Structure of the Nervous System [W3] Flashcards
What is the CNS?
Central nervous system - brain and spinal cord
What is the PNS?
Parasympathetic nervous system - nerves that carry info around the body
What are the components of the PNS?
Somatic nervous system; autonomic nervous system (sympathetic division, parasympathetic division)
What is white matter?
myelinated axons
What is grey matter?
cell bodies and interneurons
What is the function of the autonomic nervous system?
Regulates body’s internal environment; more automatic processes, like heartbeat, organ function etc.
What is the function of the somatic nervous system?
Interacts with the external environment?
What is a bundle of axons called in the brain? In the body?
brain –> tract ; body –> nerve
function of the parasympathetic division of the ANS?
rest + digest
function of the sympathetic division of the ANS?
activation, fight/flight
What is processed in the grey matter of the spine? What is the function of the spine?
pattern generators (i.e., for walking), simple reflexes (i.e., pulling hand away from hot stove), and more complex reflexive movements; transmit information to/from brain
layers of protection around the brain (outside to inside)
skull; meninges (Dura mater, arachnoid layer, pia mater); subarachnoid space (filled with CSF); brain
def: Blood Brain Barrier
barrier to entry for substances to get to the brain; Capillaries in brain have tight junctions which prevents free movements of substances (esp. larger substances) in/out of blood
Brain folds – why?
more surface area
def: gyrus
bumps in the brain
def: sulcus
shallow grooves in the brain
function of cerebrospinal fluid
protects the brain by acting as a “cushion”; helps to remove waste products from brain to CNS functions properly
function of cerebrospinal fluid
protects the brain by acting as a “cushion”; helps to remove some waste products from brain; could be how some fluids get to the brain
4 lobes of the brain & approx. location
frontal (front); parietal (top, back section); occipital (back); temporal (sides – think ‘temples’)
4 lobes of the brain & approx. location
frontal (front); parietal (top, back section); occipital (back); temporal (sides – think ‘temples’)
“dorsal”
above (a.k.a. superior) [think: dorsal fin]
“ventral”
below (a.k.a. inferior) [think: toward belly]
“medial”
middle
“lateral”
side
“anterior”
front (a.k.a. rostral, frontal)
“posterior”
rear (a.k.a. caudal)
Where is the sagittal plane?
middle (on Y axis), running front to back
Where is the horizontal plane?
middle (on Y axis) running side to side
Where is the frontal plane?
middle (on X axis) running top to bottom
When does the nervous system start to develop?
3 weeks post conception
Describe how the brain is formed (brain devel.)
ovum and sperm combine to form zygote // Zygote divides to form 2, 4, 8, etc cells // cells become specialised // 3 weeks after conception, neural plate and stem cells are plentiful enough to form nervous system, neurons and glia // neural plate folds to form neural groove, which then fuses into neural tube // inside tube becomes the ventricles and spinal canal, filled with CSF // neural tube develops three chambers // neural tissue around 3 chambers become forebrain, midbrain, hindbrain
Direction of information in efferent nerve bundles?
efferent moves away from the brain [think: exist] and carries motor signals toward muscles
Direction of information in afferent nerve bundles
afferent moves toward brain and carries sensory signals from muscles to brain
What direction does information flow in the ANS?
both efferent and afferent signal flow, to and from CNS
What are the three protective membranes around the brain?
meninges [dura mater, arachnoid layer, pia mater]
Where are the blood vessels in the brain?
Main vessels are on the outside/brain surface; smaller vessels branch and go into the brain
head injury can cause _______ to swell
ventricles
What defines the boundaries of the four lobes in the brain?
the sulci and gyri in the cortex
What are the three chambers the neural tube develops into? (brain devel)
forebrain, midbrain, hindbrain
What does the forebrain develop into and how?
Folds back on itself to become the Cortex; and diencephalon (thalamus, hypothalamus)
midbrain becomes the _______
mesencephalon
hind brain develops into ______, ________, _______
pons, medulla, cerebellum
the forebrain, midbrain, and hindbrain make up the ___________
brainstem
Function of the medulla
essential life functions (i.e., breathing, heartbeat, etc.)
