Neuroscience I Flashcards
What are the general functions of the Nervous System?
- Sensory
- Communicative
- Integrative
- Motor
so as to respond to internal and external stimuli
How is the Nervous System structurally organised?
- Central Nervous System (CNS)
2. Peripheral Nervous System (PNS)
What does the CNS comprise of?
Brain and spinal cord
What does the PNS comprise of?
12 pairs of Cranial nerves
31 pairs of Spinal nerves
What are the 12 pairs of Cranial Nerves?
- Olfactory bulb
- Optic nerve
- Oculomotor nerve
- Trochlear nerve
- Trigeminal nerve
- Abducens nerve
- Facial nerve
- Vestibulocochlear nerve
- Glossopharyngeal nerve
- Vagus nerve
- Hypoglossal nerve
- Accessory nerve
How are the Spinal Nerves organised?
8 Cervical nerves 12 Thoracic nerves 5 Lumbar nerves 5 Sacral nerves 1 Coccygeal nerve
Where does the spinal cord end?
L1 vertebra
What is the Cauda Equina?
Tailbone
What is the PNS subdivided into?
- Afferent Division
2. Efferent Division
What does the Afferent Division do?
Carries info (sensory or visceral stimuli) to the CNS
What does the Efferent Division do?
Carries info from CNS to effector organs
How can the Efferent Nervous System be divided into?
- Somatic Nervous System (SNS): voluntary control
2. Autonomic Nervous System (ANS): involuntary control
What does the SNS comprise of?
Fibers of motor neurons that supply skeletal muscles
What does the ANS comprise of?
Fibers that innervate smooth muscle, cardiac muscle and glands
What does an autonomic nerve pathway consist of?
Two-neuron chain
- Pre-ganglionic neuron
- Post-ganglionic neuron
What is a ganglion?
Cluster of neuronal cell bodies
What does the Pre-ganglionic neuron do?
Synapses with the cell body of the postganglionic fiber in a ganglion outside the CNS
What does the Post-ganglionic neuron do?
Sends axons that end on the effector organ
What are the 2 pathways of the ANS?
- Sympathetic Innervation
2. Parasympathetic Innervation
What is Dual Innervation?
Innervation of a single organ by both branches of the ANS
When does Sympathetic Dominance occur?
In ‘fight-or-flight’ response
When does Parasympathetic Dominance occur?
In ‘rest-and-digest’ response
What is the one Gland that only is innervated by Parasympathetic division?
Lacrimal Gland (Tears)
What is the effect of both ANS stimulation on the Heart?
(Sympathetic) Increase HR + force of contraction
(Parasympathetic) Decrease HR + force of contraction
What is the effect of both ANS stimulation on the Blood Vessels?
(Sympathetic) Constricts
(Parsympathetic) Dilates vessels to clit & penis only
What is the effect of both ANS stimulation on the Lungs?
(Sympathetic) Dilates bronchioles + Inhibits Mucus Secretion
(Parasympathetic) Constricts bronchioles + Stimulates Mucus Secretion
What is the effect of both ANS stimulation on the Digestive Tract?
(Sympathetic) Decreases motility + Contract Sphincters + Inhibits digestive secretions
(Parasympathetic) Increases motility + Relaxes Sphincters + Stimulate digestive secretions
What is the effect of both ANS stimulation on the Urinary Bladder?
(Sympathetic) Relaxes
(Parasympathetic) Contracts
What is the effect of both ANS stimulation on the Eye?
(Sympathetic) Dilates Pupils + Contract Radial muscles + Far Vision
(Parasympathetic) Constricts Pupils + Relaxes Radial muscles + Near Vision
What is the effect of both ANS stimulation on the Liver & Adipose Cells?
(Sympathetic) Glycogenolysis+ Lipolysis
What is the effect of both ANS stimulation on the Exocrine Glands?
(Sympathetic) Inhibits pancreatic secretion + Stimulates secretion by sweat glands + Small vol of saliva
(Parasympathetic) Stimulates pancreatic secretion + Large vol of saliva
What is the effect of both ANS stimulation on the Endocrine Glands?
(Sympathetic) Epinephrine + Norepinephrine + Glucagon
(Parasympathetic) Insulin + Glucagon
What is the effect of both ANS stimulation on the Genitals?
(Sympathetic) Controls Ejaculation & Orgasmic Contractions
(Parasympathetic) Controls Erection
What is the effect of both ANS stimulation on the Brain?
(Sympathetic) Increase Alertness
What are the 2 types of effects of the ANS?
- Inhibitory
2. Excitatory
How is the CNS divided?
- Grey Matter
2. White Matter
What is Grey Matter?
Generic Term for collection of CNS cell bodies (soma)
What is White Matter?
Generic term for collection of CNS axons
What are the major features that protect the brain from injury?
- Cranium and Vertebral Column
- Meninges
- Cerebrospinal Fluid (CSF)
- Blood-brain Barrier (BBB)
What are the 3 Meningeal Membranes?
- Outer Dura Mater
- Middle Arachnoid Mater
- Inner Pia Mater
- subarachnoid space between 2 & 3
What are the functions of the 3 meningeal membranes?
Wrap, protect and nourish CNS
What is the Cranial Meninges continuous with?
