Nervous system Flashcards
Nervous system (NS) divisions and brief description?
NS - divided into the central nervous system (CNS - brain and spinal cord) and peripheral nervous system (PNS - rest of the nervous tissue around the body)
PNS
- somatic NS (external environment, voluntary control)
- autonomic NS (internal environment, involuntary control)
- enteric NS ( gut, involuntary)
ANS
- parasympathetic NS (rest and digest)
- sympathetic NS (fight or flight)
Main 3 functions of the nervous system?
- Sense information through sensory afferent nerves
- Integrate information in brain and spinal cord
- Act on information via motor (efferent) nerves
Name all cranial nerves
cn I - olfactory cn II - optic cn III - oculomotor cn IV - trochlear cn V - trigeminal cn VI - abducens cn VII - facial cn VIII - vestibulocochlear cn IX - Glossopharyngeal cn X - Vagus cn XI - accessory cn XII - Hypoglossal
Cranial nerve X. Name main 4 features
• Main location of parasympathetic motor and sensory
neurones
• Sensory neurones relay sensory info from baroreceptors
and chemoreceptors in the aortic arch, sensory receptors in the gut (hunger, fullness, discomfort) and lungs, skin, taste buds, proprioceptors in muscles of the neck and throat
• Motor neurones regulate cardiac muscle, smooth muscle in the gut, secretion of digestive fluids, smooth muscle lining the airways
• Note, the vagus also contains somatic neurones involved in neck and throat function (including swallowing and voice production)
Name regions where sympathetic and parasympathetic nerves originate
Sympathetic - T1-T12 and L1-L3
Parasympathetic - brain steam and sacral region
Spinal cord anatomy. Name some of the features
- Site of coordination between sensory neurones and motor neurones
- Dorsal root houses sensory neurones
- Anterior root houses motor neurones
- Interneurones can be found in the grey matter
- Ascending and descending tracts relay information to and from the brain
5 stages of spinal reflex
- A sensory receptor detects a stimulus
- An electrical signal is propagated along with the sensory pathway to the spinal cord
- Synaptic connections, via interneurons in the spinal cord connects the sensory neurone to the motor neurone. In a simple reflex, this will be one synapse
- An electrical signal propagates along with the motor
neurone(s) to the area that can respond effectively - An effector, usually skeletal muscle will contract appropriately to the stimulus
Neurone anatomy. Describe 3 main features
- Cell Body – contains the nucleus
- Dendrites – highly branched structures that receive messages into the neurone
- Axon – long, thin projection from the cell of a body that takes the nerve impulse towards another neurone, muscle fibre or gland cell.
Describe 3 types of neurones found in the body
- Multipolar – several dendrites and one axon (brain, spinal cord, motor neurones)
- Bipolar – one main dendrite and one axon (retina of the eye, inner ear, olfactory area of brain)
- Unipolar – dendrites are at one end of the axon instead of at the cell body (sensory neurones)
Describe main features of Neuroglia
• Smaller than neurones but 5 to 50 times more numerous
• Don’t generate action potentials
• Functions: structural support for neurones; provide
appropriate chemical environment; forming myelin sheath; removing cellular debris; regulating growth, migration and connection of neurones
• Damage or disease to neurones results in the spaces being filled by neuroglia (brain tumours derived from neuroglia divide quickly and can be very malignant)
• Makeup 50% of CNS
Glial cell types, their location in the nervous system and their function.
CNS
- astrocytes - support
- oligodendrocytes - insulation, myelin production
- microglia - immune surveillance and phagocytosis
- ependymal cells- creating CFS (sodium-rich, potassium-poor tissue fluid of the brain and spinal cord)
PNS
- Satellite cells - support
- Schwann cells - insulation and myelin production
Ion channel types. Name 5
- Sodium/potassium ATPase pump
- Leakage channels
- Voltage-gated channels
- Ligand-gated channels
- Mechanically gated channels
Neurotransmitters and receptors. Describe different effects Achetilcholine and Noradrenaline exhibit depending on receptors they bind to.
- In somatic NS, ACh is exitatory at NMJ (neuromuscular junction) - bind to nicotinic receptors
- In autonomic NS (PSNS branch) ACh acts as inhibitory not. on myocardium. - bind to muscarinic receptors
Adrenergic receptors are divided into 2 main types
(α and β)
- In the gut NA acts on muscle fibres of the gut blood
vessels to cause vasoconstriction (via α1 receptors)
- In skeletal muscle blood vessels NAcauses vasodilation (via β2 receptors)
- In the heart, NA excites cardiac muscle fibres (via β1
receptors)
• In the lungs, NArelaxes the muscle in the walls of
the airways (via β2 receptors)
Seratonin pathway
Acetylcholine pathway
Catecholamine pathway
