The nervous system Flashcards
What is neurology?
the branch of medical science that deals with normal functioning and disordered of the nervous system
What does the central nervous system consist of?
the brain and spinal cord
What are the components of the PNS?
nerves, ganglia, enteric plexuses, sensory receptors
What is the peripheral nervous system divided into?
-the somatic nervous system
-the autonomic nervous system
-enteric nervous system
What does the somatic nervous system consist of?
sensory neurons that conduct impulses from somatic and special sense receptors to the CNS and motor neurons from the CNS to skeletal muscles
What does the autonomic nervous system consist of?
sensory neurons from visceral organs and motor neurons that convey impulses from the CNS to smooth muscle tissue, cardiac muscle tissue, and glands
What branches does the autonomic nervous system consist of?
-sympathetic nervous system
-parasympathetic division
What does the sympathetic division do?
supports exercise and emergency actions or flight or fight response
What does the parasympathetic nervous system do?
takes care of rest and digest activities
What does the enteric nervous system consist of?
-neurons in enteric plexuses in the gastrointestinal tract that function somewhat independently of the ANS and CNS
-it monitors sensory changes in and controls operation of the GI tract
What are the 3 basic functions of the nervous system?
- detecting stimuli
- analysing, integrating and storing sensory information
- responding to integrative decisions
What are neurons?
cells specialised for nerve impulse conduction and provide most of the unique functions of the nervous system e.g sensing, thinking, remembering, controlling muscle activity
What are neuroglia cells? Give examples
-support nourish and protect the neurons and maintain homeostasis in the interstitial fluid that bathes neurons
-astrocytes, oligodendrocytes, microglia, ependymal
-in the parasympathetic NS includes Schwann cells and satellite cells
What are the 3 parts of neurons?
-the dendrites
-cell body
-axons
What are the 3 classifications of neurons?
-multipolar
-bipolar
-unipolar
What are sensory neurons (afferent)?
-carry information into the CNS
What are motor neurons (efferent)?
carry information out of the CNS to effectors (muscles and glands)
What are interneurons? (Relay)
located within the CNS between sensory and motor neurons
What is white matter compared to grey matter?
-white matter is composed primarily of myelinated axons
-grey matter contains neuronal cell bodies, dendrites, axon terminals, unmyelinated axons and neuroglia
What is a ganglion?
Refers to a cluster of neuronal cell bodies located in the PNS, closely associated with cranial and spinal nerves
What is a nerve?
-a bundle of axons that is located in the PNS
what are cranial nerves and spinal nerves?
-cranial nerves= connect the brain to the periphery
-spinal nerves= connect the spinal cord to the periphery
what is a tract?
a bundle of axons that is located in the CNS, they interconnect neurons in the spinal cord and brain
What is an action potential?
generation of action potentials depends on the existence of a membrane potential and the presence of voltage-gated channels for sodium and potassium
What is the resting membrane potential?
-70mV
How does the resting membrane potential rise?
An unequal distribution of ions on either side of the plasma membrane and a higher membrane permeability to K+ than to Na+. The level of K+ is higher inside and the level of Na+ is higher outside, a situation that is maintained by sodium–potassium pumps.
What happens during an action potential?
voltage-gated Na+ and K+ channels open in sequence. Opening of voltage-gated Na+ channels results in depolarization, the loss and then reversal of membrane polarization (from –70 mV to +30 mV). Then, opening of voltage-gated K+ channels allows repolarization, recovery of the membrane potential to the resting level.
What is synaptic transmission?
neurons communicate with other neurons and with effectors at synapses in a series of events
What is an excitatory neurotransmitter?
depolarizes the postsynaptic neuron’s membrane, brings the membrane potential closer to threshold, and increases the chance that one or more action potentials will arise.
What is an inhibitory neurotransmitter?
hyperpolarizes the membrane of the postsynaptic neuron, thereby inhibiting action potential generation.
Give examples of important neurotransmitters?
acetylcholine, glutamate, aspartate, gamma aminobutyric acid (GABA), glycine, norepinephrine, dopamine, serotonin, neuropeptides, and nitric oxide.
What is the spinal cord?
-spinal cord contain neural pathways that control some of your rapid reactions and environmental changes
What are the different layers of the spinal cord which protect and cover it?
-vertebral column protects the spinal cord
-meninges are three layers of connective tissue coverings around the brain and SC
-dura mater (outermost)
-arachnoid mater (middle layer)
-pia mater (innermost)
-cerebrospinal fluid (CSF) circulates in the subarachnoid space
What is the length of the adult spinal cord?
42-45cm
What is a reflex arc?
the pathway followed by nerve impulses that produce a reflex
What are the 5 basic components of a reflex?
- sensory receptor
- sensory neuron
- integrating centre
- motor neuron
- effector
What are the 4 major parts of the brain?
- brain stem
- diencephalon
- cerebrum
- cerebellum
What does the brain stem consist of?
