AUTONOMIC NERVOUS SYSTEM Department of human … AUTONOMI… · Autonomic nervous system...
Transcript of AUTONOMIC NERVOUS SYSTEM Department of human … AUTONOMI… · Autonomic nervous system...
Hpothalamus
AUTONOMIC NERVOUS SYSTEM
Department of human Physiology UPJS MF
Prof. Viliam Donic and Doc. Pavol Svorc
Distant teaching
6th week summer semester 2020
Autonomic nervous system – autonomic centers
The centers of the autonomic nervous system are seen as integrators of responses
to the internal and external facts, which are related to the control of autonomic
functions.
- of spinal cord - although all sympathetic and sacral parasympathetic fibers are
going out from spinal cord, it is not clear whether there are centers controlling and
coordinating the activities of the relevant part of the autonomic nervous system, or
they are only peripheral centers.
From this point of view, it is problematic inclusion:
- of cortex - which is involved in the control of autonomic functions, whose
importance is in the integration and the creation of conditioned reflexes associated
with the autonomic nerves.
Autonomic nervous system – autonomic centers
Is taken into account brainstem and hypothalamus.
Reticular formation - is responsible for regulation of the cardiovascular system,
respiratory system and is the center of some autonomic reflexes.
Cardiovascular center includes the following structures:
- ncl. dorsalis n.vagi – source of vagal parasympathetic afferentation
- pressoric area – is located on both sides in the dorsolateral part of reticular
formation. Increased activity leads to an increase in blood pressure. Sympathetic
preganglionic neurons innervating heart, blood vessels and juxtaglomerular
apparatus are efferent pathways from this center.
- depressoric area - is located in the ventromedial part of both sides of reticular
formation. Increased activity leads to decrease of blood pressure and, reciprocally, it
is connected with pressoric area.
Autonomic nervous system – autonomic centers
Respiratory center - is functionally situated into autonomic centers,
because it affects the spinal motor neurons controlling breathing
movements through the autonomic respiratory rhythm generator and
inspiration rhythm.
Autonomic reflexes - associated with input and processing of food. It is a
sucking reflex, swallowing, salivatory reflex, secretion of gastric and
pancreatic juices and vomiting reflex.
Autonomic nervous system – autonomic centers
Sensory information from the somatosensory and visceral receptors goes
to the centers for homeostasis in the hypothalamus, in the pons and in the
medulla oblongata.
postgangliové
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pregangliové
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postgangliové
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Nuclei of the hypothalamus
Paraventricular nucleus
(Water balance/stress)Lateral
hypothalamic
area
Dorsal
hypothalamic
area
Posterior
hypothalamic
area
(Shivering)
Dorsomedial
nucleus
(GI tract)
Ventromedial
nucleus
(Satiety)
Mammilary
body
(Feeding)
Suprachiasmatic
nuclei
(Biological Clock)
Posterior
pituitary
glandAnterior
pituitary
gland
Optic chiasm
Optic nerve
Supraoptic
nucleus
(Water balance)
Anterior
hypothalamic area
(Body temperature)
Medial preoptic
(Blood pressure)
Autonomic nervous system – hypothalamus
ANTERIOR HYPOTHALAMUS
Preoptic preoptic nucleus thermogegulation
Medial medial preoptic nucleus regulates the release of gonadotropic
hormones from the adenohypophysis
Contains the sexually dimorphic nucleus,
which releases GnRH, differential
development between sexes is based upon
in utero testosterone levels
thermoregulation
supraoptic nucleus vasopressin, oxytocin releasing
paraventricular nucleus thyrotropin-releasing hormone,
corticotropin releasing hormone, oxytocin,
vasopressin, somatostatin
anterior hypothalamic nucleus thermoregulation, panting, sweating,
thyrotropin inhibition
suprachiasmatic nuclei circadian rhythm
Lateral lateral nucleus primary source of orexin neurons that
project throughout the brain and spinal
cord
Autonomic nervous system – hypothalamus
TUBERAL HYPOTHALAMUS
Medial dorsomedial preoptic nucleus blood pressure, heart rate, GI stimulation
ventromedial nucleus satiety, neuroendocrinne control
arcuate nucleus growth releaing hormone, feeding,
dopamine mediated prolactin inhibition
Lateral lateral nucleus primary source of orexin neurons that
project throughout the brain and spinal
cord
POSTERIOR HYPOTHALAMUS
Medial mammilary nuclei memory
posterior nucleus increase blood pressure, pupilary
dilation, shivering, vasopressin release
lateral nucleus primary source of orexin neurons that
project throughout the brain and spinal
cord
Lateral tuberomammillary nucleus arousal (wakefulness and attention),
feeding and energy balance, learning,
memory, sleep
Autonomic nervous system – functions of hypothalamus
Hunger is a feeling (unconditioned reaction of the body), caused by lack of food. It
is an important signal, saying to the body about the need for food intake and
energy from it.
