The Nervous System

1. The Nervous System “The right half of the brain controls the left half of the body. This means that only left handed people are in their right mind.”

2. The Nervous System The Nervous System Central Nervous System (CNS) Peripheral Nervous System (PNS) Brain Spinal Cord Motor Neurons Sensory Neurons Somatic Nervous System • voluntary movements via skeletal muscles Autonomic Nervous System • organs, smooth muscles Sympathetic - “Fight-or-Flight” responses Parasympathetic - maintenance

3. Central Nervous System • Made up of brain and spinal cord • Acts as body’s control center, coordinates body’s activities • Impulses travel through the neurons in your body to reach the brain • Central Nervous System is yellow in this diagram.

4. Peripheral Nervous System • Made up of all the nerves that carry messages to and from the central nervous system. • Similar to telephone wires that connect all of our houses in the community • Central Nervous System and Peripheral Nervous System work together to make rapid changes in your body in response to stimuli. • Peripheral Nervous System is green in this diagram.

5. Peripheral Nervous System: 2 parts • Somatic Nervous System • Relay information between skin, skeletal muscles and central nervous system • You consciously control this pathway by deciding whether or not to move muscles (except reflexes) • Reflexes: Automatic response to stimulus • Autonomic Nervous System • Relay information from central nervous system to organs • Involuntary: You do not consciously control these • Sympathetic Nervous System: controls in times of stress, such as the flight or fight response • Parasympathetic Nervous System: controls body in times of rest

6. CNS PNS Motor division Sensory division Sympathetic division Autonomic nervous system Somatic nervous system Parasympathetic division

7. Neurons • The basic unit of structure and function in the nervous system • Cells that conduct impulses. • Made up of dendrites, cell body and an axon

8. Structure of the Neuron • cell body (soma): the central part of the neuron, contains the nucleus • regulates cell functioning • dendrites: the branching part of the neuron that receives messages from other neurons and relays them to the cell body

9. Structure of the Neuron • axon:the long, cable-like extension that delivers messages to other neurons • myelin sheath: layer of fatty tissue that insulates the axon and helps speed up message transmission • multiple sclerosis: deterioration of myelin leads to slowed communication with muscles and impaired sensation in limbs • knobs:structure at the end of one of the axon’s branches that releases chemicals into the space between neurons, when the neuron is fired

10. From Neuron to Neuron • ≈100 billion neurons in a human brain, connected to an average of 10,000 others; some up to 100,000 • synapse: the place where an axon of one neuron meets with the dendrite/cell body of another neuron

11. How is an impulse transmitted? • Stimulus excites sensory neuron. • Depolarization (a change in charge due to sodium ions) creates a wave of changing charges down the axon. • Impulse moves across synapse (tiny space between one neuron’s axon and another’s dendrites) with the help of neurotransmitters This is an image of neurons located in the cerebral cortex of a hamster.

12. From Neuron to Neuron

13. From Neuron to Neuron • neurotransmitters: a chemical that sends signals from one neuron to another over the synapse

14. From Neuron to Neuron • Neurotransmitters are stored in vesicles in the knobs, and bind to receptors on the cell membrane of the next neuron. • Each receptor can only bind with one kind of neurotransmitter.

15. 3 types of neurons • Sensory Neurons: carry impulses from inside and outside the body to brain and spinal cord. • Interneurons: found within brain and spinal cord, process incoming impulses and pass them on to motor neurons. • Motor Neurons: carry impulses away from the brain and spinal cord.

16. So how do these neurons work if someone taps you on the shoulder . . . • Receptors in the skin sense touch or other stimuli. • Sensory neurons transmit the touch message. • Information is sorted and interpreted in the brain. A response in determined by interneurons. • Motor neurons transmit a response message to the shoulder muscles. • The shoulder muscles are activated, causing the head to turn.

17. Three main sections Cerebrum 2 hemispheres Controls memory, intelligence, muscles Cerebellum Controls balance, posture and coordination Brainstem Controls involuntary activities such as breathing The Central Nervous System

18. The Cerebrum • Controls conscious activities, intelligence, memory, language, muscles. • Wrinkled with countless folds and grooves and covered with an outer layer of gray matter called the cerebral cortex. • Divided into 4 lobes

19. Frontal Lobe • Largest Lobe • Planning • Complex Thinking • Reasoning • Imagining

20. Parietal Lobe Process messages related to: Touch Taste Temperature Controls muscle movements

21. Occipital Lobe • Processes Sight • Receives input from the eyes • Interprets color and other aspects of vision

22. Temporal Lobe Processes: Hearing Some Memory Speech

23. LEFTvs RIGHT

24. Corpus Callosum • The Corpus Callosum is the part of the brain that allows communication between the two hemispheres. • It is responsible for transmitting neural messages between both the right and left hemispheres.

25. Right brain vs left brain damage Left Brain Right Brain Visual-spatial impairment Visual memory deficits Left neglect Decreased awareness of deficits Altered creativity and music perception Decreased control over the left side of the body • Difficulties in understanding language • Difficulty in speaking and verbal output • Sequencing difficulties • Impaired logic • Decreased control over the right side of the body

26. The Cerebellum • Muscle coordination is developed here as well as the memory of physical skills. • If the cerebellum is injured, your movements become jerky. • When you see an amazing athlete perform, you are watching a well-trained cerebellum at work.

27. Cerebellum • Coordination and voluntary movement • Balance and equilibrium • Coordinates fine movements

28. The Brainstem • Made up of the medulla oblongata, pons and midbrain. • Medulla oblongata controls involuntary activities such as heart rate and breathing • Pons and midbrain act as pathways connecting various part of the brain with each other. • Sometimes called the reptilian brain, because it resembles the entire brain of a reptile.

29. Brainstem • Controls essential survival functions: • Breathing • Heart Rate • Swallowing • Reflexes to seeing and hearing • Controls sweating, blood pressure, digestion, temperature • Affects levels of alertness

30. Limbic System Regulates: Temperature Blood Pressure Heart Rate

31. Thalamus • The thalamus is similar to a doctor that diagnoses a patient's disease or sickness. • It diagnoses different sensory information that is being transmitted to the brain. It is like a “Switch Board” receiving messages and directing them to the proper area. • It directs the sensory information to the different parts and lobes of the cortex.

32. Hypothalamus • Hunger and Thirst • Maintains a constant temperature. • Connects the endocrine system with the nervous system

33. Amygdala • When you think of the amygdala, you should think of one word. Fear. • The amygdala is the reason we are afraid of things outside our control. • It also controls the way we react to certain stimuli, or an event that causes an emotion, that we see as potentially threatening or dangerous

34. Hippocampus • Plays important roles in the consolidation of short term memory to long term memory • Memory of the location of objects or people.