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OVERVIEW
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Neurotransmission
Neurotransmitters
Endocrine System
Hormones
Feedback Systems
NEUROTRANSMISSION
THE NEURON
Multipolar: more than two processes
from cell body
Unipolar: one process from cell body
Bipolar: two processes from cell body
Interneurons: short or no axons
Supportive cells: glial cells, satellite
cells, astrocytes, oligodendrocytes,
Schwann cells
http://www.utexas.edu/research/asrec/synapse_m.html
COMMUNICATION.. con’t
COMMUNICATION
•Action potentials: Ionic basis
•Conduction of Action Potentials
•Chemical Transmission at the
Synapse
ACTION POTENTIALS
mV = millivolts
http://artsci-ccwin.concordia.ca/psychology/psyc358/Lectures/actpotent1.htm
MEMBRANE POTENTIAL
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Random motion
Electrostatic pressure
Membrane permeability
Sodium-potassium pumps
http://web.psych.ualberta.ca/~msnyder/Academic/Psych104/ch6/lec2/P104.6.2.html
When NTs bind to postsynaptic
receptors…
• Depolarize: Excitatory Postsynaptic
Potentials (EPSP)
• Hyperpolarize: Inhibitory Postsynaptic
Potentials (IPSP)
• Action potential: reversal of membrane
potential
ACTION POTENTIALS
mV = millivolts
http://artsci-ccwin.concordia.ca/psychology/psyc358/Lectures/actpotent1.htm
http://luna.cas.usf.edu/~husband/expsych/fig_axon.htm
http://luna.cas.usf.edu/~husband/expsych/fig_axon.htm
NEUROTRANSMITTERS &
HORMONES
CHEMICAL COMMUNICATION
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Intracrine mediation: intracellular
Autocrine mediation: feedback loops
Paracrine mediation: adjacent cells
Endocrine mediation: bloodstream
Ecotcrine mediation: pheromones
HOW THEY DIFFER..
NEUROTRANSMITTERS
• DF
HORMONES
• KJH
NEUROTRANSMITTERS
STEPS OF NT ACTION
• NTs are synthesized
from precursors
• NTs are stored in
vesicles
• Leaking NTs are
destroyed
• Action potentials
cause NTs to bind
presynaptic membrane
& be released into
synapse
• Released NTs bind
with autoreceptors and
inhibit more release
• Released NTs bind to
postsynaptic receptors
• Released NTs are
deactived by reuptake
or enzymatic
degradation
http://www.nipissingu.ca/saari/slides/pinel13/sld023.htm
AGONISTIC EFFECTS
• Agonist: drug that
facilitates the effects
of a particular
neurotransmitter
– ex. Cocaine: dopamine
& norepinephrine
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Increases synthesis of NTs
Destroys degrading enzymes
Increases release of NTs
Blocks inhibitory effects of
NTs
• Activates postsynaptic
receptors or increases effects
of NTs
• Blocks degradation or
reuptake
ANTAGONISTIC EFFECTS
• Antagonist: drug that
inhibits the effects of a
particular
neurotransmitter
– ex. Curare: cholinergic
receptors
• Blocks synthesis of NTs
• Causes NTs to leak from
vesicles & to be destroyed by
degrading enzymes
• Blocks release of NTs into
synapse
• Activates autoreceptors &
inhibits NT release
• Blocks postsynaptic
receptors
UPREGULATION
Http://www.utexas.edu/research/asrec/dopamine.html
DOWNREGULATION
Http://www.utexas.edu/research/asrec/dopamine.html
CLASSES OF NTs
Amino Acids
Catecholamines
Dopamine
Epinephrine
Norepinephrine
Indolamines
Serotonin
Monoamines
Glutamate
Aspartate
Glycine
GABA
Soluble Gases
Nitric Oxide Carbon
Monoxide
Acetylcholine
Acetylcholine
Neuropeptides
Hormones*
Http:/web.indstate.edu/thcme/mwking/aminoacidderivatives.htm#tyrosine
DOPAMINE
• found primarily in the limbic system, parts
of the hypothalamus, the frontal cortex, and
forebrain (basal ganglia)
• thought disorders
• motor disorders
• pleasure & pain
• role in addiction
http://www.nipissingu.ca/saari/slides/pinel13/sld033.htm
SEROTONIN
• high concentrations in the brain stem and
thalamus
• sleep/wake cycle
• sensory perception
• emotional behaviour: depression, impulsive
behaviour, aggression
NOREPINEPHRINE
• high concentrations in the cortex and limbic
system
• Also works as hormone
• respiration
• activity, stimulation, and arousal
• rate of metabolism
http://www.nipissingu.ca/saari/slides/pinel13/sld030.htm
ACETYLCHOLINE
• Major NT of the motor system
– found at neuromuscular junction
• Learning and Memory
– memory loss of Alzheimer’s patients
• Sleep
• Nicotinic and muscarinic receptors
http://www.nipissingu.ca/saari/slides/pinel13/sld024.htm
GABA/GLUTAMATE
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GABA: inhibitory effects
Glutamate: excitatory effects
scatter throughout the brain
Unique because:
– # of synapses using G/G > than any other NT
combined
– important functions in the body, not only the
brain
THE ENDOCRINE SYSTEM
GENERAL FEATURES..
