The hypothalamus is a small region located inferior to the thalamus that regulates many essential body functions such as blood pressure, heart rate, temperature, hunger, and hormone secretion through the autonomic nervous system, endocrine system, and limbic system. It is divided into anterior, middle, and posterior regions that control different processes like circadian rhythms, reproduction, feeding, and emotional responses. The hypothalamus communicates with the pituitary gland to regulate hormone release and various homeostatic mechanisms in the body.

1. HYPOTHALAMUS
Dr Saadiyah
Department of Physiology
DIMC

3. PROSENCEPHLON
(Forebrain)
TELENCEPHALON DIENCEPHHALON
THALAMUS
HYPOTHALAMUS
EPITHALAMUS

4. HYPOTHALAMUS
• Located inferior to thalamus
• Very small size; few cubic centimeters
• Comprises less than 1% of human brain
• Almost every part of ANS & CNS communicate
with it
• Act on three major systems: ANS, Endocrine &
limbic system
• An integrative center essential for survival &
reproduction of organism

5. Regulates:
• Blood pressure
• Heart rate
• Electrolyte composition
• Body temperature
• Body water
• Feeding
• Endocrine hormone secretion by anterior pituitary
• Uterine contractility
• Milk ejaction
• Reproduction
• Emergency responses to stress

6. • Divided into following regions:
Anterior (Supraoptic)
Preoptic
Middle (tuberal)
Posterior (mammillary)

7. Anterior (supraoptic)Region:
•Superior to
optic chiasm
•Paraventricular,
Supraoptic,
Anterior &
Suprachiasmatic
nuclei

8. Anterior (supraoptic)Region:
• Vasopressin & oxytocin
• Circadian rhythm
• Temperature

9. Preoptic Area:
• Anterior to
supraoptic region
• Medial & lateral
preoptic nuclei
• Regulates certain
autonomic activies

10. Preoptic area:
• Temperature
• Blood pressure
• Reproduction
• Drinking
• Feeding
• Hormone (thyrotropin)

11. Middle (tuberal) region:
• Dorsomedial,
Ventromedial,
Lateral &
Arcuate
nuclei
• Infundibulum
connects it
with pituitary
gland

12. Middle (tuberal) region:
• Satiety center (VMN)
• Hunger center (Lat)
• Thirst center (Lat)
• Neuroendocrine control
• GI stimulation

13. Posterior ( mammillary) Region:
•Most posterior
part of
hypothalamus
•Adjacent to mid
brain
•Mammillary
bodies &
posterior nuclei

14. • Temperature control
• Relay station for sense of smell
• Feeding reflex

15. Mammillary bodies:
• Two small rounded projections.
• Are component of limbic system
• Limbic system: Emotional Brain
Ring of structures on the inner border of
cerebrum
Plays primary role in range of emotions
including pain, pleasure, affection & anger.
Also involved in olfaction & memory

16. MEDIAL ZONE
• Preoptic (part)
• Anterior
• Suprachiasmatic (part)
• Parventricular
• Dorsomedial
• Ventromedial
• Arcuate
• Posterior

17. LATERAL ZONE
• Preoptic (part)
• Suprachiasmatic (part)
• Supraoptic
• Lateral

18. Cardiovascular Regulation
• Stimulation in posterior & lateral
hypothalamus INC arterial pressure &
heart rate
• Stimulation in preoptic area DEC arterial
pressure & heart rate

19. BODY TEMP. REGULATION
• Anterior portion of hypothalamus
especially Preoptic area is concerned
• Inc in temp of blood flowing through this
area inc activity of temp sensitive neurons

20. • Fall in body temp below set point
• Temp monitoring nerve cells
+
• Temp control center
+
• Skeletal muscles & other effector organs
• Inc heat production
• Inc in body temp to set point

22. • Infection
• Macrophages
• Prostaglandins
• Inc Hypothalmic set point
• Inc heat producton, Dec heat loss
• Inc body temp to new set point=fever

23. BODY WATER REGULATION
• Two ways:
• Water drinking (Thirst center= Lateral
hypothalamus)
• Excretion (ADH=Supraoptic)

24. FEEDING REGULATION
• Hunger center is located in lateral
hypothalmic area
• Damage to this area causes loss of desire
for food
• Satiety center is loated in ventromedial
nuclei
• Damage to this area causes voracious
appetite

25. ENDOCRINE REGULATION
• Thyrotropin releasing hormone
• Corticotropin releasing hormone
• Growth hormone releasing hormone
• Growth hormone inhibitory hormone
(somatostatin)
• Gonadotropin releasing hormone
• Dopamine/ Prolactin inhibiting factor
• ADH
• Oxytocin

26. Hypothalamic Control of the
Anterior Pituitary
• Hypothalamus
neurons synthesize
releasing and
inhibiting hormones.
• Hormones are
transported to axon
endings of median
eminence.
• Hormones secreted
into the hypothalamo-
hypophyseal portal
system regulate the
secretions of the
anterior pituitary

27. Hypothalamic Control of Posterior
Pituitary
• Hypothalamus
neuron cell bodies
produce:
– ADH: supraoptic
nuclei.
– Oxytocin:
paraventricular
nuclei.
• Transported along
the hypothalamo-
hypophyseal tract.
• Stored in posterior
pituitary.

28. EMOTIONAL CONTROL
• Stimulation in Lateral hypothalamus inc
general activity, sometimes leading to
overt rage & fighting
• Stimulation in Ventromedial nucleus
causes opposite effects-------Tranquility

29. REGULATION OF CIRCADIAN
RHYTHMS
• Supachiasmatic nucleus establishes
patterns of awakening & sleep
• Receives input from retina
• Sends output to other hypothalmic nuclei,
reticular formation & pineal gland

30. Circumventricular Organs
• Parts of diencephalon, called CVO b/c
they lie in walls of 3rd & 4th ventricals.
• Component: Hpothalamus, pineal &
pituitary gland.
• Monitor chemical changes in blood b/c
lack a blood brain barrier
• Thought to be the site of entry of HIV into
brain