Nervous systems and neurones

Describe how a stimulus brings about a response

A stimulus will bind to a receptor The receptor will turn this binding into an electrical signal The sensory neurone takes the electrical signal to the nervous system It then is processed and leaves the nervous system by a motor neurone The motor neurone will go to an effector which will bring about a response

What direction do axons transmit an electrical impulse?

Away from the nerve cell body towards synapses

What are the main two nerve fibres that carry electrical impulses?

Axon Dendron

How are nerve cells connected?

By dendrites

How do nerve cells carry information?

By electrical impulses

Describe the structure of a sensory neurone

Cell body above the nerve fibre and in the middle Left of the cell body is the axon Right of the cell body is the dendron Dendrites far right side connected to a receptor Synaptic bulbs far left side Axon and dendron covered in myelin sheath Direction of impulse right to left

Describe the structure of a motor neurone

Cell body at far right side with dendrites coming of it Axon with direction of impulse going right to left Synaptic bulbs at far left side connected to an effector Myelin sheath covering the axon

Describe the structure of a relay neurone

Cell body in the middle Axon on the left Dendron on the right Dendrites on the far right side Synaptic bulbs on the far left side Direction of impulse right to left

What are the two parts of the nervous system?

Central nervous system Peripheral nervous system

What determines the speed of an impulse?

Diameter of the fibre (thicker the fibre, faster it travels) Presence or absence of myelin sheath

What is myelin sheath and what cells is it made of?

Fatty insulating wrapped around some neurones made up of Schwann cells

What are the nodes of Ranvier?

Gaps between the Schwann cells that enable saltatory conduction

What are sense organs?

Groups of receptors working together to detect changes in the environment

What does the myelin sheath do to transmission speed and how?

It speeds up the rate of transmission because an action potential cannot occur where the myelin sheath is present as a result the action potential jumps between the nodes of ranvier

What is a neurone and it's function?

It's a nerve cell which carries electrical signals in the nervous system

What is a dendron, what nerve cell is it found in and what's it's role?

Long nerve fibre found in a sensory neurone and it carries the nerve impulse towards the cell body

What is the peripheral nervous system made of and what's its role?

Made of sensory and motor neurones and it's role is to connect sensory receptors and effectors to the CNS

What is a nerve impulse and what causes it?

Minute electrical event caused by the charge difference between the outside and inside of the neurone membrane

What is an axon and what's its role?

Nerve fibre which carries the nerve impulse away from the cell body to the synapse

What does a cell body in a neurone contain?

Nucleus and other organelles such as mitochondria and ribosomes

What is the peripheral nervous system?

Parts of the nervous system not involved in the CNS

Why is myelin sheath important?

Protects the never from damage Speeds up transmission of never impulses

What is saltatory conduction?

Saltatory conduction is the "jumping" of an action potential between the unmyelinated nodes of ranvier in myelinated neurones

What are the 3 types of nerve cells?

Sensory neurones Motor neurones Relay neurones

What are dendrites and their role?

Small extensions from the cell body of a neurone and connect with neighbouring neurones and their role is to receive signals

What are neurones and what are they responsible for?

Specialised cells for the rapid transmission of impulses throughout an organism

What are effector cells?

Specialised cells that bring about a response when stimulated by a neurone

What is the central nervous system (CNS)?

Specialised concentration of nerve cells where incoming information is processed and impulses are then sent out through motor neurones which carry impulses to the effector organs

What are sensory/neurone receptor cells and what do they do?

Specialised neurones that detect changes in the environment

What is a Schwann cell and what does it form?

Specialised type of cell associated with myelinated neurones It forms the myelin sheath

What is the role of a motor neurone?

They receive signals from relay or sensory neurones and then contact effectors (muscles or glands) to stimulate a response

What is the role of a sensory neurone?

To take information from a receptor and pass it on to other neurones to take it to the CNS (brain and spinal cord)

What is the role of a relay neurone?

To transfer a signal from a sensory neurone to a motor neurone

What direction do dendrons transmits an electrical impulse?

Towards the cell body