the biological perspective

1. 2 the biological perspective

2. why study the nervous system and the glands?How could we possibly understand any of our behavior, thoughts, or actions without knowing something about the incredible organs that allow us to act, think, and react? If we can understand how the brain, the nerves, and the glands interact to control feelings, thoughts, and behavior, we can begin to truly understandthe complex organism called a human being.

3. Learning Objectives • LO 2.1 What are the nervous system, neurons and nerves? • LO 2.2 How neurons use neurotransmitters to communicate • LO 2.3 How brain and spinal cord interact • LO 2.4 Somatic and autonomic nervous systems • LO 2.5 Hormones and Behavior • LO 2.6 How psychologists study the brain and how it works • LO 2.7 Structures and functions of the bottom part of the brain • LO 2.8 Structures that control emotion, learning, memory, motivation • LO 2.9 Parts of cortex controlling senses and body movement • LO 2.10 Areas of the cortex involved in higher forms of thought • LO 2.11 Left and Right brain differences

4. Overview of Nervous System LO 2.1 What are the nervous system, neurons and nerves? • Nervous system • Network of cells carrying information to and from all parts of the body • Neuroscience • Emphasis on structure and function of neurons, nerves, and nervous tissue • Branch of life sciences

5. Structure of the Neuron LO 2.1 What are the nervous system, neurons and nerves? • Biological psychology (behavioral neuroscience) • Branch of neuroscience • Focuses on the biological bases of psychological processes, behavior, and learning

6. Figure 2.1 An Overview of the Nervous System

7. Structure of the Neuron LO 2.1 What are the nervous system, neurons and nerves? • Neuron • Specialized cell in the nervous system • Sends and receives nervous system messages • Parts of the Neuron • Dendrites • Branch-like structures that receive messages from other neurons

8. Structure of the Neuron LO 2.1 What are the nervous system, neurons and nerves? • Parts of the Neuron • Soma • Cell body of the neuron • Responsible for maintaining the life of the cell • Axon • Long tube-like structure • Carries the neural message to other cells

9. Figure 2.2 The Structure of the NeuronThe electronmicrograph on the left shows myelinated axons.

10. Other Types of Brain Cells LO 2.1 What are the nervous system, neurons and nerves? • Glial Cells • Provide support for the neurons to grow on • Deliver nutrients to neurons • Remove waste products and dead neurons • Types include oligodendrocytes and Schwann cells • Produce myelin to coat axons

11. Myelin Sheath LO 2.1 What are the nervous system, neurons and nerves? • Fatty substances produced by glial cells • Coats the axons insulate, speed neural impulse • Oligodendrocytes produce myelin for brain and spinal cord • Schwann cells produce myelin for rest of body • Multiple sclerosis • Causes destruction of myelin sheath

12. Generating the Message: Neural Impulse LO 2.1 What are the nervous system, neurons and nerves? • Neurons are electrically charged with ions • Ions are located inside and outside of the cell • More negatively charged inside the cell, more positively charged outside the cell • Difference in charges creates an electrical potential

13. Generating the Message: Neural Impulse LO 2.1 What are the nervous system, neurons and nerves? • Resting potential • State of neuron when not firing a neural impulse • Channels for sodium not open • Action potential • Release of the neural impulse • Consists of reversal of electrical charge within the axon

14. Generating the Message: Neural Impulse LO 2.1 What are the nervous system, neurons and nerves? • All-or-none • Neuron either fires completely or does not fire at all

15. Figure 2.3 The Neural Impulse Action PotentialIn the graph below, voltage readings are shown at a given place on the neuron over a period of 20 or 30 milliseconds (thousandths of a second). At first the cell is resting; it then reaches threshold and an action potential is triggered. After a brief hyperpolarization period, the cell returns to its resting potential.

16. Figure 2.3 (continued) The Neural Impulse Action PotentialIn the graph below, voltage readings are shown at a given place on the neuron over a period of 20 or 30 milliseconds(thousandths of a second). At first the cell is resting; it then reaches threshold and an action potential is triggered. After a brief hyperpolarization period, the cell returns to its resting potential.

17. Sending the Message to Other Cells LO 2.2 Neuron communication • Axon terminals • Branches at the end of the axon • Synaptic knob • Rounded areas on the end of axon terminals • Synaptic vesicles • Sack-like structures inside the synaptic knob • Contain chemicals called neurotransmitters

18. Sending the Message to Other Cells LO 2.2 Neuron communication • Axon terminals • Neurotransmitters, when released, affect neighboring cells

19. This electromicrograph shows a motor neuron making contact with muscle fibers.

20. Sending the Message to Other Cells LO 2.2 Neuron communication • Synapse/synaptic gap • Fluid-filled space between end axon terminals of one cell and surface of the next cell • Receptor sites • Ion channels, proteins on dendrite surface • Shaped to accept specific neurotransmitter

21. Figure 2.4 The SynapseThe nerve impulse reaches the synaptic knobs, triggering the release of neurotransmitters from the synaptic vesicles. The molecules of neurotransmitter cross the synaptic gap to fit into the receptor sites that fit the shape of the molecule, opening the ion channel and allowing sodium ions to rush in.

