Hypothalamus – Neuronal Functions

HYPOTHALAMUS – NEURONAL FUNCTIONS

Q. 1

Which of the following is not a function coordinated at the level of hypothalamus?

 A

Food intake

 B

Hypophyseal control

 C

Temperature regulation

 D

Increase heart rate with exercise

Q. 1

Which of the following is not a function coordinated at the level of hypothalamus?

 A

Food intake

 B

Hypophyseal control

 C

Temperature regulation

 D

Increase heart rate with exercise

Ans. D

Explanation:

Thirst is also controlled by receptors in the anterior hypothalamus.


Q. 2

In the CNS, where is the key regulators of sleep located?

 A

Putamen

 B

Thalamus

 C

Limbic cortex

 D

Hypothalamus

Q. 2

In the CNS, where is the key regulators of sleep located?

 A

Putamen

 B

Thalamus

 C

Limbic cortex

 D

Hypothalamus

Ans. D

Explanation:

The normal circadian rhythm is regulated by the paired suprachiasmatic nuclei of hypothalamus, one on either side above the optic chiasm. These nuclei receive information about the light dark cycle via special neural pathway, the retinohypothalamic fibers that pass from the optic chiasm to the suprachiasmatic nuclei. Efferents from the suprachiamatic nuclei initiate neural and hormonal signals that entrain a variety of well known circadian rythms. These include rythms in the secretion of ACTH and other pituitary hormones, sleep wake cycle, activity patterns and secretion of pineal hormone melatonin.

Ref: Harrison’s Principles of Internal Medicine, 16th Edition, Page 155; Textbook of Medical Physiology By Guyton and Hall, 10th Edition, Page 689, 690


Q. 3

Which of the following nucleus of Hypothalamus is most closely related to sexual activity in males

 A

Preoptic nucleus

 B

Supraoptic nucleus

 C

Lateral hypothalamic nuclei

 D

Posterior hypothalamic nuclei

Q. 3

Which of the following nucleus of Hypothalamus is most closely related to sexual activity in males

 A

Preoptic nucleus

 B

Supraoptic nucleus

 C

Lateral hypothalamic nuclei

 D

Posterior hypothalamic nuclei

Ans. A

Explanation:

A i.e.Preoptic nucleus

   Sexual behavior is integrated in anterior-ventral hypothalamusQ; plus piriform cortex (in males only) – Ganong

–   Sexual drive can be stimulated from several areas of hypothalamus, especially the most anterior and most posterior portions of hypothalamusQ (Guyton)

–    Medial preoptic area (MPOA) or the most anterior portion of hypothalamus is most important integrative nucleus involved in sexual behavior regulation of males in all vertebratesQ. It integrates the male sexual behavior by receiving all indirect inputs from every sensory organ and sends efferents to structures that are critical for initiation and patterning of copulation. Therefore, stimulation of MPOA enhances sexual activity in males, whereas its damage consistently impairs male sexual behavior.

Integrating Areas of Hypothalamus

Function

Anterior hypothalamus (response to heat),

Temprature regulation (anteriorly

Posterior hypothalamus (response to cold)

hot, posteriorly cold)

Suprachiasmatic nuclei

Control of circadian body rhythm

Punishment centers (esp periventricular zone of

hypothalamus adjacent to 3rd ventricle, lateral

Defensive reactions (fear, anger,

rage, punishment, fighting)=

hypothalamus & central grey area of mesencephalon)

are stimulatory and ventromedial nuclei of

hypothalamus, hippocampi, anterior limbic cortex (esp

anterior cingulate gyri and subcallosal gyri) are

inhibitory to fear (punishment)

Unpleasant sensation (Aversion)

Reward centers locatd along the course of medial

Calmness (Placidity, tameness &

forebrain bundleQ especially in lateral and ventromedial

tranquility) = Pleasant sensation

nuclei of hypothalamus are self stimulatory

(Reward or satisfaction)

 

Appetitive Behavior

Lateral (superior) hypothalamusQ

Thirst

Lateral hypothalamus

                                                                                                   activity level

Hunger (eating) & increased

Venteromedial nucleusQ, arcuate & paraventricular nuclei

Satiety (Decreased eating) &

tranquility

Anterior ventral hypothalamus; most anterior (medial

preoptic area=MPOA) & most posterior portions of

hypothalamusQ; piriform cortex (in males only)

Sexual drive

 

Neuroendocrinal control of

Preoptic area

FSH & LH via Gn RH

Supraoptic & paraventricular nuclei

Vasopressin, Oxytocin

Paraventricular nuclei

TSH (thyrotropin) via TRH

 

ACTH & [3- lipotropin 03-LPH) via

 

CRH

Paraventricular nucleus and arcuate nucleus

GH via somatostatin & GRH

Arcuate nucleus; (hypothalamus inhibits secretion)

