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Regulation: Nervous System A World Without Pain Perry Goldberger, 15, can't distinguish between hot and cold and cannot feel pain Four-year-old Roberto Salazar does not feel pain because of a rare genetic disorder. NERVOUS SYSTEM NERVE REGULATON STIMULUS: Example – heat From a stove IMPULSE: Example – neurons Send a message to CNS to tell the hand To move RESPONSE: Example – removing Hand off the stove HUMAN NERVOUS SYSTEM Central Nervous System (CNS) – brain and spinal cord Peripheral Nervous System (PNS) – nerves outside the CNS Nerve Cells • Nerve cells = neurons • Receive impulses and send the messages to various parts of the body via Cellular Communication • Nerve cells make up: – Nerves – Brain – Spinal cord – Receptors ???? • You accidentally place your hand on a hot iron and quickly move it away. – What is the stimulus? – What is the impulse? – What is the response? • What is the difference between the CNS and PNS? • What is the function of a neuron? Neuron Structure • 1. Cyton- cell body • 2. Cell nucleus • 3. Dendrites – receive impulses Neuron Structure Cont… • 7. Axon – carries impulses away from the dendrites • 6. Myelin Sheath – fatty covering of the axon which speeds up impulses • 5. Schwann Cells (make myelin) Neuron Structure Cont… • 9. Terminal Branches • Synapse – gap where impulses travel from the axon of one neuron to the dendrites of another neuron. • Neurotransmitters – chemical messengers that cross the synapse Types of Neurons – Sensory: carry impulses to the CNS – Motor: carry impulses from the CNS to other parts of the body such as muscles – Mixed: contain both Receptors • Receive messages • Found on the cell membrane and are VERY SPECIFIC!!! CNS The Brain • Cerebrum – thinking, memory, voluntary actions, emotions • Cerebellum – coordination and balance • Medulla (brain stem) – involuntary actions like breathing and heartbeat Spinal Cord • Mass of nerve cells • Vertebrae – protect it • Function – – relays impulses to and from the brain – center for some reflex actions Autonomic Nervous System • Part of the peripheral nervous system • Controls involuntary behavior (automatic) • Examples: – Breathing – Heart rate – Blinking, dilation of pupil – Production of saliva – Increases and decreases the rate of these involuntary behaviors to help maintain homeostasis Reflexes- Reflex arc • Involuntary behavior • Reflex: – Receptor (nerve endings in the knee) receive a message – Sensory neuron sends to message to the spinal cord (CNS) – The interneuron connects the sensory neuron to the motor neurons – The motor neuron sends the message to the muscle in the leg (EFFECTOR) – Effector then reacts such as a knee jerk Somatic Nervous System • Part of the peripheral nervous system • voluntary behavior • Examples: movement of skeletal muscles Disorders of the Nervous System Cerebral Palsy • Birth disorder that affects motor function. Polio • a viral pathogen that weakens muscles and leads to paralysis Stroke • When a free-floating blood clot reaches the brain • Blood vessel ruptures in the head/neck Meningitis • Inflammation of the meninges (membrane surrounding the brain and spinal cord) • Can be viral (not severe) or bacterial (VERY severe) • Symptoms come quickly – Fever and chills, nausea and vomiting, sensitivity to light, severe headaches The meningococcal vaccination is recommended for: • Adolescents ages 11 - 12 and adolescents entering high school (about age 15) who have not already received the vaccination. • All college freshmen who have not been vaccinated and are living in dorms. • Those traveling to countries where diseases caused by meningococcus are very common