1. Neural and Hormonal Systems
Module 3
Neural and Hormonal Systems

2. Neural Communication The Nervous System The Endocrine System Neurons
How Neurons Communicate
How Neurotransmitters Influence Us
The Nervous System
The Peripheral Nervous System
The Central Nervous System
The Endocrine System

3. History of Mind Phrenology
In 1800, Franz Gall suggested that bumps of the skull represented mental abilities. His theory, though incorrect, nevertheless proposed that different mental abilities were modular.
Preview Question 1: Why do psychologists study biology?
Bettman/ Corbis

4. The Nervous System Neuron Approx. 100 billion neurons (1011)
a nerve cell
the basic building block of the nervous system
Approx. 100 billion neurons (1011)
Approx trillion synapses (1014)

5. Hummm???
How many is 400 trillion really?

6. The Nervous System Nervous System Central Nervous System (CNS)
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

7. 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

8. The Nervous System Sensory Neurons Motor Neurons
neurons that carry incoming information from the sense receptors to the central nervous system
Motor Neurons
carry outgoing information from the CNS to muscles and glands

9. The Nervous System Interneurons
CNS neurons that internally communicate and intervene between the sensory inputs and motor outputs

10. Central Nervous System
The Brain and Neural Networks
Interconnected neurons form networks in the brain. Theses networks are complex and modify with growth and experience.
Complex Neural Network

11. Neural Communication Dendrite Axon Myelin [MY-uh-lin] Sheath
the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body
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 segmentally encasing the fibers of many neurons
enables vastly greater transmission speed of neutral impulses

12. Neural Communication

13. Threshold
Threshold: Each neuron receives excitatory and inhibitory signals from many neurons. When the excitatory signals minus the inhibitory signals exceed a minimum intensity (threshold) the neuron fires an action potential.

14. Action Potential Properties
All-or-None Response: A strong stimulus can trigger more neurons to fire, and to fire more often, but it does not affect the action potentials strength or speed. Intensity of an action potential remains the same throughout the length of the axon.

15. Synapse
Synapse [SIN-aps] a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. This tiny gap is called the synaptic gap or cleft.
Preview Question 3: How do nerve cells communicate? Synapse was coined by Lord Sherrington ( ) who inferred it through behavioral experiments. Cajal ( ) described the synapse based on his anatomical studies of the brain.

16. Neurotransmitters
Neurotransmitters (chemicals) released from the sending neuron travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing it to generate an action potential.

17. Reuptake
Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake. This process applies the brakes on neurotransmitter action.

18. Neural Communication

19. How Neurotransmitters Influence Us
A particular pathway in the brain may use only one or two neurotransmitters and particular neurotransmitters may have particular effects on behavior and emotions

20. How Neurotransmitters Influence Us
Serotonin pathways are involved with mood regulation.
Preview Question 4: How do neurotransmitters influence human behavior?
From Mapping the Mind, Rita Carter, © 1989 University of California Press

21. Dopamine Pathways
Dopamine pathways are involved with diseases such as schizophrenia and Parkinson’s disease.
From Mapping the Mind, Rita Carter, © 1989 University of California Press

22. Neurotransmitters

23. Lock & Key Mechanism
Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism.

24. Agonists

25. Antagonists

26. How Neurotransmitters Influence Us
Endorphins [en - DOR-fins]: “morphine within”— natural, opiatelike neurotransmitters linked to pain control and to pleasure.
Drugs and other chemicals affect brain chemistry at synapses: Agonist molecules bind to a neurotransmitter’s receptor and mimics its effects. Antagonists bind to receptors and block a neurotransmitter’s functioning.

27. Peripheral Nervous System
Somatic Nervous System: The division of the peripheral nervous system that controls the body’s skeletal muscles.
Autonomic Nervous System: Part of the PNS that controls the glands and other muscles.

28. The Nervous System Autonomic Nervous System Sympathetic 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

29. Nervous System
Preview Question 4: What are the functional divisions of the nervous system?

30. Autonomic Nervous System (ANS)
Sympathetic NS “Arouses”
(fight-or-flight)
Parasympathetic NS “Calms”
(rest and digest)

31. A Simple Reflex

32. The Endocrine System
The Endocrine System is the body’s “slow” chemical communication system. Communication is carried out by hormones synthesized by a set of glands.
Preview Question 5: How does the endocrine system-the body’s slower information system-transmit its messages?

33. Hormones Hormones are chemical messengers that are
manufactured by the endocrine glands,
travel through the bloodstream, and affect
other tissues..
For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood sugar, and feelings of excitement during emergency situations.

34. The Endocrine System
adrenal [ah - DREEN-el] glands: pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress. pituitary gland: the endocrine system’s most influential gland. Under the influence of the hypothalamus, it regulates growth and controls other endocrine glands.