Prolactin via PIH & PRH

Dorsal & posterior hypothalamus

Catecholamines



Q. 4

Injection of hypertonic saline in which region of hypothalamus produces intense thirst:

 A

Posterior region

 B

Paraventricular

 C

Preoptic

 D

Supraoptic

Q. 4

Injection of hypertonic saline in which region of hypothalamus produces intense thirst:

 A

Posterior region

 B

Paraventricular

 C

Preoptic

 D

Supraoptic

Ans. C

Explanation:

C i.e. Preoptic


Q. 5

Osmoreceptors are present in :

 A

Anterior hypothalamus

 B

Internal carotid artery

 C

Left atrium

 D

Ventricle

Q. 5

Osmoreceptors are present in :

 A

Anterior hypothalamus

 B

Internal carotid artery

 C

Left atrium

 D

Ventricle

Ans. A

Explanation:

A i.e. Anterior hypothalamus


Q. 6

Shivering is controlled by:

September 2012, March 2013

 A

Dorsomedial nucleus

 B

Posterior hypothalamus

 C

Perifornical nucleus

 D

Lateral hypothalamic area

Q. 6

Shivering is controlled by:

September 2012, March 2013

 A

Dorsomedial nucleus

 B

Posterior hypothalamus

 C

Perifornical nucleus

 D

Lateral hypothalamic area

Ans. B

Explanation:

Ans. B i.e. Posterior hypothalamus

Shivering/Shuddering

  • It is a bodily function in response to early hypothermia in warm-blooded animals.
  • When the core body temperature drops, the shivering reflex is triggered to maintain homeostasis.
  • Muscle groups around the vital organs begin to shake in small movements in an attempt to create warmth by expending energy.
  • Shivering can also be a response to a fever, as a person may feel cold, though their core temperature is already elevated.
  • Located in the posterior hypothalamus near the wall of the third ventricle is an area called the primary motor center for shivering.
  • This area is normally inhibited by signals from the heat center in the anterior hypothalamic-preoptic area but is excited by cold signals from the skin and spinal cord.



Q. 7

Posterior part of hypothalamus is concerned with:

March 2013

 A

Regulation of sexual function

 B

Role in circadian rhythm

 C

Regulation of response to smell

 D

Secretion of posterior pituitary hormones

Q. 7

Posterior part of hypothalamus is concerned with:

March 2013

 A

Regulation of sexual function

 B

Role in circadian rhythm

 C

Regulation of response to smell

 D

Secretion of posterior pituitary hormones

Ans. C

Explanation:

Ans. C i.e. Regulation of response to smell


Q. 8

Temperature regulation is chiefly under the control of:

September 2007

 A

Midbrain

 B

Pons

 C

Medulla

 D

Hypothalamus

Q. 8

Temperature regulation is chiefly under the control of:

September 2007

 A

Midbrain

 B

Pons

 C

Medulla

 D

Hypothalamus

Ans. D

Explanation:

Ans. D: Hypothalamus

Thermoregulation in both ectotherms and endotherms is controlled mainly by the preoptic area of the anterior hypothalamus.

Such homeostatic control is separate from the sensation of temperature


Q. 9

Sleep centre is located in –

 A

Basal ganglia

 B

Medulla

 C

Hypothalamus

 D

Cerebellum

Q. 9

Sleep centre is located in –

 A

Basal ganglia

 B

Medulla

 C

Hypothalamus

 D

Cerebellum

Ans. C

Explanation:

Ans. is ‘c’ i.e., Hypothalamus


Q. 10

Reward center is located in ‑

 A

Cerebellum

 B

Amygdala

 C

Hippocampus

 D

Hypothalamus

Q. 10

Reward center is located in ‑

 A

Cerebellum

 B

Amygdala

 C

Hippocampus

 D

Hypothalamus

Ans. D

Explanation:

Ans. is ‘d’ i.e., Hypothalamus


Q. 11

Reward center is located in ‑

 A

Cerebellum

 B

Amygdala

 C

Hippocampus

 D

Hypothalamus

Q. 11

Reward center is located in ‑

 A

Cerebellum

 B

Amygdala

 C

Hippocampus

 D

Hypothalamus

Ans. D

Explanation:

Ans. is ‘d’ i.e., Hypothalamus


Q. 12

Satiety center is located in which nucleus of hypothalamus ‑

 A

Posterior

 B

Ventrolateral

 C

Ventromedial

 D

Supraoptic

Q. 12

Satiety center is located in which nucleus of hypothalamus ‑

 A

Posterior

 B

Ventrolateral

 C

Ventromedial

 D

Supraoptic

Ans. C

Explanation:

Ans. is ‘C’ i.e., Ventromedial

The ventromedial nucleus is located in the basomedial hypothalamus, and is a critical node of the neural circuitry of female sexual behavior – so, not surprisingly . This ventromedial hypothalamus is classically known as a “satiety center



Leave a Reply

%d bloggers like this:
Malcare WordPress Security