Nervous System- nervous tissue, neurons, neuroglia Flashcards
3 neuron characteristics
- extreme longevity
- amitotic
- high metabolic rate
The biosynthetic centre of a neuron
Neuron cell body
Which part of the neuron contains an axon hillcock?
Neuron cell body
Does a neuron cell body contain a nucleus?
Yes, a large nucleus with nucleolus
Structure of a dendrite
Short, branched processes
The receptive region of a neuron
Dendrites
How do dendrites convey incoming information to a cell body?
As graded potentials
Axon contains vesicles of…
Neurotransmitter
Axons do not contain…
Ribosomes or golgi = no protein synthesis
Distal endings of an axon
Axon terminals/Terminal boutons
Axon function
Where are nerve impulses/action potential generated?
At the axon initial segment (AIS), conducted along axolemma to axon terminal
What happens if an axon gets cut or damaged?
-Anterograde degeneration-
Two functions of myelin sheath
- Protect and electrically insulate axon
- Increase speed of nerve impulse conduction
What are myelinated fibres?
Segmented sheath that surrounds most long/large-diameter axons
How is myelination in the PNS formed?
By Schwann cells
Myelination in the PNS-
What are the gaps called?
Nodes of Ranvier
How is myelination in the CNS formed?
By processes of oligodendrocytes
What is the white matter made of in CNS division?
Myelinated fibres
What is the grey matter made of in CNS division?
Neuron cell bodies
Anterograde axoplasmic transport
From terminal/membrane towards soma
3 different types of neurons
- Sensory/afferent neurons
- Motor/Efferent neurons
- Interneurons/association neurons
Function classification of sensory/afferent neurons
- Transmit impulses from sensory receptors to CNS
- Almost all are pseudounipolar
- Soma in ganglia in PNS
Function of somatic sensory neurons
Receptors monitor outside conditions
Function of visceral sensory neurons
Receptors monitor internal conditions
Functional classification of motor/efferent neurons
- Transmit commands from CNS to effectors
- Mostly multipolar
Function of somatic motor neuron
- Innervate skeletal muscle
- Conscious control or reflexes
Function of visceral/autonomic motor neurons
Innervate effectors on smooth muscle, cardiac muscle, glands, adipose
Functional classification of interneurons/association neurons
- Distribute sensory information and coordinate motor activity
- In brain, spinal cord, autonomic ganglia
Functions of neuroglia
- Surround neurons
- Insulate
- Supply nutrients and oxygen
- Destroy pathogens and remove dead neurons
What are the four main neuroglia that support CNS neurons?
- Astrocytes
- Microglial cells
- Ependymal cells
- Oligodendrocytes
Structure of astrocytes
Most abundant, versatile and highly branched
Functions of astrocytes (6)
- Blood brain barrier
- Control chemical environment
- Support neurons
- Repair
- Guide neuron development
- Information processing
Structure of microglia
Small, ovoid cells with thorny processes that touch monitor neurons
Function of microglia
CNS defence
Structure of oligodendrocytes
Wide, flat processes wrap local axons
Function of oligodendrocytes
Forms myelin sheath and node of Ranvier= faster action potential conduction
Structure of ependymal cells
- Columnar shape
- Line ventricles of brain and central canal of spinal cord
- Have cilia= circulate CSF (cerebrospinal fluid)
Functions of ependymal cells (2)
- Cushions brain
- Nutrients and gas exchange between CSF and nervous system
What are the two cells in neuroglia in PNS?
- Satellite cells
- Schwann cells
Structure of satellite cells
Surround soma in ganglia
Function of satellite cells
Regulate chemical environment of ganglia
Structure of Schwann cells
Whole cell wraps axon to form myelin sheath
Functions of Schwann cells (2)
- Forms node of Ranvier= faster AP conduction
- Vital for regeneration of damaged nerve fibres
