Nervous system: Structure Flashcards
cell body of neurone
contains nucleus and ribosomes
dendrites
receive inputs
dendritic spines
knob-like outgrowths
increase surface area
contain ribosomes
axon
long process extending from cell body (soma)
transmits outputs to target cells
initial segment
trigger zone for action potentials
axon collateral
signal can go sideways
axon terminal
end of branch
varicosities
bulging areas where signals can be released
contain neurotransmitters and mitochondria
what is myelin made by in the CNS vs in the PNS
oligodendrocytes vs schwann cells
types of axonal transport
anterograde and retrograde
use microtubules as tracks and motor proteins and transport vehicles
anterograde transport
from cell body to axon terminal
via kinesins (motor protein)
nutrients, vesicles containing neurotransmitters
retrograde transport
axon terminals to cell body
dyneins (motor protein)
recycled membrane vesicles, growth factors
3 functional classes of neurones
afferent
efferent
interneurones
afferent neurones
convey info from tissues/organs TOWARDS CNS
efferent neurones
convey information AWAY from CNS towards effectors
interneurones
convey information within CNS
most neurones
nerves
groups of efferent and afferent neurones together with connective tissue and blood vessels
(A group of many axons traveling together to and from the same
general location in the peripheral nervous system)
NO NERVES IN CNS
glial cells
make up most of CNS
surround the soma, axon, dendrites and provide physical and metabolic support
astrocyte
glial cells
remove excess potassium (K⁺) ions and neurotransmitters to maintain the ionic balance.
stimulate endothelial cells of capillaries to form tight junctions, which make up the blood-brain barrier. This barrier controls what substances can enter the brain from the bloodstream, ensuring a stable environment for neurons.
microglial cells
glial cells
specialised
similar to macrophages in that they remove pathogens and dead/damaged neurones
ependymal cells
glial cells
fluid filled cavities
regulate flow of cerebrospinal fluid
pathway/tract
group of axons travelling together in the CNS
commissure
group of axons
links the right and left
halves of the CNS:
ganglia
The cell bodies of
neurons with similar
functions in the PNS
nuclei
The cell bodies of
neurons with similar
functions in the CNS
cerebral ventricles
four interconnected cavities which are
filled with cerebrospinal fluid in brain
cerebrum
consists of left and right cerebral hemispheres
larger component of forebrain
diencephalon
central core of forebrain
contains the thalamus, hypothalamus and epithalamus
cerebral cortex
outer shell of grey matter
part of cerebral hemispheres
folded to increase surface area for cortical neurones
inner cerebral cortex
layer of white matter
mainly myelinated fibre tracts
lobes of cerebrum/cerebral cortex
frontal
parietal
occipital
temporal
cells of the cerebral cortex
pyramidal cells (major output/excitation)
non pyramidal cells (major input cells, receive signals)
grey matter
contains subcortical nuclei
basal nuclei have an important role in controlling movement/posture
contains interneurons, cell bodies and dendrites of efferent neurons, entering axons of afferent neurons, glial cells
corpus callosum
Each cortex area is separated by a deep
longitudinal division, but are connected by a
massive bundle of nerve fibers
gyri
folding of brain, ridges
sulci
grooves in brain
how is the cerebral cortex the integrating area of the nervous system
basic afferent information is processed into
meaningful perceptual images
control over the systems that govern the movement
of the skeletal muscles is refined.
thalamus
a collection of several large nuclei- role in general arousal- controlling movement/posture- focusing attention
hypothalamus
only 1% of brain mass- homeostatic regulation of internal
environment
neural and endocrine coordination
controls:–Behaviours having to do with preservation of the individual (e.g. eating and drinking) –Behaviours to do with preservation of the species (e.g. reproduction)
epithalamus
controls biological rhythms
(via pineal gland which produces melatonin)
pituitary gland
connected to hypothalamus which regulates it
controls several other hormone
glands in your body, including the thyroid and adrenals, the ovaries and testicles
cerebellum
center for coordinating involuntary movements and for controlling posture and balance. receives information from the
muscles and joints, skin, eyes and
ears and the parts of the brain
involved in control of movement
brainstem
contains midbrain, pons and medulla oblongata
receives and integrates input from all regions of the central nervous
system and is involved with-motor functions-cardiovascular, respiratory control, swallowing-regulates sleep, wakefulness and attention, eye movement
bone that protects CNS vs PNS
cranium (skull) vs vertebrae
membranes protecting CNS and PNS
Dura mater, Arachnoid mater, Pia mater
role of membranes surrounding CNS and PNS
Cover and protect the CNS
Protect blood vessels and enclose the venous sinuses
Contain cerebrospinal fluid
Form partitions in the skull
Cerebrospinal fluid
protects and cushions
the structures (made by the
choroid plexus)
blood brain barrier
a protective mechanism that helps maintain a stable environment for the brain. endothelial cells surround capillaries tightly joined by tight junctions.
Capillaries are the least permeable in the body: a very selective barrier.
white matter
surrounds grey matter and is made up on myelinated axons
how do afferent fibres arrive at the spinal cord
from peripheral nerves
enter via dorsal roots
how do efferent fibres exit the spinal cord
via ventral roots
spinal cord
cylinder of soft tissue
dorsal horn
grey matter projecting towards back of body
ventral horns
grey matter orientated towards front of body
nerves making up PNS
43 pairs of nerves in total
12 of which are cranial nerves
31 are spinal nerves
categories of spinal nerves (5)
cervical: control muscles, glands. sensory input to neck, shoulders, arms, hands
thoracic: associated with the chest and upper abdomen
lumbar: associated with the lower abdomen, hips, legs
sacral: associated with the genitals, lower digestive tract
coccygeal: associated with the tail bone
subdivisions of efferent division of PNS
somatic
autonomic nervous systems
somatic nervous system
skeletal muscle
acetylcholine
nicotinic ACh receptor
autonomic nervous system
smooth and cardiac muscle
glands
gastrointestinal neurones (GI tract actually controlled by enteric nervous system which is a subdivision of autonomic)
parasympathetic nervous system
rest or digest
muscarinic acetylcholine receptor
neurones have ganglions
sympathetic nervous system
fight or flight
adrenergic receptors
Epinephrine
Norepinephrine
adrenal medulla
one set of ganglionic neurones form a gland
(inner part of the adrenal gland). Nervous
system interacting with the endocrine system
(cortisol, adrenalin, noradrenalin,…
where do sympathetic neurones leave the CNS
from thoracic and lumbar regions
where do parasympathetic neurones leave CNS
from brainstem and sacral region
positioning of ganglia in sympathetic vs parasympathetic neurones
close to spinal cord vs close to organs being innervated
activation pattern of SNS vs PSNS
SNS tends to respond as a single unit (flight or fight, everything engaged)
PSNS tends to activate specific organs
dual innervation
Some tissues/organs are innervated by both SNS and PSNS
reciprocally activated
