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Chemical Messengers

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Nerve gases and Black Widow spider venom - too much ACh leads to severe muscle ... can artificially stimulate skeletal muscles, leading to slight, trembling movements ... – PowerPoint PPT presentation

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Title: Chemical Messengers


1
Chemical Messengers
  • Neurotransmitters
  • Hormones
  • Neurohormones

2
Types of Neurotransmitters
  • Acetylcholine
  • Serotonin
  • Norepinephrine
  • Dopamine
  • Endorphins
  • GABA
  • Glutamate

3
Acetylcholine
  • Found in neuromuscular junction
  • Involved in muscle movements

4
Disruption of Acetylcholine Functioning
  • Curare - blocks ACh receptors
  • paralysis results
  • Nerve gases and Black Widow spider venom - too
    much ACh leads to severe muscle spasms and
    possible death

5
Disruptions in ACh Functioning
  • Cigarettes - nicotine works on ACh receptors
  • can artificially stimulate skeletal muscles,
    leading to slight, trembling movements

6
Alzheimers Disease
  • Deterioration of memory, reasoning and language
    skills
  • Symptoms may be due to loss of ACh neurons

7
Serotonin
  • Involved in sleep
  • Involved in depression
  • Prozac works by keeping serotonin in the synapse
    longer, giving it more time to exert an effect

8
Norepinephrine
  • Arousal
  • Fight or flight response

9
Dopamine
  • Involved in movement, attention and learning
  • Dopamine imbalance also involved in schizophrenia
  • Loss of dopamine- producing neurons is cause of
    Parkinsons Disease

10
Parkinsons Disease
  • Results from loss of dopamine-producing neurons
    in the substantia nigra
  • Symptoms include
  • difficulty starting and stopping voluntary
    movements
  • tremors at rest
  • stooped posture
  • rigidity
  • poor balance

11
Parkinsons Disease
  • Treatments
  • L-dopa
  • transplants of fetal dopamine-producing
    substantia nigra cells
  • adrenal gland transplants
  • electrical stimulation of the thalamus to stop
    tremors

12
Endorphins
  • Control pain and pleasure
  • Released in response to pain
  • Morphine and codeine work on endorphin receptors
    Involved in healing effects of acupuncture

13
Endorphins
  • Runners high - feeling of pleasure after a long
    run is due to heavy endorphin release

14
Gamma-Aminobutyric Acid (GABA)
  • Main inhibitory neurotransmitter
  • Benzodiazepines (which include tranquilizers such
    as Valium) and alcohol work on GABA receptor
    complexes

15
Huntingtons Disease
  • Involves loss of neurons in striatum that utilize
    GABA
  • Symptoms
  • jerky involuntary movements
  • mental deterioration

16
Glutamate
  • Major excitatory neurotransmitter
  • Too much glutamate (and too little GABA)
    associated with epileptic seizures

17
Hormones
  • Chemical messengers secreted into bloodstream

18
Hormones vs. Neurotransmitters
  • Distance traveled between release and target
    sites
  • hormones travel longer distances
  • neurotransmitters - travel across a synaptic
    cleft (20 nm)
  • Speed of communication
  • hormones - slower communication
  • neurotransmitters - rapid, specific action

19
Hormones
  • Released by organs, including the stomach,
    intestines, kidneys and the brain
  • Also released by a set of glands called the
    endocrine system

20
Endocrine System
  • Consists of hormone-releasing glands
  • Includes
  • hypothalamus
  • pituitary gland
  • adrenal glands
  • thyroid gland
  • parathyroid glands
  • pineal gland
  • pancreas
  • ovaries and testes

21
Hypothalamus and Hormones
  • Hypothalamus releases hormones or releasing
    factors which in turn cause pituitary gland to
    release its hormones

22
Pituitary Gland
  • Master endocrine gland
  • Produces hormones that control hormone production
    in other endocrine glands

23
Pituitary Gland
  • Also produces growth hormones
  • Too little pituitary activity produces dwarfism
  • Too much leads to gigantism

24
Pituitary Gland
  • Also involved in breastfeeding
  • Produces prolactin
  • stimulates milk production
  • Produces oxytocin
  • involved in milk release

25
Adrenal Glands
  • Involved in stress response
  • Hormones released include
  • epinephrine (a.k.a. adrenaline)
  • norepinephrine (a.k.a. noradrenaline)

26
Endocrine Glands
  • Thyroid gland - metabolism
  • Pineal gland - sleep and wakefulness
  • Pancreas - regulates blood sugar level
  • Ovaries and testes - secrete sex hormones such as
    testosterone and estrogen
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