Center of hunger and satiety
Autonomic nervous system – functions of hypothalamus
Center of hunger and satiety
Satiety center is located in the hypothalamus, near the regulatory centers for
secretion of hormones and endocrine processes in our body. Center of hunger is
located near at the center of satiety.
Signals for center of satiety
- stretching of stomach and intestines
- increased external and internal temperature
- glucose, amino acids, fatty acids
- dopamine
- intestinal peptide PYY
- peptides released from the digestive tract (cholecystokinin, bombesin, glucagon,
enterostatin, somatostatin)
- leptin
- ghrelin
- insulin
Center of hunger Center of satiety
ncl. lateralis ncl. ventromedialis
- is continuously active
increase in plasma glucose levels
Autonomic nervous system – functions of hypothalamus
- lesion of ncl.ventromedialis
leads to hyperphagia- stimulation of the lateral hypothalamus leads to
increase in eating-oriented behavior (looking for
food)
activates glucoreceptors
located in
ncl.ventromedialis
Control of food intake
Autonomic nervous system – functions of hypothalamus
It is assumed that the information from
the periphery (sensory inputs from the
digestive tract, including gustatory
afferentation) are guided into
ncl.arcuatus in
hypothalamus
lateral part of
hypothalamusncl.paraventricularis ncl.dorsomedialis
projections
into
All of these structures contain two types of neurons:
- orexigenic neurons - synthesize substances, which higher levels correlate with increased
income of food and activate ncl.ventromedialis
- anorexigenic neurons – synthesize substances, which higher levels correlate with reduced
intake of food
Control of food intake
Autonomic nervous system – functions of hypothalamus
Neurons releasing amphetamine (CART) and
proopiomelanocortin (POMC)
Neurons releasing agoutin-related protein
(AgRP), neuropeptide Y (NPY) and γ-
aminobutyric acid (GABA)
Important for the regulation of body weight
Control of food intake
Autonomic nervous system – functions of hypothalamus
Ghrelin is "hunger hormone".
Ghrelin is a peptide hormone produced by
ghrelinergic cells in the gastrointestinal
tract which functions as a neuropeptid in
the CNS.
Ghrelin regulates appetite, and also
distributiom and rate of use of energy.
When the stomach is empty, ghrelin is
absorbed. When the stomach is stretched,
secretion stops.
Ghrelin acts on hypothalamic brain cells and
increases not only hunger, but also
increases gastric acid secretion and
gastrointestinal motility to prepare the body
for food intake.
Control of food intake
Autonomic nervous system – functions of hypothalamus
Leptin is “the hormone of energy
expenditure“.
Leptin is a hormone predominantly made by
adipose cells that helps to regulate energy
balance by inhibiting hunger.
Leptin is opposed by the actions of the
hormone ghrelin, the "hunger hormone".
Leptin and ghrelin act on receptors in the
arcuate nucleus of the hypothalamus to
regulate appetite to achieve energy
homeostasis.
In obesity, similar to resistance of insulin in
type 2 diabetes , a decreased sensitivity to
leptin occurs, resulting in an inability to
detect satiety despite high energy stores and
high levels of leptin.
Center of thirst
Autonomic nervous system – functions of hypothalamus
Thirst is the body's response to lack of fluids.
We have two types of dehydrations:
One lies in the fact that man has shortage of water (mostly in well-trained athletes who
secrete thin "water" sweat). In this case, the blood is concentrated, but only briefly,
since immediately water from the intercellular spaces starts to flow into blood
resulting in increase the salt concentration in the extracellular fluid. For compensation
of this concentration with concentration in cells, water from cells moves into the
intercellular spaces and thus results in their partial dehydration.