1. Endocrine glands are ductless
2. Endocrine glands have a rich blood supply
3. Hormones are secreted into the bloodstream
4. Hormones can travel to every cell in the
body
5. Hormone receptors are specific binding
sites
ENDOCRINE GLANDS
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Hypothalamus
Pituitary Gland
Thyroid Gland
Pancreas
Gastrointestinal Tract
Adrenal Glands
Pineal Gland
Gonads: Testes &
Ovaries
• Placenta*
http://www.ama-assn.org/ama/pub/printcat/7157.html
biological
clock
STI MULI
HYPOTHALAMUS
CRH GnRH GHRF TRH
ANTERIOR
PITUITARY
ACTH
ADRENALS
(Cortisol)
MIF Somatostatin PIF
TSH
THYROID
(Thyroid H)
PRL GH MSH
OTHER TISSUE
FSH&LH
TESTIS
OVARIES
(T)
(Estrogen)
HYPOTHALAMUS
• Releasing hormones
• produced by various
nuclei of the
hypothalamus
• involuntary body
functions
• many simple body
functions
http://www.cwru.edu/dental/web/neuro/ghts.html
PITUITARY GLAND
THYROID GLAND
• Thyroglobulin:
converted to T3 & T4
• almost all cells are
target of THs
• calcitonin
• metabolic rate, growth
& development
TRH: Thyroid-releasing
hormone
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/tsh.html
PANCREAS
• digestive enzymes
• islets secrete insulin &
glucagon
• release dependent on
level of glucose in
blood
GASTROINTESTINAL
• hormones that aid with digestion
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gastrin
enterokinin
secretin
cholecystokinin (CCK)
glucose dependent insulinotropic hormone
vasoactive
ADRENAL GLAND
PINEAL GLAND
• biological rhythms
• Melatonin
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receptors in SCN
night
reproduction, sleep
Seasonal Affective
Disorder
http://www.crystalinks.com/thirdeyepineal.html
GONADS: TESTES &
OVARIES
TESTES
• produce sperm and
androgens
• LH & FSH
OVARIES
• produce ova, estrogen,
and progesterone
• LH & FSH
• menstrual cycle
HORMONES
• Grouped into 3 classes, based on structure:
– steroids
– peptides
– amines
STEROIDS
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookENDOCR.html
HORMONES
• Grouped into 3 classes, based on structure:
– steroids
– peptides
– amines
• Mechanisms:
– Nonsteroid: second messenger systems
– Steroid: hormone-receptor complex, DNA, &
protein production
ESTROGEN
• released by ovary
• controlled/controls
feedback
• sexual behaviour,
maternal behaviour,
menstrual cycle
• memory &
neurogenesis
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/lhfsh.html
PROGESTERONE
• produced by ovaries
• works in conjunction
with estrogen:
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menstrual cycle
pregnancy
maternal behaviour
sexual behaviour
http://www.wisc.edu/ansci_repro/lec/lec_11/lec11fig.html#figure%205
FSH & LH
• essential for reproduction
• Luteinizing Hormone:
stimulates secretion of sex
steroids; health of ovary
• Follicle-Stimulating
Hormone: maturation of
ovarian follicles; sperm
production
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/lhfsh.html
TESTOSTERONE
• maintains spermatogenesis
• act of skeletal muscle
• secondary sex
characteristics
• reproductive behaviour
• aggression
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/lhfsh.html
OXYTOCIN & VASOPRESSIN
• Vasopressin: antidiuretic
hormone; conserve water;
reproductive function; social
behaviour
• Oxytocin: birth & lactation;
anti-amnestic; maternal
behaviour, social behaviour
• Stress?
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/oxytocin.html
NEUROPEPTIDE Y &
LEPTIN
NPY
• regulation of circadian
rhythms, sexual
functioning, anxiety,
stress response,
feeding behaviour
• neuropeptide
• synthesized in arcuate
nucleus
LEPTIN
• appetite regulation?
