Cells and Tissues of the Nervous System Flashcards
What kind of cells are neurons?
Excitable cells
What are impulses through neurons carried as?
Action potentials
What kind of cells are glial cells?
Non-excitable supporting cells
What is the cytoplasm in the cell body of a neuron called?
Perikaryon
What is the cytoplasm in the axon of a neuron called?
Axoplasm
What are dendrites stimulated by?
Environmental changes of the activities of other cells
What does the cell body of a neuron contain?
Nucleus
Mitochondria
Ribosomes
+ other organelles
What does the axon of a neuron do?
Conducts nerve impulses (AP) toward synaptic terminals
What does the synaptic terminals do?
Affect another neuron or effector organ (muscle or gland)
What is the role of the myelin sheath?
Increases conduction speed in axons by saltatory conduction
What is the myelin sheath formed by in the PNS?
Schwann cells
What is the myelin sheath formed by in the CNS?
Oligodendrocytes
What is the clinical importance of the myelin sheath in multiple sclerosis?
Patchy loss/scarring of myelin sheath (demyelination) results in nerve conduction across affected axons to be abnormal = MS
What do glial cells in the CNS do?
Ependymal cells - Line ventricles
What do glial cells in the PNS do?
Satellite cells - Surround neuronal cell bodies
What do glial cells in the CNS contain?
Astrocytes
Oligodendrocytes
Microglia
What do astrocytes do?
Have end feet = surround synapses and capillaries
Help in K+ buffering
What do oligodendrocytes do?
Myelination
What do microglia?
Phagocytosis
Scar tissue formation
What do glial cells in the PNS contain?
Schwann cells
What do schwann cells do?
Myelination
What is the blood brain barrier?
A protective mechanism that helps to keep a stable environment for the brain
Prevents harmful amino acids and ions in bloodstream + blood cells entering the brain
Where are the exceptions where the BBB is absent?
In a few ‘circumventricular’ organs (e.g. parts of hypothalamus, posterior pituitary)
What is the basic role of the cerebrum?
Consciousness
What is the basic role of the cerebellum?
Balance and coordination
What is the basic role of the brainstem?
Vital centres (e.g. cardioresp.) Pathway for fibre tracts
What are the lateral ventricles?
C-shaped cavities that lie in the cerebral hemispheres
What is the interventricular forament?
Connects lateral ventricles with the 3rd ventricle
Where is the 3rd ventricle?
Cavity within the diencephalon
Where is the cerebral aqueduct?
Lies in the midbrain
Where is the 4th ventricle?
Lies in the hindbrain
What is the dura mater structure like?
Tough
Fibrous
Has dural folds
What is the pia mater structure like?
Vascularised
Dips into folds of the brain
What is the subdural space?
Potential space traversed by blood vessels penetrating into the CNS
What does the subarachnoid space contain?
CSF
What is CSF?
Fluid inside the cavity of the brain and central canal of the spinal cord
Also present surrounds brain and spinal cord between meninges layers
What is the CSF responsible for?
Maintaining intracranial pressure
Where is CSF present?
Inside ventricles
Between pia and arachnoid
Where is CSF formed?
By choroid plexus in each ventricle
Where is CSF absorbed?
By arachnoid villi into sagittal sinus (venous channel in brain)
