1. Nervous System
AP Biology
Ch. 48
Ms. Haut

2. Function of Nervous System
Sensory Input
Conduction of signals from sensory receptors
Integration
Carried out by Central Nervous System (CNS)
Brain and spinal cord
Motor Output
Carried out by Peripheral Nervous System (PNS)
Conduction of signals to muscle or gland cells
Carry out body’s responses to stimuli

3. Animal Nerve Cells
Nerves: rope-like bundles of extensions of neurons, tightly wrapped in connective tissue
Neurons: functional unit of the nervous system

4. Functional Organization of Neurons
Sensory Neurons: relay information (stimuli) from the external and internal environments to CNS
Interneurons: integrate sensory input and motor output (carry stimuli in the brain and spinal cord)
Motor Neurons: convey impulses from CNS to effector cells in muscles or glands
Glial cells: support, protect, and nourish neurons

5. Structural Diversity of Neurons

6. Overview of Vertebrate Nervous System

7. Neuron Circuitry
Simplest neural circuit involves synapses between 2 neurons, a sensory neuron and a motor neuron
Result is often an automatic response called a reflex

8. The Knee-jerk Reflex

9. Neural Signals
Nerve impulse is an electrical signal that depends on the flow of ions across the plasma membrane of a neuron

10. Membrane Resting Potential
Cell is said to be polarized

11. Action Potential
A nerve impulse is generated when the difference in electrical charge disappears
Occurs when a stimulus contacts the tip of a dendrite and increases the permeability of the cell membrane to Na+ ions
Cell is said to be depolarized

12. Graded Potentials
“All-or-none event”

13. Regulation of Action Potential

14. Propagation of the Action Potential
After the wave of depolarization has passed, the neuron reestablishes the difference in charges by pumping K+ out of the cytoplasm

15. Saltatory Conduction

16. Synapses
Nerve impulses pass down the dendrite, through the cell body, and down the axon.
At the end of the axon, the signal reaches a fluid-filled space (synapse) separating the end of the axon from the dendrite of the next neuron.
Neuromuscular junction: synapse located at the junction of a neuron and muscle fiber

17. Chemical Synapse

18. MAJOR NEUROTRANSMITTERS AND THEIR EFFECTS
Acetylcholine (ACh)
Generally excitatory
Affects arousal, attention, memory, motivation, movement. Too much: spasms, tremors. Too little: paralysis, torpor.
Dopamine
Inhibitory
Inhibits wide range of behavior and emotions, including pleasure. Implicated in schizophrenia and Parkinson's disease.
Serotonin
Inhibits virtually all activities. Important for sleep onset, mood, eating behavior.
Norepinephrine
Affects arousal, wakefulness, learning, memory, mood.
Endorphins
Inhibit transmission of pain messages.

19. Organizations of Invertebrates
Without CNS
CNS
(PNS)
CNS

20. Vertebrate Nervous System

21. Autonomic Nervous System
Works on an involuntary basis
2 subdivisions
Parasympathetic
Sympathetic
Return body to normal after an emergency
Prepare body for emergency
Heart rate slows, pupils constrict, blood vessels dilate
Increase heart rate, constricted blood vessels, pupils dilate

22. Roles of Parasympathetic and Sympathetic Divisions of the Autonomic Nervous System

23. Structure of Brain

24. Brainstem Medulla oblongata Pons Midbrain
Contains centers that control visceral (autonomic, homeostatic) functions
Breathing, heart and blood vessel activity, swallowing, vomiting, and digestion
Pons
Have nuclei in the medulla that regulate breathing centers
Midbrain
Centers for receipt and integration of sensory information
Coordinates large-scale body movements such as walking

25. Cerebellum Primary function is coordination of movement
Receives information about position from joints and length of muscles, as well as auditory and visual systems
Plays role in learning and remembering motor responses (hand-eye coordination)

26. Thalamus and Hypothalamus
Main input center for sensory information going to cerebrum
Receives input from cerebrum to regulate emotion and arousal
Hypothalamus
Source of posterior pituitary hormones and releasing hormones that act on anterior pituitary
Regulates body temp, thirst, hunger, other basic survival mechanisms
Plays role in sexual response and mating behaviors, fight-or-flight response, and pleasure

27. Structure and Function of Cerebrum

28. Primary Somatosensory cortex
Primary Motor cortex

30. Sleep and Arousal
Controlled by several centers in the cerebrum and brainstem
Reticular formation: neurons that pass through the brainstem
Reticular activating system--regulates sleep and arousal
Increased input to cortex, increases alertness
Medulla and pons
Nuclei stimulated induces sleep
Serotonin may activate sleep centers

31. Lateralization, Language, and Speech
Association areas of cerebral cortex are lateralized (specialized functions)
Left hemisphere
Speech, language, calculation, and rapid serial processing of details
Right hemisphere
Overall context, spatial perception, and creative abilities

32. Emotions
Limbic system-functional group of nuclei and interconnecting axon tracts in the CNS
Includes parts of the thalamus and hypothalamus, and portions of the cerebral cortex
Linked to areas of cerebral cortex involved with complex learning, reasoning, and personality
Amygdala-prominent component of limbic system
Major organizer of emotional information
Plays role in memory association