-its continuous with the spinal cord
-consists of the medulla oblongata, pons, and midbrain
What is cerebrospinal fluid?
-a clear, colourless liquid that carries oxygen, glucose, and other chemicals to neurons and neuroglia and removes their wastes and toxic substances
What does cerebrospinal fluid do?
it protects the spinal cord from chemical and physical injury
What is the function of the medulla?
regulates the rate and force of the heartbeat and the diameter of blood vessels
What does the medullary respiratory centre do?
adjusts the basic rhythm of breathing
What are the two types of nuclei in the midbrain?
-red nuclei= reddish due to rich blood supply and iron
-substantia nigra= large and darkly pigmented, loss of these neurons associated with Parkinson’s disease
What are the major regions of the diencephalon in the brain?
-thalamus
-hypothalamus
-pineal gland
What is the function of the thalamus?
major relay station for most sensory impulses that reach cerebral cortex
What is the function of the hypothalamus?
controls and integrates activities of the autonomic nervous system, pituitary gland, regulation of emotion and eating and drinking
What is the function of the pineal gland?
secretes the hormone melatonin
What is the function of the cerebellum?
to compare intended movements programmed by the cerebral cortex with what is actually happening, receiving sensory impulses from muscles, tendons joints, and visual receptors
What is the function of the cerebrum?
-consists of the cerebral cortex
-allows us to read, write, speak, remember and create
What 4 lobes does the right and left cerebral hemisphere have
-frontal lobe
-parietal lobe
-temporal lobe
-occipital lobe
What is the function of the limbic system?
controls emotions including pain, pleasure, docility, affection, and anger
What is the difference between the left and right side of the brain?
-left side controls the right side of the body
-left hemisphere responsible for spoken and written language, numerical and scientific skills and reasoning
-right side controls the left side of the body
-right side involved with spatial and pattern recognition and emotional content
What are cranial nerves?
-apart of the parasympathetic nervous system
-there are 12 pairs and are designated with roman numerals and with names
What is the role of cranium nerve 1, the olfactory nerve?
-in the lining of the nose
-allows smell
What is the role of cranium nerve 2, the optic nerve?
-in the retina of the eye
-allows vision
What is the role of cranium nerve 3, the oculomotor nerve?
-axons of somatic motor neurons that stimulate muscles of the upper eyelid and four muscles that move the eyeballs
-movement of upper eyelid and eyeball, altering shape of lens for near vision and constricts pupils
What is the role of cranium nerve 4, the trochlear nerve?
-axons of somatic motor neurons that stimulates the superior oblique muscles
-movement of the eyeball
What is the role of cranium nerve 5, the trigeminal nerve?
-has 3 branches (tri)
-touch pain temperature sensations and muscle sense
What is the role of cranium nerve 6, the abducens nerve?
-axons of somatic motor neurons that stimulates the lateral rectus muscles
-movement of eyeballs?
What is the role of cranium nerve 7, the facial nerve?
-axons from taste buds on tongue and axons from proprioceptors in muscles of face and scalp and neck muscles, plus parasympathetic axons that stimulate lacrimal glands and salivary glands
-facial expressions, secretion of tears and saliva
What is the role of cranium nerve 8, the vestibulocochlear nerve?
-axons from semicircular canals, saccule, and utricle
-equilibrium
What is the role of cranium nerve 9, the glossopharyngeal nerve?
-axons from taste buds and somatic sensory receptors on part of tongue from proprioceptors in some swallowing
-taste and somatic sensations (touch, pain), monitoring blood pressure, oxygen and carbon dioxide
What is the role of cranium nerve 10, the vagus nerve?
-axons from taste buds in throat
-taste and somatic sensations (touch, pain), monitoring blood pressure, oxygen and carbon dioxide
What is the role of cranium nerve 11, the accessory nerve?
-axons of somatic motor neurons that stimulates the sternocleidomastoid and trapezius muscles of the throat and neck
-movements of head and shoulders
What is the role of cranium nerve 12, the hypoglossal nerve?
-axons of somatic motor neurons that stimulates muscles of the tongue
-movement of tongue during speech and swallowing
What does the autonomic nervous system regulate?
-smooth muscle
-cardiac muscle
-certain glands
What brain regions control the autonomic nervous system?
-hypothalamus
-brain stem
what does the somatic nervous system control?
-sensory neurons convey input from receptors for special senses (visual, hearing, taste, smell, equilibrium) and from receptors for somatic senses (pain, temperature, touch and proprioceptive sensations)
How and where does autonomic motor neurons regulate activities?
-in their effector tissues (cardiac and smooth muscle) and glands
-by excitation and inhibition
What is dual innervation?
-when organs receive impulses from both sympathetic and parasympathetic neurons
-nerve impulses from one division stimulate the organ to increase its activity (excitation) and impulses from other division decrease the organs activity (inhibition)
