Download M 3 Neural and Hormonal Systems

Module 3
Neural and Hormonal
Systems
Action plan
•
We will follow a bottom-up approach
1. Neurons & their intercommunications (M3)
2. Brain & the nervous sytem (M4)
3. Genetic influences (nature) and Environmental
influences (nurture) (M5 & M6)
Body’s communication system:
Neural Communication
• All movements require the brain to send
appropriate messages to the muscles and
coordinate incoming messages from
sensory organs and glands etc.
• Such messages - movement, feelings,
thinking – are communicated through
specialized cells called neurons. 
The structure of a neuron
Neuron: the building block of the nervous system
How do the neurons communicate?
How do the neurons
communicate? Neurotransmitters
• Chemical messengers that go across the
synaptic gaps between neurons.
• They bind to the receptor sites on the
receiving neuron
• They influence whether the receiving
neuron will respond with a “neural
impulse”.
Acetylcholine
• involved in muscle contraction, learning
and memory
• Video about neural communication and
acetylcholine
Neural communication
within the brain
Serotonin Pathways
Dopamine pathways
Neurotransmitters
• Acetylcholine: Learning, memory, muscle
contraction (Alzheimer’s)
• Endorphins: (“morphine within”) pain control and
to pleasure
• Dopamine: Movement, learning, attention,
emotion (Schizophrenia, Parkinson’s)
• Serotonin: Mood, hunger, sleep, arousal
(depression)
• Norepinephrine: alertness and arousal
• GABA: Inhibitory (undersupply causes seizures,
tremors, insomnia)
• Glutamate: Excitatory, memory (oversupply
How do the drugs work?
1. Mimic a natural neurotransmitter (heroin
and morphine)
2. Block the reuptake of the neurotransmitter
3. Inhibit release of the neurotransmitter
4. Occupy the receptor sites of a
neurotransmitter
Drug addiction
• When the brain is flooded with opiate
drugs such as heroin and morphine, it may
stop producing its own natural opiates,
• Withdrawal of these drugs may result in
pain until the brain resumes production of
its natural opiates.
Dopamine and cocaine
• Video
The Nervous System
Neurons of different
systems
• CNS
• Interneurons
• CNS’s internal
communications
• Peripheral system
• Sensory neurons
• From tissues to CNS
• Motor neurons
• From the CNS to the tissues
The Central Nervous System
• There exist an intense information network
within the brain
•
•
•
•
40 billion neurons
Each with 10,000 contacts
400 trillion synapses
Organized into neural networks
• Spinal cord maintains the communications
between the peripheral system and the
brain
• Reflexes
The Peripheral Nervous
System
• Somatic division
• Controls voluntary movement
• Autonomic division
• Controls that parts of the body that keep us alive –
the heart, blood vessels, glands, lungs, etc.)
• Two parts of the autonomic system
• Sympathetic
• Acts to prepare the body for action in stressful situations,
engaging all the organism’s resources to respond to a threat
• Parasympathetic
• Acts to calm the body after an emergency or stressful
situation has ended
Automatic NS: the
Sympathetic System
Automatic NS: the
Parasympathetic System
The Endocrine System
• the body’s “slow”
chemical communication
system
• a set of glands that
secrete hormones into
the bloodstream
• Act on brain to influence
our growth/ emotions/
motivations/ mood.
The Endocrine System:
Hormones
 Hormones: chemical messengers
 manufactured by the endocrine glands
 Produced in one tissue and affect another
 Pituitary Gland (in the brain)
 Controlled by the hypothalamus
 regulates growth and controls other endocrine glands
 Adrenal Glands
 just above the kidneys
 secrete epinephrine (adrenaline) and norepinephrine
(noradrenaline), which help to arouse the body in times
of stress
Feedback system between the
nervous and endocrine systems
CNS
Behavior
changed
DANGER
Pituitary
Message to
adrenal glands
Other
glands
Hormones
Epinephrine
is released