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