Exam 3- Hypothalamus

c. anterior nucleus: called the ... - its neurons are sensitive to ... - activates neural mechanisms that result in ... and ... when blood temperature ...

"heat dissipation center" blood temperature sweating vasodilation increases

b. ventromedial hypothalamic nucleus (VMN): also known as the ... - its neurons are sensitive to ... - activates neural mechanisms that inhibit ... - lesions of the VMN in rats results in extreme ... response - the portion of the lateral hypothalamic zone located lateral to the VMN is called the ... (lesion of this region results in inhibition of ... )

"satiety center" blood glucose levels eating over-feeding "feeding center" feeding

Nuclei of the HT are grouped into 3 main hypothalamic regions:

1) Anterior (chiasmal) hypothalamic region 2) Tuberal (middle) hypothalamic region 3) Posterior (mammillary) hypothalamic region

b. Two part pathway: neural and humoral 1) ... 2) ...

1) Tuberoinfundibular tract 2) Pituitary portal system

III. Connections A. Inputs There are ... inputs to the hypothalamus:

2 1) amygdala 2) hippocampal formation

3. Posterior (Mammillary) hypothalamic region Has ... nuclei:

2 1) mammillary nucleus 2) posterior hypothalamic necleus

... zones of the hypothalamus:

3 1) Periventricular zone 2) Medial zone 3) Lateral zone

2. Tuberal (Middle) HT region Has ... nuclei:

3 1) dorsomedial hypothalamic nucleus 2) ventromedial hypothalamic nucleus 3) arcuate nucleus

1. Anterior (Chiasmal) HT region Has ... groups of nuclei:

4 1) preoptic nuclei 2) suprachiasmic nucleus 3) anterior nucleus 4) supraoptic and paraventricular nuclei

C. Signs and symptoms of hypothalamic damage (in the order of frequency of occurrence) 1. ... (most common) a. children: ... - there appears to be a hypothalamic mechanism which inhibits ... by preventing the secretion of ... This mechanism may be destroyed by hypothalamic lesions b. adults: regression of ... - due to loss of ... for ...

Sexual abnormalities precocious puberty puberty gonadotrophin releasing factors secondary sexual characteristics releasing factors gonadotrophins

b. suprachiasmatic nucleus: located ... the optic chiasm - receives fibers from the ... and constitutes the ... necessary for circadian rhythms

above optic nerve "biological clock"

7. Excessive ... Irritative lesions in the region of the hypothalamus produce excessive activation of ... in the brain stem and ... (sometimes called "...")

autonomic activity ("autonomic storms") visceral nuclei spinal cord "diencephalic epilepsy"

The hypothalamus regulates each of these physiological processes by producing a ... involving ... components: Each of these components is associated with a ... of the hypothalamus

coordinated response 3 visceral, endocrine, and behavioral major connection

Increases in osmolarity, which could be produced by dehydration, ... the supraoptic and paraventricular neurons that release ...

excite vasopressin

2. Hippocampal formation (part of limbic system) - connects with the hypothalamus via a ... called the ... - the fornix synapses primarily in ... - provides the hypothalamus with information concerning ...

fiber bundle fornix mammillary bodies memory

Hypothalamic syndromes: Because different ... occur in close proximity to each other, usually several hypothalamic symptoms occur together as recognizable ... For example, Frohlich's syndrome is characterized by ... combined with regression of ... It is caused by lesions in the region of the ... (satiety center and source of releasing factors for ... )

functional centers hypothalamic syndromes obesity secondary sexual organs ventromedial hypothalamic nucleus gonadotropins

a. mammillary nucleus: has connections with the ... and is involved in ...

hippocampus memory

c. arcuate nucleus - modulates ... from the ...

hormonal release anterior pituitary

d. supraoptic and paraventricular nuclei: regulate ... from the ...

hormonal release pituitary

B. Regions, nuclei, and functions Structures along the ... of the hypothalamus define four levels of the hypothalamus (from rostral to caudal): 1) ... 2) ... 3) ... 4) ...

