Exam 2 Tissue Biology Nerve Addition

What are the main components of the CNS and PNS?

CNS has the brain and spinal chord, the PNS has the ganglia, nerves, and receptors

What is classification of the PNS based on?

Whether it sends or receives messages to/from the PNS

What is the name of the PNS component that sends messages to the CNS?

The Afferent (sensory) NS, which has components with homogeneous structure and functional parts

What is the name of the PNS component that receives messages from the CNS?

The Efferent (motor) NS, which has components with distinct and diverse function and structure

How are the 2 types of the Efferent NS classified? What are the 2 types?

Based on tissue type innervated and composed of the Somatic and Autonomic NS

What tissue does the Somatic NS innervate?

Skeletal muscle, with voluntary actions

What tissue does the Autonomic NS innervate?

Cardiac muscle, smooth muscle, and certain glands, with involuntary (visceral) actions

How are the 2 types of the Autonomic NS classified? What are the 2 types?

Based on location and function, composed of the Sympathetic NS and Parasympathetic NS

What is the location and function of the Sympathetic NS

Located in the mid spinal chord to respond to stress

What is the location and function of the Paraympathetic NS

Located in the upper spinal chord, lower spinal chord, and the brain stem to carry out resting activities and regular body function

How does the Nervous System Communicate?

Using Action Potentials (APs) which are immediate and short lasting electrical messages

How are the 2 types of Nervous Tissue classified? What are the 2 types?

Classified based on function, with nerve cells and glial (supporting) cells

What are the 2 ways Nerve Cells can be classified?

Based on location relative to CNS and function, and based on the number of processes on the cell body

Based on location relative to the CNS and function, what are the 3 types of nerve cells?

Motor neurons, sensory neurons, and interneurons

What are Motor Neurons?

Part of the Efferent NS, and the CNS sends a signal so they give a response (effector structure)

What are Sensory Neurons?

Part of the Afferent NS, serve as the receptor structure to generate AP to send information to the CNS

What are Interneurons?

The most abundant neurons in the CNS (99.8%)

Based on the number of processes on the cell body, what are the 3 types of nerve cells?

Multipolar, bipolar, and pseudo-neuropolar

What are Multipolar Neurons?

Neurons with 1 axon and multiple dendrites, the most abundant type of neuron

What are Bipolar Neurons?

Neurons with 1 axon and 1 dendrite, rare type found in areas with special senses like the eye, ear, and nose

What are Pseudo-Neuropolar Neurons?

Neurons with 1 axon (that has 2 branches) and has no dendrites

Where are sensory neurons found?

Pseudo-unipolar neurons

Where are motor neurons found?

Multipolar neurons

Where are interneurons found?

Multipolar neurons

How do nerve cells communicate?

Using neurotransmitters like acetylcholine (Ach) and norepinephrine (NE)

What neurotransmitter does the somatic NS use?

Ach only

What neurotransmitter does the Autonomic NS use?

The sympathetic uses both NE and Ach, the parasympathetic uses Ach

What is the function of Glial Cells?

Support neuronal survival and activities. They surround neuronal cell bodies and processes of axons and dendrites in the CNS (except around large blood vessels and locations with low CT and collagen)

What are Oligodendrocytes?

A CNS glial cell that covers the axon in myelin, which electrically insulates and facilitates its rapid transmission. Predominant glial cell in white matter

What are some of the functions of Astrocytes?

Communicate via gap junctions, regulate ion concentration (especially K), support CNS neuron location and movement during development, fill tissue defects after CNS injury, and line meninges as a barrier of protoplasmic processes

How are astrocytes structured?

Have proximal processes which are reinforced with intermediate filaments made of GFAP and have terminal processes which can associate with more than 1 million synaptic sites

What are the 2 types of astrocytes?

Fibrous, which are found in white matter and have long delicate process and Protoplasmic, which are found in gray matter and have short processes

What are Ependymal Cells?

CNS Columnar or cuboidal cells that line fluid filled ventricles of the brain and central spinal cord, also facilitate movement and production of CSF

What are Microglia?

Small glial cells with mobile processes in gray and white matter, they originate from blood monocytes and are highly concentrated in certain CNS regions. Overall not as common as astrocytes or oligodendrocytes

What are the functions of Microglia

Their processes scan neuropil to remove damaged synapse and fibrous components. They are also a major immune defense for the CNS because they secrete immunoregulatory cytokines

What are Schwann Cells/Neurolemmocytes?

PNS counterparts of oligodendrocyte, they have trophic interactions with axons and form their myelin sheathes

What is a satellite cell

A glial cell that forms a thin layer around large neuronal bodies in PNS ganglia. They have a trophic/supportive effect which insulates, nourishes, and regulates neuron environment.

What is the Blood Brain Barrier (BBB)?

The barrier which controls the passage of substances from the blood to the CNS. It protects against bacteria, infection, and other exogenous substances. It also maintains ion concentration in interstitial fluid

What brain regions lack a BBB?

Hypothalamus, posterior pituitary, and choroid plexus

What aspect of the BBB envelops the basement membrane of most capillaries in the CNS?

The limiting layer of perivascular astrocytic feet

What/Where is the Choroid Plexus?

Regions where pia mater and ependymal cells touch (The roofs of the 3rd and 4th ventricle and parts of two lateral ventricle walls)

What is the Choroid Plexus?

A highly vascular folded tissue with ependymal-cell-covered-villi that contain pia mater. It produces CSF by removing water from blood

What is Neural Plasticity?

The reorganization of neuronal circuits and formation of new synapses

What are neurotrophins?

Family of proteins in neurons and glial cells that control reformation of processes

What are Neuronal STEM Cells?

Found in the adult CNS, often among ependymal cells, they supply new neurons, astrocytes, and oligodendrocytes

What is the Neural Crest?

Developmentally important cells that move to the PNS and other non neuronal cells

How large is a neuronal cell body?

About 150 micrometers

What is the axolemma?

Plasma membrane of the axon, containing axoplasm and concentrated ion channels

What are the contents of the axoplasm?

Mitochondria, microtubules, neurofilaments, and transport vesicles, but few polyribosomes or cisternae of rough ER

Where does the axon originate from?

The pyramid shaped axon hillock

What is anterograde transport?

Movement of organelles and macromolecules from the cell body to the synapse using kinesin

What is retrograde transport?

Other macromolecules moving from synapse to the cell body using dynein

What are collaterals?

Major branches off the axon, they influence other neuron activity and are found in interneurons and some motor neurons

What are terminal buttons?

The dilated/bulbous ends of small axon branches which release neurotransmitters