Neurones Flashcards
What does the cell body of neurones contain?
The nucleus, surrounded by cytoplasm
Why does the nucleus of neurones have large amounts of endoplasmic reticulum and mitochondria?
They are involved in the production of neurotransmitters
What are dendrons and what do they split into?
Short extensions which come from the cell body and transmit electrical impulses towards the cell body. These extensions divide into smaller branches called dendrites
What is the axon?
The singular nerve fibre that transmits impulses away from the cell body
What are the 3 types of neurone?
Sensory, relay and motor neurone
What is the role of sensory neurones?
Transmit impulses from sensory receptor to relay neurone, motor neurone or the brain
What is the structure of the sensory neurone?
They have one dendron, which carries the impulse towards the cell body, and one axon, which carries the impulse away from the cell body
What is the role of relay neurones?
Transmit impulses between neurones
What is the structure of relay neurones?
They have many short dendrons and a short axon
What is the role of motor neurones?
Transmit impulses from a relay or sensory neurone to an effector
What is the structure of motor neurones?
They have many short dendrites going into the cell body and then one long axon which carries the impulse away from the cell body
What are Schwann cells?
Cells that produce many layers of membranes by growing around the axon many times.
What are the layers of membranes around axons known as?
Myelin sheath
What is the impact of myelinated sheaths on transmission speed?
Myelinated neurones transmit impulses much faster than non-myelinated neurones
What are nodes of Ranvier?
The small gaps between Schwann cells, which creates gaps in the myelin sheath
Why do myelinated neurones transmit impulses faster than non-myelinated neurones?
In myelinated neurones, the impulse jumps from one node of Ranvier to the next as it travels along the neurone, allowing the impulse to be transmitted much faster.
In non-myelinated neurones, the impulse transmits continuously along the axon without jumping, so is much slower
What is found at the end of axons?
Axon terminals
What do axon terminals do?
Make synaptic connections with another nerve cell or with an effector cell
What do sensory receptors do?
Convert the stimulus they are specific to into a nerve impulse
What are the four main types of sensory receptors?
Mechanoreceptor
Chemoreceptor
Thermoreceptor
Photoreceptor
What do mechanoreceptors detect?
Pressure and movement
What do chemoreceptors detect?
Chemicals