the brain + hypothalamic control of the ANS

Question 1

what is the cerebral cortex?

Answer 1

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)

Question 2

describe the layout of the four lobes of the neocortex?

Answer 2

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

Question 3

describe the cytoarchitecture of the neocortex and how Brodmann’s amp relates

Answer 3

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

Question 4

how was Brodmann’s map confirmed?

Answer 4

invasive electrodes and lesions in certain areas of the brain

non-invasive imaging now possible too

Question 5

the neocortex can be split up into areas?

Answer 5

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

Question 6

describe the limbic lobe and it’s function

Answer 6

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

Question 7

where is the insula cortex and what does it do?

Answer 7

Hidden deeper, between frontal and temporal lobe
Range of functions, emotional regulation, sensorimotor processing

Question 8

the basal ganglia are where?

Answer 8

still from the telencephalon, deep area of the forebrain, quite central
we know - pre-motor cortex, movement, effected by Parkinson’s

Question 9

amygdala?

Answer 9

emotion motivation and fear

Question 10

white matter - what are the three kinds of fibres?

Answer 10

commissural - connect between hemispheres
projection - link to non-cortical areas
association - link two areas within a hemisphere, cortex to cortex

Question 11

biggest example of commissural and projection fibres?

Answer 11

commissural = corpus callosum
projection = internal capsule

Question 12

the thalamus - structure and function?

Answer 12

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)

Question 13

the hypothalamus - general structure and function?

Answer 13

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

Question 14

how is the hypothalamus involved in homeostasis?

Answer 14

When a parameter is disrupted, the hypothalamus is what integrates the sensory inputs and sends outputs to wherever necessary (ANS, neuroendocrine etc…)

Question 15

what are the key nuclei of the hypothalamus and how does it link to the pituitary?

Answer 15

paraventricular and supraoptic

via infundibular stalk

Question 16

how does the anterior pituitary work?

Answer 16

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

Question 17

how does the posterior pituitary work?

Answer 17

Magnocellular (large diameter) neurons in the paraventricular and supraoptic nuclei release hormones directly into systemic circulation

Question 18

anterior vs posterior hormones?

Answer 18

anterior = a lot of trophic hormones (cause the release of hormones elsewhere)

posterior - ADH, oxytocin etc…

Question 19

describe the organisation of the ANS

Answer 19

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

Question 20

describe the organisation of the sympathetic nervous system - NTs and neurons

Answer 20

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

Question 21

describe parasympathetic organisation

Answer 21

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

Question 22

the experiment where thewy stimulated the medulla to see where they could detect something gin the IML found what?

Answer 22

the rostral ventrolateral medulla is directly linked to the IML

Question 23

cranial nerve X?

Answer 23

80% parasympathetic output