Neurobiology 1 Flashcards
Neurons and Nervous Systems
What are the components of the nervous system do? What do they do?
Sensory system- receive and interpret information about the internal and external environments of the body.
Integrating system- to make decisions about this information, making decisions from sensory input and stored record of previous experience (memories).
Motor system- to organise and carry out action, control movement- conscious and unconscious.
What does the sensory system include?
-Sense organs
-Sensory nerves
-Central sensory areas
What does the motor system include?
-Motor neurones
-Central motor areas
-All muscles
-Ducted glands of the body
What does the Neuron doctrine state?
circa 1894
-The neurone is the structural and functional unit of the nervous system.
-Neurons are individual cells, which are not continuous to other neurones.
-The neuron has 3 parts: dendrites, soma (cell body) and axon.
-Conduction takes place in the direction from dendrites to soma, to the end arborisations of the axon.
How was the neuron doctrine enhanced?
It was enhanced by the golgi technique, a neuron staining technique.
The whole of neurone was stained and also only a few number of neuron are stained- we are unsure why.
What are the units of the nervous system?
-Dendrites
-Axon
-Myelin
-Node of Ranvier
-Terminals
What is the role of the dendrites?
To increase the surface area.
To receive inputs.
What is the role of the axon?
Carries information over distances.
What is the role of myelin?
Coats axon.
Improves conduction, by making transmission more reliable.
What is the role of the node of ranvier?
Provides a break in myelin sheath.
What is the role of the terminals?
Output region.
Transmitter release.
Synapse with other neurones or muscle.
Branch out.
How should we classify neurones?
-Morphology (multipolar, unipolar ect)- polarised, have specific functions.
-Interneuones (typically inhibitory) vs principle (excitatory) neurones.
-Neurotransmitter (chemical molecule that they recieve)- cholinergic, glutamatergic, GABAergic ect.
Are all neurones physically the same?
No, they come in all shapes and sizes.
What are unique problems to neurones? How is this done?
How to get material from soma to terminals and back again?
-Anterogade transport
-Retrograde transport
What is anterograde transport?
(WGA-HRP)
From soma, down axon to terminals
Two kinds:
-rapid: 300-400 mm/day (up to 1 um/s)
-slow: 5-10 mm/day
What is retrograde transport?
(HRP)
From terminals to soma
Remove and recycle
Worn out mitochondria, SER
Rapid: 150-200 mm/day
How can things moving to and from axon terminals be observed?
Transport process can be observed using WGA/HRP labelled. Therefore can identify the rate which transport occurs.
WGA- wheat germ agglutinin
HRP- horseradish peroxidase
What does the mechanism for axonal transport require?
-Hydrolysis of ATP
-Microtubules
Transport proteins can move on microtubules due to polarity.
What is the mechanism of axonal transport?
Retrograde: to cell body
Anterograde: to terminals
Transport has combination of proteins, molecular motor, allows cargo to move in correct direction.
How did the nervous system structure evolve?
Nerve cells- individual neurones, coordinating functions.
Nerve ring- migration of neurones, so they are close together.
Ganglia- easier to coordinate activity.
Fusion of ganglia- ganglia merge together, leads to development of the brain.
What is the collective name for other units of the nervous system?
Glia
What are the myelinated cells in the CNS and PNS?
CNS- oligodendrocyte
PNS- Schwann cells
What is a microglial cell?
-Acts as scavengers.
-Cleans up cellular debris.
-Launch immune response.
What is an oligodendrocyte?
-Form myelin sheath in CNS
-Can sense and possibly influence activity.
-Sends out processes which wrap various parts of the same axon or other axons, 1 oligodendrocyte can myelinate multiple axons.
