Bio 111 exam 3 notes

Bio 111 exam 3 notes - Bio 111 Lecture notes for Exam 3...

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Bio 111 Lecture notes for Exam 3 Nervous system Responding to Stimuli -Sensory receptors detect stimulus -Motor effectors respond to stimulus -Nervous system links sensation and response through neurons and neuralgia (supporting cells) Types of Neurons -Vertebrates have 3 types - Sensory neurons (afferent neurons) associated with sensory receptors and carry impulses to central nervous system (CNS) - Motor neurons (efferent neurons) carry impulse away from CNS to effectors (muscles, glands, etc.) - Interneurons (association neurons) make up the CNS providing a link between sensory and motor neurons Nervous System Organization Peripheral nervous system (PNS) -sensory & motor neurons - Somatic -stimulates voluntary responses (using skeletal muscles) - Autonomic -stimulates involuntary responses ( smooth & cardiac muscles) -Requires no conscious effort: digestion, respiration, salivation, blinking, sexual arousal Neuron Anatomy - Cell body -enlarge part containing nucleus - Dendrites -numerous short cytoplasmic extensions receiving stimuli
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- Axon -single, long extension that conducts impulses away from cell body Neuroglia -Neuroglia supports nervous system both structurally and functionally -They produce myelin sheaths (phospholipid layer) that surround the axons in layers like a jelly roll - Oligodenrocytes in the CNS - Schwann cells in the PNS -Aid in transmission of electrical current, supply nutrients, and carry away waste -In the PNS myelinated axons are bundled together to form nerves Resting Potential An electrical potential exists across every cell membrane -Difference in electrical charge; ions carry units of electrical charge -Negative on cytoplasmic side ( inside the cell) -Positive on extracellular fluid side (outside of the cell) -Nerve resting potential is ~70mV but can range from -40 to -90mV Nerve Potential -Inside more negative because of differential membrane permeability to ions via channels -Sodium-potassium pump- uses active transport to bring 2 K+ in and 3Na+ out -Ion leakage channel allows K+ to diffuse out -Somewhat permeably to K+ but not other ions Equilibrium Potential -Diffusion of K+ out of a cell balanced by K+ flowing in because the electric potential attracts ions back into the cell -Balance between active transport and bidirectional movement of K+ maintains equilibrium potential
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-Resulting in: - High Na+ outside cell (low inside) - High K+ inside cell (low outside) -Inside of cell also contains Cl- and proteins- which make it more negative Graded Potential -Changes in membrane permeability leads to potential changes -Open/closing ion channels changes permeability - Graded potentials are small short lived changes in membran potential due to activation of gated ion channels -Most channels are closed in normal resting neuron -Chemically-gated/ligand-gated -Use hormones or neurotransmitters -Provides opening (example: Acetylcholine; which then opens Na+
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Bio 111 exam 3 notes - Bio 111 Lecture notes for Exam 3...

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