Describes the structure and functions of hypothalamus along with their clinical relevance. The physiological basis of hypothalamic regulations and functions are also described.

1. PHYSIOLOGY OF HYPOTHALAMUS
Dr. REVAND R.
IMS-BHU
Varanasi

2. At the end of the class students will be able to
• Point out the location of hypothalamus in the brain
• Enumerate the various nuclei of physiological importance present in
the hypothalamus
• Describe the various functions of hypothalamus along with their
mechanisms in brief
• Clinically comprehend lesions involving hypothalamus

3. Clinical case:1
16-year-old girl was taken by her mother to a pediatrician because she was
rapidly losing weight. The mother stated that the weight loss started about 1 year
ago. The child's eating habits had changed from eating practically anything put
before her to being a very choosy eater. Her personality had also changed, and she
feared meeting strangers. On being urged to eat more food, the girl countered by
saying she was getting fat and must diet to improve her figure. Although she would
not admit to having anything wrong with her, she admitted that menstruation had
ceased 3 months previously.

4. Clinical case:1 (continued)
On being questioned by the pediatrician, the girl admitted to
calorie counting, and sometimes, when she felt she had overeaten, she
went to the toilet and forced herself to vomit by sticking her fingers
down her throat. On physical examination, she showed obvious signs of
weight loss with hollow facial features, prominent bones, and wasted
buttocks. Apart from having cold extremities and a low blood pressure
of 85/60 mm Hg, no further abnormalities were discovered.

5. Clinical case:2
A 17-year-old boy was admitted into the medical ward with 3-month history
of severe headaches. More recently, he had had attacks of vomiting and 1 week
ago he had noticed problems with his eyesight. The patient said that he had
difficulty seeing objects on the lateral side of both eyes. His parents were
concerned that he was putting on weight, as he was especially fat over the lower
part of the trunk. On physical examination, the boy was found to be 6 feet 3 inches
tall; he had excessive trunk obesity. The testes and penis were small and pubic and
axillary hair was absent. What is wrong with the patient?

6. Clinical case:2 (continued)

7. BRAIN
PROSENCEPHALON
(FOREBRAIN)
RHOMBENCEPHALON
(HINDBRAIN)
MESENCEPHALON
(MIDBRAIN)
DIENCEPHALON
TELENCEPHALON
(CEREBRUM)
HYPOTHALAMUS
THALAMUS
MEDULLA
PONS

8. • Located below the thalamus
• Forms the inferior part of
the lateral wall of the third
ventricle
• Lies posterior to the optic
chiasm

9. Functions of hypothalamus
1. Regulation of activity of anterior pituitary gland
2. Formation and regulation of secretion of posterior pituitary hormones
3. Control of water intake
4. Control of hunger and feeding
5. Regulation of body temperature
6. Control of circadian rhythm and sleep – wake cycle
7. Control of emotional behaviour
8. “Head ganglion” of autonomic nervous system

10. Functions of hypothalamus
1. Regulation of activity of anterior pituitary gland
2. Formation and regulation of secretion of posterior pituitary hormones
3. Control of water intake
4. Control of hunger and feeding
5. Regulation of body temperature
6. Control of circadian rhythm and sleep – wake cycle
7. Control of emotional behaviour
8. “Head ganglion” of autonomic nervous system

11. Three – hormone sequence
Stimulating hormone
(Tropic hormone)
Releasing hormone
(hypophyseotropic hormone)
Hormone

12. Hypothalamo – hypophyseal portal system
• Portal system starts in the
median eminence
• Releasing hormones reach
anterior pituitary via blood
capillaries
• Anterior pituitary hormones
are also released into the
blood capillaries

13. Advantages of portal system
• Hypophyseotropic hormones reach anterior pituitary without delay
• Small volumes of hypophyseotropic hormones do not dilute in the larger
volumes of systemic circulation as it remains confined to the portal
circulation
• Volume of hypophyseotropic hormones reaching the general circulation is
very low reducing unnecessary side effects systemically
• The flow of blood is very slow in the portal vessels. This allows the small
volumes of hypophyseotropic hormones to concentrate in the portal
circulation and delivered to the anterior pituitary (amplification)

