Autonomic Ner Sys Hypothalamus Limbic MedEng 1010

8/13/2019 Autonomic Ner Sys Hypothalamus Limbic MedEng 1010

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AUTONOMIC NERVOUS SYSTEMHYPOTHALAMUSLIMBIC SYSTEM

Lecturer: assoc. prof. P. Kupenov a

Dept. Physio log y, Medic al Universit y-Sofia, 2010


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Autonomic nervous system:

regulates internal organ functions is not under voluntary control participates in homeostatic control via reflex mechanismsand complex behavioural responses


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S2-S4

Lymbic

system

III

VII

IX

X

H

Th1-L2

Brain stem

Internal organs

eyes

heart

bronchi.

.

Extramural ganglia

Paravertebral

ganglia

Prevertebral

ganglia

Intramural

ganglia

Peripheral

(local)

neural

circuits

Interoreceptors

-mechanoreceptors

-chemoreceptors- osmoreceptors

-thermoreceptors

From interoceptorsFrom exteroceptors

Spinal and

cranial nerves

Spinal

ganglia

Spinal nerves

Special senses(vision, taste,olfaction, hearing

)

Somatosensory

Skin

-pilomotor

muscles

-sweat glands

Skeletal muscles-blood vessels

ORGANIZATION OF THE AUTONOMIC NERVOUS SYSTEMAfferent part Efferent p art


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CHARACTERISTICS OF THE AUTONOMIC NERVOUS SYSTEM

Afferent part somatosensory intero- and exteroceptors via spinal and cranialnerves, special senses

Visceral and somatic afferents project to differentlocations in the spinal cord


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Higher level afferents


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Some afferents do notreach c.n.s and participate in local peripheralresponses or give collaterals to the autonomic ganglia, where they exert

modulatory effects

Modulation of the efferent signal by collaterals of a sensory neuron,

releasing substance


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Branches of visceral afferentsmay participate in axon reflexes.(e.g. bronc hoco nstr ic t ion up on st imulat ion of bron chop ulmonary receptors)


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. LEVELS OF INTEGRATION:

1. Peripheral level (local neural networks, out of c.n.s)

entericnervous system, lung networks, etc.

2. Spinal cord and cranial nerve nuclei (III, VII, IX, X).

Sympathetic and parasympatheticdivision.

3. Brain stemother(vardio-vascular center,

vomiting center, etc.)

4. Hypothalamuscomplex adaptive responses, stress reactions, feeding

behaviour, body fluid balance, thermoregulation, circadian rhythms,sleep and wakefulness, endocrine control.

5. Limbicsystemautonomic and behavioural responses,

motivation, emotions, learning and memory.


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Efferent part Motoneuron is always out of c.n.s. and is unmyelinated

- somatic motor neuron autonomic motor neurons


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Complex synaptic transmission in the autonomic ganglia


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Characteristics of the peripheral synapses of the autonomic

nerves


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Variety of receptors:

- adrenergic : 1, 2, b1, b2 b3- cholinergic: N, 1, 2, 3, 4, 5

- tachikinin: NK1q NK2, NK3

- neuropeptide Y: Y1Y5- cholecystokinin: CCK A(CCK1) CCK (CCK2)

- purinergic: P1, P2y, P2x
http://content.nejm.org/content/vol334/issue17/images/large/07t1.jpeghttp://content.nejm.org/content/vol334/issue17/images/large/07t1.jpeghttp://content.nejm.org/content/vol334/issue17/images/large/07t1.jpeghttp://content.nejm.org/content/vol334/issue17/images/large/07t1.jpeg


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Autonomic effects are often only modulatory They can be excitatory or inhibitory


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Organization of the enteric nervous system

1.Peripheral level


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+

.

Example of a peripheral integration peristalsis


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2.Spinal and cranial nerve level III, VII, IX, X).Sympatheticand parasympatheticdivision.


