BSC Chapter 13 Nervous and Endocrine system

What are the two anatomical subdivisions of the nervous system?

The central and peripheral nervous systems tend

Define the central nervous system

The subdivision of the nervous system comprised of the brain and spinal cord

Define the peripheral nervous system

The subdivision of the nervous system that is comprised of the remainder of the nervous system and serves for input two and output from the CNS/central nervous system system

Nerve

A bundle of nerve fibers wrapped in fibrous connective tissue, often emerging from the CNS through foreman of the skull and vertebral column

Ganglion

and not like swelling in a nerve where the cell bodies of neurons are concentrated

What is the peripheral nervous system (PNS) Divided into

The sensory division and motor division

What divisions do the sensory and motor division of the peripheral nervous system (PNS) contain

both are split into the visceral and somatic versions of each

Receptors

Cells and organs that detect Stimuli

Defined the sensory division of the peripheral nervous system system

Carries sensory signals by way of afferent nerve fibers from sensory receptors to the CNS

Defined the visceral sensory division

Carries signals, mainly from the viscera of the thoracic and abdominal cavities such as the heart, lungs stomach and urinary bladder

Define the somatic sensory division

Carry signals from receptors in the skin, muscles, bones, and joints

Define the motor division of the peripheral nervous system system

Carries motor signals by way of effort, nerve fibers from the CNS to effectors

Effectors

Cells and organs that carry out the bodies responses mainly gland in muscle cells

T/F: The visceral motor division is voluntary

False

Defined the visceral motor division Of the motor division of the peripheral nervous system

Carries signals to glands, cardiac muscle and smooth muscle. The system operates at an unconscious level where we need no voluntary action to control.

What divisions make up the visceral motor division (the automatic nervous system)

The sympathetic and parasympathetic divisions

Define the sympathetic division of the automatic nervous system

A division that tends to prepare the body for action for example by accelerating the heartbeat and increasing respiratory airflow, but it inhibits digestion

Defined the parasympathetic division of the automatic nervous system system

A division that tends to adapt the body to a state of rest, reducing the heart rate and respiratory airflow, for example but stimulating digestion

Defined the somatic motor division of the Motor division of the peripheral nervous system

Carry signals to the skeletal muscle muscles this output produces muscular contractions that are under voluntary control, as well as involuntary muscle contractions called somatic reflexes

What are the three physiological properties of all nerve cells

Excitability, conductivity and secretion

Explain excitability in a nerve cell

The ability to respond to environmental changes called stimuli

Explain conductivity in a nerve cell

The ability for neurons to produce electrical signals that reach other cells in response to stimuli

Explain secretion in nerve cells

The ability of a nerve cell to produce, and secrete neurotransmitters used to stimulate the next nerve cell

What are the three general classes of neurons?

Sensory neurons, intern, neurons, and motor neurons

Define a sensory neuron

A specialized neuron that is sensitive to stimuli and detect things such as light, heat, pressure and chemicals and transmits That information about them to the CNS

Define interneurons

A specialized neuron only found in the CNS that receive signals from many other neurons and carry out the integrative function of the nervous system, like processing storing and retrieving information and the decision-making

Define motor neurons

A specialized nerve cell that has the ability to transmit electrical signals from the brain and spinal cord two muscle muscles and glands to control movement in bodily function

Define the Soma of a neuron

The central bulb is part of a neuron that contains the nucleus and controls of the cell cells metabolic activities

Define the dendrites of a neuron

Thick processes that extend in branch from the Soma of the neuron that are the primary receiving signal sites from other neurons

T/F: The more dendrites a neuron has the more information it can recieves from other cells to decide its reaction

True

Define the axon of a nerve cell

The “sending” side of the nerve cell usually elongated and un-branching until the end of its length

What is terminal arborization

An extensive complex of fine branches, extending at the end of the axon

What is a synaptic knob

The end of an axon that contains a synapse junction connect, connecting it to a muscle cell gland, cell or another neuron

What are neurofibril’s in a neuron?

The neurons cytoskeleton consisting of a dense mesh of microtubules that compartmentalize the rough ER Into dark staining regions, called Nile bodies unique to neurons

T/F: all neurons built the same

False

Define multipolar neurons

The most common type of neuron containing one axon and two or more, but usually many dendrites, often found in the brain and spinal cord.

Define a bipolar neuron

Roads that have one axon and one dendrite, often sensory neurons

Define unipolar neurons

A type of neuron that has one fused axon bypassing the soma and acts as a messenger neuron to most receptive neurons

Define an anaxonic neurons

A neuron with no axon and multiple dendrites that communicate to each other through their dendrites and produce no action potential, mostly found in the brain and Retina

Name all types of glial cells

oligodendrocytes, astrocytes, ependymal cells, microglia, Schwann cells, and Satellite cells

Glial cells

Cells found around neurons that protect and support that

Define oligodendrocytes

Boldest bodied glial cells with arm like processes that wrap around nerve fibers and spiral around them spiral wrapping known as the myelin sheath speeding up conduction

Define astrocytes

Glial cells that are most abundant in functionally, diverse in the CNS and constitute over 90% of the tissue in some areas of the brain that help form a supportive framework for the nervous tissue using extensions called perivascular feet that connect nerve fibers to blood capillaries in tight junctions. They also nourish the neurons as well as promote synapse growth.