14. Medial eminence is outside blood – brain barrier
• Hypothalamic hormones can be directly emptied into
blood
• Osmoreceptors directly detect the change in the
osmolality of blood, helping in regulation of blood
volume and water intake
• Regions located outside BBB are:
Organum vasculosum of lamina terminalis (OVLT)
Sub – fornicial organ (SFO)
Area postrema

15. HYPOTHALAMIC NUCLEI
MED. EM.
ANT. PIT. POST. PIT.
ANT.HY.N.
POST.HY.N.
HHPORT.SYS.
SYSTEMIC CIRC.

16. INFUNDIBULAR
(ARCUATE)
SUPRA
CHIASMATIC
DORSO
MEDIAL
PARA
VENTRICULAR
PREOPTICANTERIOR

17. “In – sequence” feedback regulation
+

18. “Non – sequence” regulation of pituitary hormones

19. Functions of hypothalamus
1. Regulation of activity of anterior pituitary gland
2. Formation and regulation of secretion of posterior pituitary hormones
3. Control of water intake
4. Control of hunger and feeding
5. Regulation of body temperature
6. Control of circadian rhythm and sleep – wake cycle
7. Control of emotional behaviour
8. “Head ganglion” of autonomic nervous system

20. Posterior pituitary secretions
• Two neurophysins – preprooxyphysin and prepropressophysin
• Produced by magnocellular neurons of hypothalamus

21. PARAVENTRICULAR NUCLEI
POST. PIT.
POST.HY.N.
SYSTEMIC CIRC.
c
c
c
cc
Contraction of
myoepithelial
cells
Contraction of
uterine smooth
muscles

22. SUPRAOPTIC NUCLEI
POST. PIT.
POST.HY.N.
SYSTEMIC CIRC.
c
c
c
cc
ANT. HYPOTH.
Angiotensin II
binds to SFO
and OVLT
Incorporate
aquaporins in
DCT and CT
Vasoconstriction
V1 receptor
Activates
phospholipase C;
hydrolyses PIP;
increase Ca
V2 receptor
Activates
adenylyl cyclase
– cAMP ;
increase Ca
Move
endosomes
containing
aquaporins in
DCT and CT
Increase water
reabsorption

23. Oxytocin and vasopressin secretion - variations
• Stimulation of the nipples causes a synchronous (same time in all
neurons secreting oxytocin), high-frequency discharge of the oxytocin
neurons. This discharge causes release of a pulse of oxytocin and
consequent milk ejection in postpartum females.
• Stimulation of vasopressin-secreting neurons by a stimulus such as an
increase in blood osmolality or loss of blood volume, causes an
asynchronous initial steady increase in firing rate followed by a
prolonged pattern of phasic discharge in which periods of high-
frequency discharge alternate with periods of electrical quiescence
(phasic bursting).
Phasic bursting is well-suited to maintain a prolonged increase in the output of vasopressin needed for correction of the water
imbalance

24. Functions of hypothalamus
1. Regulation of activity of anterior pituitary gland
2. Formation and regulation of secretion of posterior pituitary hormones
3. Control of water intake
4. Control of hunger and feeding
5. Regulation of body temperature
6. Control of circadian rhythm and sleep – wake cycle
7. Control of emotional behaviour
8. “Head ganglion” of autonomic nervous system

25. ANTERIOR
HYPOTHALAMUS
Angiotensin II
binds to SFO
and OVLT
CAROTID BODY
and
AORTIC ARCH
ADH secretion
Reduce water
loss Dryness of
mouth and
throat
Metering of
water intake by
GIT

26. Functions of hypothalamus
1. Regulation of activity of anterior pituitary gland
2. Formation and regulation of secretion of posterior pituitary hormones
3. Control of water intake
4. Control of hunger and feeding
5. Regulation of body temperature
6. Control of circadian rhythm and sleep – wake cycle
7. Control of emotional behaviour
8. “Head ganglion” of autonomic nervous system

