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NEUROENDOCRINOLOGY, KEY POSITION OF HYPOTHALAMUS
Olga Vajnerová, 2nd Faculty of Medicine, Charles University, Prague,
2011
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Hypothalamus, a major control headquarters for the limbic system
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Hypothalamus, a major control headquarters for the limbic system
Hypothalamus Cortex
Thalamus Temporal lobe Basal ganglia Septum Paraolfactory
area
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Hypothalamus, a major control headquarters for the limbic system
Hypothalamus Cortex
Thalamus Temporal lobe Basal ganglia Septum Paraolfactory
area
cingulate gyrusParahippocampal gyrusOrbitofrontal cortex
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Hypothalamus, a major control headquarters for the limbic system
Hypothalamus Cortex
Thalamus Temporal lobe Basal ganglia Septum Paraolfactory
area
cingulate gyrusParahippocampal gyrusOrbitofrontal cortex
Anterior nuclei
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Hypothalamus, a major control headquarters for the limbic system
Hypothalamus Cortex
Thalamus Temporal lobe Basal ganglia Septum Paraolfactory
area
cingulate gyrusParahippocampal gyrusOrbitofrontal cortex
Anterior nuclei
Hippocampus
Amygdala
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Functions of hypothalamus
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Functions of hypothalamus
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Relation to autonomic function
Parasympathetic responses
Urinary bladder contraction
Sympathetic responses
Increased adrenal medullary secretion
Vasoconstriction
Stress – fight or flight
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Cardiovascular regulation
Arterial pressure
Heart rate
Specific cardiovascular control centres are in….
Reticular regions of the pons and medulla
Cardioexcitatory area
Cardioinhibitory area
Vasomotor area
Via Sympathetic and Parasympathetic nerves
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Influence on respiratory and gastointestinal reflexes
Olfactory stimulus – from paleocortex
Signals to visceromotor centres in medulla – nausea, vomiting
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Transmission of emotions from limbic system
Rage, anxiety and fear, joy, sadness
Is connected with visceromotor and somatomotor reaction
Hear rate, breathig rate, vasomotor reaction – pale or red skin, sweat glands, gastrointestinal motility and secretion, smooth muscle in skin, shivering
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Biological rhythms
Suprachiasmaticus nuclei – retinohypothalamic tract
Pacemaker of circadian rhythms
Sleep – wake cycle
ACTH secretion
Melatonin secretion
Body temperature rhythm
Activity patterns of animals
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Regulation of body water
1. Thirst center
Lateral hypothalamus
Osmoreceptors – when the EF is too concetrated – develops intense desire to drink water
2. Antidiuretic hormone
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Gastrointestinal and feeding regulation
Hunger center
Lateral nuclei of the hypothalamus
stimulation – extreme hunger, appetite,
craving for food, hyperphagia
Destruction of this area – lethal starvation, weight loss, muscle weakness, decreased metabolism
Is permanently active
Satiety center
Ventromedial nuclei of the hypothalamus
Stimulation – sense of complete satiety, refusal of food, aphagia
Destruction – hunger centers overactive, continuing eating, obesity
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Other important nuclei in feeding regulation
Paraventricular, dorsomedial and arcuate nuclei of the hypothalamus
ncl arcuatus = ncl infundibularis
The site where multiple hormones converge to regulate food intake and energy expenditure
Hypothalamus
Receives hormonal signals (from GIT, adipose tissue)
neural signals (from GIT)
chemical signals (from blood about nutrients)
signals from cerebral cortex (sight, smell and taste)
Draw a picture
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Orexigenic substances ??
Anorexigenic substances
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Orexigenic substances stimulate feeding
Ghrelin
Anorexigenic substances ???
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Orexigenic substances stimulate feeding
Ghrelin
Anorexigenic substances inhibit feeding
CCK, insulin, leptin
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Short-term regulation of food intake
- gastrointestnal filling- GIT hormonal factors – CCK, insulin, ghrelin
- oral receptors meter food intake
Oral factors related to feeding
such as chewing, salivation, swallowing, tasting
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Intermediate and long-term regulation of food intake
- concentration of glucose, amino acids, and lipids
glucostatic theory of hunger and feeding regulation(rise in blood glucose level increases firing of neurons in the satiety center, decrease in hunger center
- Temperature regulation and food intake
Cold increased feeding
Interaction between temperature-regulating systém and food intake-regulating systém
- Feedback signals from adipose tissue - leptin
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Regulation of body temperature
Temperature regulating centers
Temperature receptors
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Regulation of body temperature
Temperature regulating centers
Temperature receptors
1. Peripheral
Skin receptors (cold and warm)
Deep body temperature receptors
Spinal cord, abdominal viscera and great veins
2. Central
Temperature detectors in hypothalamus
Heat sensitive neurons, cold sensitiv neurons
Praeoptic area
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Posterior hypothalamus integrates the central and peripheral temperature sensory signals
Control Heat-producing
Heat- conserving reaction of the body
Set point – crucial temperature level 37.1ºC
Feedback gain for body temperature control
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Temperature-decreasing mechanisms
Vasodilation of skin blood vessels
Inhibition of the sympathetic centers in the posterior hypothalamus
Sweating
Praeoptic area, via autonomic pathways to the spinal cord
Sympathetic but cholinergic
Decrease in heat production
Inhibition of shivering and thermogenesis
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Temperature-decreasing
mechanisms
Vasodilation of skin blood vessels
Inhibition of the sympathetic centers in the posterior hypothalamus
Sweating
Praeoptic area, via autonomic pathways to the spinal cord
Sympathetic but cholinergic
Decrease in heat production
Inhibition of shivering and thermogenesis
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Temperature-decreasing
mechanisms
Vasodilation of skin blood vessels
Inhibition of the sympathetic centers in the posterior hypothalamus
Sweating
Praeoptic area, via autonomic pathways to the spinal cord
Sympathetic but cholinergic
Decrease in heat
production
Inhibition of shivering
and thermogenesis
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What are temperature-increasing mechanisms ??
No Vasodilation of skin blood vessels
NO Sweating
Increase in heat production
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Temperature-increasing mechanisms
When the body is too cold
1. Vasoconstriction of skin blood vessels
Stimulation of the sympathetic centers in the posterior hypothalamus
2. Piloerection
via autonomic pathways to the spinal cord
Sympathetic stimulation causes
arrector pili muscles to contract
3. Increase in heat production, thermogenesis
Shivering, sympathetic excitation of heat production,
Thyroxin secretion
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3. Increase in heat production, thermogenesis
ShiveringPrimary motor center for shivering in the dorsomedial portion of the posterior hypothalamusExcited by cold signals from the skin and spinal cordTr hypothalamoreticularis, hypothalamospinalis to spinal motoneuronsNon rhytmical signals, increase the tone of the skeletal musclesProbably feedback oscillation of the muscle spindle stretch reflex
Sympathetic excitation of heat productionChemical thermogenesis, E and NE uncouple oxidative phosphorylation, energy in the form of heat but do not cause ATP to be formed
Thyroxin secretion
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Sympathetic excitation of heat productionChemical thermogenesis, E and NE uncouple oxidative phosphorylation, energy in the form of heat but do not cause ATP to be formed
Thyroxin secretion