L9 - Nervous System and Neural Tissue

The nervous system has three anatomical components:

• Central Nervous System

• Peripheral Nervous System

• Enteric Nervous System

The central nervous system consists of:

• _________: has more __________

• _________: mostly connects with ____

• Brain: neurons

• Spinal cord: PNS

Most nervous tissue is found within:

The CNS

The PNS consists of:

• _______: groups of ________

• ___________: interact with _________

• Ganglia: cell bodies

• Peripheral Nerves: non-neuronal cells/organs

Enteric Nervous System is made of ______ cells in the ___________. Communication is by:

neural cells - digestive tract - to the CNS via the PNS

Nervous tissue has two classes of cells:

• Neurons

• Neuroglia

Neurites are projections from the cell body(_______) such as:

soma - axon - dendrite

Neuroglia are _____ cells that _____ and ______ neurons. They make up ______ of nervous tissue.

glial - protect - maintain

Within the CNS, the glial cells that are present are:

• ___________

• ___________

• ___________

• ___________

• Astrocytes

• Ependymal Cells

• Microglia

• Oligodendrocytes

Ependymal cells are a type of _______ tissue and are found within the ___ and their function is to:

• epithelial - CNS

• Line ventricles and secrete CSF

Oligodendrocytes are found in the ____ and their function is to:

• CNS

• Produce myelin sheath (fats + protein) around axons

Astrocytes are found within the _____ and their function is to maintain homeostasis in the _________ environment:

• Regulate __________, __________, and __________ concentrations.

• Recycle and buffer ___________

• Regulate ________ flow

CNS - extracellular

• ion - nutrients - oxygen

• Neurotransmitters

• CSF

Microglia are within the _____ and are _____ cells that perform ______ functions.

CNS - WBC - immune

The glial cells within the PNS are:

• _________: function similar to ___________

• _________: function similar to ___________

• Schwann cells: oligodendrocytes

• Satellite Cells: astrocytes

Series of cavities within the CNS:

Ventricles

The four compartments of a neuronal cell:

• Axon

• Axon terminal

• Cell body/Soma

• Dendrites

Receives input from other cells

Dendrites

Recieves input and produces proteins

Cell Body / Soma

Transports action potentials

Axon

Converts action potentials into chemical signals

Axon terminals

Within a neuron, information flow is from _________ → _________ → _________

dendrite → axon → axon terminal

Between neurons, information flow is from _________ → _________ → _________

sensory neuron → interneuron → motor neuron

White matter is made of _________ _____ which are found within the perimeters of the _______ and around the core of the ___________

myelinated axons - brain - spinal cord

Grey matter consists of:

• _________ and __________ cells

• ___________, ___________, __________ on neurons

• Astrocytes & Microglial cells

• Axon terminals, dendrites, and cell bodies

Electrical signals are ________________ of the plasma membrane that occur _______ neurons

brief changes of transmembrane potential - within

Chemical signals are ________________ in synapses that occur _______ neurons

the release of neurotransmitters - between

Neural pathways mediate both/either involuntary and voluntary

both

Two key types of spinal reflexes are the _________and ________ reflexes.

Withdrawal - stretch/jerk

The stretch reflex is a _________ reflex including ____(multi)____ neurons

monosynaptic - motor - sensory

The withdrawal reflex is a _________ reflex including ____(multi)____ neurons

multisynaptic - motor, sensory, inter

Neurons can be classified by their organ systems:

• somatic

• Visceral/autonomic

Which neuron group includes the following:

• Motor Neurons: Skeletal Muscle

• Sensory Neurons: Integument and Skeletomuscular System

Somatic Nervous System (not ALWAYS considered voluntary)

Which neuron group includes the following:

• Motor Neurons: non-skeletal muscle

• Sensory Neurons: Smooth/cardiac muscle, glands, adipose tissue

Visceral/autonomic nervous system

• Afferent axons such as the ones on __________carry information to/from the spinal cord

• Efferent axons such as the ones on __________ carry information to/from the spinal cord.

• sensory neurons - to

• motor neurons - away

The spinal cord is organized into ___ pairs __________.

In adults, inferior to ____ is only ______ and no _________.

31 - topographically

L1 - nerves - spinal cord tissue

Each spinal cord segment processes information from different regions in the body:

• Cervical: ____________

• Thoracic: ____________

• Lumbar: ____________

• Sacral: ____________

• Upper limbs

• Trunk

• Lower limb

• lower limb / ano-genital region

The ______________ region(s) of the spinal cord have more gray matter because:

Cervical & Lumbar: there are more muscles in the limbs

A simple spinal reflex circuit comes through the ______ gray matter and leaves through the ________ gray matter.

dorsal - ventral

Dorsal white matter projects to/from the brain _________ information.

Lateral white matter projects to/from the brain for _______________.

to - sensory

from - voluntary motor control

All neurons are post-mitotic meaning:

Cannot return to the cell cycle, once a neuron dies, it cannot be replaced

Neurons can die from:

• Trauma to the ____________ or _____________

• Excitotoxicity: _____________

• cell body - axon

• excessive excitatory synaptic activity

Axons in the _______ may repair and regrow with the help of _________.

PNS - schwann cells (local glia)

Apoptosis: (clue: mode of death)

A neuron dies due to the lack of active axon terminals

In the ______, axons cannot repair because of the presence of ___________.

CNS - Astrocytes