27. Lateral
hypothalamus
(Feeding centre)
Feeding
Ventromedial
Hypothalamus
(Satiety centre)
Blood glucose
Glucoreceptors
(Glucostats)
Neuropeptide Y,
Orexin A and B,
Ghrelin
Free fatty acids,
Leptins, CCK

28. Functions of hypothalamus
1. Regulation of activity of anterior pituitary gland
2. Formation and regulation of secretion of posterior pituitary hormones
3. Control of water intake
4. Control of hunger and feeding
5. Regulation of body temperature
6. Control of circadian rhythm and sleep – wake cycle
7. Control of emotional behaviour
8. “Head ganglion” of autonomic nervous system

29. Anterior
hypothalamus
Heat loss
Posterior
hypothalamus
Heat gain
High body
temperature
sensed by central
and peripheral
receptors
Low body
temperature
sensed by central
and peripheral
receptors
Cutaneous
vasodilation,
sweating (37°C)
Cutaneous
vasoconstriction
(36.8 °C),
shivering (35.5 °C)

30. Pathogenesis of fever
Antipyretics

31. MCQ : 1
Choose the correct statement with respect to temperature regulation
A. The thalamus integrates information regarding temperature regulation
B. Fever is caused by the action of prostaglandins on hypothalamus
C. Shivering is a mechanism of heat gain on prolonged exposure to cold
D. When the body temperature is above the set point temperature, heat gain is
more than heat loss
E. Sweating occurs as a response to external temperature > 37 ° C

32. MCQ : 1 (discussion)
Choose the correct statement with respect to temperature regulation
A. The thalamus integrates information regarding temperature regulation
B. Fever is caused by the action of prostaglandins on hypothalamus
C. Shivering is a mechanism of heat gain on prolonged exposure to cold
D. When the body temperature is above the set point temperature, heat gain is
more than heat loss
E. Sweating occurs as a response to external temperature > 37 ° C

33. Functions of hypothalamus
1. Regulation of activity of anterior pituitary gland
2. Formation and regulation of secretion of posterior pituitary hormones
3. Control of water intake
4. Control of hunger and feeding
5. Regulation of body temperature
6. Control of circadian rhythm and sleep – wake cycle
7. Control of emotional behaviour
8. “Head ganglion” of autonomic nervous system

34. Retina
Supra chiasmatic
nucleus
Sleep – wake
cycle
(Biological
clock)
Diurnal
variation of
hormonal
secretions
Retino–hypothalamic
tract
Reticular
activating system
Mammillary body
Pineal gland
Nocturnal
secretion of
melatonin
WAKE
SLEEP
Mammillo – tegmental
tract

35. Functions of hypothalamus
1. Regulation of activity of anterior pituitary gland
2. Formation and regulation of secretion of posterior pituitary hormones
3. Control of water intake
4. Control of hunger and feeding
5. Regulation of body temperature
6. Control of circadian rhythm and sleep – wake cycle
7. Control of emotional behaviour
8. “Head ganglion” of autonomic nervous system

36. Papez circuit
Anterior
nucleus of
thalamus
Cingulate gyrus
Hippocampus
Hypothalamus
Mammillary
body
Prefrontal
cortex
Brainstem
nuclei
Fornix
Mammillo-thalamic
tract of Vicq d’Azur
MemoryMotivation
AmygdalaStria terminalis

37. Functions of hypothalamus
1. Regulation of activity of anterior pituitary gland
2. Formation and regulation of secretion of posterior pituitary hormones
3. Control of water intake
4. Control of hunger and feeding
5. Regulation of body temperature
6. Control of circadian rhythm and sleep – wake cycle
7. Control of emotional behaviour
8. “Head ganglion” of autonomic nervous system

38. Lateral and
posterior
hypothalamus
Anterior and
preoptic
hypothalamus
Sympathetic
system
Parasympathetic
system
Sham rage

