Neural and Hormonal Systems Module 3 Neural and Hormonal Systems Videos for the lecture: Show zimbardo #3 – dakika 1.35 -4.2. Neural networks Cocaine and dopamine ----------------------------------------------------------------------- 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, feeling, thinking – are communicated through specialized cells called neurons – NERVE CELLS Only type of cells in the body that can communicate – Basıc elements of the NS – Almost 1 trilllion on them exist throughout the body controlling our behaviors.

Action plan We will follow a bottom-up approach Neurons & their intercommunications (M3) Brain & the nervous sytem (M4) Genetic influences (nature) and Environmental influences (nurture) (M5 & M6) To understand the biological functions influencing our behaviors, emotions and thoughts, we will follow a bottom- up approach: First study the building blocks of nervous sytem – then their functions.

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 4

How do the neurons communicate? Each neuron is a decision maker --- communicates with thousands of other neurons (depending on which part of the CNS they are at). A combination of these impulses --- either excite (send the message) or ---- inhibit (do nothing – like pushing a brake and not passing along the impulse). Impulse --- lıke a gun firing. ALL or NONE – once triggered bullet comes out. But speed and frequency of firing may differ. Then neurons have to communicate with each other. (kulaktan kulaga) This is more of a chemical process. Neurons do not touch each other. There is a small gap – full of fluid. Neurotansmitters – messengers, travel within this gap – in between neurons – from the axons of one to the dendrites of the other. -- several types of neurotransmitters. Where exactly matters.

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”. NTS come out of axon terminals and fit into receptors on the dendites of the receiving neuron. They fit like a key fitting in a lock. This starts the electrical charge in the receiving neuron. Excess ampunts of neurotansmitters go back through the synaptic cleft and then are reuptaken – absorbed– by the sending neuron. Many drugs intervene at this stage --- Show neurotransmitters video Like a vapur carrying passengers from besiktas to kadikoy--- carry the chemical messengers from one nuron to the neighboring one. ----------------------------------------------------------------- Structure, operation and functions of neurons are fundamnetal biological aspects of the body – that underlie several primary psychological processes. Our understanding would have been limited if we did not know these. Within – electric Between – chemical 6

Acetylcholine involved in muscle contraction, learning and memory Video about neural communication and acetylcholine

Neural communication within the brain Dopamine pathways Dopamine --- controls movement, attention and learning. -- deficiency – parkinsons -- excess --- schizophrenia and other mental disorders. Serotonin 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 causes seizures, migraines) Different neurotransmitters have different effects on behavior and emotion. (Influence all motions and emotions. ) -- depends on specific parts of the CNS they are at --- Later will talk about their role in depression, hunger, memory, thinking, addictions, therapies etc. BALANACE IS IMPORTANT. To give an example. ACh --- one of the best understood chemicals. Vital in learning and memory Also release of ACh controls muscle contracts. If blocked --- mucsles do not contract --- one method used in hunting. – animal becomes paralyzed For humans – there is a drug called botox that blocks release of ACh? ----- what happens Paralyzes wrinkles underneath the facial muscles. Balck widow spider---- poison – causes excessive amounts of ACh to be released--- cannot control muscle contaction and die. Dopamine ve Seretoninden de bahset. 9

How do the drugs work? Mimic a natural neurotransmitter (heroin and morphine) Block the reuptake of the neurotransmitter Inhibit release of the neurotransmitter Occupy the receptor sites of a neurotransmitter heroin and morphine brain may stop producing its own endorphins  withdrawal  sensation of pain E.g., release of acetylcholine, the neurotransmitter found at every junction between a motor neuron and skeletal muscle, causes the muscle to contract. The brain’s endorphins, natural opiates released in response to pain and vigorous exercise, explain the “runner’s high” and the indifference to pain in some injured people. Some drugs mimic a natural neurotransmitter or may block its reuptake. Some opiate drugs amplify arousal or pleasure. Other drugs block a neurotransmitter’s effects by inhibiting its release or occupying its receptor site. Same for alcohol, nicotine, cocaine etc.. Mood altering drugs. They alter the balance of the nts. İncreased level in the synaptic cleft or prevent reuptake. ----------------------------------- During the discovery of the drug morphine --- used to elevate mood and cease pain – Realized that brain contained receptors for these morphine molecules to lock in. So brain should also have alreasy existing neurotransmitters to fit in these receptors… similar to morphine --- endorphine – natural opiates. Released in pain and in vigarious exercise. – explain runner’s high. ---painkilling effects of acupuncture. -- reaction to pain when severly injured – don’t feel. 10

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 13

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 14

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 15

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 Somatic NS: Controlled behaviors. Ex: your eye movement in reading this slide. Automatic NS: Ex. Hearbeating, blood circulating, digestive etc. Esp. İmportant in emergencies--- homeostatis

Automatic NS: the Sympathetic System 17

Automatic NS: the Parasympathetic System 18

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 . 20

Feedback system between the nervous and endocrine systems CNS DANGER Behavior changed Pituitary Message to adrenal glands Other glands Epinephrine is released Hormones 21