
2. Peripheral Nervous System
3. Motor (efferent) Division
4. Autonomic and Somatic Nervous System
5. Sympathetic and Parasympathetic Division

What is the Sensory (afferent) division?

Sends impulses from the senses to the Central Nervous System

What is the Peripheral Nervous System?

Comprised of all nerves not in the brain or spinal cord

What is the Motor (efferent) system?

Sends impulses from the Central Nervous System to muscles and glands

What is the Autonomic Nervous System?

Involuntary muscle control

What is the Somatic Nervous System?

Voluntary Nervous System

What is the Sympathetic Division?

* Part of the Autonomic Nervous System
* Initiated during emergency situations
* Fight or Flight

What is the Parasympathetic Division

* Reduces sympathetic response
* Resting functions like Digestion and Urination

What is the function of the nervous system?

It is the master control center for the body

What are the 3 things that the nervous system uses to do it’s job?

Sensory Input, Integration, and Response

What is Sensory Input?

It detects stimuli inside and outside of the body

What is Integration?

It processes and interprets information

What is Response in the NS?

It is the activation of muscles or glands

What is the function of Neurons?

* Conducts impulses around the body
* 10% of all Nerve Cells

What is the function of Neuroglia

* Support Cell, Insulate, and Protects the Neurons
* 90% of all Nerve Cells

What do all Neuron structures have?

Cell body with processes extending outwards

What does the Cell Body Contain?

Nucleus, cytoplasm, and organelles

How are Processes divided?

* Dendrites (impulses toward the body)
* Axon (impulses away from the body)
* Axon terminals release neurotransmitter
* Pass impulses to next neuron

What are the two ways neurons are classified?

1. Number of processes
2. Function

Neurons Classification (number of processes)

1. Unipolar (one processes)
2. Bipolar (two processes)
3. Multipolar (many processes)

Neuron Classification (function)

1. Afferent (carry towards CNS)
2. Efferent (carry away from the CNS)
3. Inter (connect the afferent to efferent)

What are axon’s wrapped in?

Myelin, which is a waxy insulation

How is myelin formed?

* Schwann cells wrap itself around the axon
* Like a scarf
* Outer layer is called the neurilemma
* Myelin wrappings are called Myelin Sheaths
* Made of Schwann Cells
* Gaps called node of Ranvier

What is the function of Astrocytes?

* Within the CNS
* Support and Anchor neurons to nearby capillaries

What is the function of Microglia?

* Within the CNS
* Provides immune response to the CNS

What is the function of Ependymal Cells?

* Within the CNS
* Secrete cerebrospinal fluids

What is the function of Oligodendrocytes?

* Within the CNS
* Myelin insulation for nerves in CNS

What is the function of Satellite Cells?

* Within the PNS
* Support and anchor neurons to PNS

What is the function of Schwann Cells?

* Within the PNS
* Myelin insulation for nerves in PNS

What is a nerve impulse?

An electrical signal that travels along the neuron

What is resting potential?

Intracellular Space = negative charge

Extracellular Space = positive charge

How is a nerve impulse passed along a neuron?

1. Neuron is stimulated by environment or another neuron
2. Sodium rushes into neuron and reverses the charge (depolarization and action potential)
3. Potassium diffuse out of the neuron (repolarization)
4. Sodium-potassium pump restores the ion concentration back to resting potential

What is a synapse?

Where two neurons meet

What is a synaptic cleft?

The space between two neurons

What events occur at a synapse?

1. Impulse stimulates vesicles to release neurotransmitters across the synaptic cleft
2. The neurotransmitters cause channels to open in the next neuron