Neurons: Synaptic Transmission and Action Potential

1. Review – Neuron and Action Potential • 3 types of neurons • Schwann cells • Direction of flow of AP • Action Potential • Intensity of stimulus

2. Review – Neuron and Action Potential

3. Review – Neuron and Action Potential

6. Synaptic Transmission Neurons and Neurotransmitters

7. Neurotransmitters • As the message travels down the neuron towards the axon terminal, reaching the end, the cell is stimulated to release neurotransmitters • Neurotransmitters are chemicals that are released from the neurons, travel across the synapse, to other neurons • This elicits a response in the post-synaptic neuron • Through this process, messages can travel from the PNS to the CNS and back again

8. The Synapse • Small spaces between neurons are known as synapses or synaptic cleft • Neuromuscular junction – synapse of neuron with muscle cell • Small vesicles, often called synaptic vesicles, carry neurotransmitters from the pre-synaptic cell(s) to the post-synaptic cell(s) • Although the spaces may be small, synapses slow the rate of transmission, as chemicals must diffuse across the extracellular space • The reflex arc has fewer synapses than the rest of the nervous system

9. Synaptic Transmission - Summary http://www.nelson.com/ABbio20-30/student/protect/media/neuromuscular.html • Action Potential reaches axon terminal • Synaptic vesicles fuse with neuron membrane and release NT (exocytosis) • NT diffuse across the synapse and bind to receptors on post-synaptic neuron • NT cause depolarization (excitatory) or hyperpolarization (inhibitory) • Excitatory NT cause neuron to become MORE PERMEABLE to Na+ • Inhibitory NT cause neuron to become MORE PERMEABLE to K+ • Enzymes are released into the synapse to break down the NT for re-uptake into the pre-synaptic neuron

10. Neurotransmitters • Two main chemicals within the nervous system are acetylcholine and cholinesterase • Acetylcholine acts as an excitatory transmitter, which causes sodium ion channels to open, thus stimulating a neural response • Cholinesterase is the enzyme that destroys acetylcholine and causes the cell to return to a normal state http://www.youtube.com/watch?v=HXx9qlJetSU&feature=related

12. Other common Neurotransmitters • Dopamine • Control of body/muscle movement • Pleasure sensations (emotions) • Linked to Parkinson’s Disease • Serotonin • Mood, sleep, appetite • Linked to depression • Endorphins • Natural painkillers, emotions • Block pain NT • GABA – BRAIN • Regulates neuronal activity (prioritizes incoming info) • Induces relaxation, sleep, control of anxiety • INHIBITORY

13. Summation • Sometimes neurotransmitters can work together to reach threshold, when individually, they could not reach threshold • The action together to reach threshold is called summation • Summation is the accumulation of transmitters that work together, or perhaps can work against each other

14. Complimentary Transmitter Actions • Often the body will have complimentary actions caused by excitatory and inhibitors • For example, to throw a baseball, as the arm swings back, the triceps are excited and contract and the biceps are inhibited and relax

16. The Brain – Structure and Function

17. CNS - The Brain and Spinal Cord • Acts as a coordinating center for the nervous system • The brain is protected by a protective membrane known as the meninges • The outer membrane is the dura mater • The middle layer is the arachnoid • The inner layer is the pia mater • Cerebrospinal fluid circulates between the inner most layers and middle layers of the meninges and through the central canal of the spinal chord • The cerebrospinal fluid acts as both a shock absorber and a transport medium

18. The Spinal Cord • Carries sensory nerve messages from the receptors to the brain and back to the motor neurons • The spinal cord emerges through a hole in the skull called the foramen magnum and extends downward through the backbone • Contains both gray matter and white matter • The dorsal nerve tract brings information to the CNS and brain • The ventral nerve tract brings information from the CNS to the motor neurons

19. Structures of the Brain • Olfactory Lobes • Cerebrum • Cerebral Cortex • Corpus Callosum • Cerebellum • Thalamus and Hypothalamus • Pons • Medulla Oblongata http://www.nelson.com/ABbio20-30/teacher/protect/otr/Bio2030OTR/attachments/i_AnimationSimulation/sagittal_brain.html

20. Structures of the Brain

21. Phineas Gage Story • http://www.youtube.com/watch?v=kc213mMSsjY&feature=related (6 min) • http://www.youtube.com/watch?v=EBBdxnXhbz8&feature=PlayList&p=D3475FD9FD746D3B&playnext=1&playnext_from=PL&index=9

22. Olfactory Lobes • Centers that receive information about smell

23. Cerebrum • Two hemispheres that act as the coordinating center for sensory and motor activity • Speech, reasoning, memory and personality reside in the cerebrum

24. Cerebral Cortex • The surface of the cerebrum • Composed of gray matter • Has many folds (Fissures) to increase surface area • Information differs between the two hemispheres (right brain vs. left brain) • Right and Left hemispheres • RIGHT = visual, spatial awareness, intuitive • LEFT = language, logical, sequential thought, verbal skills • Can be divided into four lobes

25. Corpus Callosum • Allows communication between the left and right hemispheres Joe – Split Brain (5 min) http://www.youtube.com/watch?v=ZMLzP1VCANo&feature=PlayList&p=49F78B8CF7107C31&playnext=1&index=2

26. Four lobes of the Cerebral Cortex Frontal Lobe: • Motor control (walking, speech) • Conscious thought • Inhibition of behavior • Intelligence • Memory • personality Temporal Lobe: • Associated with vision, hearing and memory Parietal Lobe: • Touch and temperature awareness • linked to emotions and interpreting speech • Pain interpretation • Body position or orientation Occipital Lobe: • Sensory organs associated with sight

27. Occipital Lobe(1 min) • http://www.youtube.com/watch?v=Ddznuzf1TaM&feature=related Frontal and Temporal Lobe(6 min)http://www.youtube.com/watch?v=agPUoKB8eEk&NR=1 Drugs and the Brain (5 min) http://www.youtube.com/watch?v=hzP-4N2Qfs0&NR=1

28. Cerebellum • Located directly below the cerebrum • Largest section of hind brain • Controls limb movements/coordination, balance and muscle tone • Fine and voluntary motor skills

29. Thalamus and Hypothalamus • Thalamus interprets and coordinates sensory information • DIRECTS INCOMING INFO TO APPROPRIATE AREAS OF THE BRAIN • Hypothalamus coordinates activities between the nervous system and the endocrine system

30. Pons • Helps coordinate information passing between the two regions of the cerebellum and the cerebellum and medulla oblongata

31. Medulla Oblongata • The posterior region, also known as the hind brain • Contains the nerve tract that runs from the higher brain centers to the spinal cord • Helps regulate involuntary muscle actions • Pupil dilation

32. Brain Games

33. Occipital Lobe - Sight

34. Pons and Corpus Callosum – two half coordination

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36. The Boy with the Incredible Brain ( 1min) • http://www.youtube.com/watch?v=LU9pcPDvQWg

37. Kim Peek – The Real Rain Man (11 min) http://www.youtube.com/watch?v=k2T45r5G3kA&feature=related The Boy With the Incredible Brain- 2/5 (10 min) Daniel and Dane http://www.youtube.com/watch?v=WfoGsXYLxcs The Boy With the Incredible Brain (8 min) http://www.youtube.com/watch?v=8Vs6R5YZQ3c