the brain + hypothalamic control of the ANS Flashcards
what is the cerebral cortex?
outside layer of the brain, following the gyri (bumps) and sulci (grooves)
has three parts - the neocortex, the olfactory cortex and the hippocampus in the temporal lobe (one in each hemisphere)
describe the layout of the four lobes of the neocortex?
frontal lobe (essential in movement as it has the motor cortex as well as personality due to the prefrontal cortex)
then there’s the central sulcus separating frontal from parietal lobe in the middle
like off to the side there’s the lateral fissure separating the parietal form the temporal lobe
at the back is the occipital lobe, just above the cerebellum and brainstem
describe the cytoarchitecture of the neocortex and how Brodmann’s amp relates
there are 6 layers with the outermost being the molecular which is white matter
these layers differ in proportions which was used to map out areas of the brain with different functions, this has now been confirmed
how was Brodmann’s map confirmed?
invasive electrodes and lesions in certain areas of the brain
non-invasive imaging now possible too
the neocortex can be split up into areas?
primary sensory areas (visual, hearing and feeling)
secondary sensory areas - involved in supporting the primary sensory areas
association areas - involved in things other than these essential processes - therefore it is quite a lot of space in human brains
describe the limbic lobe and it’s function
looking at the brain medially - you’ve taken a sagittal section and are looking at the central area, like layers
contains the cingulate gyrus, the hippocampus, some of the cortex of the medial (central) aspect of the temporal lobe
function is a lot to do with emotion
where is the insula cortex and what does it do?
Hidden deeper, between frontal and temporal lobe
Range of functions, emotional regulation, sensorimotor processing
the basal ganglia are where?
still from the telencephalon, deep area of the forebrain, quite central
we know - pre-motor cortex, movement, effected by Parkinson’s
amygdala?
emotion motivation and fear
white matter - what are the three kinds of fibres?
commissural - connect between hemispheres
projection - link to non-cortical areas
association - link two areas within a hemisphere, cortex to cortex
biggest example of commissural and projection fibres?
commissural = corpus callosum
projection = internal capsule
the thalamus - structure and function?
still came from forebrain/prosencephalon, but from the diencephalon not the telencephalon
has over 50 nuclei
acts as a relay station - lots of peripheral/sensory info goes to thalamus before cortex
connects to neocortex via internal capsule (projection fibres)
the hypothalamus - general structure and function?
11 major nuclei, master regulator of homeostasis
three sections = periventricular, medial and lateral (surrounds the third ventricle)
linked to pituitary gland, pons and medulla
also controls motivated behaviour like thirst and hunger
how is the hypothalamus involved in homeostasis?
When a parameter is disrupted, the hypothalamus is what integrates the sensory inputs and sends outputs to wherever necessary (ANS, neuroendocrine etc…)
what are the key nuclei of the hypothalamus and how does it link to the pituitary?
paraventricular and supraoptic
via infundibular stalk
how does the anterior pituitary work?
Parvocellular neurons (small diameter) when excited stimulate neurohormones into the blood, through a portal vein into another capillary bed to the Troph cells
this stimulates them to release another hormone, which can then enter systemic (normal/rest of the body) circulation
how does the posterior pituitary work?
Magnocellular (large diameter) neurons in the paraventricular and supraoptic nuclei release hormones directly into systemic circulation
anterior vs posterior hormones?
anterior = a lot of trophic hormones (cause the release of hormones elsewhere)
posterior - ADH, oxytocin etc…
describe the organisation of the ANS
two efferent pathways:
parasympathetic = brainstem and sacral spinal cord
sympathetic = thoracic and lumbar spinal cord
they effect smooth muscle, cardiac muscle, glands and adipose cells
can function independently but hypothalamus can modulate output
describe the organisation of the sympathetic nervous system - NTs and neurons
T1 to L3 of the spinal cord
afferent inputs come into the dorsal horn from the periphery
efferent outputs are sent from the ventral horn
in between the two is the intermediolateral cell column, where the sympathetic preganglionic neurons are
these preganglionic neurons must send info through the sympathetic chain ganglion which runs alongside the spinal cord
the preganglionic release ACh
the postganglionic neurons are adrenergic and activate nicotinic ACh receptors
describe parasympathetic organisation
sacral area
dorsal = afferent, ventral = efferent
between the two is the intermediate grey (not IML)
preganglionic neurons are super long and go straight to postganglionic neurons (no chain ganglion)
they both use ACh and activate muscarinic ACh receptors
the experiment where thewy stimulated the medulla to see where they could detect something gin the IML found what?
the rostral ventrolateral medulla is directly linked to the IML
cranial nerve X?
80% parasympathetic output