inferior surface 1) optic chiasm (chiasmal level of the HT) 2) infundibulum (infundibular level) 3) tuber cinereum (tuberal level) 4) mammillary body (mammillary level)

The concept of "functional centers" is based on lesion studies performed in animals during the second half of the 20th century. While these studies demonstrated that certain hypothalamic nuclei were essential for particular functions, we now know that each hypothalamic function is dependent upon ... among multiple interconnected brain areas. Nevertheless, the concept of "functional centers" is useful clinically since lesions of these centers in human patients produce deficits in their ...

interactions associated functions

- the medial forebrain bundle (MFB) runs through the ... and contains both descending fibers (from the ... and ... : conveying olfactory and ... information) and ascending fibers (from the ... : conveying ... information). The fibers in the medial forebrain bundle synapse in both the ... and ... zone of the hypothalamus

lateral hypothalamus olfactory cortex septum emotional reticular formation visceral lateral medial

C. Behavior and emotion: via hypothalamic connections with the ... of the forebrain ( ... structures such as the amygdala and ... are very important for behavior and ... , especially behavior related to basic biological drives such as fight/flight/fear, ... and drinking, and reproduction. The ... components of these behaviors are generated mainly by projections of the hypothalamus to the ... origins of the ...

limbic system limbic system hippocampus emotion feeding somatomotor reticular formation reticulospinal tracts

I. Overview of functions and connections The main function of the hypothalamus (HT) is to ... It does this by regulating a wide variety of basic physiological processes including: - ... - Circulation - ... - Metabolism - Food and Water Intake - ... - Reproduction - Regulation of ...

maintain homeostasis Respiration Digestion Sleep Body Temperature

3. Mammillothalamic tract - originates in ... and terminates in the ... - this tract is an important part of the circuitry of the ... ("Papez circuit"), which is involved in memory, behavior and ...

mammillary bodies anterior thalamic nucleus limbic system emotion

3. Emotional and behavioral disturbances a. disturbances may range from ... to ... or involve other kinds of inappropriate behavior such as ...

mania depression excessive rage

The periventricular zone contains .. The medial zone contains ... The lateral zone contains ...

many fibers most of the nuclei the Medial Forebrain Bundle

3. Olfactory cortex, septum (a region adjacent to the anterior commissure) and reticular formation; all these regions connect with the hypothalamus via the ...

medial forebrain bundle

B. Output pathways 1. Hypothalamotegmental tracts: = fiber pathways that originate in the hypothalamus, course in the ... , and terminate in the ... (One special component, the ... , originates solely in the mammillary bodies) The ... , in turn, projects to ... (via the ... ) to produce behavioral responses and to ... in the brain stem and spinal cord to produce the accompanying ...

medial forebrain bundle reticular formation mammillotegmental tract reticular formation somatic motor nuclei reticulospinal tracts visceral nuclei visceral responses

2. Pituitary portal system - runs from the ... to the ... ... cause the release of their respective hormones into the circulation

median eminence anterior pituitary Releasing factors

b. posterior hypothalamic nucleus: lesions cause ... ; the posterior hypothalamic region also contains a ...

narcolepsy "heat conservation center"

c. Functional aspects: - the activity of supraoptic and paraventricular neurons can be affected by ... and by changes in ...

neural inputs osmolarity of the blood

5. Eating disorders a. ... or emaciation depending on the location of the lesion in respect to ... or ...

obesity feeding satiety centers

a. preoptic nuclei: located in front of the ... - although actually part of the ... , the preoptic area is closely related to the hypothalamus both structurally and ... - important for ... function - it is ...

optic chiasm telencephalon functionally reproductive sexually-dimorphic

B. Endocrine function: via hypothalamic influence over the ...

pituitary

4. Sleep disorders a. lesions of the ... region often result in ...

posterior hypothalamus narcolepsy

A. Visceral function: via connections with the ... - Visceral centers in the ... activate visceral ... in the brain stem and ... to produce visceral responses. There are also direct connections of the hypothalamus with ...

