Compendium 8 How do we control ourselves?

Functions of the nervous system include (select five)

Functions of the nervous system include maintaining homeostasis

The Two main structural divisions of the nervous system are:

The Central Nervous System (CNS) comprises of the Brain and spinal cord

The Central Nervous System (CNS) comprises of the spinal nerves, cranial and sensory nerves

The Peripheral Nervous System (PNS) comprises of the spinal nerves sensory and cranial nerves

The Peripheral Nervous System (PNS) comprises of the brain and spinal cord

The divisions of the Peripheral Nervous System comprise of:

The Central Nervous System comprises of the Enteric Nervous System

The division of the Autonomic nervous system comprise of Motor (efferent) and Sensory (afferent)

Terminology: • [blank_start]Neuron (nerve cell)[blank_end]: basic structural unit of the nervous system • [blank_start]Axon[blank_end]: nerve fiber • [blank_start]Nerve[blank_end]: bundle of axons (or nerve fibers) and their sheaths (outer covering) • [blank_start]Sensory receptors[blank_end]: separate specialised cells which detect temperature, pain, touch, pressure, light, sound, odour and other stimuli • [blank_start]Action potential[blank_end]: electrical signal • [blank_start]Effector organ or effector cell[blank_end]: the organ, tissue or cell in which an effect or an action takes place

An Axon is a nerve fiber

Effector organ or effector cell is an organ, tissue or cell in which an effect or an action takes place

Axon: the organ, tissue or cell in which an effect or an action takes place

Neurons (nerve cells) are separate specialized cells which detect temperature, pain, touch, pressure, light, sound, odour and other stimuli

• [blank_start]Ganglion[blank_end]: collection of cell bodies located outside the CNS • [blank_start]Plexus[blank_end]: extensive network of axons or cell bodies

Ganglion: collection of cell bodies located outside the CNS

Plexus: extensive network of axons or cell bodies

Ganglion: extensive network of axons or cell bodies

Plexus: collection of cell bodies located outside the CNS

What is a Synapse?

Select the correct subdivision this information pertains to: • Involuntary and under subconscious control • Action potentials in the motor neurons travel from the CNS to smooth or cardiac muscle, or glands • Two-neuron system • Cell bodies of the neurons are located in the CNS and autonomic ganglion

Autonomic subdivision: • Involuntary and under subconscious control • Action potentials in the motor neurons travel from the CNS to smooth or cardiac muscle, or glands • Two-neuron system • Cell bodies of the neurons are located in the CNS and autonomic ganglion

Somatic subdivision: • Involuntary and under subconscious control • Action potentials in the motor neurons travel from the CNS to smooth or cardiac muscle, or glands • Two-neuron system • Cell bodies of the neurons are located in the CNS and autonomic ganglion

Which subdivision does this information pertain to? • Voluntary and under conscious control • Action potentials in the motor neurons travel from the CNS to skeletal muscles • Single neuron system • Cell bodies are located in the CNS

In the Somatic subdivision, action potentials in the motor neurons travel from the CNS to skeletal muscles

In the Somatic subdivision, cell bodies are located in the CNS

Single neuron system is part of the

The two-neuron system is part of the:

Somatic subdivision: Voluntary and under conscious control

Autonomic subdivision: Voluntary and under conscious control

Autonomic subdivision: Involuntary and under subconscious control

Somatic subdivision: Involuntary and under subconscious control

Autonomic subdivision: Cell bodies of the neurons are located in the CNS and autonomic ganglion

The enteric nervous system (ENS) or intrinsic nervous system is one of the main divisions of the autonomic nervous system (ANS) and consists of a mesh-like system of neurons that governs the function of the gastrointestinal tract.

The somatic nervous system (SNS) or intrinsic nervous system is one of the main divisions of the autonomic nervous system (ANS) and consists of a mesh-like system of neurons that governs the function of the gastrointestinal tract.

The autonomic nervous system functions to regulate the body's unconscious actions.

The sympathetic nervous system's primary process is to stimulate the body's fight-or-flight response.

The autonomic nervous system's primary process is to stimulate the body's fight-or-flight response.

Types of functional classification of neurons: • [blank_start]Sensory (afferent) neuron[blank_end] – information to the CNS • [blank_start]Motor (efferent) neuron[blank_end] – information away from the CNS • [blank_start]Inter-neuron[blank_end] – information from one neuron to another neuron

Motor (efferent) neuron – information away from the CNS

Motor (efferent) neuron – information to the CNS

Select the Three types of structural classification of Neurons

[blank_start]Multipolar[blank_end] neurons are a type of neuron that possesses a single axon and many dendrites (and dendritic branches), allowing for the integration of a great deal of information from other neurons. [blank_start]Bipolar[blank_end] neurons are specialized sensory neurons for the transmission of special senses. As such, they are part of the sensory pathways for smell, sight, taste, hearing and vestibular functions. [blank_start]Unipolar[blank_end] neurons are the most common type of sensory neuron. In addition to pain and image description, touch etc. they also carry information about temperature, taste.

Select Three correct statements about Astrocytes

Astrocytes form a supporting framework for blood vessels and neurons. They also assist in the formation of tight junctions between endothelial cells of the capillaries

Astrocytes contribute to differentiation of the blood–brain barrier.

Ependymal cell, type of neuronal support cell (neuroglia) that forms the epithelial lining of the ventricles (cavities) in the brain and the central canal of the spinal cord.

The cerebrospinal fluid (CSF) is produced from arterial blood by the choroid plexuses of the lateral and fourth ventricles by a combined process of diffusion, pinocytosis and active transfer. A small amount is also produced by ependymal cells.

