Lecture 12 - the Ancient Forebrain - Hypothalamus and Thalamus Flashcards Preview

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Flashcards in Lecture 12 - the Ancient Forebrain - Hypothalamus and Thalamus Deck (40)
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1
Q

What are the wrinkles in the brain called?

A

Gyri and Sulci

Gyri - raised ridges of tissue
Sulci - rifts and valleys

2
Q

What do the 4 lobes correlate to?

A
Frontal = Motor/Cognition
Parietal = Sensory 
Occipital = Vision  
Temporal = Auditory
3
Q

What parts of the brain can be seen from a ventral perspective?

A

spinal cord, the brainstem and the midbrain of the medulla and the pons

4
Q

What is the cerebral hemisphere split by?

A

lateral fissure

lateral fissure is a major landmark in normal brains

5
Q

What are fissures?

A

Enlarged Sulci

6
Q

What are the other 2 lobes in the brain?

A

Insula and Limbic Lobe

7
Q

What does the nervous system develop from?

A

neural tube (in which contains a space in the middle)

8
Q

What does the space in the neural tube become?

A

the ventricles of the brain, where csf flows for homeostasis and support

9
Q

What shape do the lateral ventricles adopt around the brain?

A

a C shape

10
Q

What are the ventricles to neuroanatomists?

A

They are landmarks for particular regions of the brain

11
Q

What does the forebrain consist of?

A
Cerebral hemispheres
Limbic System  
Hypothalamus  
Thalamus
Basal Ganglia
12
Q

What does the embryo regionalise itself into?

A

Three germ layers
endoderm - Gives rise to gut, liver, lungs
mesoderm - gives rise to muscle and connective tissue
ectoderm - gives rise to skin (epidermis) and the nervous system

13
Q

What is induced very early after gastrulation?

A

notochord andthe neural plate

14
Q

what do signals from the notochord cause?

A

uneven proliferation and closing of the neural plate

15
Q

What happens during the fusion event?

A

the neural plate forms a continuous and separated neural tube which is the precursor to the nervous system

16
Q

In early stages of neural development, what provides important signalling cues?

A

the neural tube is still in close proximity to the mesoderm somites and notochord and also the epidermal cells of the ectoderm

and these provide important signalling cues

17
Q

What does neural tube developing in different ways along the rostrocaudal axis cause?

A

cells in different regions of the neural tube will start to acquire regional identities

So we have formation of the different early brain regions and also the spinal cord. Driven by signals from the surrounding ectoderm and mesoderm.

18
Q

What structures develop at the caudal end?

A

there is the spinal cord which is continuos with the hind, then mid then forebrain made up of the diencephalion and most rostrally the telencephalon

19
Q

What specialist structures can we see at this early stage?

A

we can see that the thalamus and hypothalamus of the forebrain (diencephalon) are adjacent to the midbrain

The telencephalon including basal nuceli are next to this already suggesting a proximity which is also found in the adult brain.

20
Q

What does grey matter structure mostly contain?

A

neuronal bodies

21
Q

What does the hypothalamus control?

A

various autonomic body actions

hypothalamus receives afferent information and also send efferent information into various brain structures including the cortex, the brainstem and down the spinal cord.

22
Q

Where is the hypothalamus located?

A

It is located inferiorly to the thalamus and lies adjacent to the third ventricle

23
Q

What part of the hypothalamus controls feeding?

A

lateral hypothalamus

24
Q

What can lesions in the ventromedial section cause?

A

over-eating

25
Q

Which hormones are released by cells associated with eating?

A

Ghrelin

Leptin

26
Q

How does the stomach release these hormones?

A

The stomach releases ghrelin at increasing amounts after finishing a previous meal

Adipocytes will release leptin if too much fat is being consumed

27
Q

What does the arcuate nucleus have control over?

A

it controls feeding and satiety (inhibit feeding)

28
Q

By leptin activating cells in arcuate nucleus, which neurotransmitters does it express?

A

MSH and CART

29
Q

Where do the MSH and CART project to?

A

sympathetic neurons in the spinal cord,
neurons in the paraventricular nucleus
and neurons in the lateral hypothalmus

30
Q

what happens in the process of satiety?

A

activate the visera for processing food.
They also suppress activity of lateral hypo neurons or suppress feeding through activation of lateral neurons. Finally, neurons in the paraventricular nucleus stimulate release of ACTH from the anteriro pitauitary.

31
Q

What happens in the process of feeding?

A

A drop in leptin levels activtaes different neurons within the arcuate nucleus – NPY and AgRP releasing neurons which have an oppsoite effect – inhibiting paraventricular neurons and stimulaitng lateral neurons.

32
Q

What can the dicephalon be split into?

A

can be split into different regios called the hypothalamus, the epithalamus the subthalamus and the dorsalthalamus

33
Q

Why is the thalamus important?

A

The thalamus provides a kind of gateway to the cortex and is a major stop for sensory information beofre it is projected into the cortex

34
Q

Which neurones is the thalamus made up of?

A

projection and inter - neurones

35
Q

The thalamus has some white matter tracts which allows -____?

A

axons to project out into the brain

These white matter tracts are known as the internal medullary lamina (Landmark)

36
Q

The nuclei of thalamus are receiving inputs from various inputs project the information to where____?

A

cortex where it may become consious information

37
Q

What is the thalamus sometimes seen as?

A

a relay centre

38
Q

What is the thalamus split into?

A

Specialist nuclei

They are named according to their anatomical location which is general a reflection of where they are compared to the white matter tracts which run through the thalamus

39
Q

What is the function of the thalamus?

A

it appears to mediate and regulate sensory information for projection to other systems

40
Q

What are the 2 examples of projections from the spinal cord?

A

The medial lemniscus carries information relating with touch

The spinothalamic tract carries info relating with pain