reticular formation (RF) reticular formation motor neurons spinal cord visceral motor neurons

1. Amygdala (part of limbic system) - projects to hypothalamus via 2 pathways: 1) ... 2) ... - the ... projects to the ... of the hypothalamus - the ... projects to the ... of the hypothalamus - generates ... responses by activating the hypothalamus

stria terminalis ventral amygdalofugal pathway (VAFP) stria terminalis medial zone VAFP lateral zone emotional

b. Pathway: supraopticohypophysial tract - this tract is formed by the axons from ... and ... neurons - it courses through the ... and terminates upon capillaries in the ...

supraoptic and paraventricular pituitary stalk neurohypophysis

C. Influences on pituitary 1. Neurohypophysis (posterior pituitary) a. Hypothalamic regions involved: 1) ... 2) ... ( ... portion) - these hypothalamic neurons synthesize ... and ...

supraoptic nucleus (SO) paraventricular nucleus (PV), magnocellular oxytocin vasopressin (also called antidiuretic hormone, ADH)

- when these cells are excited, action potentials run down their axons (in the ... tract) and release ... or ... from the axon terminals in the ... -These hormones then enter the bloodstream

supraopticohypophyseal oxytocin vasopressin neurohypophysis

6. Disorders of ... a. often ... due to lesion of the ... center in the ...

thermal regulation hyperthermia heat dissipation anterior hypothalamus

2. Periventricular fiber system: - runs in the walls of the ... and in the floor of the ... and ... - some fibers synapse in the ... to produce behavioral responses; the remaining fibers continue caudally as the ... in the floor of the ... and ... - the fibers of the ... synapse in visceral nuclei of ...

third ventricle midbrain aqueduct fourth ventricle periaqueductal gray dorsal longitudinal fasciculus (DLF) aqueduct and fourth ventricle dorsal longitudinal fasciculus cranial nerves

1. Tuberoinfundibular tract - this tract is formed by axons of neurons in the ... and the ... of the ... The axons terminate upon capillaries in the ... When these tuberal neurons are excited (by hormones in the circulation or by neural inputs), action potentials travel down their axons and release the ... from their ... The ... travel to the adenohypophysis via the ... of veins

tuberal hypothalamus parvocellular portion paraventricular nucleus median eminence hormonal releasing factors axon terminals releasing factors pituitary portal system

2. Adenohypophysis (anterior pituitary) a. Hypothalamic region involved: ... (ventromedial and infundibular nucleus) and the ... portion of the ... - these neurons synthesize ... for the hormones of the ...

tuberal region parvocellular paraventricular nucleus releasing factors adenohypophysis

a. dorsomedial hypothalamic nucleus: exact function is ...

unknown

2. Diabetes insipidus a. increased ... (3-20 liters/day) due to a loss of ... secretion - damage: supraoptic nucleus, paraventricular nucleus, or ... containing ...

urine production ADH pituitary stalk supraopticohypophysial tract

IV. Lesions of the hypothalamus A. Often produce ... due to the close proximity of hypothalamus to the ... and ...

visual field defects optic chiasm optic tract

B. Common causes of hypothalamic damage: 1. Tumors - tumors in the ... of the ... - tumors of the ... 2. Infections - often spread along the ... of the brain to affect hypothalamus 3. Skull fractures - fractures of the ... of the skull may involve the hypothalamus

wall third ventricle pituitary base base

-Vasopressin causes ... by the kidney, which, in turn, decreases ... Oxytocin causes contraction of the ... of the uterus and ... , so it is important for birthing and lactation. It is also involved in ... (e.g., maternal-infant bonding and sexual bonding) via its actions on portions of the ...

water resorption blood osmolarity smooth muscles mammary glands social bonding limbic system