Neurology Flashcards
Understand that control mechanisms may be local (paracrine/ autocrine) or distant (endocrine/neural).
Multicellular animal do not operate in isolation, but their function is co-ordinated.
Local - unicellular organisms (all the same cell type) and multicellular.
Distant - Increased size and complexity of animals requires long distance communication
Contact-dependant
Local - Signal to adjacent cell, immediately ‘handed’ to target cell/pore
Paracrine
Local - inflammation, recruit cells and other types of cells via soluble messengers
Autocrine
Local - Signal cell is the target cell (cells that are terminally differentiating themselves into a specific cell type)
Endocrine
Distant - secretes a signalling molecule carried in blood e.g. hormones
Synaptic
Distant - neuronal signalling, signal transmitted down neurone and passed to target cell
Describe the relative advantages of endocrine versus neural control and visa versa.
Neural - Fast (action potential), energetically expensive, targeted (effector organs)
Endocrine - Slow (blood stream), cheap & widespread
List the different parts of the nervous system.
Central Nervous System (CNS)
• Brain
• Spinal cord
Peripheral Nervous System • Somatic (voluntary) • Autonomic (involuntary) • Sympathetic (fight or flight) • Parasympathetic (conserve)
Classify the Nervous System according to morphology and physiology
Morphology
• CNS – Brain & Spine
• PNS – Cranial & Spinal Nerves
Physiology • Somatic – voluntary • Visceral – vegetative • Direction of flow of info • Afferent – sensory (towards CNS) • Efferent – motor (away CNS)
Describe the general function of the Nervous System
- Receive stimuli from external & internal environments
- Analyse & integrate stimuli
- Produce a necessary response
Describe the functional unit of the Nervous System
Neurons – transmission of nerve impulses through nervous tissue
• Soma – cell body w/ nucleus & organelles
• Dendrites – short processes that conduct impulses to cell body
• Axon – relay impulses away from soma to other neurons
- Axon hillock – axon leaves cell, where action potential is generated
- Schwann cells – produce myelin sheaths
- Node of Ranvier – spaces between myelin, accelerate speed of AP
- Terminal button – neurotransmitter stored in synapse bulb
List the different cell types in the CNS.
Neurons
• Pseudounipolar – sensory (long major dendrite)
• Bipolar – sensory (short major dendrite)
• Multipolar – motor (no major dendrite)
Neuroglia
• Astrocytes – support, nutrition & structure
• Oligodendrocytes – insulate brain axons & prevent ion leakage
• Microglia – remove necrotic material
Explain the source supply of blood to the brain.
• From the heart via Internal carotid arteries
• Blood is pooled into the cerebral arterial circle (Circle of Willis) before
distribution to the brain.
• From the circle that blood vessels penetrate into brain tissue supplying
capillary blood
Explain the source and function of CSF.
- Ventricular system – cerebral hemispheres, central canal of spinal cord
- Ventricles (cavities) in CNS lined with ependymal epithelium
- Ependymal cells produce & secrete CSF from choroid plexus
- Function – provides nutrition, support, and shock protection
Describe the components of the somatic nervous system.
- Spinal nerves – carry sensory info into and motor info out of spinal cord
- Cranial nerves – carry sensory info into and motor info out of brain stem
Describe a typical signal transduction route in SNS
- Joint/skin/skeletal muscle pick up stimuli
- Somatosensory fibres passes information to CNS (brain/spinal cord)
- Sensory neuron synapses with motor neuron in CNS
- Somatomotor fibres send information to effector organs (skeletal muscle)
Describe a simple reflex arc in SNS
- Fixed involuntary response to certain stimuli
- Rapid automatic nerve pathway through spinal cord only (not brain)
- Prompt response for protection
Reflex arc
• Stimuli picked up externally
• Initiates nerve impulse along somatosensory nerve fibres to spinal cord
• In spinal cord grey matter the sensory neuron synapses with motor neuron
• Impulse passed along somatomotor fibres to effector organ & responds
List the various somatic receptors, their location and sensations involved
Golgi tendon organs - Tendons
Muscle spindles- Muscles
Meisnners corpuscles - Skin (light touch)
Merkel’s disks - Skin (touch & texture)
Pacinian corpuscle - Pain & Deep Pressure
Ruffini corpuscle- Stretch/Kinaesthesia
Free nerve endings - Pain
Nerve endings in joints - Position
Describe the components of the autonomic nervous system
Origin of Nerve Fibre
S - Vertebrae (T1 – L4/5)
P - Cranial (III, VII, IX, X) & Vertebrae (S1/2)
Preganglionic Nerve Fibre
S - Short, close to vertebrae, ganglia chain on each side
P - Long, close to organ, no ganglia chain
Postganglionic Nerve Fibre
S - Long, down ganglia chain
P - Short, from ganglion to organ
Transmitter substance between neurons
S - Acetylcholine
P - Acetylcholine
Transmitter substance at effector organ
S - Noradrenaline
P - Acetylcholine
General effect
S - Fight or flight – everything increases & dilated
P - Relax – everything slows to conserve
List the subdivisions of the Autonomic nervous system.
- Sensory division –> PNS –> CNS
- CNS –> PNS –> MOTOR –> Somatic OR Autonomic
- Autonomic –> Sympathetic OR Parasympathetic
