TP5 Nervous System Flashcards
Describe the two components of the nervous system
Central nervous system (CNS): Brain and spinal cord
Peripheral nervous system (PNS):
- Sensory and motor nervous system
- Nerve fibres extending to other parts of body
- Afferent (sensory) division - carries info from sensors to CNS
- Efferent (motor) division - transmits info from CNS to effector organs
Describe somatic and autonomic subdivisions of the nervous systems
- Subdivisions of motor neurons
- Somatic controls voluntary movements
- Autonomic controls involuntary movements
Describe the functions of the nervous system
- Co-ordination of physical activity (homeostasis and locomotion)
- Interpret information gathered by the sensory system.
Describe the sympathetic and parasympathetic subdivisions of the nervous system
- Subdivisions of the autonomic nervous system
- Sympathetic division controls fight or flight
- Parasympathetic division controls rest or digest
Describe the typical structure of a neuron
- Excitable cells - transmit electrical signals. Produce and conduct electrochemical impulses.
- Release chemical regulators
- Cannot divide by mitosis
Function of the cell body of a neuron
Controls metabolism of the cell
Description of the terminals
End of the axon
Description and function of the dendrites
- Conducts electrical impulses towards the cell body
- Collects info from cells, passes to cell body
Description and function of the terminal branches
- Branches of the axon
- Carry impulses to synaptic knobs
Description and function of the axon
- Conducts impulse away from cell body
- Carry impulses away from cell body over long distances
Description and function of the Nissl body
- Rough ER
- Processes proteins
Description and function of the Nodes of Ranvier
- Myelin-free gaps between the Schwann cells
- Allows rapid conduction of impulses - forces them to jump
Description and function of the Axon hillock
- Where axon starts
- Start of axon potential
Description and function of the Schwann cell
- Glial cell covering the axon
- Inner layer forms myelin sheath
Function of the myelin sheath
Insulation prevents distortion of impulses
List the different neuron structure classifications
- Unipolar
- Bipolar neurons
- Pseudounipolar
- Multipolar (most common)
List the different neuron functional classifications
- Sensory (afferent): Transmits impulses towards the CNS
- Motor (efferent): carry impulses away from CNS
- Interneurons: shuttle signals through CNS pathways
Describe afferent neurons
- sensory receptor - at peripheral end
- peripheral axon - extends sensory receptor to cell body
- cell body - in dorsal root ganglion outside CNS
- central axon - extends from cell body to spinal cord
Describe efferent neurons
- Dendrites and cell body in CNS
- Axon - projects to effector organ
Describe interneurons
- Lie entirely within the CNS
- Integration of peripheral responses to peripheral information
Describe glial cells
- Connective tissue of the CNS
- Do not initiate or conduct nerve impulses
- Maintain composition of the ECF environment surrounding neurons
- Important in learning and memory
List and describe the four types of glial cells
- Astrocytes: support neurons
- Oligodendrocytes: myelin sheaths
- Ependymal cells: form cerebrospinal fluid
- Microglia: immune defense of CNS
Describe polarization
Charges are separated across plasma membrane
Describe depolarisation
Membrane less -ve
Describe repolarisation
Membrane returns to resting potential after being depolarised
Describe hyperpolarisation
Membrane is more -ve than resting potential
Describe the conditions during resting membrane potential
- Plasma membrane polarised - more +ve ions outside than inside - maintained by Na+/K+ pump
What is the value of a resting membrane potential
-70mV
Describe the conditions of a cell/nerve at rest
- Membrane relatively impermeable to ions: Na+/K+ will not freely diffuse
Describe the conditions of a cell/nerve at stimulation
- Ion channels open = ions move = influx of Na+
Describe an action potential
- Occur due to movement
- Brief and rapid
- threshold potential not reached = no action potential
List the steps in an AP
- Depolarisation
- Repolarisation
- Hyperpolarisation
- Return to rest
What determines the rate of impulse propagation
- Axon diameter: larger = faster
- Presence of myelin sheath = faster
Describe the two types of conduction
- Contiguous conduction: neurotransmission of action potentials along unmyelinated fibres
- Saltatory conduction: current jumps from node to node
Describe pre and post synaptic neurons
- Pre-synaptic neuron: conducts impulses towards synapse
- Post-synaptic neuron: transmits impulses away from synapse
List the two types of transmission signals
- Electrical: direct
- Chemical: indirect (much slower)
Describe the GABA neurotransmitter
- Gamma aminobutyric acid
- Inhibitory neurotransmitter in the brain
- opens CL- channels, Indirectly opens K+ and blocks Ca2+ channels
Describe the Glutamate neurotransmitter
- Excitatory neurotransmitter in the brain
