Myers PSYCHOLOGY

1. Myers PSYCHOLOGY Module 4 Neural and Hormonal Systems

2. Neural Communication • Biological Psychology • branch of psychology concerned with the links between biology and behavior • some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologist, or biopsychologists • Neuron • a nerve cell • the basic building block of the nervous system

3. Neural Communication • Dendrite • the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body (receives) information. • Axon • the extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands • Myelin [MY-uh-lin] Sheath • a layer of fatty cells covering the axons of many neurons • enables vastly greater transmission speed of neutral impulses

4. Neural Communication

5. Resting potential • A neuron at rest has more negatively charged ions (tiny particles) inside then exist outside the cell • The neuron maintains this negative charge at rest by actively pumping out positively charged ions and keeping the negatively charged ions inside.

6. Action Potentials I • When a neuron is stimulated to fire, it responds by opening a tiny portion of its membrane and allowing positive ions to rush in. • The neuron then quickly pushes the positively charged ions back out again and closes that section of its membrane. • The neuron then opens the next section of its membrane and allows the positively charged ions to rush in, and quickly pushes them back out again. • The shift from negative to positive across the cell’s membrane creates an electrical impulse which travels down the cell. • When the impulse reaches the axon terminals, it causes the neurotransmitters to be released into the synapse.

7. Action Potentials II • Action potentials are all or nothing: either they fire or they don’t. Also, for each cell, all action potentials are the same size and intensity. • Action potentials range in speed from 2 to 200 miles an hour. Thicker and more myelinated axons conduct impulses more quickly. • Following an action potential, a cell has a short refractory period, during which it cannot fire.

8. The Synapse • Once neurotransmitters are released into the synapse, they can be: • Received by their appropriate receptor site • Carried away and broken down by the body • “Reuptaken” by the neuron that they came from • A neurotransmitter can only take its action in the brain or body if it is received by its appropriate receptor site. • If enough neurotransmitters are received by the postsynaptic neuron, a postsynaptic potential is created, causing the next cell to fire.

9. Neural Communication • Synapse [SIN-aps] • junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron • tiny gap at this junction is called the synaptic gap or cleft • Neurotransmitters • chemical messengers that traverse the synaptic gaps between neurons • when released by the sending neuron, neuro-transmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse

10. Effects of Neurotransmitters • Excitatory - Neuron’s cell membrane becomes depolarized (more positively charged) making it more likely that the cell will fire. • Inhibitory - the neuron’s membrane becomes hyperpolarized (more negatively charged) making it less likely that the cell will fire.

11. To fire or not to fire? • Whether or not a neuron will fire depends upon the total summation of input: • from a single cell firing many times or • many cells firing simultaneously • Because some neurotransmitters are excitatory and some are inhibitory, a neuron must receive more excitatory than inhibitory stimulation in order to fire.

12. Neural Communication

13. Dopamine pathways Neural Communication Serotonin Pathways

14. What disease is related to degeneration of the neuron’s myelin sheath? A. Parkinson’s disease B. multiple sclerosis C. Alzheimer’s disease D. schizophrenia

15. Neural Communication

16. Neurotransmitters I • Acetylcholine: Important in movement, attention, arousal and memory. Anything that interferes with acetylcholine will produce paralysis. Alzheimer’s Disease results from degeneration of the cells that produce acetylcholine. • Norepinephrine: Important in arousal, wakefulness, learning, and mood. Both a hormone and a transmitter. Can be excitatory or inhibitory. Released during stress reactions. Imbalance associated with depression. • Serotonin: Important in mood, sleep, aggression, impulsive behavior, movement, attention and learning. Serotonin level is related to carbohydrate intake.