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Spinal autonomic reflexes - defecation


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Cardiovascular system

Heart:

-excitability

-conduction

-heart rate

-contractility

Arterioles

-heart

-skin

-skeletal muscle

-brain

-lung

-gut

-salivary

Systemic veins

Effector organ Sympathetic effect Receptors

SYMPATHETIC PERIPHERAL EFFECTS

Increase +++

Increased velocity +++

Increase +++

Increase +++

Constriction+/dilation ++ (in situ

dilation dominating)

Constriction +++

Constriction ++

Dilation (working mm.) ++Constriction (week)

Constriction +

Constriction +++

Constriction ++

Constriction +++

b1b1b1b11 /b211b211111


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Respiratory system

-bronchial muscle

-bronchial glands

Gastrointestinal system

-motility

-sphincters

-gallbladder

-secretion(overall)

-salivary glands

-pancreas

-liver

Eye

- m dilatator pupillae

- m sphincter upillae

- m ciliaris


SYMPATHETIC PERIPHERAL EFFECTS (continued)

Bronchodilation+

Decreased secretion +

Decrease

Contraction+++

Relaxation

Decrease

Increased secretion (rich in

amylase) +

Exocrine secretion decrease

Insuline secr. increse/decreaseGlycogenolysis, glyconeogenesis

Contraction ++

b2 (via circul CA)

b21, 2b21,b1,b22 / b2b21


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Urinary system

-kidney

-ureter

-urinary bladder

-sphincter-detrusor

Skin

-pilomotor muscles

-sweat glands

Male reproductive system

Adipose tissue

Uterus


Increased renin secretion++

Contraction ++Relaxation +

Contraction ++

Increased secretion +++

Ejaculation +++

Lipolysis

Contraction / relaxation

b1

1b21 cholino-R, b1b2, b31 / b2

SYMPATHETIC PERIPHERAL EFFECTS (continued)


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Cardiovascular system

Heart

-excitability

-conduction

-heart rate

-contractility

Arterioles

-heart

-skin

-skeletal muscles

-brain

-lungs

-gastrointestinal

-salivary glands

Systemic veins

Effector organ Parasympathetic effect Receptors

decrease +++

decrease+++

decrease +++

decrease(atria)

Dilation(?)

Dilation

Dilation +++

2

2

2

2

(NANC)

1,3(NOdependent)

NANC (VIP)

PARASYMPATHETIC PERIPHERAL EFFECTS


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Respiratory system

-bronchial muscle

-bronchial glands

Gastrointestinal system

-motility

-sphincters

-gallbladder

-secretion (overall)

-salivary glands

-pancreas

-liver

Eye

- m dilatator pupillae

- m sphincter upillae

- m ciliaris


Constriction/dilation

Increased secretion

IncreasedRelaxation

Contraction +++

Increase +++

Secretion increase +++

Exocrine secretion increase

Insuline secretion increase

Contraction +++

Contraction+++

3; NANC (SP,N-)/NANC (VIP,NO)

3

3

3

1, 3

3,VIP, NO

1, 3

1, 3

3

3

PARASYMPATHETIC PERIPHERAL EFFECTS(continued)


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Urinary system

-kidney

-ureter

-urinary bladder

-sphincter-detrusor

Skin

-pilomotor muscles

-sweat glands

Male reproductive system

Adipose tissue

Uterus


Contraction +++

Erection

3

NO

PARASYMPATHETIC PERIPHERAL EFFECTS(continued)


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3. HIGHER INTEGRATIVE CENTERS


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HYPOTHALAMUS


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Hypothalamic connections with the brain stem, limbic system

and neocortex through the medial forebrain bundle


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Hypothalamic connections with limbic structures


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Hypothalamic connections with the thalamus, subthalamus and corpus striatum


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Circumventricular organs


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Receptor-mediated transport across the blood-brain barrier (leptin)


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HYPOTHALAMIC FUNCTIONS- Endocrine function- Control of pituitary secretion- Higher authonomic center- Thermoregulation- Food intake control- Water intake control- Metabolic function- Circadian rhythm regulation- Emotions, behaviour


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Endocrine regulation


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Hypothalamic hormones


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THERMOREGULATION


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-

-.

