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The Nervous System (Different parts of the brain (cerebellum) (Frontal…
The Nervous System
Different parts of the brain (cerebellum)
Parietal lobe
Temporal lobe
Frontal lobe
Primary motor cortex
Directs voluntary movements
Occipital lobe
Parietal-occiptal sulcus
Lateral sulcus
Central sulcus
Sulci and gyri
Gyrus
Longitudinal fissure
Peripheral nervous system
Sensory
Specialised cells that detect changes inside or outside the body
General senses
Provide info about the body and its environment
Temperature, pain, touch, pressure, vibration and proprioception
Special senses
Smell, taste, sight, equilibrium (balance), and hearing
Specificity (type of stimulus)
The eye's visual receptors(very specific)- light only
Free nerve endings- non specific (chemical , pressure, temperature, trauma)
Types of sensory receptors
Tonic receptors
Always active
Slow adapting receptors (pain)
Change in rate when a change in stimulus occurs
Phasic receptors
Somatic
Nociceptors
Pain recpetors
Large receptive fields
3 main populations
All 3 activated by strong stimulus
Temperature, mechanical, chemical
free nerve endings
Myelinated axons- fast pain, prickling pain
Skin, joints, bones, blood vessels
Unmyelinated axons- slow pain, burning, aching sensations
Tonic receptors
Thermorecpetors
Skin, skeletal muscles, liver
Phasic recpetors
Mechanoreceptors
Twist
Stretch
Pressure
Touch
Three different types
Baroreceptors
Blood vessels, respiratory system
Type of stretch receptor
Monitor change in pressure
Phasic- respond rapidly to changes, then adapt
Proprioreceptors
Monitor position of joints, muscle contraction
3 types
Muscle spindles
Golgi tendon tension
Joint capsule- pressure and tension in joint
Tactile
Detect info about texture, shape pulsation
Fine touch- small receptive fields
Crude touch
Large recepetive fields
Simple or complex
Chemoreceptors
Phasic
Brain, carotid arteries, aorta
Detect changes in chemical concentration
Monitor pH, CO2 and O2 levels
Central Nervous System (CNS)
Brain
White and grey "matter"
Grey matter
Carries information from place to place
Rapid transport of neuronal signals
Myelinated axons
White matter
Signal integration and command initiation
Slower transport of neuronal signals
Cell bodies of neurons, neuroglia and unmyelinated axons
Parts of the brain
Cerebrum
Memory storage and processing
Conscious and subconscious regulation of skeletal muscle contraction
Conscious thought, intellectual functions
Cerebellum
Somatic motor patterns- movement of limbs
Adjusts output of other somatic motor centres in brain and spinal cord
Diencephalon
Hypothalumus
Centers controlling emotions, autonomic functions and hormone production
Thalamus
Relays and preocesses for sensory info
Brain stem (mesencephalon) (midbrain)
Processing of visual and auditory data
generation of reflexive sootic motor responses
Maintenance of consciousness
Pons
Information relayed via the pons to the cerebellum
Medulla Oblongatta
Relays sensory information to thalamus and other portions of the brain stem
Autonomic centres for visceral functions (cardiovascular, respiratory and digestive system activities)
Spinal cords
Limbic system
Functions:
Emotions
Links conscious functions of cerebral cortex with unconscious and autonomic functions
Facilitation of memory storage and retrieval
Functional rather than anatomical grouping
motivational system
Amygdaloid bodies
Link emotions to specific memories
Hippocampus
Retrieval of long term memories
Anatomy of a typical neuron
Nucleus
Oligodendrocyte
Cell membrane
Dendrite
Communication cells (incoming information)
Axon
telodendria
Synaptic terminals
Myelin sheath
Electrical insulation for the cell and increases the speed at which the electrical signals (action potentials) travel along the axon- speeds up rate of action
Cell body (soma)
Spinal cord
Posterior median sulcus
Shallow groove that runs down the centre of the dorsal surface
Anterior Median Fissure
Deep groove that runs down ventral surface
Enlargements
Thickened regions of the spinal cord associated with control of the limbs
Conus Medullaris
Conical tip, terminates at Filum Terminae
Cross section of the spinal cord
Dorsal roots
Contain axons of sensory neurons
Ventral roots
Contain axons of motor neurons
Relay information to effectors
Dorsal root ganglia
Small bulges near spinal cord
Contain axons of sensory neurons
Electrical activity of neurons
Resting membrane potential
Transmembrane potential of an undisturbed cell
-70 milli volts (mv)
Transmembrane potential
Electrical potential of the cell's interior relative to its surroundings
Membrane action potentials
Action potentials are nerve impulses
Propagated change in trans-membrane potential
Occur via "all or none" principal
A stimulus either triggers a typical action potential, or it does not produce one at all e.g. flushing of a toilet.
-60millivolts (mv)
More positive charge into cell = rapid depolarisation, to about +10 millivolts
Once we get to +30 milli volts, is when we have influx of positive potassium ions in the cell
When action meets the end of the membrane it reaches a synapse.
Structure of a synapse
Chemical synapse (abundant)
Involves a neurotransmitter
Electrical synapse (rare)
Direct physical contact between cells (gap junctions)
Peripheral Nervous System (PNS) (everything else)
Peripheral nerves
Afferent division
Sensory
Temperature
Pain
Approach central nervous system
Efferent division
Somatic motor
Autonomic motor
Sympathetic
Times of stress and panic, high activity
Parasympathetic
Rest and repose
Exit central nervous system