Nervous System

1. Nervous System

3. Organization of Peripheral Nervous System (PNS)

4. Peripheral Nervous System Sensory Motor Sensing external environment Sensing internal environment Somatic nervous System (voluntary) Autonomic nervous System (involuntary) Parasympathetic slowing down Sympathetic Speeding up

5. Autonomic nervous System (involuntary) This is a continuation of the previous flow chart Sympathetic Speeding up Parasympathetic Slowing down Rest and Digest Fight or Flight

7. Organization of Central Nervous System(CNS)

8. Cerebrum Thalamus Hypothalamus Cerebral cortex Pituitary gland Midbrain Pons Medulla oblongata Cerebellum Spinal cord Forebrain Hindbrain

9. Frontal Lobe Parietal Lobe Corpus Callosum Occipital Lobe Temporal Lobe Left Hem. Right Hem. • Frontal • Association • Speech • Motor Cortex • Taste • Speech • Reading • Smell • Auditory • Association • Hearing • Vision • Visual • Association On your notes you need to have the left picture and labels

10. Nervous Tissue • Glial Cells • 90% of CNS • Structural framework • Fatty Myelin sheath • Phagocytosis • Cerebrospinal fluid circulation

11. Structure of Single Neuron

12. Neurons I • Cell Body • Nucleus • Cytoplasm • Other common organelles • NO mitotic spindles! (what problems does this cause?) • Dendrites • Highly branched • Receive impulses

13. Neurons II • Axon • Always only 1 • Conducts impulse AWAY from cell body • Can extend as much as 1 meter • Encased by Schwann cells  Myelin sheath • (In CNS, Oligodendrocytes may provide sheath) • Nodes of Ranvier

14. 3 types of Neurons Sensory Neurons – neurons that carry incoming information from the sense to the CNS Interneurons – CNS neurons that internally communicate and intervene between the sensory inputs and motor outputs Motor Neurons – Carry outgoing information from the CNS to muscle and glands

15. How do cells detect and respond to changes in their internal and external environment to successfully survive and maintain homeostasis?

16. Detection of signals from the outside environment or detection of deviation (change) from homeostasis from the internal environment.

17. 2) Integration of multiple signals from outside and inside to produce appropriate response. BRAIN

18. 3) Response to counteract stimulus being detected. Draw your own picture to represent RESPONSE

19. Detection of signals from outside environment or detection of deviation (change) from homeostasis from internal environment. • Integration of multiple signals from outside and inside to produce appropriate response. • Response to counteract stimulus being detected System builds a Reflex Arc

20. Sensor Receptor (Detection) Peripheral Nervous System (PNS) Central Nervous System(CNS) Sensory Input Integration Effector (Response) Motor Output

23. Neuron SignalsACTION POTENTIAL

25. When an impulse reaches the Axon Terminal, dozen of vesicles fuse with the cell membrane and discharge the Neurotransmitter into the Synaptic Cleft (GAP). • The molecules of the neurotransmitter diffuse across the gap and attach themselves to SPECIAL RECEPTORS on the membrane of the neuron receiving the impulse. • When the neurotransmitter becomes attached to the cell membrane of the adjacent nerve cell, it changes the permeability of that membrane. • As a result, Na+ ions diffuse through the membrane into the cell. • If enough neurotransmitter is released by the axon terminal, so many Na+ ions diffuse into the neuron that the neuron becomes DEPOLARIZED.

26. DEPOLARIZED = Inside the membrane becomes more positive than outside. • This causes a THRESHOLD to be REACHED and an impulse (ACTION POTENTIAL) begins in the second cell. • After the neurotransmitter relays it message it is rapidly REMOVED or DESTROYED, thus halting its effect. • The molecules of the neurotransmitter may be broken down by ENZYMES, taken up again by the axon terminal and recycled, or they may simply diffuse away. • NERVE GAS prevents enzymes from breaking down neurotransmitters, as a result muscles in the respiratory and nervous system becomes paralyzed.

29. The point of contact at which impulses are passed from one cell to another are known as THE SYNAPTIC CLEFT OR SYNAPSE. • Neurons that transmit impulses to other neurons DO NOT actually touch one another.  The Small Gap or Space between the axon of one neuron and the dendrites of the next neuron is called the Synapse.  • One importance of the presence of Synapses is that they ensures one-way transmission of impulses in a living person.  • The Axon Terminals at a Synapse contain tiny vesicles, or sacs. These are known as NEUROTRANSMITTERS.

31. NEUROTRANSMITTER is a chemical substance that is used by one neuron to signal another.  The impulse is changed from an Electrical Impulse to a Chemical Impulse (Electrochemical Impulses).

32. Other facts… • After the neurotransmitter relays it message it is rapidly REMOVED or DESTROYED, thus halting its effect. • Neurotransmitters may be broken down by ENZYMES, taken up again by the axon terminal and recycled, or they may simply diffuse away. • NERVE GAS prevents enzymes from breaking down neurotransmitters, as a result muscles in the respiratory and nervous system becomes paralyzed.

33. Chemical Influences • How might stimulants work? (Amphetamines, caffeine, nicotine) • Increase synaptic transmission  increased energy/mood, decreased appetite. • Increased irritability and anxiety • How might depressants work? (Alcohol, anti-anxiety drugs, heroin) • Inhibition of impulses (blocking receptors of NT • Can result in depression Animations