Unit 7 - Nervous System

Nervous System

Fast channel of communication center of nerves.

1. Receiving Sensory Inputs

2. Integrating Information

3. Controlling Muscles and Glands

4. Maintaining Homeostasis

5. Establish and Maintain Mental Activity

Major Functions of the Nervous Syatem?

1. Central Nervous System

2. Peripheral Nervous System

Main Divisions of Nervous System?

Central Nervous System

Consist of brain and spinal cord.

Peripheral Nervous System

Subdivided into motor division and sensory division.

Peripheral Nervous System

Nerves outside the brain and spinal cord.

Motor Division

Subdivided based on effector being activated by action potentials.

1. Somatic Nervous System

2. Autonomic Nervous System

3. Enteric Nervous System

Motor Division of Peripheral Nervous System?

Somatic Nervous System

Conscious, Voluntary motor responses.

Somatic Nervous System

Central Nervous System to skeletal muscles.

Autonomic Nervous System

Involuntary body movement.

Autonomic Nervous System

Central Nervous System to cardiac, smooth muscles, and glands.

1. Sympathetic Nervous System

2. Parasympathetic Nervous System

Subdivision of Autonomic Nervous System?

Sympathetic Nervous System

Fight or Flight system.

Parasympathetic

Rest and Digest system.

Enteric Nervous System

Sensory and motor neurons in gastrointestinal tract.

Neuron

Accepts stimuli, sends action potentials, and transmit signals to other neurons or effector glands.

1. Cell Body

2. Dendrites

3. Axons

Parts of the Neurons?

Cell Body

Contains nucleus, primary site of protein synthesis.

Dendrites

Receive information from cell body, shorter.

Axons

Sends information away from cell body, longer.

Nerve

Multiple axons surrounded by various layer, these are bundled axons outside the brain and spinal cord.

12 Pairs

How many pairs are Cranial Nerves?

31 Pairs

How many pairs are Spinal Nerves?

Plexus

Bundle of nerves outside the brain and spinal cord.

1. Endoneurium

2. Perineurium

3. Epineurium

Layers of Connective Tissue surrounding the nerves?

Endoneurium

Surrounds each axon or nerve fiber.

Perineurium

Heavier connective tissues that surrounds nerve fascicles.

Epineurium

Surrounds the whole nerve, dense connective tissue that binds nerve fascicles together to form a nerve.

1. Mutipolar Neuron

2. Bipolar Neuron

3. Pseudo-unipolar Neuron

Structural Classification of Neurons?

Multipolar Neuron

Many dendrites with one axon, such as interneurons and motor neurons.

Bipolar Neuron

One dendrites and one axon, components of sensory organs.

Pseudo-unipolar Neuron

Single process from cell body and subdivided with an axon that splits sensory and CNS, most sensory neurons are this kind.

Glial Cells/Neuroglia

Supporting cell that enhances neuron function.

Glial Cells/Neuroglia

Maintain neuron within nervous tissue.

1. Astrocytes

2. Ependymal Cells

3. Microglia

4. Oligodendrocytes

Glial Cells of CNS?

Astrocytes

Provide structural support for neurons and blood vessels. Form blood-brain barrier function, inhibit other signals from nearby neurons.

Blood-Brain Barrier (BBB)

Semi-permeable protective layer of brain.

Ependymal Cells

Produce cerebrospinal fluid.

Microglia

Immune defense cells that phagocytize.

Oligodendrocytes

Provide insulation and cover axons, produce myelin sheath.

Myelin Sheath

Covers axons, not continuous.

Node of Ranvier

Gaps in myelin sheath.

1. Schwann Cells

2. Satellite Cells

Glial Cells in PNS?

Schwann Cells

Enclose unmyelinated axons of PNS

Satellite Cells

Surrounds cell bodies in sensory and autonomic ganglia, encompass work, support neurons, nutrient, protection from heavy metal.

Neurilemma

Outermost Layer of Schwann Cells.

1. Gray Matter

2. White Matter

Types of Tissues?

Gray Matter

Group of neurons cell bodies and their dendrites, minimal sheath.

Cortex

In CNS, if nuclei is in deeper areas, then who's in the brain surface?

