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
White matter
Fibre tracts
Information superhighway
Connects different areas of the brain
Sensory and motor pathways
Tracts to the rest of the nervous system
White matter - corpus collpsum
Connects hemispheres
Can be cut, one side of the brain/body doesn’t know what the other side is doing
Lack of coordination
White matter - internal capsule
Connects higher cortical areas to lower brain and spinal cord
Connection to peripheral nerves
White matter - association fibres
Connects cortical areas in the same hemisphere
Internal to the brain
Local information transmission
Grey matter
Neurones
Glial cells
Blood vessels
No major (long) fibre tracts
Frontal lobe
Planning
Emotion
Mood
Behaviour
Motor function
Smell
Temporal lobe
Hearing
Language
Memory
Parietal lobe
Touch
Pain
Temperature sensation
Occipital lobe
Vision
Cerebellum
Balance
Coordination of physical movements
Brain stem
Autonomic control of body systems
Main sensory/motor pathways pass through
Insula
Smallest lobe
Deep in the cerebrum
Deep to the parietal and temporal lobe
Special senses - taste and hearing
Visceral sensation
Conscious awareness
Gestation
Cognitive emotional processing
Audio-visual integration
Interoception - autonomic sensory monitoring
Homeostatic error detection
Motor cortex somatic
Motor control of skeletal muscle
Motor planning (general)
Pre motor cortex
More rounded motions
Sensory cortex
Input from skin
Input from proprioceptors
Spatial discrimination
Associative sensory cortex
Helps coordinates memory of previous sensory information
Visual cortex
Mapping visual input
Visual recognition
Associative visual cortex
Helps coordinates memory of previous visual information
Auditory cortex
Pitch
Loudness
Location
Auditory memory/sound recognition
Wernicke’s area
Language
Reading or listening
Recognition of words
Association with meanings
Context
Found on the left side of the brain
Broca’s area
Motor control of speech
Speech planning (stutter)
Motor planning (general)
Language output area
Associated with the pre motor cortex
Found on the left side of the brain
Somatotopy
Body maps onto the brains surface
Understand which part of the brain the action potential is coming fro, e.g. which part of the body is touched
Homuculi
Brain stem (more)
Medulla, pons and midbrain
Ascending and descending nerve tracts
Origin of cranial nerves
Autonomic function
Reticular formation
Brain stem - reticular formation
Filtering incoming information
Control of sleep and consciousness
Modulation of pain
Regulation of cardiovascular and respiratory systems
Somatic motor control from cranial nerves
Gaze centres
Cerebellum (more)
Receives information from the inner ear
Control of balance
Influences posture and muscle tone
Coordination of movement
“Motor learning” - muscle memory
Blood supply to the brain
Left and right common carotid arteries ascend at the side of the neck and divide to form the internal and external carotids
Blood supply to the brain - internal carotid artery
Deep artery of the neck
Enters the skull to supply the brain, eyes, nose and forehead
Branches - ophthalmic, anterior cerebral, middle cerebral
Blood supply to the brain - vertebral artery
Arises from the subclavian artery
Ascends through the transverse foramen of the cervical vertebrae
Enters the skull via the foramen magnum
Unites with its opposite to form the basilar artery
Supply the cervical vertebrae, brain stem, cerebellum and spinal cord
Branches - spinal, posterior inferior cerebral, basilar
Blood supply to the brain - circle of Willis
Branches of the internal carotid and vertebral arteries form an arterial Cecile around the pituitary gland and optic chiasm
Anastomosis
If an artery supplying the brain becomes damages, blood flow from other vessels replace it
Blood supply to the brain - anterior cerebral arteries
Supply to the frontal and parietal lobes
Blood supply to the brain - posterior cerebral arteries
Supply to the temporal and occipital lobes
Blood supply to the brain - middle cerebral artery
Supply to the temporal, frontal and parietal lobes, also to the pre central gyrus and the post central gyrus
ANS anatomy - sympathetic nervous system
Fight or flight
Increase heart rate
Dilate pupils and vessels to muscles
Sweating
Suppress digestion
Preganglionic fibres - short, rami of T1 to L3
Post ganglionic fibres - long
ANS anatomy - sympathetic nervous system; sympathetic ganglion
Paravertebral ganglia
Next to vertebrae
ANS anatomy - sympathetic nervous system; white ramus
Myelinated fibres
From nervous system to sympathetic ganglion
ANS anatomy - sympathetic nervous system; grey ramus
Back from sympathetic ganglion to the nervous system
ANS anatomy - sympathetic nervous system; pre vertebral ganglia
From nerves to viscera
Solar plexus - pre vertebral complex
ANS anatomy - sympathetic nervous system; neurones
Release acetylcholine and norepinephrine (postganglionic transmitter)
ANS anatomy - parasympathetic nervous system
Rest and digest
Decrease heart rate
Constricting pupils and vessels to skeletal muscles
Stimulating digestion
Discrete control
Preganglionic motor neurone - long, in the four cranial nerves and the pelvic sphanchnic nerves
Postganglionic motor neurone - short, in walls of target organ
ANS anatomy - parasympathetic nervous system; neurones
Release acetylcholine - reduces heart rate
Adrenal gland - cortex
Cortisol - stress hormone, increases glucose production, regulates ion balance
Adrenal gland - medulla
Chromaffin cells - modified neurones
20% norepinephrine (noradrenaline)
80% epinephrine (adrenaline)
Sympathetic nervous system
No neural connection - nerve goes straight to the adrenal medulla
Higher control of the ANS - brain stem and spinal cord
Reticular formation direct influence
Medulla oversees gastrointestinal activities
Midbrain controls muscles involved in pupil diameter and lens focus
Higher control of the ANS - main nuclei involves in control of cardiac output
Pressor area (sympathetic)
Solitary nucleus
Depressor area (inhibition) - reduce sympathetic activation
Nucleus ambiguous - vagus nerve (PNS), activation results in vagus time and reduces Q
Higher control of the ANS - main nuclei involves in control of respiratory function
Pontine nuclei - cerebellum manages other nuclei, adjusts rate and depth of breathing
Ventral respiratory group - controls breathing in and out
Dorsal respiratory group - works together with ventral respiratory group and receives input from solitary nucleus
Higher control of the ANS - hypothalamus
Main integration centre
Anterior region - parasympathetic function
Posterior region - sympathetic function
Exerts effect directly and through the reticular formation
Higher control of the ANS - cortical control
Not fully involuntary
Input converge on hypothalamus through connections to limbic system - information processing centre
Informs hypothalamus and brain stem
