Exam 4 (Chapter 13 And 14)

Front 1

What makes up the organizational level of the nervous system?

Back 1

nerve cells (neurons)

neuroglia (support neurons function in various ways)

Front 2

Name the Subdivisions of the Nervous System?

Back 2

Central Nervous System (CNS) and Peripheral Nervous System (PNS)

Front 3

What makes up the central nervous system?

Back 3

Brain: enclosed by the cranium Spinal cord: protected by the vertebral column

Front 4

What makes up the Peripheral nervous system?

Back 4

Everything else except for the brain and spinal cord

Front 5

What's a nerve

Back 5

Nerves: bundle of nerve fibers (axons) wrapped in fibrous CT

Front 6

What's a ganglia?

Back 6

Ganglia: a knot like swellings in a nerve where the cell bodies of neurons are concentrated.

Front 7

What are the physiological properties of neurons

Back 7

Excitability: respond to environmental changes (stimuli)

Conductivity: neurons produce an electrical signal that is quickly conducted to other distant cells.

Excitability: respond to environmental changes (stimuli) Conductivity: neurons produce an electrical signal that is quickly conducted to other distant cells. Secretion: neurotransmitters cross the synapse to stimulate the next cell

Secretion: neurotransmitters cross the synapse to stimulate the next cell

Front 8

What are the three classes of neurons

Back 8

Sensory (afferent) neurons

Interneurons

Motor (efferent) neurons

Front 9

Name the structures of a neuron

Back 9

Soma (cell body): control center

Nissl Bodies: dark staining areas associated with rough ER.

Dendrites: branches off the soma that are the primary site for receiving signals from other neurons.

Axon Hillock: “little hill” or mound next to soma, gives rise to the axon.

Axon: (nerve fiber): has cytoplasm called axoplasm and a membrane called an axolemma.

Synaptic Knob: at the end of each branch of an axon, filled with synaptic vesicles.

Front 10

What are the 4 types of neurons

Back 10

Multipolar neurons: have one axon and multiple dendrites. This is the most common type and includes most neurons of the brain and spinal cord.

Bipolar neurons: one axon and one dendrite. (Olfactory cells, some in the retina, and inner ear).

Unipolar neurons: only a single process leading away from the soma. (carry sensory signals to the spinal cord)

Anaxonic neurons: very rare, have multiple dendrites but no axon. They communicate through their dendrites and do not produce action potentials. (Some in the brain, retina, and adrenal medulla).

Front 11

What are the 4 types of glial cells in the CNS

Back 11

Oligodendrocytes: Each process reaches out to a nerve fiber and spirals around it like electrical tape wrapped repeatedly around a wire. This wrapping, called the myelin sheath, insulates the nerve fiber from the extracellular fluid. For reasons explained later, it speeds up signal conduction in the nerve fiber.

Ependymal cells: resemble a cuboidal epithelium lining the internal cavities of the brain and spinal cord and produce cerebrospinal fluid (CSF), a liquid that bathes the CNS and fills its internal cavities.

Microglia: small macrophages that develop from white blood cells called monocytes. They wander through the CNS, constantly probe the tissue for cellular debris or other problems.

Astrocytes: the most abundant glial cells in the CNS and constitute over 90% of the tissue in some areas of the brain. They cover the entire brain surface and most nonsynaptic regions of the neurons in the gray matter of the CNS. They are named for their many-branched, somewhat star like shape. They have the most diverse functions of any glia:

supportive framework

perivascular feet, which contact the blood capillaries and stimulate them to form a tight seal called the blood–brain barrier

signal blood vessels to dilate or constrict with changing needs for oxygen and nutrients

convert blood glucose to lactate

secrete proteins called nerve growth factors

communicate electrically with neurons and may influence synaptic signaling between them

regulate the chemical composition of the tissue fluid

When neurons are damaged, astrocytes form hardened scar tissue and fill space formerly occupied by the neurons. This process is called astrocytosis or sclerosis

Front 12

What are the two types of glial cells in the PNS

Back 12

Schwann cells, or neurilemmocytes, envelop nerve fibers of the PNS. In most cases, a Schwann cell winds repeatedly around a nerve fiber and produces a myelin sheath similar to the one produced by oligodendrocytes in the CNS.

Satellite cells surround the neurosomas in ganglia of the PNS. They provide electrical insulation around the soma and regulate the chemical environment of the neurons

Front 13

What is a myelin sheath

Back 13

an insulating layer around a nerve fiber, somewhat like the rubber insulation on a wire. It is formed by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system.

Front 14

What is myleination?

Back 14

production of the myelin sheath

Front 15

Nodes of Ranvier

Back 15

the gaps between the myelin covered segments.

Front 16

What's an Internode

Back 16

the space from one gap to the next. The internodes are about 0.2 to 1.0 mm long.

Front 17

Whats an Initial Segment

Back 17

the short section of nerve fiber between the axon hillock and the first glial cell

Front 18

What is the Trigger zone

Back 18

axon hillock + initial segment.

Front 19

What two factors does the speed a nerve signal travels along a nerve fiber depends on

Back 19

Diameter of the fiber: Large fibers have more surface area & conduct signals more rapidly than small fibers.

Presence or absence of myelin: myelinated nerves are faster than non-myelinated