Module 7 - Hypothalamus Flashcards
The hypothalamus is part of the X, but it functions as part of the Y
diencephalon
limbic system
What is the role of the hypothalamus?
To help us maintain homeostasis in the entire body, through influences on the endocrine system and sympathetic and parasympathetic nervous system
Of what is the limbic system comprised?
A section of cortex visible on the medial section of the brain. It is comprised of the cingulate gyrus and the parahippocampal gyrus.
What is the hippocampus primarily involved in?
Memory
What is the amygdala primarily responsible for?
Emotional processing
What is the outflow from the hippocampus called?
The fornix
What is the uncus?
The uncus is the anterior extension of the parahippocampal gyrus. It is immediately recognisable through its hook like shape.
What is directly underneath the uncus?
the amygdala
Where does the amygdala lie in relation to the hippocampus?
Superior and anterior
The amygdala is a key structure in what?
emotion, emotional memory, and basic drives
Of what three structures is the diencephalon comprised?
Thalamus
Hypothalamus
Subthalamus
What are the anterior bounderies of the hypothalamus?
The anterior commissure and the optic chiasm
What is the superior boundary of the hypothalamus?
The hypothalamic sulcus
What is the inferior boundary of the hypothalamus?
The mamillary bodies
The hypothalamus forms the walls of what?
The inferior portion of the third ventricle
The hypothalamus is inferior to X
The thalamus
The hypothalamus links the neural and endocrine systems through what structure?
The pituitary gland
The hypothalamus is involved in many functions, the 4 main ones are:
- Maintenance of homeostasis
- Emotional, motivational, and affective aspects of behaviour through links with the limbic system
- Regulation of food intake, body weight, temperature, reproduction, sleep-wake cycle and circadian rhythms
- Controls the function of the pituitary gland
There are five primary groups of nuclei in the hypothalamus, what are the functions of the anterior area nuclei?
- parasympathetic
- down-regulation of body temperature
- sleep
- eating
There are five primary groups of nuclei in the hypothalamus, what are the functions of the posterior area nuclei?
- sympathetic
- up-regulation of body temperature
- wakefulness
- arousal
There are five primary groups of nuclei in the hypothalamus, what are the functions of the lateral zone nuclei?
- eating
- arousal
There are five primary groups of nuclei in the hypothalamus, what are the functions of the medial zone nuclei?
- satiety
- ADH, GH
What is the lamina terminalis?
A thin membrane extending from the anterior commissure inferiorly to the rostral edge of the optic chiasm
Briefly, describe the location of the hypothalamus.
Inferior to the thalamus, below the hypothalamic sulcus. Surrounds the third ventricle.
The columns of the fornix cut through the hypothalamus, dividing it into what two areas?
The lateral zone, containing diffuse or scattered neurons which carry two way traffic through the hypothalamus, rostrally toward the forebrain and caudally toward the brainstem
The medial zone, which contains the majority of functionally important nuclei of the hypothalamus
What separates the lateral hypothalamic nuclei from the medial hypothalamic nuclei?
The column of fornix
What are the 5 anterior hypothalamic nuclei?
- Paraventricular nucleus
- Preoptic nucleus
- Anterior nucleus
- Supraoptic nucleus
- Suprachiasmatic nucleus
What are the 3 middle/tuberal area hypothalamic nuclei?
- Arcuate nucleus
- Ventromedial nucleus
- Dorsomedial nucleus
What are the two posterior area hypothalamic nuclei?
- Posterior nucleus
- Mammillary body
How many lateral area nuclei are there?
1 - the lateral nucleus - it consists of scattered cells
The preoptic and anterior nuclei are in the medial anterior zone (of the hypothalamus) - what is their function?
Heat loss; response to hear
parasympathetic activity
sleep
The suprachiasmatic nucleus in the medial anterior zone (of the hypothalamus) - what is their function?
circadian rhythms
Secretes realeasing/inhibiting hormones
The supraoptic nucleus in the medial anterior zone (of the hypothalamus) - what is its function?
Secretes hormones (oxytocin and vasopressin, or antidiuretic hormone)
The paraventricular nucleus is in the medial anterior zone (of the hypothalamus) - what is its function?
magnocellular cells - secretes hormones (ocytocin and vasopressin)
Parvocellular cells - secrete releasing hormones
The lateral nuclei are in the lateral anterior zone (of the hypothalamus) - what is their function?
Parasympathetic activity
Contains orexingergic neurons
The dorsomedial nucleus is in the middle/tuberal area (of the hypothalamus) - what is its function?
Emotional behavior
Role in circadian rhythms
The ventromedial nucleus is in the middle/tuberal area (of the hypothalamus) - what is its function?
inhibits eating and drinking
satiety
The arcuate nucleus is in the middle/tuberal area (of the hypothalamus) - what is its function?
secretes relasing/inhibiting hormones
The posterior nucleus is in the posterior area (of the hypothalamus) - what is its function?
Heat gain/conservation; response to cold
Sympathetic activity
Arousal wakefulness
The mamillary nucleus is in the posterior area (of the hypothalamus) - what is its function?
Memory
How many major tracts connect the hypothalamus to the lymbic system?
8
What are the 8 tracts that connect the hypothalamus and the limbic system?
- hypothalamic-hypophysial
- Fornic
- Mammillothalamic
- Ventral amygdalofugal
- Stria terminalis
- Medial forebrain bundle
- Mammillotegmental tract/Dorsal longitudinal fasciculus
- Olfactory tract
What does the hypothalamic-hypophysial tract connect?
The hypothalamus to the posterior and anterior pituitary glands
What does the fornix connect?
The hippocampus to the mammillary bodies
What does the mammillothalamic tract connect?
Mammillary bodies to the ANT of thalamus
What does the ventral amygdalofugal tract connect?
Amygdala, hypothalamus, nucleus accumbens, DM of thalamus
What does the stria terminalis connect?
Amygdala, hypothalamus, septal nuclei
What does the medial forebrain bundle connect?
Septal area (via lateral hypothalamus) and the brainstem (reticular formation and autonomic nuclei)
What does the mammillotegmental tract (also known as the dorsal longitudinal fasciculus) connect?
Other pathways out of hypothalamus to brainstem
There are two olfactory tracts, what do they connect?
Olfactory bulb to contralateral olfactory, septal nuclei
Olfactory bulb to amygdala, uncus
afferent
Towards the brain
Efferent
away from the brain
What is the source of blood supply to the hypothalamus?
Small arteries that aris from the circle of Willis
What is the source of blood supply to the anterior areas of the hypothalamus?
Branches from the anterior cerebral and anterior communicating arteries supply the anterior areas
What is the source of blood supply to the posterior areas of the hypothalamus?
Branches from the posterior cerebral and posterior communicating arteries supply middle and posterior areas of the hypothalamus
