module 5 - 13.2 neurones Flashcards
what is a neurone/nerve cell?
a cell that transmits electrical impulses and communicates with other cells c=via specialised connections called synapses
what is the main component of nervous tissue in all animals (except sponges)
a neurone
- plants and fungi do not have neurones
what are the 3 types of neurones?
sensory neurone
relay neurone
motor neurone
what is the function of neurones?
to rapidly transmit electrical impulses to allow coordination
what is the cell body of a neurone?
nucleus, mitochondria and RER to allow protein synthesis, production of neurotransmitters
what are the dendrons of a neurone?
transmits electrical impulses TOWARDS cell body, form a branching pattern with smaller dendrites
what is the axon of a neurone?
transmits electrical impulses AWAY from the cell body, often very long, narrow cytoplasm covered by plasma membrane with microtubule support
what is nerve tissue?
a large bundle of neurones
what is a sensory neurone?
- transmits electrical impulses from receptor cell to brain or motor neurone
- dont detect stimulus
- have one dendron that may branch into several dendrites
- dendron carried impulse to cell body
- axon carried impulse away from cell body
what is a relay neurone?
- transmits electrical impulses between neurones
- has central cell body
- has many short dendrons branching into several dendrites
- dendrons/dendrites carry nerve impulses towards cell body
- many axons that branch our
- axons carry impulses away from cell body
what are motor neurones?
- transmit electrical impulses from relay neurone or sensory neurone to an effector
- has many dendrites that carry the impulse towards cell body
- long axon, may have branches at its terminal
- axon carries impulse away from cell body
what are effectors?
muscles or glands
what are myelinated neurones?
neurones that have an insulating layer around the axon made from myelin
what is myelin made by when in the PNS?
schwann cells when a neurone is in the peripheral nervous system (PNS)
what is myelin made by when in the CNS?
oligodendrocytes when the neurone is in the central nervous system (CNS)
what are schwann cells?
- produce many layers of plasma membrane by growing around and around the axon of neurones in the PNS (lipid based myelin sheath)
- outer layer of schwann cells is called neurilemma
what is the role of a schwann cell?
allows dead neurones to reform inside the tunnel created by the schwann cell (band of bunger)
what are oligodendrocytes?
- perform same function as schwann cells bu =t are found on neurones of the CNS
- do not have neurilemma as they wrap around multiple axons (up to 50)
what is the myslin sheath made from?
schwann cells
what are the nodes of Ranvier?
small gaps between the myelin sheath and where the axolemma is exposed to extracellular space
ow?what do the nodes of ranvier allw
allows electrical impulse to jump from one node to the next, increasing speed of transmission of impulse
- THIS IS CALLED SALTATORY CONDUCTION
what is the charcot-marie-tooth disease?
- group of inherited disorder of nerves
- characterised by loss of muscle tissue and touch sensation
- incurable
- one of the most common inherited neurological disorders
what is multiple sclerosis?
- demyelinating disease where myselin sheath of nerve cell axons in the brain and spinal cord are damaged
- damage disrupts ability of parts of nervous system to transmit signals
- results in physical, mental and psychiatric problems
- underlying mechanism is either destruction of immune system or failure of myelin producing cells
- incurable