What is the pons
[means: “bridge”] the bump where fibres cross over from one side to the other; involved in sleep and arousal
def: reticular formation
loc. in the tegmentum, runs along brainstem; includes many nuclei, net-like/web-like structure; sections within the reticular formation are main producers of various neurotransmitters
function of the cerebellum
[means: little brain] responsible for coordination and movement, skilled motor control
def: raphe nucleus
nuclei in the pons, part of the reticular activating system; neurons produce 5HT/serotonin
What are the sites of significant ACh production in the midbrain?
pedunculopontine nucleus and laterodorsal tegmental nucleus
What are the sites of significant ACh production in the midbrain reticular formation?
pedunculopontine nucleus and laterodorsal tegmental nucleus
function of the tectum
produces orienting movement in response to sensory input
what are the two parts of the tectum and what do they do?
Superior colliculus –> receives visual input from optic nerve// inferior colliculus –> receives auditory input from auditory nerve
Where is the tectum located?
midbrain
Where is the tegmentum located?
midbrain
name the parts of the forebrain
telencephalon (cerebral cortex, basal ganglia, limbic system); Diencephalon (thalamus, hypothalamus)
tegmentum contains…
groups of neurons with movement related functions
def: periaqueductal grey (PAG)
grey matter around the cerebral aqueduct, which modulates pain using opiates and is involved in species-typical behaviours
def: substantia nigra
midbrain nucleus, important for the production of dopamine; involved in reward, addiction and motivation
def: reticular activating system
consists of nuclei and tracts that are involved with regulating wakefulness, arousal, and some aspects of sleep; primary components found in the reticular formation (i.e., locus coeruleus, raphe nucleus, etc.)
What disease is associated with the loss of dopamine neurons, particularly in the substantia nigra?
Parkinson’s
What neurotoxin was found in contaminated heroin in California in 1982 and caused Parkinson’s?
MPTP
How is dopamine activated and what is its role?
activated by significant stimuli; role in motivation and selection of actions
def: thalamus
subcortical structure that acts as a relay station between cerebral cortex and sensory/motor systems, main link between the cortex and the lower brain; plays important role in consciousness and arousal
def: hypothalamus
Collection of nuclei that is located below the thalamus; controls the ANS and activity of pituitary gland; diff nuclei have diff functions; v important for maintaining homeostasis; also has a role in reproductive functions & sexual behaviour, fight-or-flight reactions, eating/drinking, lactation, and sleep
def: lateral geniculate nucleus
relay station for info from eye/optic nerve to the visual cortex
def: pituitary gland
endocrine gland that extends from the bottom of the hypothalamus; produces and secretes hormones; secretes hormones produced by the hypothalamus.
How does the pituitary gland release/control the release of hormones?
releases factors from hypothalamic neurons, which travel through portal blood vessels (anterior pituitary) or along nerves (posterior pituitary); factors trigger the release of hormones into the blood stream which act on organs (incl. glands) that also release hormones
def: leptin
a hormone released from fat cells; signals the brain when to eat/stop eating
What receptors does leptin act on?
receptors in the arcuate nucleus of the hypothalamus
def: limbic system [incl. three parts]
a group of structures in the brain associated with emotion and motivation; includes hippocampal formation, amygdala, septum
hippocampus has a key role in __________
memory
def: fornix
pathway connecting hippocampus to mammillary bodies and hypothalamus
mammillary bodies have a key role in __________
memory
In Korsakoff’s syndrome the___________ are damaged
mammillary bodies
def: cingulate cortex
structure most closely associated w/ limbic system, thought to be important in emotional responses
amygdala has a key role in…
emotion, incl. learning about fearful stimuli, emotional memories
Klüver Bucy syndrome results from damage to the ___________
amygdala
def: cortex [incl. function]
thin outer layer of the brain, function is to process and make sense of sensory information, plan based on sensory information and organise appropriate action; has specialised function areas (i.e., visual cortex, motor cortex, etc.)
How many layers of neocortex? Name them (outside in)
6 layers
how is each layer of the neocortex defined
by type and density of neurons
direction of axons in neocortex?
vertically; perpendicular to cortical surface
how many regions of the cortex? based on what?
52; defined by subtle differences in the appearance of each area and the thickness of the 6 layers
Who defined the 52 Broadman’s areas and when?
Broadman, 1909
relationship between cortex and fine motor function
more cortex devoted to parts of the body used in fine motor functions (i.e., lips, fingers, thumb…)
Penfield (1937) - cortical areas/electrical stimulation. Explain.
