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Brain and Nervous System (NS)

Brain and Nervous System (NS). Nervous System. Made up of neurons - 2 main types 1) Central NS 2) Peripheral NS. Central Nervous System. Role: coordinates incoming info and initiates outgoing messages/behaviours. Consists of brain and spinal cord. Brain = controls the decisions

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Brain and Nervous System (NS)

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  1. Brain and Nervous System (NS)

  2. Nervous System Made up of neurons - 2 main types • 1) Central NS • 2) Peripheral NS

  3. Central Nervous System • Role: coordinates incoming info and initiates outgoing messages/behaviours. • Consists of brain and spinal cord.

  4. Brain = controls the decisions • Spinal cord = communication between the brain and PNS. (sensory info inwards and motor info outwards) - coordinates reflexes.

  5. Note – • Spinal cord does not carry signals between the CNS and PNS – this is wrong as the spinal cord is part of the CNS. • Must be Brain to PNS

  6. Neurons • Building blocks of the nervous system that carry messages as an electrical impulse. • E.g. = what you touch must travel from your hand to your brain to be understood and then from your brain to your hand for a response to occur

  7. Watch • http://www.youtube.com/watch?v=CMnDiepv5Os • http://www.youtube.com/watch?v=vyNkAuX29OU

  8. 3 kinds of neurons • 1) Sensory Neurons “AFFERENT”: respond to sensory receptors then send signals to the CNS. Transmit info inwards. • 2) Motor Neurons “EFFERENT” : Transmit signals from the CNS to specific muscles. Transfer info outwards (Efferent = EXIT) • work together to allow the body to identify a stimuli and then respond to it

  9. 3) Interneuron: connects afferent and efferent neurons in the CNS(mostly at the spinal cord) • Most common!! • Found only in CNS • Responsible for the reflex arc

  10. The Reflex Arc • An automatic response in which sensory neurons (inwards) do not pass to the brain • Communicate in the spinal cord = reflex action • Acts as a survival mechanism

  11. Parts of a neuron

  12. Parts of a Neuronhttp://www.youtube.com/watch?v=cUGuWh2UeMk • Dendrites: thin extensions of a neuron that receive information from other neurons • Cell Body/soma: contains the nucleus and decides what it will do with the information • Nucleus: contains genetic material (brains of the neuron) • Axon: carries the signals and covered by myelin sheath

  13. Axon Terminals buttons: end of the axon that and release neurotransmitters • Synapse: the junction that permits the transfer of electrochemical messages form cell to cell. Connection point which has the synaptic cleft, neurotransmitters and receptor sites • Synaptic Cleft: small gap between 2 neurons which neurotransmitters cross

  14. Neurotransmitters: chemicals that are released into the synaptic cleft, where they bind to receptor sites on the other neuron receiving the signal. • Receptor Sites: sensitive to neuron transmitters which change the charge of the post neuron

  15. Communication between neurons = Action Potential • http://www.youtube.com/watch?v=XGINQ7xhPkM

  16. Communication between neurons = Action Potential • Action Potential = happens during the firing of a neuron. Pre neuron is + and Post neuron is - . Neurotransmitters cross and turn the post neuron +. • Information is transmitted from one neuron to the next via NEUROTRANSMITTERS • Happens at the synapse. Terminal buttons  neurotransmitters  cross synaptic gap  receptor sites  next neuron  continue the process

  17. 1) Pre neuron – signal travels down axon 2) Axon Terminals (at the end of the axon) hold neurotransmitters 3) Neurotransmitters are released into the synaptic gap 4) They bind with receptor sites of the post neuron 5) All this happens at the synapse

  18. The Peripheral Nervous System • All nerves outside thebrain and spinal cord. • Links the CNS to all other parts of the body • - divided into • A) somatic • B) autonomic

  19. Somatic Nervous System • Controls voluntary skeletal muscle movements. • Has a sensory (sends signal via sensory neurons ) and motor function (movement via motor neurons). • EYES • Cutting yourfinger • Bee sting

  20. Anything on the outside of the body

  21. Gathers information from the sensory receptors in the body and transmits this information to the CNS. • Effect movements by carrying motor messages from the CNS to the muscles and glands. The somatic nervous system is responsible for voluntary skeletal muscle movement. • Carries sensory information to the brain and movement information to the body