Nuclei

In CNS, if cortex is in the brain surface, then who's in deeper areas?

Ganglia

In PNS, swelling cell bodies are called?

White Matter

Bundles of parallel axons with myelin sheath.

1. Action Potential

2. Membrane Potential

Electrical Signals.

Action Potential

Electrical signals produced by the nervous system.

Membrane Potential

Measure of electrical properties by the nervous system.

1. Leak or Nongated Channels

2. Gated Channels

Types of Channel?

Leak or Nongated Channels

Flow of ions, always open, and ions moves down their gradient.

Gated Channels

Measure of electrical properties by the nervous system.

1. Sodium

2. Potassium

Chemical Difference of Cell Membrane?

Sodium

Outside, positive proteins.

Potassium

Inside, negative proteins.

Stage 1: Generation of Action Potential

Stage 2: Action Potential Conduction

Stage 3: Synapse

Nervous Communication Stages?

Stage 1: Generating of Action Potential

Membrane at rest, voltage-gated channels close, open with stimuli.

Depolarization

Resting membrane potential is -70mV and rises to 20mV.

Repolarization

Resting membrane potential is 20mV and decreases to -70mV.

Stage 2: Action Potential Conduction

Once action potential is generated, it is propagated along the cell membrane by Continuous and Saltatory Conduction.

1. Continuous Conduction

2. Saltatory Conduction

Action Potential Conduction?

Continuous Conduction

Slow conduct of action potential in unmyelinated aons by activating local currents in adjacent parts of cell membrane.

Saltatory Conduction

Rapid transmission in myelinated axons through node of ranvier to the presynaptic terminal.

Stage 3: Synapse

Also known as neuromuscular junction. Neuron to neuron, neuron to muscle, neuron to cells of effector organs, pass action potentials.

1. Presynaptic Terminal

2. Postsynaptic Terminal

3. Synaptic Cleft

Major Parts of Stage 3: Synapse.

Presynaptic Terminal

Ends of axon.

Postsynaptic Terminal

Membrane of dendrite or effector cells.

Synaptic Cleft

Space in between Presynaptic and Postsynaptic Terminal.

Synaptic Vesicles

Contain neurotransmitters.

1. Reach action potential to presynaptic terminal

2. Opening of calcium-gated channels

Conditions to Release Neurotransmitters?

Neurotransmitters

Chemical substances stored in synaptic vesicles.

1. Cholinergenic

2. Biogenic Amines

3. Amino Acids

4. Peptide

Types of Neurotransmitters?

Cholinergenic

Contains Acetylcholine.

Acetylcholine

Excitatory at neuromuscular junctions (muscle contracts), can be both inhibitory and excitatory in autonomic nervous system.

1. Norepinephrine

2. Dopamine

3. Serotonin

Biogenic Amines?

Norepinephrine

Excitatory effect at some CNS amd ANS synapses.

Dopamine

Excitatory at CNS, inhibitory at ANS, rush of adrenaline.

Serotonin

Inhibitory effect at CNS synapse.

Amino Acids

Purely inhibitory.

Gamma-aminobutyric Acid

Inhibitory effect at CNS.

Peptide

Contains endorphin.

Endorphin

Blocks pain pathways, endogenous morphine.

1. Converging Pathways

2. Diverging Pathways

3. Local Summation

4. Temporal Summation

Neuronal Pathways.

Converging Pathways

2 or more multipolar postsynaptic neurons, have many neurons synapsing with a few neurons.

Diverging Pathways

Have few neurons synapsing with many neurons.

Local Summation

Multiple local current potential synapse into 1 postsynaptic neurons.

Temporal Summation

Local potential overlaps entire and stronger duct to overlapping.

1. Cerebrum

2. Diancephalon

3. Cerebellum

4. Brain Stem

Major Regions of Brain?

Cerebrum

Longest, subdivided into left and right hemispheres. Seperate hemispheres through longitudinal tissue.

1. Gyri

2. Sulci

3. Corpus Callosum

Parts of Cerebrum?

Gyri

Folds on surface that increase surface area at cerebral cortex.

Sulci

Intervening grooves or tumors on the surface, small hills.

Corpus Callosum

White matter, connecting cerebral hemispheres.