CNS and PNS Flashcards
where are the respiratory centres in the brain?
in the brainstem: medulla and pons
which brainstem centres generate the respiratory pace?
respiratory rhythmicity centres in the medulla oblongata
what are the little branches across the subarachnoid space called?
arachnoid trabeculae
what are the outer dura mater and the inner dura mater also known as?
outer dura mater = endosteal layer
inner dura mater = meningeal layer
what is another name for the epidural space?
the dural sinus
what are the three layers of the meninges called?
dura mater
arachnoid mater
[subarachnoid space (CSF)]
pia mater
which branch of the ANS has long pre-ganglionic fibres and short post-ganglionic?
parasympathetic
how is the autonomic nervous system divided?
sympathetic nervous system
parasympathetic nervous system
which branch of the ANS has short pre-ganglionic fibres and long post-ganglionic fibres?
sympathetic
in which branch of the ANS do pre-ganglionic fibres release acetylcholine?
both
in which branch of the ANS do the post-ganglionic fibres release noradrenaline?
sympathetic
in which branch of the ANS do the post-ganglionic fibres release acetylcholine? what is its effect?
parasympathetic
may increase or decrease activity of effect (slows heart rate; increases motility)
what is special about cranial nerve x?
it’s the only non local cranial nerve
describe the blood supply to the brain
two internal carotid arteries
two vertebral arteries - join to form basilar artery
all join to form the arterial circle of Willis
identify the neuroglia (glial cells) of the CNS
ependymal cells
astrocytes
oligodendrocytes
microglia
between which two layers of the meninges is the CSF?
CSF is in the subarachnoid space between the arachnoid mater and the pia mater
which glial cell protects the CNS from chemical and hormones circulating in the blood?
astrocytes maintain the blood brain barrier
what three things protect the brain from mechanical forces?
cranium bones, cranial meninges, CSF
which neuroglia in the CNS myelinated and stabilise axons?
oligodendrocytes.
each one will myelinated several axons; each axon is myelinated by several oligodendrocytes
describe the neurilemma
the outer surface of a Schwann cell when it covers an axon is called the neurilemma
what are the anatomical divisions of the nervous system?
the CNS and the PNS
what are the functional divisions of the PNS?
the afferent division brings sensory information to the CNS from receptors in peripheral tissues and organs
the efferent division carries motor commands from the CNS to muscles, glands and adipose tissue (effectors)
SAME
what are the components of the efferent division of the PNS and what effectors do they regulate?
the somatic nervous system(controls both voluntary and involuntary contractions of the skeletal muscles) and the autonomic nervous system (regulates smooth muscle, cardiac muscle, glandular secretions and adipose tissue at the subconscious level)
how is the ANS divided?
into the sympathetic and parasympathetic divisions
name the effectors of the ANS
smooth muscle
cardiac muscle
glands
adipose tissue
which neuroglia appear in increased numbers in a person with a brain infection?
microglia - they are small mobile cells that remove cellular debris, wastes and pathogens by phagocytosis
they’re related to macrophages and monocytes
describe the function of ependymal cells
they form an epithelium known as the ependyma which lines a fluid filled passageway in the CNS
it’s known as the central canal in the spinal cord and the ventricles in the brain
the cavity is filled with CSF; ependymal cells help to produce, monitor and circulate the CSF
what is the role of astrocytes besides maintaining the blood-brain barrier?
creating a 3D framework for the CNS and regulating the interstitial environment
contrast the white matter and grey matter in the CNS
white matter dominated by myelinated axons
grey matter is areas dominated by cell bodies, dendrites, unmyelinated axons
what are the neuroglia of the peripheral nervous system? what are their roles?
satellite cells - surround neuron cell bodies in ganglia and regulate the environment (like astrocytes in the CNS)
Schwann cells - myelinate peripheral axons or else wrap around an axon to protect it without myelinating it
what type of compounds can easily cross the blood-brain barrier?
lipid soluble compounds (oxygen, carbon dioxide, lipids, ammonia)
define nerve fibre
the axon of a neuron
why is a CNS neuron not usually replaced after it is injured?
most CNS neurons lack centrioles and cannot divide
is the grey matter on the outside or the inside of the brain?
the outside
where are most interneurons found?
in the CNS
define soma
neuron cell bodies
what percentage of neurons do interneurons make up?
about 99% of all neurons
what does grey matter do?
processes information
grey matter = computer
white matter = cables
what are the major components of the CNS?
the brain and spinal cord
what is the role of interneurons?
they’re responsible for the analysis of sensory inputs and coordination of motor outputs
what is a sensory neuron also known as?
an afferent neuron
in which part of the nervous system does Wallerian degeneration occur and what does it involve?
the PNS
involves the repair of damaged nerves but often fails to restore full function
limited regeneration can also occur in the CNS but it’s more complicated there
what is a reflex?
a rapid, automatic response triggered by specific stimuli
define spinal reflex
spinal reflexes are controlled in the spinal cord and can function without any input from the brain
how many pairs of nerves does a typical spinal cord have?
31
where does the spinal cord end?
between vertebrae L1 and L2 (cord is not as long as the vertebral column)
describe the gross anatomical features of a cross section of the spinal cord
- the anterior median fissure - a deep groove along the anterior surface
- the posterior median sulcus - a shallow longitudinal groove
- white matter - dominated by myelinated axons
- grey matter - cells bodies of neurons, neuroglia, unmyelinated axons (deep to the white matter)
- the central canal (containing CSF)
- a posterior root of each spinal nerve (contains the axons of sensory neurons)
- the anterior root of each spinal nerve (contains the axons of motor neurons)
- posterior root ganglia (contains cell bodies of sensory neurons)
- spinal nerves (containing the axons of sensory and motor neurons)
where do sensory and motor neurons become a single nerve?
distal to each dorsal root ganglion
via which root does the motor nerve exit the spinal cord?
ventral or anterior root (at the front)
where are most of the cell bodies of most motor neurons found?
in the CNS
via which root does sensory information enter the spinal cord?
the dorsal (posterior) root