22. Neuron Communication LO 2.2 Neuron communication • Neural cells can be turned either on or off • Excitatory synapses • Cause receiving cell to fire • Inhibitory synapses • Cause receiving cell to stop firing

23. Neuron Communication LO 2.2 Neuron communication • Chemical substances affect neural communication • Agonists • Mimic or enhance the effects of a neurotransmitter on the receptor sites • Antagonists • Block or reduce a cell’s response to the action of other neurotransmitters

24. Table 2.1 Some Neurotransmitters and Their Functions

25. Cleaning up the Synapse LO 2.2 Neuron communication • Reuptake • Neurotransmitters are taken back into the synaptic vesicles • Acetylcholine does not go through reuptake • Needs to be available for quick muscle activity • Reuptake too slow for process • Is instead broken down in the synapse by enzymatic degradation

26. Central Nervous System LO 2.3 Brain and spinal cord • Part of the nervous system consisting of the brain and spinal cord • Brain • Interprets information from senses • Spinal cord • Long bundle of neurons • Carries messages to and from the body to the brain • Also responsible for very fast, lifesaving reflexes

27. The Reflex Arc: Three Types of Neurons LO 2.3 Brain and spinal cord • The reflex arc forms a connection between a sensory, a motor and an interneuron • Sensory neuron • Carries messages from the senses to spinal cord • Also called afferent neuron

28. This electronmicrograph shows a stem cell in the process of becoming a neuron.

29. The Reflex Arc: Three Types of Neurons LO 2.3 Brain and spinal cord • Motor neuron • Carries messages from spinal cord to muscles and glands • Also called efferent neuron

30. The Reflex Arc: Three Types of Neurons LO 2.3 Brain and spinal cord • Interneuron • Found in spinal cord and brain • Receives information from sensory neurons • Sends commands to muscles through the motor neurons • Make up the bulk of the neurons in the brain

31. Figure 2.6 The Spinal Cord ReflexThe pain from the burning heat of the candle flame stimulates the afferent nerve fibers, which carry the message up to the interneurons in the middle of the spinal cord. The interneurons then send a message out by means of the efferent nerve fibers, causing the hand to jerk away from the flame.

32. Neuroplasticity LO 2.3 Brain and spinal cord • Is the ability to change both the structure and function of cell involved in trauma • Implanted nerve fibers from damaged area • Damaged spinal nerves grow through fiber “tunnels” • Possibility of transplanting stem cells to repair damaged tissue being explored

33. Peripheral Nervous System LO 2.4 Somatic and autonomic nervous systems • Consists of nerves and neurons not contained in the brain and spinal cord • Nerves run through the organs and extremities of the body • Divided into: • Somatic nervous system • Autonomic nervous system

34. Figure 2.7 The Peripheral Nervous System

35. Somatic Nervous System LO 2.4 Somatic and autonomic nervous systems • Division of PNS • Consists of nerves carrying information: • From the senses to CNS • From the CNS to voluntary muscles of the body

36. These young soccer players are using their senses and voluntary muscles controlled by the somatic division of the peripheral nervous system. What part of the autonomic nervous system are these girls also using at this time?

37. Somatic Nervous System LO 2.4 Somatic and autonomic nervous systems • Division of PNS • Sensory pathway • Afferent neurons coming from sensory organs • Motor pathway • Efferent neurons coming from the CNS to the voluntary muscles

38. Autonomic Nervous System LO 2.4 Somatic and autonomic nervous systems • Division of PNS • Functions automatically • Sympathetic division (fight-or-flight system) • Reacts to stressful events and bodily arousal

39. Figure 2.8 Functions of the Parasympathetic and Sympathetic Divisions of the Nervous System

40. Autonomic Nervous System LO 2.4 Somatic and autonomic nervous systems • Division of PNS • Functions automatically • Parasympathetic division • Restores body to normal functioning after arousal • Responsible for the day-to-day functioning of the organs and glands

41. Snowboarder Shaun White of the U.S.A. 2010 Olympics Team won the gold medal in the halfpipe competition in Vancouver. What part of the autonomic nervous system is likely to be working as Shaun flies through the air, as in this picture?

42. The Endocrine Glands LO 2.5 How hormones interact with the nervous system and affect behavior • Are glands that secrete chemicals called hormones directly into the bloodstream • Endocrine communication is slower than synaptic communication • Hormones • Chemicals released into the bloodstream by endocrine glands

43. The Endocrine Glands LO 2.5 How hormones interact with the nervous system and affect behavior • Pituitary gland • Located in the brain • Secretes human growth hormone • Influences all other hormone-secreting glands (also known as the master gland)

44. Figure 2.9 The Endocrine GlandsThe endocrine glands secrete hormones directly into the bloodstream, which carries them to organs in the body, such as the heart, pancreas, and sex organs.

45. The Endocrine Glands LO 2.5 How hormones interact with the nervous system and affect behavior • Pineal gland • Located near the base of the cerebrum • Secretes melatonin • Thyroid gland • Found in the neck • Regulates growth and metabolism • Pancreas • Controls the levels of sugar in the blood • Secretes insulin and glucagons

46. When the pancreas does not secrete enough insulin, the result is diabetes. Many diabetic people must give themselves insulin shots to supply enough of the hormone.

47. The Endocrine Glands LO 2.5 How hormones interact with the nervous system and affect behavior • Gonads • Sex glands • Secrete hormones that regulate sexual behavior and reproduction • Ovaries - female gonads • Testes - male gonads

48. The Endocrine Glands LO 2.5 How hormones interact with the nervous system and affect behavior • Adrenal glands • Located on top of each kidney • Secrete over 30 different hormones • Deals with stress • Regulates salt intake • Provides secondary source of sex hormones during adolescence

49. Looking Inside the Living Brain LO 2.6 Study of the brain • Lesioning studies • Deep lesioning • Insertion of a thin, insulated wire into the brain • Electrical current destroys brain cells at tip of wire • Shallow Lesioning • Cells are destroyed on the surface of the brain

50. Looking Inside the Living Brain LO 2.6 Study of the brain • Electrical stimulation of brain (ESB) • Mild electrical current passed through probe • Causes neurons to react as if had received a message