Nervous System. Oct 15 10:00 AM

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1 Nervous System Oct 15 10:00 AM 1

2 Nerve net = series of interconnected nerve cells Nerve = axons of many nerve cells Oct 15 10:10 AM 2

3 bilateral organisms exhibit cephalization (evolutionary trend towards clustering sensory and interneurons at the anterior end) Oct 15 10:14 AM 3

4 In animals, nervous system organization correlates to lifestyle Ex. slow moving chiton simple sense organs, little/no cephalization Oct 15 10:17 AM 4

5 In faster moving molluscs (squid) sophisticated nervous systems In vertebrates have brain and spinal cord form CNS and ganglia for peripheral nervous system (PNS) Oct 15 10:20 AM 5

6 Reflexes automatic repsonse to certain stimuli method of protection What other reflexes does our body have? Oct 15 10:22 AM 6

7 brain and spinal cord come from dorsal embryonic nerve cord (characteristic of chordates) Oct 15 10:24 AM 7

8 embryonic nerve cord is transformed into central canal of spinal cord and ventricles of brain filled with cerebral spinal fluid (comes from blood) helps supply nutrients, hormones and takes away wastes cushions brain Oct 15 10:26 AM 8

9 Supporting cells in CNS Astrocytes forms blood brain barrier, structural support for neurons, regulate ions and neurotransmitters, increase blood flow to brain Oligodendrocytes mylenate the axons Ependymal cells move cerbral spinal fluid Microglial cells phagocytic cells Schwann cells myelinate PNS axons Oct 15 10:29 AM 9

10 Peripheral Nervous System Oct 15 10:35 AM 10

11 Autonomic nervous system regulates the internal environment controls smooth and cardiac muscle involutary three divisions: sympathetic, parasympathetic and enteric Sympathetic "fight or flight" dilates pupils increases heart rate and breathing rate slows down digestive activities increases blood flow to skeletal muscles Parasympathetic "rest and digest" constricts pupils decreases heart rate and breathing rate increases digestive activities blood flow more to digestive organs Oct 15 10:37 AM 11

12 Enteric division normally regulated by parasympathetic or sympathetic NS deals with digestive tract, pancreas and gall bladder controls secretion and smooth muscles that regulate peristalsis All help maintain homeostasis Oct 17 4:02 PM 12

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14 Vertebrate Brain Embryo (1 month) forebrain, midbrain, hindbrain 5 weeks five brain regions Adult Major areas: brain stem cerebellum Diencephalon Cerebrum Oct 17 4:05 PM 14

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17 Oct 15 10:50 AM 17

18 I. Brainstem Functions: homeostasis, coordination of movement, conduction of information to an dfrom higher areas of brain 3 areas: midbrain receives and integrates sensory information, send info to forebrain pons regulates breathing centers in the medulla oblongata medulla oblongata controls breathing, heart rate, swallowing, vomiting, blood vessel activity, digestion Oct 17 4:10 PM 18

19 Other function of brainstem: control arousal (state of awareness of outside world) and sleep (reticular formation area found in core of brainstem) melatonin (hormone produced by pineal gland) production increases at night synthesized from serotonin which is synthesized from tryptophan sleep is essential believed to consolidate learning and memory Oct 17 4:17 PM 19

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21 II. Cerebellum Functions:coordinates movement and balance receives input from muscles, joints, auditory and visual systems Ex. hand eye coordination Oct 17 4:24 PM 21

22 III. Diencephalon 3 regions: a. thalamus main input center for sensory information (relay station) b. hypothalamus controls homeostasis temperature, hunger, thirst, pleasure, fight or flight response, mating behaviors c. epithalamus includes pineal gland, contains capillaries that make cerebral spinal fluid Oct 17 4:26 PM 22

23 Hypothalamus also regulates circadian rhythm (daily cycles) relies on biological clock based on 24 hr cycle do not need cues of light and dark for this to happen Oct 17 4:31 PM 23

