ASU HLTH 1020 Health Anatomy Week 3 Lecture Notes and Tutorials (Nervous System) University of South Australia

ASU HLTH 1020 Health Anatomy Week 3 Lecture Notes and Tutorials (Nervous System) University of South Australia

WEEK 3 – NERVOUS SYSTEM

LEARNING OBJECTIVES:

• Explain the role of the nervous system as the control system of the body and describe a basic neural circuit • Have an understanding of the structural and functional divisions of the nervous system • Discuss the levels of organisation in the nervous system • Name and know the functions of glial cells • Describe the mechanisms of action potential generation including the transmembrane potential, movement of ions and changes in transmembrane potential, and propagation of action potentials.• What is a synapse? Understand the process of synaptic transmission and be able to detail the general activity of some common neurotransmitters.

• Define terms: grey matter, white matter, nucleus, ganglia, nerve and tract.

• Identify key structures (subdivisions) of the brain and give functions for each.• Identify anatomical and functional areas of the brain important in motor control and sensation including ascending and descending pathways.• Identify the major blood vessels that supply the brain.• Describe the gross structure of the spinal cord • Have an appreciation of the structure and function of the autonomic nervous system • Have a functional knowledge of the eye and ear special senses in how they detect information and we interpret than information

NERVOUS SYSTEM

DESCRIPTION:

The sum total of the tissues that record and distribute information within a person, and does so by electrical and chemical means.

FUNCTION:

• maintain homeostasis by controlling organ systems and behavioural drives (e.g.

hunger, thirst)

• cognition and memory
• provides and interprets sensory information about external conditions
• control of skeletal muscle (movement)
• electrical signals and chemical signals

MAJOR ORGANS:

• Brain & spinal cord
• peripheral nerves
• sense organs

TWO SYSTEMS

CENTRAL NERVOUS SYSTEM:

DESCRIPTION: Brain and spinal cord

FUNCTION:

• integrating and processing information
• sensory information → commands

Interpreting info and making decisions

PERIPHERAL NERVOUS SYTEM:

NEUROGLIA/ GLIA (supporting cells):

DESCRIPTION: Everything else

FUNCTION:

• Commands from CNS → body
• Body sensory information → CNS
• Message transport system

CELL TYPES IN THE NERVOUS SYTEM

NEURONS (carry messages):

DESCRIPTION:

- Neurons: ~100 billion

• Neuron distribution is not equal throughout the body
• e.g. cerebellum is smaller than cerebrum but contains a similar number of

neurons

• Certain regions have a high density of axons. White in colour (white matter)
• Certain regions have a high density of neuronal cell bodies Gray in colour

(gray matter) (Typical neurons cannot undergo cell division) i.e. they cannot be replaced if lost due to lack centrioles

• Neural stem cells are present in the adult nervous system but are typically

inactive active in the nose (regeneration of olfactory receptors) and hippocampus (memory)

FUNCTION:

• process information (e.g. sense changes, communicate changes, command a

response)

• Communication & bringing information together

DESCRIPTION:

• Neuroglia: human brain: ~1,000 billion
• They outnumber neurons
• They monitor cerebrospinal fluid

-

ASTROCYTES

FUNCTION:

• insulate, support, and nourish neurons
• Account for half of the volume of the nervous system

FUNCTION:

• structural support
• regulate chemical environment
• maintain blood-brain barrier

DESCRIPTION:

• layers of fatty membrane that insulate axons
• myelin configuration increases speed of information transfer down axons

FUNCTION:

• Myelin quickens nerve signals.

Cell types that make myelin differ in CNS and PNS

MYELINE

whole covering is called the ‘myelin sheath’ myelin sheath gaps called ‘nodes of Ranvier’ Myelination in the PNS • Myelin sheath gaps • Gaps between adjacent Schwann cells • Sites where axon collaterals can emerge • Formerly called nodes of Ranvier • Nonmyelinated fibers • Thin fibers not wrapped in myelin; surrounded by Schwann cells but no coiling; one cell may surround 15 different fibers

MYELIN SHEATHS IN CNS :

• White matter- regions of brain and spinal

cord

• grey matter- neuron cell bodies &

nonmyelinated fibers

MYLIEN CELLS