Compendium 8 How do we control ourselves?

Functions of the nervous system include maintaining homeostasis

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 Central Nervous System comprises of the Enteric Nervous System

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

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

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

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

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

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.

Motor (efferent) neuron – information away from the CNS

Motor (efferent) neuron – information to the CNS

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.

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.

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

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 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.

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

Repolarisation – membrane potential returns to normal

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

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