-

- . -

-

-

-

-

- . -

-

-

-

-

:

-

-

-

(, )


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Hypothalamic areas contributing to thermoregulation during bodyheating and cooling


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0 7 14 21 28

370

360

380

Diurnal variations of the body temperature left) andvariations during the ovarian cycle right)


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Schematic drawing showing major pathways of the temperature control

center. Heat sensors in the median preoptic hypothalamus (MnPO) project to

neurons in the hypothalamic paraventricular nucleus (PVN) and dorsomedial

nucleus (DMN) or directly to the raphe pallidus (RPa) in the brainstem to control

autonomic responses mediated through preganglionic neurons in the spinal cord.


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REGULATION OF FOOD INTAKE


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Regulation of food intake depends on the coordinated

activity of several hypothalamic nuclei, which are in

turn regulated by:

1) Adipose tissue peptides

2) Gastrointestinal peptides

3) Blood glucose concentration and glucose utilization

4) Body temperature

5) Concentration of 3


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Hypothalamic structures involved in the control of food intake

OREXIGENIC FACTORS ANOREXIGENIC FACTORS


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Neuropeptide Y

Agouti-related protein (AgRP)

Orexin

MCH

Endocannabinoids (anandamine, 2-arachidonyl glycerol)

Ghrelin

-MSH (POMC)

CART

Brain-derived neurotrophic

factor (BDNF)

Leptin

Adiponectin

Insulin

Incretins

PYY (colon)Cholecystokinin

Glucagon-like peptide

Pancreatic polypeptide

Oxyntomodulin

Amylin

Hypothalamus

Adipose tissue

Gastro0intestinal system

OREXIGENIC FACTORS ANOREXIGENIC FACTORS


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Stomach bypass to prevent appetite stimulation by ghrelin


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Regulation with feedback but

without setpoint

Regulation with and without feedback

(partially opened system)

Models of food intake regulation


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Change in the set point in a case of lateral hypothalamus damage


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Water intake regulation

ADH secretion depends on both osmolarity and extracellular fluid volume


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ADH secretion regulation


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Thrust stimuli


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The positron emission tomography (PET) image at top, taken after subjects received an

infusion of a concentrated saline solution into the blood to stimulate thirst, shows regions of

activity in the left side of the brain in thirsty subjects. This activity changed dramatically after

their thirst was quenched. In particular, the yellow and orange areas above indicate activity

along the cingulate cortex that was extinguished later.


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Sleep-wake cycle

++


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(VLPO)

()(DM, PF)

(TM)

SCN

++

+

+

+ (PPN/LdT)

(LC)

(NR)

REM-on

REM-off

D2

(IL1)

t02

+


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Daily rhythms in restactivity,body temperature, potassium

excretion, computation speed

(number of computations

performed per minute), and timeestimation (accuracy with which

short intervals of time are

assessed). From Wever (1974)

with permission.

Circadian rhythm regulation


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Suprachiasmatic nucleus


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When the suprachiasmatic nuclei are destroyed, the circadian rhythm is lost


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Cyclic changes in activity of the suprachiasmatic (SCN) nucleus (left).

When the SCN and its connections are preserves, 24h rhythms of many body

functions such as sleep-wake cycle and body temperature are observes (right, a). If

the SCN is destroyed, the 24 h rhythmicity of the same body functions is lost.


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Features ofpertiminteractions. (A) Profiles of PER and TIM mRNA and protein levels across a light (open bar)dark (filled bar) cycle.

The shaded area shows when PERTIM heterodimers are present in the nucleus. (B) Structures of PER and TIM proteins. Theconnecting lines indicate areas of each protein thought to be involved in PERTIM dimerization. A, acidic region; B, basic region. (C)

Interdependent negative feedback control loops of per and tim. See text for description. From Reppert and Sauman (1995).


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SCN structure


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Melatonin secretion


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Sexual function and sexual dimorphism of some hypothalamic nuclei


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HYPOTHALAMUS AND LIMBIC SYSTEM


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Structures of the limbic system


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Circuits in the limbic system


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Emotional reaction - anxiety


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Experiments proving the existence of reward and avoidance centers


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The pleasure centers


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Behavioural responses


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(.;

. )

(, )

? ?

Learning and memory - types


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Long-term potentiation (LTP) and depression (LTD)


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Autonomic Ner Sys Hypothalamus Limbic MedEng 1010

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