Nervous System Flashcards
Role
Monitor internal and external environment
Process information
Direct behaviour ad body processes
Typical neurone - cell body (soma)
Surrounds the nucleus
Contains cytoplasmic organelles
Dendrites and axon branches off
Typical neurone - dendrites
Short, cytoplasmic branches off of the soma
Receive input from the axons of other neurones
Typical neurone - hillock
Expanded area of the soma
Origin of the axon
Nerve impulses arise from here
Typical neurone - axon
Carries information to other neurones, muscles, glands, or lymphatic tissue
Axoplasm
Myelin sheath - axolemma
Typical neurone - terminal arborisations/telodondria
Branches of the axon
Tips form expansions known as synaptic knobs - form synapses
Filled with neurotransmitters
Neuroglia
Hold nervous tissue together, providing it with structural and functional support
Local concentrations of neurotransmitters
Supply nutrients
Support neuronal development
Stabilise neuronal networks
Improve communication speed
Provide immunological defence
Neuroglia of the CNS
Astrocytes
Oligodendrocytes
Microglial cells
Ependymal cells
Neuroglia of the PNS
Schwann cells
Satellite cells
Anatomical conceptual division - central nervous system
Brain - cranial cavity
Spinal cord - continuous with medulla oblongata, descends into the vertebral canal
Anatomical conceptual division - peripheral nervous system
Cranial nerves - brain stem to the face and internal organs
Spinal nerves - 31 pairs, spinal cord to the body
Ganglia
Part of the PNS
Collection of neuronal cell bodies
Relay stations
Relays sensory information to motor information
Functional conceptual division - somatic nervous system
Voluntary control
Sensory receptors - head, body surface, limbs, special sense organs
Somatic sensor nerve fibres - afferent
Somatic motor nerve fibre - efferent
Effector organs - skeletal muscle
Functional conceptual division - autonomic nervous system
Involuntary control
Sensory receptors - visceral organs, e.g. lungs
Autonomic sensory nerve fibres - afferent
Sympathetic and parasympathetic motor nerve fibres - efferent
Effector organs - smooth muscle, cardiac muscle, flands
Meninges
Surrounding the brain and spinal cord
Three layers
Protect and support the brain
Prevent spread of infection
Hold the cerebrospinal fluid
Meninges - pia mater
Innermost layer
On surface of the brain
Very thin and transparent
Closely follows the gyri and sulci
Subarachnoid space - cerebrospinal fluid circulates
Meninges - arachnoid mater
Middle layer
Spider-web appearance
Arachnoid trabeculae project into the pia material and reabsorb the cerebrospinal fluid to the blood
Meninges - dura mater
Outer most layer
Dense
Meningeal layer - folds inwards to form double thickness sheets; dural folds, holds the brain in place
Periosteal layer - adheres to the cranium, lies directly touching the meningeal layer, meningeal vessels course between this layer and cranium
Cerebrospinal fluid
Protective medium for the brain
Nutritive - e.g. glucose, oxygen
Removal of metabolites - e.g urea, lactate
Provides stable ionic environment - e.g. Na+, K+, Mg2+, Cl- and bicarbonate
Cerebrospinal fluid - choroid plexuses
Cerebrospinal fluid secreted from networks of capillaries in ventricle wall
Formed from filtrated blood plasma by ependymal cells
Adjoined by tight junctions, for a blood-cerebrospinal fluid barrier
Lateral ventricles
Large C-shaped
One in each cerebral hemisphere
Beneath the corpus callosum, between caudate nucleus and septum pellucidum
Communicates inferiorly to the third ventricle via the interventricular foramen
Third ventricle
Tobin space in the midline of the diencephalon
Bridged by interthalamic adhesion
Communicates superiorly with the lateral ventricles via the intraventricular foramen
Communicates inferiorly with the fourth ventricle via the cerebral aqueduct
Fourth ventricle
Small, triangular chamber found between the pons and the cerebellum
Narrows to form the central canal
Three openings allow the cerebrospinal fluid to leave the brain and enter the subarachnoid space
Gyrus (gyri)
Peaks of the ridges and folds
Sulcus (sulci)
Dips or trenches of the ridges and folds
Fissure
Deep sulcus
Can divide the two hemispheres of the brain
Pre-central gyrus
Posterior border of the frontal lobe, in front of the central sulcus
Descends downwards and forwards from the top of the hemisphere
Forms primary motor cortex
Central sulcus
Descending downwards and forwards from the top of the hemisphere
Divides the frontal and parietal lobes
Post-central gyrus
Anterior border of the parietal lobe
Behind the central sulcus
Descends downwards and forwards from the top of the hemisphere
Forms primary somatosensory cortex
Lateral sulcus
Lateral side of the brain
Almost horizontal
Ascends gradually from the front of the brain to the angular gyrus
Separates the temporal lobe from the frontal lobe