intro to neurophysiology Flashcards
Which divisions act as a medium for the input to the CNS, and conduct impulses from the periphery to the brain and spinal cord?
Afferent division
How many sections is the efferent division split into, and what are the names?
2
Somatic Nervous system
Autonomic Nervous Sytem
What is the somatic nervous system composed of?
Motor neurons conduct the impulses to skeletal muscles.
What is the autonomic nervous system composed of?
Sympathetic and Parasympathetic:
controls Smooth and Cardiac muscles
and Exocrine and some endocrine glands
Enteric nervous system:
Digestive organs only
It can receive stimuli from both the efferent division and the digestive tract.
Which cells make up the nervous system? How do they differ?
Neurons:
>100 bil
basic structured
Mostly myelinated
Can generate an electrical potential
damage causes neurological disorders
Glial cells
2-10 times more
Dendrites and axons are absent
Not electrically excitable
both arise from the same precursors differ in function.
Describe a neuron’s structure and how each compartment relates to the following processes: input, integrative, conductive, and output.
input:
Dendrites- cytoplasmic extensions of the cell body.
The cell body comprises a nucleus, nissl bodies (RER and free ribosomes), mitochondria, neurofilaments, and Golgi bodies.
integrative:
Axon hillock- the region between the axon and cell body.
Conductive:
Axon- surrounded by axolemma and conducts the electrical potential to the telodendria.
Output:
It occurs at the terminal branches where a synapse is formed with another neuron or target organ. Hence presynaptic terminal and postsynaptic neuron.
What are the characteristics of neurons?
High metabolic rate- abundant mitochondria
Aerobic respiration- an abundant supply of glucose and oxygen
Longevity- formed during fetal development and remains functional.
Non-mitotic- lost in fetal development
Describe the structural classifications of neurons.
Unipolar
single primary process
carries somatosensory information- sense
Bipolar
Two distinct processes
retina and olfactory system
Multipolar
a single axon, multiple dendrites
vertebrates
Describe the functional classification of neurons.
Sensory neuron:
afferent
cell body found in the posterior root ganglion
interneuron:
in the spinal cord
conducts from sensory to motor
Motor neuron:
Efferent
Name the glial cells.
Central:
Astrocytes
Ependymal cells
Microglia
Oligodendrocytes
Peripheral:
Satellite cells
Neurolemmocytes (Schwann cells)
Describe the Astrocytes.
Star like
In contact with neurons and capillaries
BBB
Regulate tissue fluid composition/ ECF
Structural support
Replaces damaged neurons
Regulate neural development
Describe Ependymal cells
Simple cuboidal
cilia on apical surfaces
line cavities in brain (ventricles) and spinal cord (central canal)
Assist in conduction and circulation of CSF
Describe the microglia cells.
Small
Monocyte lineage
least common
immune functions
clear cellular debris and dead neurons
influence synaptic transmissions and synaptogenesis.
Describe Oligodendrocytes.
Round cells
Slender cytoplasmic extensions- wraps around CNS axons
Myelinates and Insulate axons
fastens nerve impulse conduction
Describe satellite cells
Flattened cells
clustered around neuronal cell bodies in the ganglion
Protect and regulate nutrients for cell bodies
Describe neurolemmocytes.
Myelinates axons
1 Schwann cell= one segment of the myelin sheath
Gaps- Nodes of Ranvier
Describe periphery myelination.
Schwann cell cytoplasm surrounds the axon.
Its membrane then enwraps the axon.
The membrane then becomes compacted.
Describe the relationship between the thickness of myelin and the speed of the conduction.
The thicker the myelin the faster the speed.
What are the functions of the gyrus and sulcus?
It creates folds and ridges in the brain separating it into different compartments or regions.
Allows the brain to fit into the cranium whilst providing a large surface area.
Describe the functional areas found in the frontal lobe of the brain.
Primary motor cortex (in the precentral gyrus just before the central sulcus)- voluntary movement
Premotor cortex- coordination of complex movements.
Frontal eye field
Motor speech area (Broca’s area)- Speech formation
Prefrontal association cortex- planning of voluntary activity, decision-making, and personality traits. Working memory?
Describe the functional areas of the parietal lobe.
Primary somatosensory cortex (postcentral gyrus)- sensation and proprioception
Somatosensory association area- spatial perception
Wernicke’s area- speech and writing understanding.
Gnostic area- integration of all sensory input, important in language
Describe the functional region in the Occipital lobe.
Primary visual cortex
Visual association area
Describe the functional regions of the temporal lobes.
Primary auditory cortex
auditory association area
Limbic association cortex- motivation and emotion and memory.
Describe the functional regions of the insula.
Primary Gustatory cortex- taste
Describe the structures found in the Diencephalon.
Thalamus- centers all information except olfactory and relays this information to different parts of the cerebrum
Hypothalamus
Epithalamus-Pineal gland- melatonin- sleep.
What are the names of the autonomic respiratory centers in the Pons? Explain their functions.
Pneumotaxic and Apneustic
Sets pace and rate
initiation of respiration
What is the function of the medulla?
Cardiac center and vasomotion nuclei.
sets heart rate and controls the total peripheral resistance.
Describe the cranial meninges.
Pia Mater:
innermost
thin. delicate areolar CT
Highly vascularize
tightly adheres to the brain
Arachnoid mater:
delicate web collagen and elastic fibers
arachnoid trabecular
Dura mater:
An external tough, dense, and irregular connective tissue
Fibrous layers: meningeal(deep) and periosteal
Explain how the ventricles protect the brain.
It contains the choroid plexus, a highly vascularised area in which the cavities are lined by ependymal cells.
The blood is used to produce CSF, which creates buoyancy and also regulates the environment of the neurons.
Describe the flow of CSF.
Lateral ventricles- 3rd ventricle- 4th ventricle into meninges and suprascapular spaces and then empties into the superior sagittal sinus.
