BIO 241 : Test 5 : Neuron, Central Nervous System

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central nervous system (CNS)

One of the two divisions of the nervous system. Includes the brain and the spinal cord.

peripheral nervous system (PNS)

One of the two divisions of the nervous system. The XXX is everything outside of the central nervous system. So all nervous system material that isn't in the brain and spinal cord . Has two sub-groups: afferent division and the efferent division

2 subdivisions of the PNS

afferent division and the efferent division

Afferent division

One of the two divisions of the Peripheral Nervous System. Takes messages IN to the central nervous system (primarily sensory input).

Efferent division

One of the two divisions of the Peripheral Nervous System. Takes messages OUT from the central nervous system to the peripheral nervous system. It's called the "motor division" since its info causes movement and is translated along motor units. Has two sub-divisions: somatic nervous system and the autonomic nervous system.

2 subdivisions of the efferent division:

somatic nervous system and the autonomic nervous system.

Somatic Nervous System

One of the two divisions of the efferent system. All of the nervous system under voluntary control. The system that stimulates the skeletal muscles (voluntary). Some involuntary responses are included (reflexes).

autonomic nervous system

One of the two divisions of the efferent system. All involuntary. Controls organs, smooth muscle, cardiac muscle, glands, adipose tissue. It has two subdivisions: sympathetic and parasympathetic.

function (neuron calculation - 3)

sensory (afferent) neurons
motor (efferent) neurons
interneuron (association) neuron

Sensory neuron (afferent system)

XXX system. Type of neuron?

Carry impulses IN from outside the CNS to the CNS. Made up of unipolar neurons. Action potential moves from the synaptic terminal (receptive endings), past the cell body to the central process and into the Central Nervous System.

motor neurons (efferent system)

XXX system. Type of neurons?

Take signals from the CNS to the organs that do the "work."

interneurons
(aka association neurons )

Are IN the CNS. Pass info from one neuron to another. There are a lot of these in the CNS. "go between"

Sensory (afferent) neuron (unipolar)

motor neuron

interneurons (association neuron)

neuron classification by structure

multipolar

Multipolar (nerve cell type)

One axon and multiple dendrites i.e. multiple processes comes out of their cell body. An example would be motor neurons in the efferent system and interneurons inside the CNS

Bipolar

Bi - two processes coming out of the cell body: one dendrite, one axon. Sensory neurons - afferent system. These are only found in the eye, ear and nose.

Unipolar

Uni - one process coming out of the cell body. It becomes an axon. Sensory neurons - afferent system. They relay info to the CNS. Their cell bodies are OUTSIDE the CNS.

Neurons

The main cells of the nervous system - they do the actual work of moving signals / messages. They don't divide (reproduce). They live a long time. They are constantly making proteins to repair themselves and are making neurotransmitters (i.e. "metabolically active")

4 kinds of glial cells (neuroglia) in CNS

ependymal cells, astrocytes, oligodendrocytes, microglia

2 types of glial cells found in the PNS

satellite cells and schwann cells

Ependymal cells

1 of 4 types of neuroglia. They help make and circulate cerebrospinal fluid which is key for protecting the brain and spinal cord. They line the brain and the spinal cord.

Astrocytes

1 of 4 types of neuroglia. Very diverse set of cells that scientists keep finding do more jobs. One of their jobs is keeping the blood-brain-barrier so substances in the blood do not get into the brain. Recycle neurotransmitters. Make scar tissue. Regulate concentrations of ions and gasses. Provide structural support.

Oligodendrocytes

1 of 4 types of neuroglia. "Myelinate CNS axons" (meaning they provide the myelin that protects the axons of CNS nerves. Also provide structure

Microglia

1 of 4 types of neuroglia. Macrophages (phagocytic) cells of the CNS. They keep it clean ! They remove debris, waste products and harmful substances.

Ependymal cells

Astrocytes

Oligodendrocytes

Neuron Cell Body

"Soma." Made up of the perikaryon (cytoplasm around the nucleus) and the nucleus. Along with the dendrites, it is the portion of the nerve cell that receives signals from other neurons. Usually the XXX is located in the CNS (brain or spinal cord) except for unipolar (sensory) neurons that have their cell bodies outside the CNS.

