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
Describe the functions of the Autonomic nervous system.
• Visceral motor neurons regulating smooth muscle, glandular activity & cardiac
tissue
- Controls unconscious system
- Fight or flight or conserving
Gain understanding of the importance of membrane transport
- Phospholipid bilayer – barrier for selective movement
- Membrane proteins – peripheral, integral & glycoprotein
- Passive transport – no energy required to reach equilibrium
- Active transport – move solute against conc. gradient & requires ATP energy
Learn the different mechanisms, uses and overall structures of membrane transport
Membrane proteins
• Channel Proteins – gated or leaking channel
• Receptor Proteins – bind substance on peripheral protein to open up
channel/pore
• (Na-K) Pump Proteins – maintain resting potential via ATP –> ADP + P
energy driving out sodium & driving in potassium
(active transport)
Membrane Carriers
• Uniporter – high to low concentration ion channels (passive - one direction)
• Symporter – two substances in same direction (energy dissipated from 1st
substance in gradient direction drives 2nd IN) (sodium
transporter)
• Antiporter – two substances opposite direction, energy dissipated from 1st
substance in gradient direction drives 2nd OUT) (active
transport)
(Olfactory & Gastatory) To understand the special sensory organs functions and specific adaptations associated with each sensory modality and their unique cellular response to external environment
Olfaction (Smell)
• Glomeruli – group cells that pick up same type of smell
• Rod-shaped bipolar neurons in nasal cavity & turbinate bone
• Chemicals dissolve in mucus & stimulate nerve impulse through cribriform
late of the ethmoid bone into olfactory bulb in brain
• Jacobson’s Organ – ducts in nasal cavity to detect pheromone conc. in air
Gustatory (Taste)
• Taste buds send info to brain via CN 7 & 9
• Link directly to digestive system – salivation, diuresis, apnoea
• Aroma = taste + smell
(Vision) To understand the special sensory organs functions and specific adaptations associated with each sensory modality and their unique cellular response to external environment
Transparent media
• Cornea, acqueous humour, lens and vitreuos humour
• direct and converge light on the retina
Non-Transparent media
• Choroid, Uvea, Sclera
• Support transparent media
The photosensitive layer
• retina made up of rod and cones.
Light splits chemical compound
• Rhodopsin in cones & rods and triggers signal transduction via optic nerve.
(Ear) To understand the special sensory organs functions and specific adaptations associated with each sensory modality and their unique cellular response to external environment
Auditory Sound detection:
• Outer ear : Sound collected from external auditory canal to the tympanic
canal and tympanic membrane.
• Middle ear: Maleus , Incus and Stapes conducts sound to the oval window.
• Inner ear: Oval window transmit waves to the cochlea and then to the brain
through CN VIII.
Vestibular Balance and Motion – inertia causes fluid to bend cupula & hair cells
• Semicircular canals detect angular movement via hair cells
• Cupula – angular movement (CN VIII)
- Maculae detect linear acceleration via hair cells.
- Saccule (h)/Utricle (v)– linear movement 90 degrees (CN 7)