Select the Three correct statements

Ependymal cells cilia assist in the circulation of CSF

Ependymal cells cilia assist in the circulation of Mucus

Microglial cells monitor the health of surrounding neurons and phagocytose microorganisms, infection, trauma or inflammation.

Ependymal cells monitor the health of surrounding neurons and phagocytose microorganisms, infection, trauma or inflammation.

As the resident macrophage cells, microglial cells act as the first and main form of active immune defence in the central nervous system (CNS).

Oligodendrocytes form the isolating sheath around the axons, which is essential for fast signal conduction.

Schwann cells are the supporting cells of the PNS.

Schwann cells are the supporting cells of the CNS.

[blank_start]Oligodendrocytes[blank_end] wrap themselves around numerous [blank_start]axons[blank_end] at once, where as single [blank_start]schwann cells[blank_end] make up a single segment of an axon's [blank_start]myelin sheath[blank_end].

Satellite cells: • Provide support and nutrition to cell bodies in ganglia • Protect cell bodies from harmful substances

Myelinated axons have a node of Ranvier

Unmyelinated axons do not have a node of Ranvier

[blank_start]Grey Matter[blank_end]: BRAIN: outer cortex of brain and nuclei. SPINAL CORD: inner “grey” part [blank_start]White Matter[blank_end]: BRAIN: deeper nerve tracts. SPINAL CORD: outer part

A resting (non-signaling) neuron has a voltage across its membrane called the

Neurons generate electrical signals through brief, controlled changes in the permeability of their cell membrane to particular ions such as Na+ and K+.

If the membrane potential becomes more positive than it is at the resting potential, the membrane is said to be [blank_start]depolarized[blank_end]. If the membrane potential becomes more negative than it is at the resting potential, the membrane is said to be [blank_start]hyperpolarized[blank_end].

If the membrane potential becomes more positive than it is at the resting potential, the membrane is said to be hyperpolarized. If the membrane potential becomes more negative than it is at the resting potential, the membrane is said to be depolarized.

If the membrane potential becomes more positive than it is at the resting potential, the membrane is said to be depolarized. If the membrane potential becomes more negative than it is at the resting potential, the membrane is said to be hyperpolarized.

Where does the resting membrane potential come from?

Types of ions found in neurons In neurons and their surrounding fluid, the most abundant ions are: Positively charged: [blank_start]Sodium and potassium[blank_end] Negatively charged: [blank_start]Chloride and organic anion[blank_end]

Ion channels are the ubiquitous trans-membrane proteins that allow the selective transport of ions and solutes across the plasma membrane.

[blank_start]Non-gated ion channels[blank_end] • Also known as ‘leak’ ion channels • Ion specific • Cell membrane has more K+ leak ion channels compared to Na+ leak ion channels [blank_start]Gated ion channels[blank_end] – require signals to open them (1) Ligand-gated ion channel (2) Voltage-gated ion channel (3) Other-gated ion channel

[blank_start]Voltage gated[blank_end] ion channels open in response to voltage [blank_start](i.e. when the cell gets depolarized)[blank_end] where as [blank_start]ligand gated[blank_end] channels open in response to a ligand [blank_start](some chemical signal)[blank_end] binding to them. Both types of channels are critical for proper activation of the post synaptic neuron.

Repolarisation – membrane potential returns to normal

[blank_start]Resting membrane potential[blank_end]: the difference in charge across the cell membrane in a resting or unstimulated cell [blank_start]Membrane potential[blank_end]: the difference in charge across the cell membrane

Graded potentials are changes in membrane potential that vary in size, as opposed to being all-or-none.

Afterpotential – short period of hyperpolarisation of an action potential

Resting membrane potential: • All gated Na+ and K+ channels are closed. • K+ leak channels (not visible on this image) are open which allow movement of K+ to the outside of the cell. This creates a negative intracellular charge = RMP. • Na+/K+ pump also creates the RMP [blank_start]Depolarisation:[blank_end] • Na+ gated channels open and Na+ moves into the cell and inside of the cell becomes more positive. • K+ gated channels are closed. • Membrane potential becomes more positive. [blank_start]Repolarisation:[blank_end] • Na+ gated channels close. • K+ gated channels open and K+ moves out of the cell and the intracellular side becomes more negative. • Membrane potential becomes more negative. [blank_start]Afterpotential:[blank_end] • Na+ gated channels close. • K+ gated channels close as well but they close slowly so K+ continues to leave the cell and this produces the afterpotential. • Membrane potential becomes very negative [blank_start]Resting membrane potential:[blank_end] • Na+ gated channels are closed. • K+ gated channels are closed. • Resting membrane potential is re-established by Na+/K+ pump (an active process as it is against their concentration gradients) which redistribute ions as all Na+ and K+ gated channels are closed.

2. [blank_start]Graded potential[blank_end] 3. [blank_start]Repolarization[blank_end] 4. [blank_start]Afterpotential[blank_end] 1. [blank_start]Depolarization[blank_end]

Reflex arc diagram - 1. [blank_start]Interneuron[blank_end] 2. [blank_start]Dorsal root[blank_end] 3. [blank_start]Dorsal root ganglion[blank_end] 4. [blank_start]Sensory neuron[blank_end] 5. [blank_start]Sensory receptor[blank_end] 6. [blank_start]Ventral root[blank_end] 7. [blank_start]Motor neuron[blank_end] 8. [blank_start]Effector organ[blank_end]

Sensory receptors: separate specialised cells which detect temperature, pain, touch, pressure, light, sound, odour and other stimuli

Neuroglia are cells other than neurons found within the nervous system. These cells have a supportive role. There are [blank_start]4[blank_end] different neuroglia in the central nervous system (CNS) and [blank_start]2[blank_end] in the peripheral nervous system (PNS).