W7 Nervous system Flashcards
List three basic functions of the NS
- Detect changes (stimuli) in the external and internal environment
- Evaluates info
- Responds by initiating changes in muscles or glands
Name and define major anatomical subdivisions of the NS
- The central nervous system
* Peripheral nervous system
What are the subdivisions of the PNS?
- The somatic NS
- The autonomic NS
- The enteric nervous system
Define neuron
Carry out most of the functions of the NS.
*Sensing changes on the outside and inside of the body
Moving muscles
Forming memories
Regulating behaviour
Describe a neurons important structural components
Axon terminal , axon , cell body , dendrites
Define neurons and relationship to each functional role
Dendrites receive infomation
Cell body - performs function of a cell
Axon - transmits messages to terminal
Axonterminal - communication to other cells (neurotransmitters)
Name 3 functional classes of neurons
Multipolar
Bipolar
Unipolar
Describe the function of Sensory neurons
Sensory (Afferent( neurons - detect changes in external and internal environment
Identify types of neuroglia in CNS
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
Explain the importance of the myelin sheath
Formed from wrappings of plasma membrane - appear white
The presence of myelin increases the speed of signal conduction
Describe how the myelin sheath is formed in the CNS and PNS
Produced by two neuroglia:
Obligodendrocytes - produce myelin sheath in the CNS
Schwann cells - produce myelin sheath in the PNS
What is SAME?
Somatic Afferent
Motor Efferent
What are the two main cell types in the NS?
Neurons and Neuroglia
Name 3 functional classes of neurons
- Sensory (afferent) neurons
- Interneurons
- Motor (efferent) neurons)
Describe the function of Interneurons
Involved in the processing of infomation coming into the CNS and initiating actions through motor responses ( telephone component)
Describe the function of Motor (efferent) neurons
Involved in controlling muscles or glands
What is Neuroglia?
Provides chemical and structural support for neurons.
Define Astrocytes
(CNS)Star shaped; largest most numerous type of glia , which transfer nutrients from the blood to neurons. ( neurganglia function)
Define Obligodendrytes
(CNS)Produce a myelin sheath that wraps around axons of CNS neurons (insulation)
Define Microglia
Acts as immune cells in the CNS destroying foreign organisms and damaged nervous tissue
Define Ependymal cells
(CNS)Responsible for the production of cerebrospinal fluid. They also aid in the movement of this fluid though ventricles
Define Obligodendrytes
(CNS)Produce a myelin sheath that wraps around axons of CNS neurons (insulation)
Describe the function of Satellite cells in the neuroglia PNS
Produce structural support and aid in the exchange of nutrient and the surrounding fluids
What parts of neurons make up white matter?
Consists of primarily myelinated axons
What part of neurons make up grey matter?
Consists of neuron cell bodies, dendrites, unmyelinated axons and neurolgia
What part of neurons make up grey matter?
Consists of neuron cell bodies, dendrites, unmyelinated axons and neurolgia
Describe the electrochemical basis of the resting membrane potential
Polar heads prevent movement of charged particle through the membrane
What does the term membrane potential refer to?
The difference in voltage between the inside and outside of the cell
How is membrane potential measured?
Recording electrodes is inserted into the cell the voltage different between the two electrodes is about -70mV
What is the resting membrane potential?
Resting membrane potential is the membrane potential recorded when a neuron is not receiving any input
What is the sodium potassium pump function?
PUMPS out 3 Na+ (sodium ions) PUMPS IN 2 K+ ions
What does the sodium-potassium pump do?
It helps to establish concentration gradients between the inside and the outside of the cell membrane
What is the potassium leak-channel?
Allows potassium to move down(leak out) it’s concentration gradient and outside of the cell
How is the resting membrane potential established??
K+ (sodium ions) wants to move DOWN the concerntration gradient out of the cell though the K+ (potassium ions) leak channels. As K+ moves out, the cell becomes more negative.
How can the membrane potential change?
Graded potentials
Action potentials
What is a graded potential?
A graded potential is a small deviation from the resting membrane of the neuron
What is summation?
Is the process by which graded potentials occurring close enough in time together can produce a bigger change in membrane potential
What is summation?
Is the process by which graded potentials occurring close enough in time together can produce a bigger change in membrane potential
How do neurons communicate?
- The generation of action potentials
2. The release of neurotranmitters
What is action potential?
Rapid and brief reversal of the membrane potential
Where are action potentials initiated?
At the axon hillock has a high concentration of voltage-gated sodium ion channels
What are voltage-gated ion channels?
Are proteins that respond to changes in the membrane potential by opening a channel in the membrane
What are voltage-gated potassium channels?
Opens in response to depolarisation and let K+ move out of the cell (down the concentration gradient)
What are voltage-gated sodium channels?
Channels that open response to a depolarisation of the membrane and let Na+ move into the cell