Overview of the nervous system Flashcards
What are the features of the axon and describe these features
Axons conduct nerve impulses.
Axon hillock - Tapers away from soma to form initial segment
Axon ‘proper’ - Branching to form axon collaterals (and recurrent collaterals)
Axon terminal - Site at which axon comes into contact with other neurons at a synapse
How are axon terminals different to the axon proper
Cytoplasm - Microtubules do not extend into terminals from proper.
Axon terminal contains synaptic vesicles available for neuron to neuron communication. Rich in proteins and mitochondria, higher energy needs
What is myelin
Membranous sheath that wraps around and insulates axon
What are nodes of Ranvier
Gaps within the myelin sheath - Enriched in voltage-gated Na+ ion channels
What are dendritic spines
Sacs of membrane protruding from dendrites to receive synaptic input
They come in sizes and types (e.g. cups, mushrooms) sensitive to type and amount of synaptic activity
What are the two parts of the human nervous system
CNS - Brain and spinal cord
PNS - Autonomic, somatic nervous systems
What is the somatic nervous system
Component of peripheral nervous system that innervates the skin, joints and skeletal muscle
Helps movement
What is the autonomic nervous system
Sympathetic and parasympathetic divisions - Innervation to cardiovascular system, internal organs and smooth muscle
Heart rate, bp, breathing, digestion
What physical features are present in the cerebrum of the brain
Bumps called gyri
Grooves called sulci
Deep grooves called fissures
What are the postcentral and precentral gyrus responsible for and what are they separated by
Postcentral - Somatic sensation e.g. touch
Precentral - Voluntary movement
Separated by central sulcus
What does the superior temporal gyrus do and what is it separated by
Audition
Separated by lateral fissure
What is the frontal lobe responsible for
Voluntayr movement, behaviour
Attention, planning, decision making, motivation, emotional regulation
What is the temporal lobe responsible for
Auditory processing and interpretation, memory
What is the parietal lobe responsible for
Sensory processing and interpretation
Proprioception (I.e. equilibrium and balance of the body)
What is the occipital lobe responsible for
Visual processing and interpretation (Distance, depth perception, colour, object and face recognition)
Where is the hippocampus and what is its function
Embedded within the temporal lobe
Learning, memory formation and retrieval
REgulation of hypothalamus-pituitary-adrenal axis
What happens if there is hippocampal dysfunction
Anterograde amnesia - Unable to create new memories
Retrograde amnesia - Generally unable to recall past memories
What is the basal ganglia
Large and functionally diverse set of neural structures embedded deep within the cerebral hemispheres
Caudate, putamen globus pallidus
Describe basal ganglia functions
Regulation of movement
What happens with basal ganglia dysfunction
GABAergic neurons - Huntington’s disease
Dopaminergic neurons - Parkinson’s disease
What is the diencephalon
Between cerebrum and midbrain, consist of thalamus and hypothalamus
What is the diencephalon
Between cerebrum and midbrain, consist of thalamus and hypothalamus
Describe thalamic function
Thalamus contain lots of nuclei. Some nuclei relay between sensory and motor systems and the cerebral cortex.
Some nuclei regulate arousal and pain, mood, motivation and cognition
What is synaesthesia
Blending of information streams - Some people can ‘hear colour’ or ‘feel sounds’
Describe hypothalamic function
Smaller collection of nuclei
Some nuclei involved in homeostatic, reproductive and other diverse functions (fight/flight)
What happens in hypothalamic dysfunction
Hypothyroidism - Underproduction and release of thyroid
Hyperthyroidism - Excessive
What is the brainstem
Between diencephalon and spinal cord, comprises midbrain, pons and medulla oblongata
What does the midbrain do
Control of eye movements, auditory and visual processing
What do the pons do
Relay of motor information from cerebral hemispheres to medulla, spinal cord and cerebellum
What does the medulla oblongata do
Cardiovascular and respiratory homeostasis
Reflexive actions including vomiting swallowing coughing and sneezing
What is ‘brainstem dead’
Unable to regain consciousness or breath without life support
There is a loss of blood circulation to all brainstem regions
Describe locked-in syndrome
When you are awake and conscious but have no means of producing speech, limb or facial movements
Involves loss of blood circulation to pons
What is the function of the cerebellum
Detects differences in ‘motor error’ between intended and actual movement.
Helps the motor cortex to produce precise and co-ordinated movement
How are seal and other animal cerebellums similar to human’s
Cerebellum utilised in synchronisation of movement with musical rhythm. (e.g. seals doing tricks)
Name the vertebrae of the spinal cord and their location
Cervical vertebrae - Neck, C1-C7
Thoracic vertebrae - Ribs, T1-T12
Lumbar vertebrae - Lower back, L1-L5
Sacral vertebrae - Pelvic area, S1-S5
What is a dorsal root
Bundle of sensory neuron axons that carry sensory information into the spinal cord
What is a ventral root
Bundle of motor neuron axons that carry information away from the spinal cord to striated muscle
What is grey and white matter
Grey - Neuronal cell bodies divided into horns
White - axon bundles divided into columns.
Describe spinal cord function
Motor neurons innervate skeletal muscle allowing for movement. Also contains motor tracts that carry information for motor movement down from the brain.
Spinal cord also receives sensory information from the periphery of body and contains pathways by which sensory information is transmitted to the brain.
Describe tetraplegia
Full or partial loss of sensation and movement in all four limbs and torso (damage in cervical area)
Describe paraplegia
Full or partial loss of sensation and movement in both legs and torso
Caused by damage in the thoracic, lumbar or sacral areas
What is the meninges and describe its function
3 membrane layers covering the brain and spinal cord - Dura mater, arachnoid membrane and pia mater
Protection, passage of CSF, and support of cerebral and spinal blood vessels.
What is the ventricular system and describe its function
Comprises of CSF-filled spaces - Lateral ventricles, third ventricle, fourth ventricle
Protection of the brain, transport of nutrients and waste, regulation of buoyancy (through CSF)
What is the vasculatory system and describe its function
Two pairs of arteries suppliyng blood to the brain - Internal carotid and vertebral
Anterior circulation - Carotid arteries, supplies forebrain
Posterior circulation - Vertebral arteries, supplying brainstem, cerebellum and upper spinal cord
They deliver oxygen, remove CO2 and transport nutrients and waste