  22. Autonomic Nervous System (PNS) • Modifies automatic(visceral / involuntary) muscles. • Digestion, heart rate, respiration, kidneys • Walking down a dark ally • Divided into 2 which control opposite reactions • 1) Sympathetic NS • 2) Parasympathetic NS

  23. Divided into the

  24. Parasympathetic dominates in day to day functioning. • Sympathetic dominates when under threat. • They work in cooperation, • One always dominates depending on the situation

  25. Flight or Fight Response • Adaptive purpose with the aim of survival • A state of high arousal that prepares the body to confront a situation or fight it, or, flee from the situation or flight it. • Arousal = generallevel of alertness. • Confront NOT deal

  26. All Physiological Arousals

  27. Physical Responses by the Sympathetic NS - 168 • Pupils dilate – allows to gather info immediately • Tears – inhibited • Heart Rate increases – increase blood flow to working/essential muscles • Bronchi relax/expand – increase O2 consumption • Digestion – inhibited • Salivary glands – decreases/dries up • Adrenaline increase – released to speed up HR • Sugar – increased to provide extra energy • Bladder – relaxes (temporary loss)

  28. Not more blood – we do not get more blood in the body.

  29. Role of the hormones • Adrenal glands release adrenaline • Allows for burst of energy • Takes some time for hormones to leave the blood stream due to increased arousal. • Enter fast and remove slow

  30. http://www.youtube.com/watch?v=tm-YGOFhhHE

  31. ____________ neurons carry information from organs and muscles to the central nervous system while ____________ neurons carry information to organs, muscles and glands from the central nervous system. • A. Sensory, motor • B. Motor, sensory • C. Peripheral, autonomic • D. Autonomic, peripheral

  32. The motor function of the somatic nervous system can be demonstrated by • A. experiencing the cold sensation of ice on your skin. • B. reflexively moving your hand away from a hot stove. • C. feeling muscle soreness after playing sport. • D. scratching your head.

  33. The sympathetic and parasympathetic nervous systems • A. are part of the reflex arc. • B. cannot both be active at the same time. • C. have opposite effects although they work together. • D. are inactive unless the fight/flight response is activated.

  34. Which of the following is true of the autonomic nervous system (ANS)? • A. The ANS is a vital part of the central nervous system (CNS). • B. It is impossible to consciously influence the functioning of the ANS. • C. The ANS ensures that the constantly changing energy requirements of the body are met. • D. The ANS relays messages between the CNS and the voluntary muscles that control our internal organs and glands.

  35. Questions • Attempting to become part of the Australian Olympic team, Renee is waiting to compete in her 400m trial. In reference to this scenario, explain how Renee’s somatic NS and Autonomic NS (sympathetic and parasympathetic) would work together to help her compete in this race? • 4 marks

  36. Her somatic NS controls voluntary actions via its connections with the skeletal muscles. Renee’s ears would relay the information about the starting gun, and her CNS would send instructions for Renee’s muscle groups in her arms and legs to move. • Her autonomic NS controls involuntary actions of internal organs. At the start of the race her sympathetic NS would be activated, resulting in an increase in Renees’ adrenaline, heart rate, respiration and sweating. After the race her parasympathetic NS would slow her heart rate and respiration rates to restore her body to a balanced state.

  37. http://www.biologymad.com/nervoussystem/nervoussystemintro.htm - website

  38. Brain / Cerebrum - ‘master organ’ – makes the decisions

  39. Facts • Weighs 1.4 kg • 100 billion neurons • Structure = what it looks like • Function = what it does

  40. Cerebral Cortex Location • Folded outer covering the cerebrum Structure • 2 – 4 mm thick • Largest area of the brain = 2/3 of all neurons • Wrinkled/ folded /convoluted – Increase surface area

  41. Function Covers all of the brain therefore, is responsible for all major cognitive functions • Motor coordination • Processing of sensory info • Higher mental processes – language, thinking, problem solving • Personality Comparison of human cerebral cortex to animals Our cortex is more proportionally significant to other areas of the brain (contains 75% of all neurons).

  42. The human brain structure which contains almost three quarters of the brain’s neurons and which is responsible for processing information as well as reasoning, planning and imagining is the • A. frontal lobe. • B. temporal lobe. • C. cerebral cortex. • D. cerebral hemisphere.

  43. The cerebral cortex • A. is wrinkled and this increases the surface area. • B. connects the two hemispheres of the brain. • C. is approximately 3.5 cm thick. • D. controls sleep functions

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