24 IV. Cerebrum divided into right and left cerebral hemispheres cerebral cortex = outer layer of gray matter internal white matter basal nuclei group of neurons deep in white matter important for planning and learning movement sequences damage to this area can cause cerebral palsy Oct 17 4:34 PM 24

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26 Cerebral cortex functions:perception, voluntary movement and learning 80% of brain mass is here convoluted for more surface area (1000 cm3) each half responsible for other side Ex. right hemisphere controls left side Corpus callosum thick band of axons that connect right and left sides Oct 17 4:39 PM 26

27 Epilepsy is a problem with the cerebrum episodes of electrical disturbances causing seizures if happen in infants and do not respond to medication can remove a hemisphere and other one takes over and can perform normal functions, but one side weaker Oct 17 4:43 PM 27

28 Cerebral Cortex controls voluntary movement and cognitive functions Oct 15 10:46 AM 28

29 cerebral hemispheres have different functions Left dominant role in language (Broca's area/wernicke's area) has role in math and logical operations Right dominant in recognition of faces and patterns, spatial relathionships and nonverbal thinking Differences = lateralization Oct 17 4:51 PM 29

30 Body part representation in primary motor and primary somatosensory cortices Oct 15 10:46 AM 30

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32 Limbic system deals with emotions includes amygdala, hippocampus and thalamus functions in emotions, motivation, olfaction, behavior and memory Oct 17 4:55 PM 32

33 Changes in synaptic connections underlie memory and learning Neural plasticity capacity for a nervous system to be remodeled occurs at synapses Oct 17 5:01 PM 33

34 memory and learning short term memory information is accessed via temporary links to hippocampus damage to hippocampus lose short term memory Long term memory links in hippocampus are replaced by more permanent connnection with cerebral cortex Oct 15 10:48 AM 34

35 Long term potentiation alters a synaptic connection a. NMDAglutamate receptors open to glutamate, blocked by magnesium b. nearby synapse activity depolarizes membrane, magnesium released, receptor allows Na+ and Ca+2 to enter; tiggers insertion of AMPA into membrane c. AMPA triggers depolarization so creates an action potential Oct 15 10:49 AM 35

36 Nervous system disorders most diosorders only partly due to genetics, most comes from environment do family studies to find relationship Oct 17 5:16 PM 36

37 Schizophrenia psychotic episodes with distortion of reality hallucinations (ex hear voices) delusions affects dopamine neural pathways treatment meds Oct 15 10:49 AM 37

38 Depression 1. major depressive disorder long periods of normally pleasurable activities no longer provoke interest 2. bipolar disorder (manic depressive disorder) mood swings from happy (high self esteem, high energy, increased risk taking) to sad (loss of pleasure, loss of motivation, feelings of worthlessness) Treatment meds Ex. prozac Oct 17 5:21 PM 38

39 Drug Addiction drug increases activity of brain's reward system (pleasure, motivation and learning neural circuits) involves dopamine each drug enhances the activity of dopamine pathway Oct 17 5:42 PM 39

40 How some drugs work Oct 15 10:50 AM 40

41 Alzheimer's Disease mental deterioration, age related, progressive death of neurons in brain, shrinkage of brain tissue amyloid plaques and neurofibrillary tangles seen when dead Oct 15 10:50 AM 41

42 Parkinson's Disease difficulty initiating movements, slowness of movements, muscle tremors progressive brain illness symptoms caused by death of neurons that release dopamine in basal nuclei some genetic link no cure; treatment with meds Ex. L dopa Oct 18 8:41 AM 42

43 Stem cell based therapy brain tissue cannot repair itself; however evidence that hippocampus cells can divide = stem cells some neurons take over for damaged ones Ex. stroke in brain stem cells are called neural progenitor cells scientists are looking at ways to use stem cells to make new neurons have already replaced stem cells in spinal cord injuries with some success Oct 18 8:45 AM 43

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