Introduction to the Nervous System Flashcards
Briefly describe the Central nervous system
It is found in the encephalon and spinal cord, covered with a system of membranes (meninges) and it is suspended in cerebrospinal fluid
Anatomically, briefly describe the Peripheral nervous system
It is composed of the cranial and spinal nerves and their ganglia
In more depth, anatomically describe the central nervous system
It is composed of the;
- Spinal cord
- Brain Stem (medulla, pons and midbrain)
- Cerebellum
- Cerebrum (Telencephalon and Diencephalon)
Name and describe the Glial cells of the peripheral nervous system
Satellite cells (supports neurons) and Schwann cells (myelination cells)
Name and describe the Glial cells of the central nervous system
Oligodendrocytes (myelination, they are able to myelinate many neurons at a time), Astrocytes (important in the blood brain barrier), Ependymal cells (produce CSF) and microglial (remove dead or damaged cells)
Describe some of the features of myelin
It is an insultation material that is rich in lipids and proteins and makes conduction faster, therefore requiring less energy.
Describe the basics of neural communication
Neurons release vesicles full of neurotransmitters. The receptors for these are on the surface of another neuron. The release and binding of neurotransmitters occurs in a synapse. This communication can occur between axons and dendrites.
What is a ganglion?
It is a collection of nerve cell bodies outside of the central nervous system. The axons that enter these ganglia are called preganglionic fibres and axons that exit are called postganglionic fibres
Name the two gross appearances the nervous system has
White and grey matter
Describe grey matter
Predominately cell bodies of neruons, neuroglia (glial cells) and unmyelinated neurites (axons or dendrites)
Where ganglions are found in the PNS/ Nucleus in the CNS.
Describe the location of Grey and white matter in the brain and spinal cord.
Brain - Grey matter on the surface, white matter in the centre
Spinal Cord - White matter on the surface and grey matter in the centre
White - Usually myelinated axons
Describe the features of Afferent (sensory) and Efferent (motor) divisions
Afferent - transmits signals from the PNS to the CNS, comprised of sensory neurons.
Efferent - Transmits signals CNS to the PNS to cause a reaction, comprised of motor neurons
What does the somatic nervous system involve?
Innervation of the skeletal muscle which is voluntary.
What does the autonomic/visceral nervous system involve?
Innervation of the cardiac. smooth muscle and glands. Important for homeostasis and is involuntary.
What is the autonomic/visceral nervous system divided into?
The sympathetic and parasympathetic
Describe some of the features of the sympathetic nervous system
Activates the body under conditions of emergency - therefore causing pupils to dilate, increase the heart and respiratory rate and blood glucose levels, it causes vasoconstriction but dilates bronchial smooth muscle and induces sweating. The preganglionic sympathetic neurons are loacted in the T1-L2 spinal cord segments. It has short pre-synaptic fibres and long post-synaptic fibres.
Describe some of the features of the parasympathetic nervous system
It conserves body energy and maintains body activities at basal levels. Its preganglionic parasympathetic neurons arise from the brain stem and S2-S4. It has long pre-synaptic fibres and short post-synaptic fibres
What is an example of a neurotransmitter in the somatic nervous system and its effector organs
Acetylcholine which stimulates skeletal muscle
Name an example of a sympathetic NS neurotransmitter and its effector organ
Acetylcholine which stimulates the release of noradrenaline which causes an effect on smooth muscle, cardiac muscle and glands
Name an example of a parasympathetic NS neurotransmitter and its effector organ
Acetylecholine which stimulates the release of more acetylcholine which causes an effect on smooth muscle, cardiac muscle and glands
What is the encephalon and spinal chord protected by?
Bone, meninges and cerebro-spinal fluid (CSF)
Describe the features of Dura matter (outermost layer of the meninges)
It is the most superficial and touch,
Composed of two layers;
Inner meningeal and periosteal. These two layers are adherent except when they create the dural venous sinus.