Stimulated cortex in awake patients before surgery. Electrical stimulus caused movement in part of the body. Part of the body depended on where the electrode was placed on the cortex. Experiment helped create a ‘map’ of the body within the cortex (homunculus)
def: motor homunculus
“map” of the body in the cortex
where is the motor cortex?
strip of cortex in front of central sulcus
What happens when an electrode stimulates the cortex in front of the central sulcus? Behind the central sulcus?
in front –> body part moves based on part of cortex stimulated
behind –> subject experiences sensation of touch
relationship between cortex and physical sensation
more cortex devoted to parts of the body with greater sensory capacity (i.e., lips, thumb…)
Broadman’s area(s) associated with touch
1, 2, & 3
Broadman’s area(s) associated with motor cortex
4
Broadman’s area(s) associated with primary visual cortex
17; around occipital lobe at the back
Where is the auditory cortex?
temporal lobe, by ears, below the parietal lobe (behind central sulcus)
def: sensory cortex [incl. levels]
primary level, secondary level, tertiary level; process sensory information starting in primary, moving through secondary, and finally to tertiary level
def: cerebral lateralisation
the difference between hemispheres of the brain
difference between fissures and sulci in the brain?
fissures –> deep grooves; sulci –> shallow grooves
def: fissures
deep grooves in the brain
def: corpus callosum
set of axons that connect the left and right hemispheres
Other than the corpus callosum what are the other areas of information exchanges between the two hemispheres?
anterior commissure, hippocampal commissure
What happens to the brain in split-brain patients/animals?
corpus callosum is severed
how are the lobes in the brain divided?
by the lateral and central fissures
function of the lobes (excl. frontal)?
occipital –> visual perception; temporal –> auditory processing, memory; parietal –> visuomotor guidance; frontal –> higher-order cognitive functions (ie. attention, planning)
def: lateral geniculate nucleus
sensory (visual) relay area of the thalamus
def: lateral geniculate nucleus
sensory (visual) relay area of the thalamus
def: nucleus accumbens
part of the mesolimbic dopamine system; has role in addiction
def: basal ganglia [incl. components]
collection of subcortical structures that are v important in motor control and other behaviours; includes striatum, substantia nigra, globus palliduc and subthalamic nucleus
tectum comprises ___________ and _________
inferior and superior colliculi
mesencephalon comprises the _________ and ________ [incl. loc]
tectum (dorsal); tegmentum (ventral)
function and loc of inferior colliculi
func: auditory; loc: mesencephalon (midbrain) tectum
function and loc of superior colliculi
func: visual; loc: mesencephalon (midbrain) tectum
def: medula oblongata
the lower half of the brainstem; connects pons with spinal cord; important in regulating the ANS
def: pons
bridge between hemispheres; contains numerous cranial nerves and thus important in relaying efferent and afferent information
What artery(ies) supply oxygenated blood to the brain?
cartoid artery, vertebral artery
def: optic chiasm
the point where visual signals travelling along the optic nerve cross over to the opposite hemisphere
def: vertebral artery
artery located at back of neck; carries oxygenated blood from heart to brain, spine and neck muscles; enters brain at level of medulla
def: carotid artery
major artery in the neck that supplies oxygenated blood from heart to face, neck and brain
def: circle of Willis
connection of the carotid and vertebral arteries, which forms a circle around the optic chiasm and pituitary stalk; can compensate for a blockage in one of the feeder arteries (safety net) that supplies blood to the brain
how does blood exit the brain?
through the subarachnoid space, penetrates the subarachnoid mater and the meninges (through dura), draining into the sinuses, which then empty into the L& R jugular veins
def: pituitary gland [incl. loc]
major endocrine gland located below the hypothalamus, connected via the pituitary stalk; releases specific hormones based on info from hypothalamus; divided into anterior and posterior regions
def: hormones
chemical substances, often a steroid or peptide, produced in specific glands/tissues in the body and transported through the bloodstream to another part of the body to cause a physiological effect
main endocrine glands [6]
pineal gland; hypothalamus; pituitary gland; thyroid gland; pancreas; ovaries/testes
def: hypothalamic-pituitary-adrenal (HPA) axis
a set of direct influences and feedback among the hypothalamus, pituitary gland and adrenal glands; involved in stress response
function of endocrine system
maintain homeostasis; support cell growth; coordinate development and reproduction; facilitate responses to external environment