Spinal Meninges
What is the CSF?
Shock absorbing fluid surrounding and cushioning the brain and spinal cord
What does the brain float in?
Its own special CSF
What is the CSF formed by?
Choroid plexuses in ventricles (brain) - 2 Lateral, 3rd and 4th
What are the functions of the CSF?
- Supports Brain
- Cushions delicate Neural Structures
- Transport nutrients, chemical messengers and wasted products
What are the processes the CSF and Meninges undergo?
- Produced by Ependymal Cells of Choroid Plexuses
- Circulate throughout Ventricle
- Exit 4th Ventricle
- Flow in Subarachnoid space
- Reabsorb into venous bloodp
What is the name of the process through which CSF is collected?
Lumbar puncture (lumbar tap, spinal tap)
Where is the CSF collected from?
Subarachnoid space
What is the BBB formed by?
Network of tight junctions between Endothelial cells of CNS capillaries
What does a highly-selective BBB do?
Regulate exchanges between blood and brain
Does the BBB limit the use of drugs for treatment of CNS؟
Yes
What are the factors that the brain mainly depend on?
Delivery of Oxygen and glucosr
What does the brain only utilise but not store?
Glucose
How many percentage of body weight is the CNS?
2%
How many percentage of the CO is supplied to CNS?
13-15%
What happens when a person is oxygen-deprived?
Brain damage
What are the general functions of the CNS?
- Subconsciously regulate homeostatic responses
- Experience emotion
- Voluntarily control movements
- Perceive body and surroundings
- Engage in higher cognitive processing
What are the main components of the brain?
- Brain Stem
- Cerebellum
- Forebrain (Diencaphalon: Thalamus and Hypothalamus)
- Cerebrum (Basal Nuclei, Cerebral Cortex)
What is the function of the Cerebral Cortex?
- Sensory perception
- Voluntary movement
- Language
- Personality traits
- Sophisticated mental events
What is the function of the Basal Nuclei?
- Inhibition of muscle tone
- Slow, sustained movement
- Suppression of useless movements
What is the function of the Thalamus?
- Relay station for all sensory input (except for smell)
- Sensation
- Consciousness
- Motor control
What is the function of the Hypothalamus ?
- Regulation of homeostatic functions
- Link between NS and Endocrine systems
- Emotion and behavioural patterns
- Sleep-wake cycle
What is the function of the Cerebellum?
- Balance
- Enhancement of muscle tone
- Skilled voluntary movement
What is the function of the Brain Stem?
- Origin of most peripheral cranial nerves
- Muscle reflexes involving equilibrium and posture
- CVS, Digestive and RS control centers
- Reception and integration of all synaptic input from spinal cord (arousal and activation of cerebral cortex)
- Sleep-wake cycle
What are the four pairs of lobes in the Cerebral Cortex?
- Prefrontal Lobe
- Parietal Lobe
- Occipital Lobe
- Temporal Lobe
What is the Prefrontal lobe associated with?
Complex, cognitive, decision making, personality, social behaviour
What is the Temporal lobe associated with?
Memory formation
What is the Parietal lobe associated with?
Somatosensory processing
What is the Occipital lobe associated with?
Visual
What is the Central Sulcus associated with?
Motor functions
Where is the Central Sulcus located?
Between the Frontal and Parietal lobes
What is a somatotopic map?
Relative proportion of somatosensory cortex devoted to reception of sensory input from each area
What is the Spinal Cord?
Long, slender tissue that extends from brain stem through the vertebral canal. It is connected to spinal nerves and enclosed by the protective vertebral column.
How is the Spinal Cord arranged?
White matter is organised into tracts (bundle of nerve fibers with similar function)
How is the arrangement of White and Grey matter for the Brain and Spinal Cord?
(Brain) Inside: White, Outside: Grey
(Spinal Cord) Inside: Grey, Outside: White
What are Dermatomes?
Area of skin supplied by one spinal cord level, or one side, by a single spinal nerve
What is the Clinical Significance of Dermatomes?
- Localise lesions to specific spinal level
2. Useful in neurological examination
What are Myotomes?
Portion of skeletal muscle innervated by a single spinal cord, or on one side, by a single spinal nerve
What is the Clinical Significance of Myotomes?
Testing movement at successful shoulder joints to determine spinal nerve or localised lesions
What is the Anterior Ramus associated with?
The Ventral root carrying Motor information away from the CNS to effectors
What is the Posterior Ramus associated with?
The Dorsal root carrying Sensory information to the CNS
What are the types of Nerve Plexuses?
- Somatic
2. Visceral
What do Nerve Plexuses do?
Combine fibers from different sources of to form new nerves with specific targets or destinations
What is the benefit of Nerve Plexuses?
Damage to a single spinal nerve is less likely to result in total paralysis of a muscle innervated by nerves of the plexus
What are the main Somatic Plexuses?
- Cervical plexus (C1 - C4)
- Brachial plexus (C5 - T1)
- Lumbar plexus (L1- L4)
- Sacral Plexus (L4 - S5)
What are the Somatic Plexuses associated with?
Anterior Rami
What are the main Visceral Plexuses?
- Cardiac plexus
- Esophageal plexus
- Thoracic aortic plexus
- Prevertebral plexus