1. Nervous System Notes Part 2 AP Biology 2012

2. 2 Parts to the Nervous System 1.Central Nervous System – CNS – Contains the brain and the spinal cord – Information is transmitted from sensory cells to the CNS, and from the CNS to effectors, via neurons 2.Peripheral Nervous System – PNS – Contains the neurons and their supporting cells – 2 portions 1.Afferent – carries sensory information to CNS 2.Efferent – carries information from CNS to muscles/glands – 2 divisions 1.Voluntary (conscious movements) 2.Involuntary (autonomic )

4. Autonomic Nervous System ANS Controls involuntary functions that are crucial to homeostasis (heart rate, sweating, digestion) 2 divisions 1.Sympathetic – produces fight or flight response, increased heart rate, bp etc., preparing body for emergencies 2.Parasympathetic – opposite, slows heart, lowers bp, increases digestion

6. Spinal Cord Has afferent and efferent tracts of axons communicating between brain and organs Cross section reveals a central area of gray matter in shape of a butterfly, surrounded by area of white matter – Gray matter – rich in cell bodies of spinal neurons – White matter – rich in myelinated axons that conduct information up and down spinal cord

8. Spinal Nerves Extend from spinal cord at regular intervals Each nerve has 2 roots – One connecting with the dorsal horn of the gray matter – One with the ventral horn Afferent (sensory) axons enter spinal cord through dorsal root Efferent (motor) axons leave through ventral root Capable of simple reactions that don’t involve the brain called spinal reflexes

9. Spinal Reflex Simplest type has 2 neurons involves with 1 synapse between them – monosynaptic reflex Example if knee jerk reflex

10. Knee Jerk Reflex Dr. taps knee with little hammer, which stretches the patella tendon connecting the quadriceps to the femur in lower leg. Stretching the muscle generates action potentials in that sensory neuron. The axon of the sensory neuron travels to the spinal cord, enters the dorsal horn, and continues to ventral horn where it synapses onto a motor neuron. This synapse is excitatory and causes the motor neuron to fire action potentials that travel in the axon of that motor neuron back out to the quadriceps, causing it to contract. Result is that your lower leg kicks forward

11. Basic Spinal Reflex Information enters the spinal cord from sensory neurons Commands leave the spinal cord through motor neurons All this happens without involving brain Spinal reflexes allow rapid responses to certain simple stimuli and are important in maintaining posture and balance.

12. Adult Brain 3 major divisions during development 1.Hindbrain – Produces cerebellum (controls motor control and some cognitive functions 2.Midbrain 3.Forebrain – Develops into the cerebral hemispheres, thalamus, hypothalamus and the pituitary Physiological functions such as heart beat and breathing

13. Cerebrum Has left and right cerebral hemispheres Outermost layer is the cerebral cortex Thin layer, but folded into ridges to increase surface area Sensory perception, learning, memory, and conscious behavior Different regions have specific functions Most of the cortex is involved in higher- order information processing and is called the association cortex

15. Each cerebral hemisphere has 4 lobes 1.Temporal lobe 2.Frontal lobe 3.Parietal lobe 4.Occipital lobe

16. Temporal Lobe Upper region receives and processes auditory information Lower regions are involved with visual processing Also involved in recognizing, identifying, and naming objects Damage to this lobe results in disorders called agnosias, in which the individual is aware of an object but cannot identify it

17. Frontal Lobe Largest lobe Feeling and planning and contribute to “personality” Damage causes drastic alterations of personality and difficulty planning future events The strip of the frontal lobe cortex that is just anterior to the parietal lobe is the primary motor cortex – control muscles in specific parts of the body

18. Occipital Lobe Receives and processes visual information Essential for making sense of the visual world and translating it into language Damage causes people to not see motion

19. Parietal Lobe Attends to complex stimuli Helps translate visual information into a perception of objects located in a 3D space Behind primary motor cortex of the frontal lobe is a strip called the primary somatosensory cortex. – Receives touch and pressure information

21. Concept 34.5 Specific Brain Areas

22. Lateralization Phenomenon that language ability resides in one cerebral hemisphere, the left Individuals who suffer damage to the left hemisphere have some form of aphasia Defect in the ability to use or understand words Allowed the identification of two language areas Broca’s area and Wernicke’s area

23. 2 Language Areas Broca’s Area – Located in the frontal lobe – Essential for production of language – Damage results in poorly articulated speech or complete loss of speech, as well as loss of the ability to write – They can still read and can understand speech Wernicke’s area – Located in the temporal area – Essential for understanding language – Damage results in loss of the ability both to read and to understand speech – Patients can still produce fluent, but nonsensical speechlike sounds

25. Learning and Memory can be localized to specific brain areas

26. Learning Modification of behavior by experience Learning that leads to long term memory must involve long-lasting synaptic changes – Long Term Potential High frequency electrical stimulation of certain neuronal circuits makes these circuits more sensitive to subsequent stimulation 2 types of learning – Associative learning – Observational learning

27. Associative Learning 2 unrelated stimuli become linked to the same response Example is conditioned reflex (Pavlov – Russian) – Dog salivates at sight or smell of food (simple autonomic reflex) – If he rang a bell before food was presented, after a few trials, the dog would salivate at the bell even if no food followed – Salivation reflex was conditioned

28. Observational Learning Foundation of human intelligence 3 elements 1.We pay attention to another person’s behavior 2.We retain a memory of what we have observed 3.We try to copy or use that information Creates memories

29. Optional topics in Ch 34 Memory REM and nonREM sleep What is consciousness?