Functional distinctions in the nervous system
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Somatic / autonomic nervous system: Somatic: Concerned with conscious, voluntary activity and perception (Skeletal muscle, sensory receptors and nerves) ...

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Functional distinctions in the nervous system l.jpg
Functional distinctions in the nervous system

  • Central / peripheral nervous system:

    • Central: Brain and spinal cord

    • Peripheral: Nerves connecting the CNS with the rest of the body; ganglia (nodes) halfway between CNS and target organs, and plexus (braids) in the internal organs

  • Somatic / autonomic nervous system:

    • Somatic: Concerned with conscious, voluntary activity and perception (Skeletal muscle, sensory receptors and nerves).

    • Autonomic: Involuntary control of internal organs. Examples: Blood pressure, heart rate, sweat glands


Schematic of a nerve cell l.jpg
Schematic of a nerve cell

Dendrites

Terminal buttons

Synapse

Soma

Axon

Soma = body (greek) Dendron = tree

Synapse = junction button = button (engl.)



Different anatomical types of synapses l.jpg

neuromuscular

(smooth muscle)

Different anatomical types of synapses

neuro-neural

neuromuscular

(skeletal muscle;

‘myoneural junction’)




How a synapse works l.jpg

Transmitter

Nerve fiber (axon)

Action

potential

Ca + +

Receptor

How a synapse works

Voltage-sensitive

channel


Ca in neurotransmitter exocytosis l.jpg

+

Ca++ in neurotransmitter exocytosis

Action potential

Synapsin

CaM

Ca++

Synapto-

tagmin

Kinase II

P

Synapto-brevin

Ca++


Synaptic transmission is an important target of drug action 1 l.jpg
Synaptic transmission is an important target of drug action (1)

Agonists (‘mimetic’ drugs) can augment or entirely substitute the effect of a neurotransmitter

+

+

+


Synaptic transmission is an important target of drug action 2 l.jpg
Synaptic transmission is an important target of drug action (2)

Antagonists (‘lytic’ drugs) can inhibit or entirely abrogate the effect of a neurotransmitter

-

-

-


Synaptic transmission is an important target of drug action 3 l.jpg
Synaptic transmission is an important target of drug action (3)

‘Indirect mimetic’ drugs can promote the effect of the transmitter by interfering with its inactivation

reuptake

enzymatic

inactivation


Synaptic transmission is an important target of drug action 4 l.jpg
Synaptic transmission is an important target of drug action (4)

Presynaptic receptors form a feedback loop that can be selectively targeted by agonists and antagonists


Indirect agonists and antagonists may modify the availability of transmitter l.jpg

synthesis

storage

breakdown

reuptake

enzymatic

inactivation

Indirect agonists and antagonists may modify the availability of transmitter


Types of synapses transmitters l.jpg
Types of synapses: Transmitters

Acetylcholine

Norepinephrine

(Noradrenaline)


More transmitters l.jpg
More transmitters

Glutamate

Glycine

Tyr-Gly-Gly-Phe-Met-Thr-

Ser-Glu-Lys-Ser-Gln-Thr-

Pro-Leu-Too-Muc-Hse-Xma-

Kes-You-Sho-Rts-Igh-Ted-

Val-Lys-Asn-Ala-His-Lys-

Lys-Gly-Gln

-Aminobutyrate

(GABA)

…and many more…

-Endorphin


Neurotransmitter receptors l.jpg
Neurotransmitter receptors

  • Ligand – gated channels:

    • Nicotinic acetylcholine receptor

    • NMDA-type glutamate receptor

    • Glycine receptor

    • GABAA receptor

    • Serotonin receptor (5-HT3,)

  • G protein-coupled receptors:

    • Muscarinic acetylcholine receptor (several types)

    • ‘Metabolic’ glutamate receptors

    • Catecholamine receptors

    • 5-HT receptors other than 5-HT3

    • GABAB receptors

    • Peptide receptors


Slide17 l.jpg

Parasympathetic

Sympathetic

Somatic

M

Medulla

oblongata

Heart

Smooth muscle

in gut and blood

vessels

Ganglia

N

, 

M

N

M

Glands

D1

Kidney arteries

Spinal

cord

N

N

Adrenal gland

Skeletal muscle

N


Synapses in the autonomic nervous system as drug targets l.jpg

Why target the autonomic nervous system? It controls

Hypertension, cardiovascular

disease

  • Heart rate

  • Blood pressure

  • Blood flow distribution

  • Motility of the digestive tract

  • Bronchial contraction / dilatation and secretion

  • Body temperature; sweating

Surgical patients

Surgical patients

Asthma / bronchitis

Synapses in the autonomic nervous system as drug targets


Slide19 l.jpg

‘Mydriasis’ = wide pupils

Sympathetic

stimulation

Parasympathetic

stimulation

‘Miosis’ = narrow pupils


Slide20 l.jpg

‘Mydriasis’ = wide pupils

Sympathetic

stimulation

(cocaine, ‘speed’)

Parasympathetic

stimulation

  • -opiod receptors

    (heroin)

‘pinpoint pupils’


The nervous and the endocrine system are not cleanly separated l.jpg

Somatic NS

Autonomic

NS

Endocrine

system

Somatic NS Autonomic NS Endocrine system

The nervous and the endocrine system are not cleanly separated

Noradrenaline

Acetylcholine


Different anatomical types of synapses22 l.jpg

neuromuscular

(smooth muscle)

Different anatomical types of synapses

neuro-neural

neuromuscular

(skeletal muscle;

‘myoneural junction’)


Portal vessels may direct hormones to specific tissues l.jpg
Portal vessels may direct hormones to specific tissues

CRH, …

Neurons in the hypothalamus

anterior lobe:

ACTH, …

Hypophyseal gland

posterior lobe: oxytocin,

vasopressin


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