Inwards septae of dura (dural partitions) secure the brain to skull, dampen movement of the brain in cranial cavity and divide cranial cavity into freely communicating compartments.
Describe the features of the arachnoid matter
Adhere closely to dura and are web-like in appearance
Describe the features of the pia matter
This is the deepest layer and is in direct contact with tissue of the CNS, it is highly vasuclar and enters every sulci
Name the spaces between the meninges layers
Epidural (extra dura) space - between dura and bone
Subdural - between dura and arachnoid
Subarachnoid - between arachnoid and pia (contains CSF and cerebral arteries)
What are the cerebral ventrical and where are they located?
They are interconnected spaces filed with CSF. This is where CSf is produced by ependmyal cells in the choroid plexus. There is a lateral ventrical found in the cerebral hemisphere, 3rd ventrical in the diencephalon, 4th ventrical in the brain stem and central canal in the spinal cord
Describe some of the features of cerebro spinal fluid
It is a clear cell-free fluid, produced by the choroid plexus found in the lateral and 3rd ventricle.
CFS passes from the ventricles to the subarachnoid space. It is then absorbed by arachnoid granulations into dural venous sinuses.
What are the bumps and dips called in the brain?
The bumps are called gyri (gyrus for singular)
Dips are called sulci (sulcus for singular)
Describe the features of the cerebrum
It is two hemispheres divided by a medial longitudinal fissure.
Each hemisphere consists of a cerebral cortex, cerebral white matter and nuclei
Name the different lobes of the cerebrum
Frontal lobe, Parietal lobe, Occipital lobe, Temporal lobe Limbic lobe Insula
Describe the functions of the cerebrum
Motor - primary motor and premotor areas in the frontal lobe
Sensory - Primary somatosensory and somatosensory association areas in parietal lobe
Vision - primary visual and visual association areas found in the occipital lobe
Auditory - primary auditory and auditory association areas in temporal lobe
What do the two hemispheres of the cerebrum
Left hemisphere is specialized for language and math skills.
Right hemisphere is specialized for visual-spatial skills and creativity.
Describe the function of the thalamus
Major relay station for:
Sensory impulses ascending to sensory cortex ,
inputs from subcortical motor nuclei and cerebellum travelling,
encolses the 3rd ventricle
Describe the function of the hypothalamus
It is autonomic control, endocrine control,
It regulates thirst (fluid electrolyte balance)
Eating (energy balance)
Sexual Reproduction behavior
Body temperature
Describe some of the functions of the midbrain
It has superior and inferior colliculi which are centres for visual and auditory reflexes
Red nucleus which is the centre for subcortical motor control
Substantia nigra which is involved in reward-seeking and motor learning
The midbrain also surrounds the
cerebral aqueduct
Describe some of the functions of the Pons
It is a conduction areas, providing connections between the forebrain and the cerebellum.
The nuclei found in the pons contribute to the regulation of respiration as well as hearing and balance.
Describe some of the functions of the medulla
It contains vital centres for regulating respiratory rhythm, heart rate and blood pressure.
It also contains no vital centres that regulate coughing, sneezing, swallowing and vomiting.
Describe some of the functions of the cerebellum
Composed of two hemispheres in cerebellar fossa. With internal grey matter, surrounded by white matter with an outer cortex of grey matter
It is connected to the brain stem by cerebellar peduncles
It processes and interprets impulses from motor cortex and sensory pathways and coordinates motor activity for movement (important in balance)
Describe some of the features of a section of cross sectioned spinal chord
It contains grey matter in an H-shape which contains neural cell bodies with different horns.
This grey matter is surrounded by white matter, this contains columns with a number of ascending and descending tracts. (Ventrical/anterior column, lateral columns and dorsal/posterior column)
Of the spinal cord name the different horns and their function
Dorsal/posterior horns - contains interneurons
Lateral horns - visceral/autonomic motor neurons
Ventrical/anterior horns - somatic motor neurons
How many cranial nerves are there?
12