A second type of dehydration of the body is that the person loses not only water but
also a large amount of salts (untrained athletes secrete dense "salty" sweat), which
are mainly in the blood and in the extracellular fluids. This usually results in only a
slight increase in the concentration of ions (salts) in the extracellular fluid. At this type
of dehydration, water content remains stable in the cells, but the amount of circulating
blood and intercellular fluid are reduced.
Center of thirst
Autonomic nervous system – functions of hypothalamus
Nc.paraventricularis - in this center are the cells that are in the contact with the blood flow and
cerebrospinal fluid and respond either by calling thirst or vice versa calling the urge to urinate.
Stimulus Osmoreceptors - increase of
osmotically active substances
(electrolytes - cations and anions)
in ECF.
Baroreceptors - decrease in
plasma volume. If the body fluid
deficiency there is, the pressure
in the veins is small and blood is
too "dense".
Renin - angiotensin system - at
the decreased plasma volume,
greater concentrations of
angiotensin II raise blood
pressure and causes a feeling of
thirst.
Psychological and social factors
The stimulus for thirst and thus for fluid intake is stimulation
of the mucous cells in the mouth and throat by the partial
dehydration of the cells (the stimulation can also sometimes
come from other causes, such as a cold, considerable moisture,
for example, after eating of ice cream).
Dry mouth can be result of using by certain drugs (e.g. drugs
for allergy), or can be due to insufficient production of saliva
(e.g. in disease called xerostomia), increases thirst.
In older people, generally, centre of thirst failures. Older
people do not feel thirst and they have to regulate the fluid
intake themselves.
Control of the body temperature
anterior hypothalamus posterior hypothalamus
- output of heat
hypothermia
- production of heat
hyperthermia
Autonomic nervous system – functions of hypothalamus
THERMOREGULATION – mechanisms of thermoregulation
HYPOTHALAMUS
centrum of thermoregulation
receives the informations about the central and
peripheral temperature and also about the temperature
of the environment
Central thermal
receptors
Peripheral thermal
receptors
- they are in the anterior
hypothalamus in the preoptic area
- the are sensitive for the higher
temperatures
- approximately 1/3 from the
total amount of the central
thermosensitive neurons reacts
for the decrease of the body
temperature
Cold receptors Warm receptors
THERMOREGULATION – nervous control
ncl. dorsalis
ncl. ventromedialis
ncl. paraventricularis
lamina terminalis
ncl. supraopticus
chiasma opticum
portal vessels
NEUROHYPOPHYSIS
ADENOHYPOPHYSIS
AREA
HYPOTHALAMICA
POSTERIOR
AREA
PREOPTICA
PREOPTIC AREA
AREA HYPOTHALAMICA
POSTERIOR
- it is responsible for monitoring of
the body temperature and also for
the reactions at the increase of
temperature
- at the injury of this area, we can
see the extreme increase of
temperature
- neurons don’t directly monitore
the body temperature, but they
react to the informations from
peripheral and central receptors
and activate output functions of
thermoregulation
- output functions of thermoregula-
tion are concentrated on the
maintenance of the adequate body
temperature and protection of the
organism before hypothermia
- irritation of this area causes the
muscle tremor
Control of the endocrine glands
Directly through nervous connections
posterior
pituitary gland
ncl. paraventricularis
- antidiuretic hormone (vasopressin)- oxytocin
adrenal medulla
- hypothalamic
sympathetic fibres
influence adrenaline
and noradrenaline
secretion
- control through
hypothalamus -
hypophyseal tract
Autonomic nervous system – functions of hypothalamus
ncl. supraopticus
Indirectly through vascular connections
aterior pituitary
gland
- releasing factors - liberins
- inhibitory factors -inhibins
Relation to sexual functions
- sexual development
- menstrual cycle
- ovulation
- erection
- copulation
- ejaculation
- pregnancy
- birth
- lactation
- sexual feeling
- sexual behavior
Injury of the anterior hypothalamus
- disordered interest about the sex
Injury of the posterior hypothalamus
- increased sexual activity
Autonomic nervous system – functions of hypothalamus
Control of the emotions
ncl. lateralis
Center of the fury
ncl. ventromedialis
Center of the placiditybalance
Brain cortex
Autonomic nervous system – functions of hypothalamus
Emotions are psychological processes that involve subjective experience of
comfort and discomfort linked to physiological changes (changes in heart rate,
respiratory rate change), motor manifestations (mimics, gesticulation), change
readiness and concentration. Induce and influence other psychological processes.