Chemically-gated Channels

"Ligand gated" channels. The presence of a chemical at the channel gate causes it to open. Ex: Acetylcholine causing the ion channels to open at the motor end plate.

Voltage-gated channels (mV triggers? define.)

Open in response to a change in electrical voltage level.
Ex: Na+ gate: At the normal resting potential of -70mV it stays closed. At -60mV it opens. At +30mV it is closed again.

Mechanically-gated channels

Open in response to pressure.
Ex: receptors in the ear that open in response to the pressure in the fluid of the inner ear.
Ex: touch receptors that open in response to mechanical pressure from touch.

Depolarization

The potential of the membrane becomes LESS negative. When XXX happens, the normal resting potential of -70mV becomes -60mV and much higher until it actually becomes positive. It must reach a threshold potential to start the domino effect of action potential.

hyperpolarization

The potential of the membrane becomes MORE negative (more than -70mV). This acts as an inhibitor. Since the threshold stays the same at approx. -60mV, any XXX forces a stronger signal to start the actual potential.

Chemically-gated Channels

Voltage-gated channel

Mechanically-gated channels

Depolarization

hyperpolarization

cell body (soma)

perikaryon

axon hillock

telodendria

synaptic terminal (exact name of neuron part used)

the secretory region on the telodendria

axon collateral

The axons of some neurons branch to form XXX that can be divided into a number of smaller branches called telodendria. Along these the bifurcated impulse travels simultaneously to signal more than one other cell.

chemical synapse

overall, this is a picture of what?

synaptic cleft

synaptic vesicles

myelin sheath

insulating sheath. Formed by Schwann cells (PNS) or oligodendrocytes (CNS)

neurilemma

outermost portion of Schwann cells with nucleus and bulk of cytoplasm

plasma membrane

edge of the cell. Resting membrane potential happens here.

nodes of Ranvier

gap in myelin sheath between individual myelinating cells

myelin sheath

neurilemma

Action Potential Phases: Na K (Na+, K+ channel activity: 5 steps) 1

Action Potential Phases: Na K (Na+, K+ channel activity: 5 steps) 2

Action Potential Phases: Na K (Na+, K+ channel activity: 5 steps) 3

Action Potential Phases: Na K (Na+, K+ channel activity: 5 steps) 4

Action Potential Phases: Na K (Na+, K+ channel activity: 5 steps) 5

overview of action potential phases

periosteal layer - dura mater

meningeal layer - dura mater

arachnoid mater

dura mater (tough mother)

arachnoid mater (spider mother)

pia mater (small mother)

How are the meninges different in the spinal cord?

only one meningeal layer

falx cerebri

falx cerebelli

tentorium cerebelli

tentorium cerebelli

falx cerebri

falx cerebelli

dural septa (1. falx cerebri 12-to-6-for-cerebrum. 2. falx cerebelli 12-to-6-on-cerebellum. 3. tentorium cerebelli tent-over-cerebellum)

nuclei (in the context of the brain)

gray matter

neuronal cell bodies (what makes up the XX XXX ?)

white matter

myelinated axons (what part of the brain and spinal cord is this?)

cerebellum (white and gray matter)

brain stem (white and gray matter)

spinal cord (white and gray)

commisural fibers (corpus callosum) (1 of 3 white matter fiber tracts)

projection fibers (1 of 3 white matter fiber tracts)

(type of fibers)

association fibers (1 of 3 white matter fiber tracts)

association fibers (1 of 3 white matter fiber tracts)

commissural fibers (corpus callosum) (1 of 3 white matter fiber tracts)

projection fibers (1 of 3 white matter fiber tracts)

decussation of pyramids

cerebrum (function)

cerebellum (function)

cerebrum (location)

diencephanlon (location)

cerebellum (location)

brain stem (location)

diencephalon (3 in group)

1. Thalamus
2. Hypothalamus
3. Epithalamus

brain stem (3 in group)