- learning and memory
Describe acetylcholine (ACh)
- Fast excitatory neurotransmitter
- Released in the PNS (neuromuscular junction) and CNS (synapses in the brain/spinal cord)
List some of the most common neuropeptides
- Catecholamines: dopamine and noradrenaline/adrenaline
- Indolamines: serotonin and histamine
List the major subdivisions and components of the brain
- Brainstem: midbrain, pons, medulla oblongata
- Cerebellum
- Forebrain: hypothalamus, thalamus, pituitary, cerebellum
List and describe the structures protecting the CNS
- Bony structures: cranium and vertebral column
- Meninges: 3x membrane between brain and nervous tissue
- Cerebrospinal fluid (CSF)
- Blood-brain barrier: junctions between capillary endothelial cells
List the three meninges
- Dura mater
- Arachnoid mater
- Pia mater
Describe cerebral ventricles
- Spaces within the brain: connected and continuous with the spinal cord
Describe the role of CSF
- Shock absorption / mechanical trauma
- Exchange of materials between neural cells and ISF
Describe the role of the BBB
- Highly selective - exchanges across capillaries in brain strictly regulated and limited
- BBB acts to limit exchange
Describe White matter in the brain
- dense collections of myelinated fibres
Describe Grey matter in the brain
- mostly cell bodies, dendrites and unmyelinated fibres
List the four main lobes of the cerebrum and their functions
- Frontal: voluntary motor activity, planning, reasoning
- Parietal: receives and integrates sensory information, movement
- Temporal: hearing, smell, learning, memory
- Occipital: visual center
Describe the roles of the Sulci and gyri
The sulci and gyri are the grooves and folds in the brain increasing the S.A. in mammals
Describe the inner and outer layer of the cerebrum
Inner layer consists of the basal nuclei/cerebral medulla
Outer layer - cerebral cortex consists of three functional types of cortexes: motor, sensory, association
List the regions of the brain involved with the control of movement, memory formation, storage and emotion
Frontal lobe and temporal lobe
List the regions of the brain involved with receiving information
Primary motor cortex and somato-sensory
Describe the role of the Thalamus
- Relaying and processing/filtering sensory information
- Role in motor control
- Acts as filter for info
Describe the role of the hypothalamus
- Regulates many homeostatic functions:
- temp, thirst, urine, food intake
- links nervous and endocrine systems
- involved in emotion and behaviour
- Sleep and emotions
Describe the role of the cerebellum
- coordinating and modulating motor commands
- balance
- posture
- co-ordination and planning skilled voluntary
muscle activity
- Posture and balance
Where do cranial nerves come from?
Cranial nerves come directly from the brain
How many pairs of cranial nerves are there?
12 pairs - 2x from forebrain and 10x from mid/hind brain
List the different cranial nerves
- Olfactory: smell (sensory)
- Optic: vision
- Oculomotor: Eye movement (motor)
- Trochlear: Eye movement (motor)
- Trigeminal: Mastication, speech, facial sensation (both)
- Abducens: Eye movement (motor)
- Facial: Facial movements (both)
- Vestibulocochlear: Hearing and balance (sensory)
- Glossopharyngeal: swallowing, muscles and taste (both)
- Vagus: motor control (both)
- Accessory: head, shoulders and neck movement (motor)
- Hypoglossal: Tongue movement (motor movement)
Where is the spinal cord located?
Within the spinal canal of the vertebral column
Describe the structure of the end of the spinal cord
Spinal cord ends in lumbar region and fans out
Describe the structure of the epidural space
Meninges, like in the brain but dura mater not fused to bone
Describe the grey matter of the spinal cord
- “Horns”
- Dorsal: interneuron cell bodies
- Ventral: motor neuron cell bodies
- Lateral: autonomic nervous system
Describe the White matter of the spinal cord
- “columns”
- Axons
- Grouped into tracts of common locations and functions
What are the roots of the spinal cord?
Connecting points between spinal nerves and spinal cord
Describe the function of the spinal cord
- Links the brain and body
- integrates information without brain input
Describe the process of a typical reflex arc
- Receptor -> 2. Afferent pathway -> 3. Integration center -> 4. Efferent pathway -> 5. Effector
List the two types of reflex arcs
Monosynaptic and polysynaptic reflexes
List the main structures of the autonomic nervous system
- smooth, cardiac muscles, glands
List the functions of the autonomic nervous system
- Regulates all body systems
- Including skeletal muscle since muscles contain blood vessels
List the main functions of the sympathetic system
- Prepares for strenuous physical activity in emergency situations
- Heart rate increases
- Respiratory airways open
- Glycogen and fat stores broken down
- Blood vessels supplying skeletal muscles dilate
- Pupils dilate
List the main functions of the parasympathetic system
- General housekeeping activities in relaxed situations
- Digestion
- Emptying urinary bladder
