15.1 Neurones and Nervous Coordination Flashcards
What are the two forms of coordination in animals
- The Nervous System 2. The Hormonal System
What does the nervous system use to coordinate responses
Nerve cells to pass electrical impulses along their length
What do electrical (nervous) impulses do
Stimulate their target cells by secreting neurotransmitters directly on them. This results in rapid and specific communication between specific parts of organisms
How long are nervous responses
Short lived
Where do nervous impulses occur
In localised regions
What does the hormonal system use to coordinate responses
Hormones which are transported in blood plasma to target cells
What do hormones do
Target cells have specific receptors on their cell-surface membranes and the change in hormone concentration stimulates them
How long are hormonal responses
They are long-lasting
Where do nervous impulses occur
Widespread
What are neurones
Specialised cells adapted to carrying nerve impulses from one part of the body to the other
What are the components of a mammalian motor neurone
- Cell body
- Dendrons
- An Axon
- Schwann cells
- Nodes of Raviner
- Myelin sheath
What is the cell body of a neurone
The cell body contains all usual organelles, but a large number of RER
This large number of RER is because of neurotransmitter and protein production
What are the dendrons of a neurone
Extensions of the cell body that further branch out into smaller fibres called dendrites, that carry nerve impulses TOWARDS the body
Where to dendrons/dendrites carry nerve impulses
TOWARDS the cell body
What is the axon of a neurone
A single long fibre that carries nerve impulses AWAY from the cell body
Where does the axon carry nerve impulses
AWAY from the cell body
What are Schwann cells
They surround the axon, protecting it and providing electrical insulation
They also carry out phagocytosis, so clear up cell debris.
Schwann cells wrap themselves around the axon many times to build up several layers of membranes
Hormonal system vs Nervous system
What is the myelin sheath of a neurone
A covering to the axon and is made up of the membranes of schwann cells. These membranes are rich in myelin, a lipid
What are neurones with a myelin sheath called
Myelinated neurones
What are Nodes of Raviner
Constrictions between adjacent schwann cells where there is no myelin sheath
How are neurones classified
To their function
What are the different types of neurones
- Motor neurones
- Intermediate/Relay neurone
- Sensory neruone
What is the function of sensory neurones
To transmit nerve impulses from a receptor to an intermediate or motor neurone
What is the structure of a sensory neurone
One dendron that is long, carries the impulse towards the cell body and also contains one axon that carries it away
What is the function of sensory neurones
Transmit nerve impulses from an intermediate or relay neurone to an effector (muscle or gland)
What is the structure of a motor neurone
A long axon and many short dendrites
What is the function of intermediate/relay neurones
Transmit nerve impulses between neurones. e.g. from sensory to motor neurones