1. midbrain
2. pons
3. medulla oblongota

gyrus (definition)

ridge of tissue

sulcus (definition) (not a LARGE groove)

groove in tissue

fissure (definition)

a DEEP sulcus (i.e. a deep groove in the tissue)

gyrus (location)

sulcus (location)

fissure (location)

frontal lobe (location)

central sulcus (location)

parietal lobe (location)

lateral sulcus (location)

occipital lobe (location)

temporal lobe (location)

transverse cerebral fissure (location)

thalamus (function)

relay station for cerebral cortex

hypothalamus (function)

emotions, autonomic control, homeostasis, sleep, endocrine system regulation
(part of brain controlling)

midbrain (function)

visual & auditory reflexes, motor control (part of brain controlling these)

pons (function)

mostly nerve tracts between brain and spinal cord

medulla oblongata (function)

cardiovascular, respiratory regulation

primary somatosensory (greek soma = body. sensory = the senses) cortex and postcentral gyrus

primary motor cortex and precentral gyrus

left hemisphere

seems to be specialized in reading, writing,
speaking, logic, math, etc. Performs: analytical tasks, language-based skills (speaking, writing, reading, etc.) and logical decision making. People that are XXX
brain dominant have a tendency to be more scientific.

right hemisphere

seems to be more specialized in interpreting sensory information, determining spatial relationships, interpreting emotional responses, etc. Performs analysis of sensory
information and comprehending three-dimensional relationships. XXX brain dominant people are more artistic.

cerebral cortex

Primitive emotions are spontaneous (requiring no conscious thought). It is this characteristic that differentiates them from the higher emotional states (i.e., jealousy, humor, etc.) produced in the XXX . XXX is convoluted to increase its gray matter capacity. This surface is marked by fissures (deep valleys), sulci (shallow grooves), and gyri (ridges) which delineate it into various regions.

midbrain

The XXX lies approximately in the center of the brain. More specifically, the XXX is inferior to the thalamus. Because of its central location, the XXX connects the lower brain stem to brain's upper regions. Therefore, it contains motor tracts that
go to the cerebellum and sensory tracts that go to the thalamus. These tracts facilitate the XXX's function which is RELAYING information to the proper brain region.

pineal gland

This structure is thought to act like a biological clock by melatonin (controls wake and sleep patterns).

central sulcus

Separates the parietal lobe from the frontal lobe. The
frontal lobe is anterior to it (in front of it), while the parietal lobe is posterior (behind it).

longitudinal (cerebral) fissure

divides the cerebrum into two regions called cerebral hemispheres. These regions are connected by a bridgelike
structure called the corpus callosum.

closed (voltage-gated Na+ channel)

opened (voltage-gated Na+ channel)

inactivated (voltage-gated Na+ channel)

Resting Membrane Potential DEPENDS ON

K+ leakage channels and Na+ leakage channels ("membrane ion permeability").

ion conentration gradients

what MAINTAINS the RMP ?

Na+ / K+ membrane pump

is the plasma membrane more permeable to K+ or Na+ ?
K+ predominates inside the cells.
Na+ predominates outside the cell

[explain plasma membrane permeability]
XX predominates inside the cell.
XX predominates outside the cell.
Leakeage channels (passive transport) let K+ diffuse OUT of the cell. Membrane less permeable to Na+ but some do diffuse into the cell.

what does the Na+ / K+ pump do?

depolarization

hyperpolarization

hyperpolarization vs. depolarization

XXX INHIBITS.
If XXX crosses the threshold potential (and voltage-gated channels are nearby) it becomes the self-propogating action potential.

graded potential

action potential

repolarization

where on the neuron does the action potential occur?

conducting region: axon and telodendria.
(axon hillock is where the XXX starts!)

where on the neuron does the graded potential happen?

The cell bodies. The receptive region of the neuron (dendrite and cell body). You don't have voltage-gated channels on the cell bodies or dendrites so you CAN'T get an action potential there, so you get XXX here.

saltatory conduction

jump from node to node i.e. myelinated
FAST .. myelin sheath slows decay of membrane potential

continuous conduction
(there is no "nonsaltatory")

unmyelinated. Propagation relatively SLOW due to time for ion flow and channel opening

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