Neuroscience Ch.1

Axon collateral:

a branch of axon that also allows terminals

Interneurons

are confined intermediary neurons.

Sensory neurons

are specialized to gather sensory information.

Reciprocal projection:

circuit dynamic where "forward" projections from one brain area to another are reciprocated by "backward" projections.

Motor nerves:

transmit information from the spinal cord and brain to muscles and glands.

Spanish anatomist Santiago Ramón y Cajal (1852-1934) was able to show that although neurons come very close together, they are not quite continuous with one another......

(1) neurons and other cells of the brain are structurally, metabolically, and functionally independent. (2) information is transmitted from neuron to neuron across tiny gaps, later named synapses.

Unipolar neurons

(also called monopolar neurons) A single extension branches in two directions, forming an input and output zone. Unipolar neurons transmit touch information from the body into the spinal cords.

Motor neurons:

(also called motoneurons) are large with long axons reaching out to synapse on muscles, causing muscular contractions. Motor neurons have the longest axons. It can be several feet long from your head down your back.

Oligodendrocytes:

A type of glial cell that form the myelin sheaths IN the brain and spinal cord.

Schwann cell:

A type of glial cell that forms myelin in the peripheral nervous system, OUTSIDE the brain and spinal cord.

Microglial Cells

Also called microglia. Extremely small motile glial cells that remove cellular debris from injured or dead cells.

What is the key feature that defines a neural circuit?

Its ability to carry out a specific function!

The postsynaptic density is a complex network of proteins that anchor _______ in the postsynaptic membrane

Neurotransmitter receptors

What two types of glial cells make up myelin in your nervous system? Which is in your PNS only and which is in your CNS?

Oligodendrocytes and Schwann cells. Schwann cells are PNS only, while oligodendrocytes are CNS only

The Neuron has Four Principal Divisions:

The input zone, the integration zone, the conduction zone, and the output zone

Topographic projection:

neighbouring neurons project to neighboring neurons in the target region.

Neurotransmitters

are specialized chemical signals released in response singles released in response to electrical activity in the axon terminal

The _______ nervous system is primarily connected to your internal organs and responsible for controlling their function

automatic nervous system

Most neurons feature a distinctive....

axon hillock

Divergence:

axon splits. They form into two or more and can act on a completely different population of neurons.

The peripheral nervous system:

consists of nerves. Collections of axons bundled together—that extend throughout the body. Includes everything outside the spinal cord and the brian.

The motor neurons in your spinal cord that project to the muscles in your arm also get input from sensory neurons in that arm as well as additional input from your cerebellum, motor cortex, and several brainstem structures. This is a real-world example of what type of neural circuit feature?

convergence

Sensory nerves

convey information from the body to the CNS. The various nerves of the body are divided into two distinct systems:

Neurotransmitter receptors

in the postsynaptic membrane are specialized proteins that react to neurotransmitter molecules.

Convergence:

neurons receive input from two or more other neurons.

Synaptic vesicles are small spheres in the presynaptic terminal that hold __________ in preparation for their release into the synapse.

neurotransmitters

Which of the following types of a glial cells can create myelin?

oligodendrocytes, schwann cells

What are four key points of microglial cells?

- They are tiny and mobile. - Remove debris from injured orf dead cells - Act as the brain's resident immune cells. - However, astrocytes and microglia may also worsen some problems, such as harmful swelling (edema) following brain injury, and degenerative processes like Alzheimer's disease and Parkinson's disease.

Three key facts about denderites:

1. At cellular extensions called dendrites, neurons receive information through synapses from other neurons. 2. Some neurons have dendrites that are elaborately branched, providing room for many synapses. 3. Dendrites may be covered in dendritic spines, small projections from the surface of the dendrite that add additional space for synapses.

Cranial Nerve:

A nerve that is connected directly to the brain. - We each have 12 pairs (left and right) of cranial nerves that arise from the brain and innervate the head, neck, and visceral organs directly, without ever joining the spinal cord. - Some carry motorinfo, sensory, sensations, or all combined.

Three key facts about neurons:

All of your organs and muscles are in communication with the nervous system. They are made up of highly specialized cells. Neurons are arranged into the circuits that underlie all forms of behavior, from simple reflexes to complex cognition. Your brain contains 80−90 billion of them

Glial cells:

Also called glia. They are nonneuronal brain cells that provide structural, nutritional, and other types of support to the brain. They also help process information.

Neurons:

Also called nerve cell. It is the basic unit of the nervous system. They are composed of receptive extensions called dendrites, an integrating cell body, a conducting axon, and a transmitting axon terminal.

Spinal Nerves:

Also called somatic nerve. A nerve that emerges from the spinal cord.

