Anatomy of the Nervous System Flashcards
What is the human nervous system?
An extensive network of specialised cells that enables the body to react to continuous changes in its external and internal environments
What are other processes that the nervous system helps to control and integrate?
Various activities of the body, such as circulation, digestion and respiration
What is the estimated number of connections that the nervous system has?
Over 100 trillion
What is the nervous system structurally divided into and what are their components?
Central Nervous System (CNS): brain and spinal cord
Peripheral Nervous System (PNS): remainder of the nervous system outside of CNS
What can the nervous system be functionally divided into?
Somatic Nervous System (SNS)
Autonomic Nervous System (ANS)
What is the key role of the CNS?
Acts as the control centre, sending and receiving information to and from muscles, glands, organs and other systems in the body through the peripheral nervous system
How do the CNS, PNS and SNS work together?
Sensory/Visceral stimuli–> Afferent division to PNS–> Input to CNS from peripheral nervous system–> Brain and spinal cord (CNS) receive–> Output from CNS to peripheral nervous system–> Efferent division to somatic nervous system–> Motor neurones–> Skeletal muscle
How do the CNS, PNS and ANS work together?
Sensory/Visceral stimuli–> Afferent division to PNS–> Input to CNS from peripheral nervous system–> Brain and spinal cord (CNS) receive–> Output from CNS to peripheral nervous system–> Efferent division to autonomic nervous system–> Sympathetic or Parasympathetic nervous system–> Effector organ (glands, tissues, organs etc.)
What are the two classes of cells that the nervous system contains?
Nerve cells/neurons [N]: information-processing and signaling elements of the nervous system
Glial cells [G]: play a variety of supporting roles
What is the approximate number of neurons and glial cells in the nervous system?
~100 billion nerve cells and a similar number of glial cells
What are the names of the glial cells in the CNS?
Astrocyte
Ependymal cells
Microglial cells
Oligodendrocytes
What are the functions of astrocytes?
Help form the blood-brain barrier
Regulate interstitial fluid composition
provide structural support and organisation to the central nervous system (CNS)
Assist with neuronal development
Replicate to occupy space of dying neurones
What are the functions of ependymal cells?
Line ventricles of the brain and central canal of the spinal cord
Assist in production and circulation of cerebrospinal fluid (CSF)
What are the functions of microglial cells?
Phagocytic cells that move through the CNS
Protect the CNS by engulfing infectious agents and other potential harmful substances
What are the functions of oligodendrocytes?
Myelinate and insulate CNS axons
Allow faster action potential propagation along axons in CNS
What are the names of the glial cells in the PNS?
Satellite cells
Neurolemmocytes
What are the functions of satellite cells?
Electrically insulate PNS cell bodies
Regulate nutrient and waste exchange for cell bodies in ganglia
What are the function of neurolemmocytes?
Surround and insulate PNS axons and myelinate those having large diameters
Allows for faster action potential propagation along an axon in the PNS
What are the major divisions of the brain?
Forebrain (prosencephalon)
Midbrain (mesencephalon)
Hindbrain (rhombencephalon)
What are the parts of the forebrain and what are their roles?
Cerebrum: executive decisions, intellect, memory, movement
Diencephalon: consists of thalamus, hypothalamus and pituitary gland
What is the function of the thalamus?
Sensory relay and processing
What is the function of the hypothalamus?
Emotions, hormone control
What is the function of the pituitary gland?
Hormone regulation
What is the function of the midbrain?
Relay centre for auditory/visual pathways, controls eye movements
What does the hindbrain consist of and what are the functions of the constituents?
Cerebellum: posture, balance, equilibrium
Pons & Medulla oblongata: relay centres, visceral function regulation
What are the gyri (pl. of gyrus)?
Folds of the cerebral surface
What are the sulci (pl. of sulcus)?
Grooves between gyri
What is a fissure?
Deep groove
What are the three membranous layers of the meninges?
Pia mater
Arachnoid mater
Dura mater
What is the purpose of the meninges and cerebrospinal fluid?
The meninges and CSF surround the CNS and protect it
What is a nucleus in the CNS?
A collection of neuron cell bodies
What is a ganglia in the PNS?
A collection of nerve cell bodies (e.g., dorsal root ganglia, autonomic ganglia)
What is a tract?
A bundle of nerve fibres (axons) within the CNS connecting neighbouring or distant nuclei of the cerebral cortex
What is a nerve in the PNS?
A bundle of nerve fibres (axons)
How many spinal nervous system and what are their divisions?
31 pairs of spinal nerves:
8 Cervical nerves
12 Thoracic nerves
5 Lumbar nerves
5 Sacral nerves
1 Coccygeal nerve
How many pairs of cranial nerves are there?
12
How is the PNS organised?
Into nerves that connect the CNS with peripheral structures
What is significant about the autonomic nervous system?
Operates without conscious control
What is the function of the autonomic nervous system?
Regulates involuntary or unconscious activity such as heart rate, breathing, (as well as glands and internal organs) blood pressure, digestion and many other chemical processes that keep the body working
What are the key characteristics of the sympathetic nervous system (thoracolumbar division)?
Fight, flight or fright
Activated during exercise, excitement or emergencies
What are the key characteristics of the parasympathetic nervous system (craniosacral division)?
Rest and digest
Concerned with conserving energy
What is the relationship between the sympathetic and parasympathetic nervous systems?
PSNS and SNS are constantly working to shift the body to more prepared states and more relaxed states
What are the components of the forebrain?
Brain poles
Frontal lobe
Parietal lobules
Temporal lobe
Occipital lobe
Thalamus
Hypothalamus
Pituitary gland
What does the hindbrain consist of?
Cerebellum
Medulla oblongata
Pons
What does the spinal cord consist of?
Gray matter
White matter
Which nerves are in the nervous system?
Cranial nerves
Spinal nerves
