Nervous System Flashcards
How and why are nerve fibres myelinated?
Schwann cell wraps around nerve fibre and forms fatty layer called myelin sheath.
Gaps between Schwann cells are called the nodes of Ranvier
Myelin sheath protects nerves from damage and also speeds up transmission of the nerve impulse
What is the peripheral nervous system?
Includes parts of the nervous system that spread through body and are not involved in the CNS.
It can be divided further into the voluntary nervous system as well as the autonomic nervous system.
What is the voluntary nervous system?
Involves motor neurones that are under voluntary or conscious control involving the cerebrum
What is the autonomic nervous system?
The involuntary nervous system. Autonomic motor neurones control bodily functions, which are not dealt by conscious are of the brain.
Split into sympathetic nervous system and parasympathetic nervous system
Describe sympathetic nervous system
Involves autonomic motor neurones with very short myelinated preganglionic fibres
There is a synapse in a ganglion very close to the CNS
Long unmyelinated postganglionic fibres
Produce noradrenaline at the synapses and often stimulate a rapid response by activating an organ system
Describe parasympathetic nervous system
Autonomic motor neurones with long myelinated preganglionic fibres
Synapse is very close to the effector organ
Short unmyelinated postganglionic fibres
Produce acetylcholine at the synapses and often have a relatively slow inhibitory effect on an organ system
How is the brain formed?
Forms as a swelling in hollow neural tube at front or anterior end of vertebrate
Basic brain pattern has 3 distinct areas; forebrain, midbrain and hindbrain
Forebrain-olfactory lobes and cerebral hemispheres
Midbrain-optic lobes
Hindbrain-Forms cerebellum and the medulla
Difference between grey matter and white matter
Grey matter-Consists of cell bodies of neurones in the CNS
White matter-Consists of nerve fibres(axons) in CNS. White colour due to myelination
Describe the cerebrum
2 cerebral hemispheres. Biggest and most highly developed part of human brain
Site of our abilities to see, think, learn and feel emotions
All motor function are controlled by cerebrum
Outer layer of cerebrum is cerebral cortex and is made up of grey matter
The right and left cerebral hemispheres are connected by a band of axons called corpus callosum
What is function of hypothalamus
Coordinates autonomic nervous system. Plays a role in thermoregulation and osmoregulation.
Monitors chemistry of blood, controls hormone secretions and basic drives such as thirst and hunger