Hypothalamic nuclei, together with the anterior nuclei of the thalamus and
cingulate gyrus, form Papez circuit, which is an important part of the limbic
system. They represent a very close structural relationship, thus represent the
basis for the formation of autonomic manifestations of emotion.
Autonomic nervous system – functions of hypothalamus
information about
light-dark cycleretinal nerves Suprachiasmatic nuclei
(in hypothalamus)
The pineal gland (acts as a photo -
endocrine transducer)
MELATONIN (regulates circadian
timing of many physiological
functions)
Control of biological rhythms
- it is rhythmic activity generated by ncl.suprachiazmaticus. Rhythmic hypothalamic
processes extend into practically to all other functions of hypothalamus as
sympathetic tone, hormone secretion, regulation of temperature, intake of food or
fluids, sexual function, emotion or immune processes.
The light is projected into retina,
resulting in the release of the
neurotransmitter glutamate into
the suprachiasmatic nuclei
(SCN). Noradrenaline activates
the pineal gland, which produces
melatonin (in this case very little
melatonin) and melatonin acts
again in the SCN through the
melatonin receptor by blocking
the re-production of melatonin.
If the light is not projected into
retina (is the dark and have
closed eyes - ie, we sleep), this
process does not take place and
the production of melatonin is
not inhibited, so melatonin acts
in melatonin receptor vice versa.
Hypothalamus – suprachiasmatic nuclei and production
of melatonin
The mammalian circadian pacemaker in the
hypothalamic suprachiasmatic nucleus is organized into
two major subdisvisions, the core and the shell. The core
region of the SCN receives information about the daily
light cycle through the retinohypothalamic tract.
Both neuronal and humoral signals act as output signals
from the SCN to other regions of the brain and the
periphery. The SCN output pathways are responsible
for proper timing of various physiological functions,
including hormone release, sleep-wake cycle, feeding
behaviour, and thermoregulation. The SCN output to
the subparaventricular zone (sPVz) and to the medial
preoptic region (MPO) is for control of circadian
rhythms of body temperature, and a separate projection
through the dorsomedial nucleus of the hypothalamus
(DMH) controls daily hormone secretion through the
paraventricular nucleus (PVN) and sleep-wake cycles
through the lateral hypothalamus (LH) and
ventrolateral preoptic nucleus (VLPO).
A schematic diagram of the
suprachiasmatic nucleus and its input and
output pathways
Relation to sleep
- sleep center in anterior hypothalamus and center of wakefulness in posterior hypothalamus
Autonomic nervous system – functions of hypothalamus
Relation to immunity
Relation to memory
- Papez’s circuit – transmition of the short-term memory to the long-term memory
Complex behavior
- motivations, emotions
- it is mediated by changes in the production of hormones (glucocorticoids production) and
changes the tone of the autonomic nervous system. Sympathetic-immune interactions affect the
particular secondary lymphoid organs (spleen, lymph nodes) and is believed that to increase the
preparedness to escape/attack.
Control of metabolism
- through control of the endocrine glands – secretion of adrenaline, ACTH etc.
Sensory function
Relation to the motor system
- involuntary movements, extrapyramidal tract, basal ganglia
Autonomic nervous system – functions of hypothalamus
Viscero - visceral reflexes
visceral receptors
visceral organs (heart, smooth muscle,
gland cells)
afferent fiber
preganglionic fiber
postganglionic fiber
Autonomic nervous system – autonomic reflexes
Viscero - motor reflexes
visceral receptors
afferent fiber
preganglionic fiber
skeletal muscle
For example: the local contraction of the abdominal muscles is produced at the inflamation of
the appendix.
Autonomic nervous system – autonomic reflexes
Viscero - cutaneous reflexex
visceral receptors
skin, vessels, sweat glands
aferent fiber
preganglionic fiber
postganglionic fiber
The capillary blood return, secretion of sweat are changed at the pathological processes in the
certain internal organs.
Autonomic nervous system – autonomic reflexes
Cutaneous - visceral reflexex
skin receptors
effectors of visceral organs (smooth
muscle, cells of glands)
afferent fiber
preganglionic fiberpostganglionic fiber
Inhibition of the pain in the region of the visceral organ by the application of the cold or warm
stimulus.
Autonomic nervous system – autonomic reflexes