Nervous System

1. Nervous System Functions 1. 2. 3. 4. 5.

2. I. Division of the Nervous System A. Central Nervous System (CNS) 1. 2. B. Peripheral Nervous System( PNS) 1. Nervous that are outside the CNS a. b.

3. 2. Sub divisions of the PNS a. (afferent)-conducts action potential from sensory receptors to the CNS. b. (efferent) – conducts action potential from CNS to PNS. (muscle or glands) a. - serves sensory nerves, receptors (skin) sensory organs (head) & motor nerves that stimulate the skeletal muscle - voluntary nervous system b. - automatic 1. - involving stressful activities 2. - normal functioning

5. II. Nerve Tissue A. - support & maintain neurons 1. - Provide insulation covering around large axons. 2. - Anchor neurons to blood capillaries. 3. - form & circulate cerebrospinal fluid. 4. - phagocytize invading microorganisms. 5. - insulation covering around the CNS.

6. B. - functional unit of the nervous system 1. Structure a. - receive impulses b. - typical to other cells 1. - similar to RER 2. - network of fine threads c. (nerve fiber) - carries impulse away from the cell body. 1. One axon to every neuron 2. – side branches 3. – site of the axon missing Nissl bodies

7. d. - insulating barrier from a schwann cell around a axon. 1. Nourishment e. - cytoplasm & nuclei of the schwann cell on the outer covering. f. - gaps where myelin sheaths are absent. g. - gray matter h. - white matter

8. 2. Types of Neurons a. - many dendrites (signal to muscles). b. - 1 dendrtie & axon (eyes, ears, & nose). c. d. Sensory (afferent) CNS. e. Association (interneurons) the CNS. f. Motor (efferent) CNS.

9. 3. Function a. potential - Polarized - mv - sodium ions the neuron than . - potassium ions the neuron than . -this is maintained by the . -but due to the large ions stuck inside.

10. b. potential – (excitable) Nerve impulse + mv – sodium moves into the cell – potassium moves outside the cell.

11. C . period - hyperpolarized mv. Inside is more .

12. Review Where do you find the following ions in relations to the neuron? chloride, sodium, potassium Why do they call it a sodium-potassium pump? What is a threshold signal?

13. 4. All or None Response a. - minimum strength that can cause an action potential. b. - cannot initiate a response. c. - series of subthreshold stimuli can have a cumulative effect.

14. 5. Transmission of impulse a. Synapse b. Presynaptic c. Postsynaptic d. Synaptic end bulb e. Synaptic vesicles f. Neurotransmitters (50 different) 6. Excitatory vs. Inhibitory transmissions a. Excitatory causes a (more Na allowed to enter the postsynaptic) b. Inhibitory

16. III. The Central Nervous System A. - Conduction pathway for impulses between the brain & the PNS, reflex center. Protected by . Compose of matter. Conduction pathway between the brain & nerves. Reflex center cm long.

17. B. Protective coverings - - membrane layers. 1. - outermost, thick, & tough. - space filled with fat between the bone & dura matter. 2. - middle layer of collagen fibers. Subarachnoid space filled with Cerebrospinal fluid (CSF) - shocking absorning & transporting. 3. - inner most, attached to the spinal cord.

18. C. Structures1. segments each with a pair of spinal nerves. 2. - center of the cord (looks like an H). a. - terminal endings of sensory neurons. b. - motor neurons of the autonomic nervous system. c. - motor neurons to skeletal muscle. 3. - Surrounds the gray matter a. Anterior Columns - b. Lateral Columns- c. Posterior Columns -

19. D. Conduction Pathways 1. - sensory info to the brain. 2. - motor info from the brain. neurons to the effectors. E. Spinal nerves 1. Mixed nerves because they contain both sensory and motor neurons. 2. Organizied into regions that they emerge. C – T – L – S – Co – 3. Plexus – nerves come together and separate. a. three main ones cervical c1-c4 brachial – c5-t1 lumbosacral – l1-s4

20. E. Reflex Center 1. Reflex is an way of responding to an emergency situation. a. at the end of the sensory neuron. b. neuron to the CNS Associated neuron in the spinal cord (reflex center). c. Motor

21. 2. Types of reflexes a. - actions involve skeletal muscles. 1. Withdrawal – protective 2. Pattellar - knee jerk (2 neurons, sensory to the motor) 3. Stretch reflex

22. b. - smooth & cardiac to maintain homeostasis. 1. Breathing, vomiting, sneezing, & coughing

23. IV Brain - integrative center of the nervous system billion neurons.One of the largest internal organs. A. Protective coverings - Meninges - membrane layers. 1. - outermost, thick, & tough. - space filled with fat between the bone & dura matter. 2. - middle layer of collagen fibers. Subarachnoid space filled with Cerebrospinal fluid (CSF) - shocking absorbing & transporting. 3. - inner most, attached to the spinal cord

24. B. Cerebrum “ ”- Largest structure in the brain 1. Cerebral hemispheres 2. Convolutions - upwards folds - inward folds 3. Fissures 4. Four lobes a. – smell, motivation, aggression, mood. b. – touch, pain, temperature, balance, taste c. – sight d. – smell, hearing, memory

25. 5. Sensory Functions a. small portion of the sensory input results in sensation. b. – sends signals to the brain. -each tract is limited ex… ex. Lateral spinothalamic tract pain & temperature. ex. Dorsal column touch, position, pressure -most tracts have 2 or 3 neurons to the brain. -almost all end in the thalamus.

26. C. – between brain stem & cerebrum 1. - relay station for sensory impulses (except smell) entering the brain. 2. – pineal body (puberty) 2. - Primary control for the autonomic nervous system (homeostasis). a. Thermostat control for body temp b. regulates food & water uptake c. maintain walking & sleeping patterns. d. associated with emotion (rage, aggression, sex drives 1. Pituitary glands - endocrine glands

28. D. - reflexes for rapid eye, head & trunk movements E. - Bridges the cerebrum & cerebellum F. - part of the brain stem & most inferior brain structures 1. Cardiac & respiratory center G. - sends signals to the skeletal muscles

29. Cranial Nerves

30. Cranial Nerves

31. V. Disorders A. – inflammation of the brain B. – inflammation of the meninges. C. – viral disease transmitted by saliva of a animal bite. D. – bacterial disease that produces a neurotoxin that affect lower motor neurons in the spinal cord & brain stem. E. – autoimmune disorder caused by a viral infection F. – general, defects in motor functions from several types of brain damage or birth related injury. G. – muscular rigidity, lack of movement H. I. – mental deterioration (dementia). J. – group of brain disorders that cause seizures K. - shingles

32. VI. Effects of Aging A. Natural decline in functioning neurons, including sensory neurons. (balance loss, coordination, blood pressure, bladder) B. By the age of 60 up to 50% loss of lower motor neurons in lumbar region. (loss of muscle mass & increase fatigue) C. Size and weight of the brain decreases, but other neurons can compensate for this loss. D. Short term (problem solving, thinking) memory decreases slowly until the age of 60. Afterwards increase rate of memory loss, especially after 70. E. Long term memory seems to be unaffected. F. More time to fall asleep, more walking periods during the night, and longer amount of time being awake at night. G. Many older people shoe no change and some show a 10% increase in thinking ability due to education, health, motivation.