Dendrites:

An extension of the cell body that receives information from other neurons. Functionally, the dendrites are the input zone of the neuron.

The neural system extends throughout the body

As a neuron number increases, neuronal connections must increase exponentially (or become less dense) The average brian has about 86 billion neurons

Glia: perform a wide range of specialised functions aimed at protecting neurons and assisting in transmission to neuron cells.

Assist in neuronal activity by providing raw materials, chemical signals and structure. They also assist in information processing Provide energy, regulate the environment, respond to damage. Glia is a greek ford for glue. Thought to hold the neural system together at first.

Neurons in the area T send axons that split and project to areas C, S, and H. This is an example of what type of neural circuit dynamic?

Divergance

What is NOT an accurate statement about the structure and function of a synapse?

Synaptic vesicles are anchored at the synapse by a huge protein complex known as the postsynaptic density (PSD)

Synapses:

The cellular location at which information is transmitted from a neuron to another cell.

Sensory neuron:

carries signals from the spindle to the CNS

Output Zone:

The part of a neuron at which the cell sends information to another cell. This zone usually corresponds to the axon terminals. - Specialized swellings at the ends of the axon, called axon terminals (or synaptic boutons), transmit the neuron's signals across synapses to other cells. - The tremendous diversity of sizes, and shapes, and functions of neurons reflects their differing processing functions.

Integration zone:

The part of a neuron that initiates neural electrical activity. This zone usually corresponds to the neuron's cell body. In addition to receiving additional synaptic inputs, the neuron's cell body (or soma, plural somata) integrates (combines) the information that has been received to determine whether or not to send a signal of its own.

The Input Zone:

The part of a neuron that receives information from other neurons or from specialized sensory structures. This zone usually corresponds to the cell's dendrites.

Conduction zone:

The part of a neuron—typically the axon—over which the action potential is actively propagated. A single extension, the axon (or nerve fiber), carries the neuron's own electrical signals away from the cell body. Toward its end, the axon may split into multiple branches called axon collaterals.

Axonal transport:

The transportation of materials from the neuronal cell body toward the axon terminals, and from the axon terminals back toward the cell body. If the cell makes proteins or molecules it can take them to the terminals. Ex. a train full of supplies.

Astrocytes: A star-shaped glial cell with numerous processes (extensions) that run in all directions. Stretch around between neurons and sometimes blood vessels.

They Maintain extracellular environment to allow for neural firing Transport nutrients and oxygen between vessels and neurons Astrocyte "feet" help form the blood brian barrier

Axon hillock:

a cone shaped area of the cell body that gives rise to the axon. Converts input input into electrical signals that travel down the axon and innervate target calls

Postsynaptic density

a huge protein complex that anchors recepters to a place in the synapse.

Rene Descartes proposed that humans gave a material body governed through an interface in the brain (the pineal gland) by a nonmaterial soul. The notion is known as:

dualism

Myelin

gives an axon the appearance of a string of elongated slender beads. Myelin doesn't cover everything on the axon.

Bipolar neurons

have ONE dendrite at one end of the cell and a single axon at the other end. Common with vision.

Multipolar neurons

have many dendrites and ONE axon. They are the most common type of neuron.

Axon initial segment:

immediately adjacent to the hillock, responsible for initiating action potentials

The autonomic nervous system

is the brain's main system for controlling the organs of the body.

Neural circuit

is the population of neurons interconnected by synapses to carry out specific functions when activated. Ex. Doctor hits your knee with the baby hammer thing

At each synapse, information is transmitted from an axon terminal of a presynaptic neuron (transmitting side) to the receptive surface of a......

postsynaptic neuron (receiving side and responds to neurotransmitters).

What is NOT a glial cell?

progenitor cells

Synaptic vesicle

small spheres in presynaptic axon terminals that contain neurotransmitter

The parasympathetic nervous system generally helps the body to relax, recuperate, and prepare for future action—

sometimes called the rest-and-digest response.

Muscle spindle:

specialised ending connected to sensory neuron

The neuronal cell body and dendrites receive information across....

synapses

Interneurons:

which analyze information gathered from one set of neurons and communicate with others. They have tiny axons

The autonomic nervous system:

which consists of nerves that connect primarily to the viscera (internal organs).

The somatic nervous system:

which consists of nerves that interconnect the brain and the major muscles and sensory systems of the body

Axons of the sympathetic nervous system exit from the middle parts of the spinal cord, travel a short distance, and then innervate the sympathetic ganglia (small clusters of neurons found outside the CNS),

which run in two chains along the spinal column, one on each side. It can also be referred to as the "sympathetic chain". Fight or flight response.