• ob/ob mice: leptin
replacement
• decreases NPY
expression
PROLACTIN
• closely related to GH
• major target:
mammary glands
– many tissues contain
receptors
• milk production
• reproductive
behaviour
• immune function
• maternal behaviour
* regulated by DA,
TRH, GnRH, E
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/prolactin.html
GROWTH HORMONE
•Direct effects: target receptors
in fat; protein, lipid, &
carbohydrate metabolism
•Indirect effects: mediated by
insulin-like growth factor-1
(IGF-1) ; muscle & bone growth
GHRH: growth hormonereleasing hormone
SS: somatostatin
http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/gh.html
HORMONES
• needed for the
immediate onset of
maternal behaviour
• progesterone
• estrogen
• prolactin
• oxytocin
• glucocorticoids
THE HPA AXIS: POSTIVE &
NEGATIVE FEEDBACK
SYSTEMS
Brain here
Cingulate Cx.
Frontal Cx.
Inferior
Temporal Cx.
Amygdala
Hippocampus
Septum
Hypothalamus
Pituitary Gland
THE HPA AXIS
Stimulus
LIMBIC SYSTEM (Hippocampus)
+ve
HYPOTHALAMUS
(Paraventricular Nucleus)
CRH
PITUITARY GLAND
(Anterior Pituitary)
ACTH
Glucocorticoid
ADRENAL GLAND
(Adrenal Cortex)
-ve
THE HPA AXIS
LIMBIC SYSTEM
Stimulus
+ve
HYPOTHALAMUS
(Paraventricular Nucleus)
CRH
PITUITARY GLAND
(Anterior Pituitary)
ACTH
Glucocorticoid
ADRENAL GLAND
(Adrenal Cortex)
-ve
INPUTS TO THE LIMBIC
SYSTEM
Stimulus
Modality specific areas
Amygdala
Entorhinal cortex
Hippocampus
Association areas
Frontal association
areas & Inferior
temporal association
areas
THE HPA AXIS
Stimulus
LIMBIC SYSTEM (Hippocampus)
+ve
HYPOTHALAMUS
CRH
PITUITARY GLAND
(Anterior Pituitary)
ACTH
Glucocorticoid
ADRENAL GLAND
(Adrenal Cortex)
-ve
LIMBIC INPUTS TO THE
HYPOTHALAMUS
CINGULATE CORTEX
HIPPOCAMPUS
FORNIX
SEPTUM
AMYGDALA
STRIA TERMINALIS
MEDIAL FOREBRAIN
BUNDLE
HYPOTHALAMUS
OTHER INPUTS
• MEDULLA: via the nucleus solitarius
(baroreceptor information)
• MIDBRAIN: via the reticular formation;
directly and indirectly through the thalamus
(chemoreceptor information)
• BRAINSTEM: monoaminergic inputs
(physiological stress)
EFFECTS OF CRH (CorticotropinReleasing Hormone)
Epi NE ACh 5-HT
STRESS RESPONSE
+ ve
• activity, aggression,
CRH
food intake, fear,
- ve
anxiety, sexual &
maternal behaviour
CRH GABA opioids GC
• metabolism &
circulation
found in brainstem, midbrain,
striatum, hippocampus, cerebral
cortex, spinal chord, sympathetic
ganglia, & adrenal gland
THE HPA AXIS
Stimulus
LIMBIC SYSTEM (Hippocampus)
+ve
HYPOTHALAMUS
(Paraventricular Nucleus)
CRH
PITUITARY GLAND
ACTH
Glucocorticoid
ADRENAL GLAND
(Adrenal Cortex)
-ve
EFFECTS OF ACTH
(Adrenocorticotropic Hormone)
STRESS RESPONSE
• attention, motivation,
learning, & memory
• aggression, grooming,
sexual & social
behaviour
• neurotrophic?
ANTERIOR
PITUITARY
POMC
ACTH
beta-lipotropin
beta-endorphin
THE HPA AXIS
Stimulus
LIMBIC SYSTEM (Hippocampus)
+ve
HYPOTHALAMUS
(Paraventricular Nucleus)
Specific Organs
CRH
PITUITARY GLAND
(Anterior Pituitary)
ACTH
Glucocorticoid
ADRENAL
GLAND
-ve
EFFECTS OF
GLUCOCORTICOIDS
STRESS RESPONSE
• heart rate, blood
pressure, respiration,
digestion, growth,
reproduction, immune
function
• learning, cognition,
emotional response,
other behaviours
GC-R I & II
• hippocampus, septum,
hypothalamus,
amygdala, & nucleus
tractus solitarius
* mobilizes energy
resources for
adaptation to stressor
HIPPOCAMPUS
• Negative Feedback:
mechanism?
• Mineralocorticoid &
Glucocorticoid
Receptors: ratio
• Species differences
• Chronic Stress =
Neuronal Death
* lack of brain “food”
HIPPOCAMPUS
glutamate
BNST
GABA
HYPOTHALAMUS (PVN)
Endocrine-related problems
• Overproduction of a hormone
– Cushing’s Syndrome
• Underproduction of a hormone
– Diabetes
• Nonfunctional receptors that cause target
cells to become insensitive to hormones
– Growth Hormone Insensitivity