17. Neurotransmitters II • Dopamine: Important in movement, attention, learning and the regulation of emotional response. Necessary for the experience of reward/pleasure. Excess associated with schizophrenia; decrease associated with Parkinson’s Disease. • GABA: gamma aminobutyric acid- an inhibitory neurotransmitter that inhibits unnecessary firings of neurons so we can move our muscles in a coordinated way. Without GABA, there can be no control of muscle movements. • Alcohol increases GABA, causing problems in thinking, judgment and motor skills • Too little GABA allows excess activity of the autonomic nervous system, causing anxiety • Hungtinton’s Disease: decreased activity of neurons that produce GABA cause uncontrollable motor movements and progressive loss of thinking abilities.

18. Neurotransmitters III • Glutamate: An excitatory neurotransmitter that helps the brain strengthen synaptic connections. • Glutamate is released in large quantities when the brain is injured, setting off an irreversible series of events that leads to cell damage. • Excess glutamate activity is associated with Alzheimer’s Disease, and a new drug (Namenda (memantine) is approved by the FDA for treatment of Alzheimer’s Disease. Namenda works by decreasing glutamate activity. • Endorphins: Naturally occurring substances that act like morphine in the body. Reduce pain and increase pleasure.

19. Neurotransmitter molecule Receiving cell membrane Agonist mimics neurotransmitter Receptor site on receiving neuron Antagonist blocks neurotransmitter Neural Communication

20. A spider’s venom causes paralysis. The venom probably affects: • Serotonin • Endorphins • Norepinephrine • Acetylcholine

21. Prozac increases the availabity of serotonin in the brain. Prozac is a(n): • A. Agonist • B. Antagonist • C. Neurotransmitter • D. MAOI

22. The Nervous System • Nervous System • the body’s speedy, electrochemical communication system • consists of all the nerve cells of the peripheral and central nervous systems • Central Nervous System (CNS) • the brain and spinal cord • Peripheral Nervous System (PNS) • the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body

23. The peripheral nervous system consists of: A. association areas. B. the spinal cord. C. the reticular formation. D. sensory and motor neurons.

24. When an angry bear enters our classroom, our _________ prepares us to fight or flee: • A. Parasympathetic Nervous System • B. Cerebellum • C. Medulla Oblongata • D. Sympathetic Nervous System

25. As Allison reaches for a box in her garage, out jumps a big spider. Her heart immediately begins to race as she withdraws her hand, but soon she realizes that the spider is harmless, and she begins to calm down. Which part of her nervous system is responsible for brining her back to a normal state of arousal? A. sympathetic nervous system B. somatic nervous system C. parasympathetic nervous system D. skeletal nervous system

26. Nervous system Peripheral Central (brain and spinal cord) Autonomic (controls self-regulated action of internal organs and glands) Skeletal (controls voluntary movements of skeletal muscles) Sympathetic (arousing) Parasympathetic (calming) The Nervous System

27. The Nervous System • Nerves • neural “cables” containing many axons • part of the peripheral nervous system • connect the central nervous system with muscles, glands, and sense organs • Sensory Neurons • neurons that carry incoming information from the sense receptors to the central nervous system

28. The Nervous System • Interneurons • CNS neurons that internally communicate and intervene between the sensory inputs and motor outputs • Motor Neurons • carry outgoing information from the CNS to muscles and glands • Somatic Nervous System • the division of the peripheral nervous system that controls the body’s skeletal muscles

29. The Nervous System • Autonomic Nervous System • the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart) • Sympathetic Nervous System • division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations • Parasympathetic Nervous System • division of the autonomic nervous system that calms the body, conserving its energy

30. The Nervous System

31. The Nervous System

32. Brain Sensory neuron (incoming information) Interneuron Motor neuron (outgoing information) Muscle Spinal cord Skin receptors The Nervous System • Reflex • a simple, automatic, inborn response to a sensory stimulus

33. The Endocrine System • Endocrine System • the body’s “slow” chemical communication system • a set of glands that secrete hormones into the bloodstream

34. Neural and Hormonal Systems • Hormones • chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another • Adrenal [ah-DREEN-el] Glands • a pair of endocrine glands just above the kidneys • secrete the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which help to arouse the body in times of stress • Pituitary Gland • under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands