physiology of Hypothalaums & limbic system

1. Functions of the thalamus ,
Hypothalamus & Limbic system
Fatima Wahid Mangrio
fatimawahid1234@gmail.com

2. • The limbic system, is a set of brain
structures located on both sides of
the thalamus, immediately beneath the
medial temporal lobe of the cerebrum
primarily in the forebrain.
• The limbic system is a set of structures in
the brain that controls emotion, memories
and arousal. It contains regions that detect
fear, control bodily functions
LIMBIC SYSTEM

4. • There are several important structures within
the limbic system:
the amygdala, hippocampus, thalamus, hypoth
alamus, basal ganglia, and cingulate gyrus.
• All the components of the limbic system work
together to regulate some of the brain's most
important processes.

7. Amygdala
• The amygdalas are two almond-shaped masses
of neurons on either side of the thalamus.
• When it is stimulated electrically, animals
respond with aggression. And if the amygdala is
removed, animals get very tame and no longer
respond to things that would have caused rage
before. But there is more to it than just
anger: When removed, animals also become
indifferent to stimuli that would have otherwise
have caused fear and even sexual responses.

8. Hippocampus
• The hippocampus consists of two “horns” that
curve back from the amygdala. It appears to
be very important in converting things that
are “in your mind” at the moment (in short-
term memory) into things that you will
remember for the long run (long-term
memory).

9. • If the hippocampus is damaged, a person
cannot build new memories, and lives instead
in a strange world where everything they
experience just fades away.
• learning how to memorize speeches or lines in
a play. Spatial relationship memories involve
pathways or routes.

10. THALAMUS
• The thalamus is a small structure
within the brain located just above the brain
stem between the cerebral cortex
and the midbrain and has extensive nerve
connections to both. The main function of the
thalamus is to relay motor and sensory signals
to the cerebral cortex.

11. • Its ventral areas are dedicated to
motor function while the dorsal regions are
involved in sensory information circuits.
The thalamus and hypothalamus are located
within the diencephalon (or “interbrain”), and
are part of the limbic system. They regulate
emotions and motivated behaviors like
sexuality and hunger.

12. Sensory Relay Station
• It acts as a sensory relay station for all sensation.
• It has specific sensory relay nuclei like lateral
geniculate body for vision, medial geniculate body for
auditory, ventral posterior lateral, and ventral
posterior medial somatosensory information.These
relay respective sensations to corresponding cortical
areas.
• Every sensation is processed & integrated here and
then sent to the cerebral cortex.
• It is therefore called ‘’ functional gateway’’ or ‘’lady
secretary’’ of the cerebral cortex.

13. Arousal & Alertness reaction
• Midline & intralaminar nuclei of thalamus
project to widespread regions of neocortex.
• These nuclei are part of RAS.
• These are responsible for arousal alertness
reaction.

14. Reflex Actvities
• It is centre for many reflex activities.
• It has ventral anterior & ventra lateral nuclei
that are concerned with motor functions.
• They receive information from cerebral
cortex, basal ganglia, and cerebellum and
project to the motor cortex.

15. Emotions
• Its anterior nuclei receive afferents from
the mamillary bodies and project to the limbic
cortex and this may be involved in emotions
and memory.

16. cingulate gyrus
• The cingulate gyrus is the part of the
cerebrum that lies closest to the limbic
system, just above the corpus collosum. It
provides a pathway from the thalamus to the
hippocampus, seems to be responsible for
focusing attention on emotionally significant
events, and for associating memories to
smells and to pain.

17. HYPOTHALAMUS
• Located superior to the pituitary gland
and inferior to the thalamus, the
hypothalamus is a small area of the
brain with many diverse functions:

18. FUNCTIONS OF THE
HYPOTHALAMUS
• Production of antidiuretic hormone
(ADH) and oxytocin; these hormones
are then stored in the posterior
pituitary gland. ADH enables the
kidneys to reabsorb water back into the
blood and thus helps maintain blood
volume. Oxytocin causes contractions of
the uterus to bring about labor and
delivery.

19. • Production of releasing hormones (also
called releasing factors) that stimulate
the secretion of hormones by the
anterior pituitary gland.
• The hypothalamus produces growth
hormone releasing hormone (GHRH),
which stimulates the anterior pituitary
gland to secrete growth hormone (GH).

20. • Regulation of body temperature by
promoting responses such as sweating in
a warm environment or shivering in a
cold environment.

21. • Regulation of food intake; the hypothalamus is
believed to respond to changes in blood
nutrient levels, to chemicals secreted by fat
cells, and to hormones secreted by the
gastrointestinal tract. For example, during a
meal, after a certain duration of digestion,
the small intestine produces a hormone that
circulates to the hypothalamus and brings
about a sensation of satiety, or fullness, and
we tend to stop eating.

22. • Integration of the functioning of the
autonomic nervous system, which in turn
regulates the activity of organs such as
the heart, blood vessels, and intestines

23. • Stimulation of visceral responses during
emotional situations. When we are
angry, heart rate usually increases.
Most of us, when embarrassed, will
blush, which is vasodilation in the skin
of the face. These responses are
brought about by the autonomic nervous
system when the hypothalamus
perceives a change in emotional state.

24. • Regulation of body rhythms such as
secretion of hormones, sleep cycles,
changes in mood, or mental alertness. This
is often referred to as our biological clock,
the rhythms as circadian rhythms, meaning
“about a day.” If you have ever had to stay
awake for 24 hours, you know how
disorienting it can be, until the
hypothalamic biological clock has been
reset.

25. • Hypothalamus is involved in expression
of emotions
• The hypothalamus also plays an important role
in emotion. Lateral parts of
the hypothalamus are involved
in emotions such as pleasure and rage, while
the median part is associated with aversion,
displeasure, and a tendency to uncontrollable
and loud laughing.