Nervous System 1 Flashcards
What does the nervous system do?
Coordinates all body systems and activities, detects and responds to stimuli, brain and spinal cord act as switching centres and nerves and tracts carry messages to and from centres.
What are functional (transmitting) cells called?
Nuerons and are 20%
What are supporting cells called?
Nueroglia and are 80%
What makes up the Central nervous system?
Brain and spinal cord
What makes up the peripheral nervous system?
Cranial nerves (carry impulses to and from brain) and spinal nerves (carry messages to and from spinal cord)
What are the characteristics of nueroglia?
Known as glial cells, support and protection roles, can derive from ectoderm of foetus,out number nuerons 5-10x and non excitable
What are the 4 types of nueroglia in the CNS with function?
Astrocytes (brace and anchor nuerons and capillaries, guide new nerves, mop up nuerotransmitters, influence information processing), Microglial (monitor nerve health and when nerve is sick migrate there and phagocytise them), Ependymal (line the fluid filled cavities of CNA, permeable to CSF pushing it around with cillia) and Oligodendrocytes (form myelin sheaths around nerve fibres in CNS)
What are the 2 types of nueroglia in PNS?
Satellies (surround cell bodies through true task) and Schwann cellls (myelinating cells that also wrap around to insulate signal)
What are the characteristics of nuerons?
Conduct nerve impulses from 1 unit of body to another, highly excitable, long living (100 years), cannot divide, high metabolic rate, basic information processing units of nervous system
What is the structure of a nueron?
Have a cell body with nucleus, axon, dendrites, myelin sheath, nodes of ranvier
What are neurites and where are they?
Ones that carry impulses away from cell body are called axons and ones that recieve impulses are dendrites. They are projections extending from the cell body
What is a sensory nueron?
An afferent nueron and conduct impulses to spinal cord/brain
What is a motor nueron?
An efferent nueron and conducts impulses to muscles/glands
What is an internueron?
Central nuerons that conduct information within CNS
What is the structure of a nerve(4 layers)?
Epineurium (protective sheath, surrounds nerve), Ganglion (cluster of nueron cell bodies), Fascicle (bundle of axons) and Perineurium (CT sheath surrounds each fascicle of nerve fibres in a peripheral nerve)
What is myelin?
Whitish fatty material that has a waxy appearance and covers most long nerve fibres. It protects and insulates fibres and increases the transmission rate of nerve impulses. No myelin=slower signal.
What are axons in the PNS myelinated by?
Schwann cells that wrap themselves tightly around axon which then encloses axon.
What are nodes of ranvier?
The gaps or indentations along the axon due to the Schwann cells.
What forms myelin sheath in CNS?
Oligodendrocytes which lack a neurilemma
What is nuerilemma?
Part of a Schwann cell external to myelin sheath which is nucleus and cytoplasm
Can CNS or PNS regenerate due to nuerilemma?
The PNS can regenerate as the nuerilemma stays intact when nerve is damaged. CNS can not regenerate
What are small collections of cell bodies called?
Ganglia which are found in the PNS
What does white and grey matter refer to?
White is dense collections of myelinated fibres and grey is mostly unmyelinated fibres
What is a synapse?
The axons branch at their terminal end. These axons transmit impulses which reach the axonal terminals and release nuerotransmitters into the space. The tiny gap that seperates the nuerons is called a synaptic cleft and this function works by diffusion and is called synapse
What occurs when there is a disruption of synaptic communication?
Diseases of the brain and psychiatric disorders