39. Functions of hypothalamus
1. Regulation of activity of anterior pituitary gland
2. Formation and regulation of secretion of posterior pituitary hormones
3. Control of water intake
4. Control of hunger and feeding
5. Regulation of body temperature
6. Control of circadian rhythm and sleep – wake cycle
7. Control of emotional behaviour
8. “Head ganglion” of autonomic nervous system

40. HYPOTHALAMIC NUCLEI – CLASSIFICATION

41. Hypothalamic nuclei
Anterior LateralMedial
Supra chiasmatic
Anterior
Posterior
Mammillary body
Preoptic
Supra optic
Ventromedial
Dorsomedial
Infundibular
Paraventricular

42. Hypothalamic nuclei
Anterior LateralMedial
Supra chiasmatic
Anterior
Posterior
Mammillary body
Preoptic
Supra optic
GnRH
Osmoreceptors
Heat loss
ParasympatheticEmotions
GnRH
Fever origin
Parasympathetic
Vasopressin
Somatostatin
Biological clock

43. Hypothalamic nuclei
Anterior LateralMedial Posterior
Ventromedial
Dorsomedial
Infundibular
Paraventricular
TRH
GHRH
TRH
CRH
Oxytocin
Satiety

44. Hypothalamic nuclei
Anterior LateralMedial Posterior
Feeding
Sympathetic
Heat gain
Sympathetic

45. Hypothalamic nuclei
Anterior LateralMedial
Supra chiasmatic
Anterior
Posterior
Mammillary body
Preoptic
Supra optic
GnRH
Osmoreceptors
Heat loss
ParasympatheticEmotions
GnRH
Fever origin
Parasympathetic
Vasopressin
Somatostatin
Biological clock
Hypothalamic nuclei
Anterior LateralMedial Posterior
Ventromedial
Dorsomedial
Infundibular
Paraventricular
TRH
GHRH
TRH
CRH
Oxytocin
Satiety
Hypothalamic nuclei
Anterior LateralMedial Posterior
Feeding
Sympathetic
Heat gain
Sympathetic

46. Clinical case:1 (discussion) – Anorexia nervosa
16-year-old girl was taken by her mother to a pediatrician because she was rapidly losing weight. The
mother stated that the weight loss started about 1 year ago. The child's eating habits had changed from eating
practically anything put before her to being a very choosy eater. Her personality had also changed, and she
feared meeting strangers. On being urged to eat more food, the girl countered by saying she was getting fat
and must diet to improve her figure. Although she would not admit to having anything wrong with her, she
admitted that menstruation had ceased 3 months previously.
On being questioned by the pediatrician, the girl admitted to calorie counting, and sometimes, when
she felt she had overeaten, she went to the toilet and forced herself to vomit by sticking her fingers down her
throat. On physical examination, she showed obvious signs of weight loss with hollow facial features,
prominent bones, and wasted buttocks. Apart from having cold extremities and a low blood pressure of 85/60
mm Hg, no further abnormalities were discovered.

47. Clinical case:2 (discussion)
A 17-year-old boy was admitted into the medical ward with 3-month history
of severe headaches. More recently, he had had attacks of vomiting and 1 week
ago he had noticed problems with his eyesight. The patient said that he had
difficulty seeing objects on the lateral side of both eyes. His parents were
concerned that he was putting on weight, as he was especially fat over the lower
part of the trunk. On physical examination, the boy was found to be 6 feet 3 inches
tall; he had excessive trunk obesity. The testes and penis were small and pubic and
axillary hair was absent. What is wrong with the patient?

48. Clinical case:2 (discussion)

49. Clinical case:2 (diagnosis)
Hypothalamic mass probably tumour causing
Bitemporal hemianopsia + obesity + hypogonadism
Babinski – Frohlich syndrome (or)
Launois – Cleret syndrome (or)
Hypothalamic infantilism with obesity (or)
Adiposo-genital dystrophy

50. THANK YOU