Define ependymal cells

Glial cells that resemble cuboidal epithelium lining the internal cavities of the brain and spinal cord that produce cerebrospinal fluid

Define microglia

Small macrophages that developed from white blood cells called monocytes introduction that phagocytize dead nervous tissue

Define Schwann cells

Glial cells that develop nerve fibers in the PNS forming a sleeve called the nuerilemma around them similar to myelin sheaths found in the CNS. These cells can assist in nerve repair to damaged nerve cells

What is a myelin sheath

An insulating layer around a nerve fiber supporting faster conduction made by oligodendracytes in the CNS and Schwann cells in the PNS

What are the gaps in between myelin sheaths called on nerve cells

Nods of Ranvier

What are the myelin covered segments of a nerve cell called

Internodes

T/F: the axon hillock and first myelin sheath are known as the trigger zone of the nerve cell

True

What gives the myelin sheath of the PNS the ability to repair damaged nerve cells.

The outer layers of the sheath only found in the PNS called the endonerurim which is external to the neurilemma outer layer

Define non-myelinating Schwann Cells

A Schwann cell that can hold multiple axons in shallow grooves of its external surface that are non-myelinated

Define action potential in nerve cells

The rapid and sudden voltage change of ions diffusing across the plasma membrane of the axon of a neuron similar to a burning fuse Igniting the fuse further

Define a nerve signal

A wave of action potential traveling down the axon

What speed do nerve signals travel in umyelinated axons

0.5 to 2 m/ses

What speed do myelinated axons send nerve signals

3 to 15m/sec

Why do myelinated axons send nerve signals faster than their non-myelinated counterparts

because ion diffusion can occur faster in the nodes of Ranvier pushing the signal faster through the axon

Synapse

The meeting point between a neuron and any other cell known as the decision-making device

Define a pre-synaptic neuron

The neuron at a synapse that is producing the signal

Define a postsynaptic neuron

The neuron at a synapse that is receiving the signal

Name the three types of synapse between neurons

Axodenritic synapse, cosmetic synapse, and a axoaxonix synapse

Define and axodendritic synapse

The synapse junction when the presynaptic nerve connects to the dendrite of the post synthetic nerve

Define an axosomatic synapse

A synapse junction where they pre-synaptic neuron connects to the Soma of the postsynaptic neuron

Define an axoaxonix synapse

A type of synaptic junction where the presynaptic neuron connects to the axon of the postsynaptic neuron

T/F: Chemical nerve signals can go in multiple directions

False - only one direction

Define the “deciding” factor of a neuron in a chemical synapse.

The process of which a neuron would activate or stay in active based on the Exide or inhibitory input from its pre-synaptic neurotransmitter diffusion, stimulating its receptors

Chemical synapse

A junction at which the pre-synaptic neuron releases a neurotransmitter to stimulate the postsynaptic cell

Synaptic knob

The Area of the terminal branch of the pre-synaptic nerve that ends and swelling and a synapse

Synaptic cleft

The tiny gap between the presynaptic neuron and the postsynaptic neuron

Synaptic vesicles

Membrane bound, organelles that hold neurotransmitters created by the neuron and held in the synaptic knob ready to be released to perform a Neuro signal

T/F: postsynaptic Neurotransmitter receptors can be folded along the membrane to create more room for more receptors

True

Electrical synapse

A type of neurological synapse that joins cells together by gap junctions that allows ions to diffuse directly from one cell to the next commonly used for quick transmission signals

Neuronal pools

The grouping of neurons specialized in one particular function of the body

Neuronal circuits

The interconnection of neurons organized to perform a certain function

Name the four types of neuronal circuits

Diverging circuit, converging, circuit, reverberating circuit and parallel after discharge circuit

Define a diverging neuronal circuit

A circuit based off of the signal of one neuron branching to more neurons which branch to more, Creating a snowball effect

Define a converging neuronal circuit

The opposite of a diverging circuit where multiple neurons funnel it’s decision-making process from multiple to one neuron

Define a reverberating neuronal circuit

A linear circuit that at a further neuron branches back to the beginning of the circuit in a circular pattern, sending the signal back to the beginning and forward branching off

Define a parallel after discharge neuronal circuit

A type of circuit where a neuron discharges, a signal to different chains of neurons, all reconvening back on to one neuron this often is considered to play in neurological function that can occur occur well after the initial signal is given

When does the first trace of the central nervous system begin to form in unborn fetuses

Week 3

Neurualation

The process of the development of the nervous system in fetus

Neural plate

The beginning of the central nervous system in the fetus

Neural groove

The forming of The neural tube in the fetus

neural fold

Two sides of the folding neural plate during 20 days of pregnancy within the fetus

Neural tube

The predecessor to the spinal cord in a fetus

Neural crest

The predecessor to the sympathetic neurons ganglia Schwan cells and adrenal medulla and the fetus

What are the three “brains” that form in early development of the fetus

The forebrain, midbrain, and hindbrain

What five secondary vesicles does the neural tube of a fetus subdivide into at the fifth week

Telencephalon, diencephalon, mesencephalon, metencephalon, and the mylencephalon