Exam II Study Guide Functional Anatomy and Physiology Nervous System Nervous system o The nervous system controls many things like our behaviors movements and memory o Sensory input Integration Motor Output Sensory senses changes both internally and externally via sensory receptors Integrative allows us the ability to analyze the sensory info received store aspects and make decisions Motor function response via movement in reaction to stimuli by initiating action Afferent Muscle brain Efferent Brain Muscle Easy way to remember which comes first A comes before E so the sensory neurons to be stimulated first then it sends impulse to the brain which processes it then the brain says what to do by stimulating the motor neurons to give a reaction movement Synapse connection If reaction involves the brain it is NOT a reflex It is only a reflex when it is involuntary and the brain is not involved o Central and Peripheral two main divisions of the nervous system Central Nervous System CNS Central center of the body The brain midbrain and spinal cord are all in the center of the body Peripheral Nervous System PNS Consists of cranial and spinal nerves these nerves contain both sensory and motor fibers Connects CNS to muscles glands and all sensory receptors Made up of two systems somatic and autonomic nervous systems o Somatic Nervous System SNS Controls muscles connected to bone Soma body o Autonomic Nervous System ANS Controls internal organs Enteric Nervous System is part of the ANS Peripheral Nervous System cont Do not focus on ANS for Exam 2 o Sensory Motor Sensory Afferent Somatic Fibers carry impulses FROM the skin skeletal muscles and joints TO the brain Visceral Fibers carry impulses FROM visceral organs TO the brain Organ brain Motor Efferent Impulses sent FROM CNS TO effector organs Brain organ o Motor Division Somatic Nervous System SNS Controls muscles connected to bone Soma body Autonomic Nervous System ANS Controls internal organs Enteric Nervous System is part of the ANS Do not focus on ANS for Exam 2 o Neurons Nerve Cells Neuron main functional unit of the Nervous system Receive stimuli and produce an action potential electrical signal Electrical excitability Neurons are excited due to the voltage difference across their membrane Structure Cell body axon dendrites axon hillock axonal terminals o Cell body soma single nucleus and a prominent nucleolus Everything organelles in a cell is in the soma Receptive or input region Contains receptors Receives stimulus Connected to dendrites Produce neurotransmitters and electrical impulses o Axon contains plasma membrane ends in an axon terminal Transmits electrical impulses produced by the soma o Dendrites receive signals o Axon hillock part of the trigger zone site where action potentials o Axon terminals where neurotransmitters are stored and released are generated upon stimulation o Functions Neurotransmitter transmit signals across synapse from one neuron to another Function of Neurons Think of baseball o Player receptor o Ball neurotransmitter o Pitcher axon terminal Myelin Sheath A lipid that increases the speed of a nerve impulse conduction from the soma to the axon terminal Myelinated axons are surrounded by myelin White matter is mostly myelinated axons Unmyelinated Axons Have slower nerve connection Grey matter contains unmyelinated axons neuronal cell bodies dendrites and axon terminals o The soma is more dense therefore it makes up the grey matter Myelin and axon diameter are factors for how fast a neurotransmitter can travel The Action Potential o Action potential o The larger the diameter the faster the impulse o Fastest Myelinated wide axon Brain gray matter surrounding the white matter Spinal cord white matter surrounding the gray matter o Types of Ion Channels Ligand gated channel Open and close in response to a stimulus Ex teacher parking lots on campus o Na car o Key neurotransmitter ACh o Gate gate o Receptor little box that reads card o The gate can only be opened with a neurotransmitter connects with a receptor in an instant then the gate opens and the Na can enter o Na diffuses into the cell Voltage gated channels Opens in response to a direct change in the membrane potential A sequence of events that causes the membrane potential to decrease so much that it reverses becomes positive and then it restores itself by becoming more negative until it reaches its resting state The signal that will propagate travel transport can travel long distances A nerve impulse stimulation that triggers the release of neurotransmitters During action potential voltage gated Na and K channels are open A stronger stimulus will not cause a larger impulse Polar meaning it is negative Neurotransmitter opens the gate of the channel allowing Na to enter the cell Na goes into the cell causes depolarization Once a cell become positive the K channels open and K leaves the cell Na channels have already closed repolarization This causes the cell to become more negative since Potassium is always positive and it is leaving the cell Even though Na is travelling into the cell there is always more Na outside of the cell than inside o 1 Depolarization make less negative AKA more positive Stimulus causes potential to exceed threshold 55mV and or become more positive than the threshold Na diffusion Positive feedback process o 2 Repolarization make more negative back to normal polarity o 3 Hyperpolarization more negative than at rest so more negative than 70 mV Is a part of the stimulation due to an action potential Hyperpolarization occurs once the potential reaches 90mV causing the K channels to close and the membrane potential returns to resting potential If it does not reach the threshold 55 mV then the action potential doesn t occur o Resting Membrane Potential Negative ions ex Cl and sodium are inside the cell membrane Positive ions are outside the cell membrane Potential energy difference at rest is 70 mV This is caused by Extracellular fluid containing high amount of Cl and Na Cytosol containing a high amount of K organic phosphate and amino acids Membrane permeability The membrane is 50 100 times more permeable for K Na K pump removes Na as soon as it leaks in K flows out of the cell at a higher rate than the flow of Na into the cell o Ionic Events Electrical properties result from ionic concentration differences across plasma membrane and permeability of membrane Axons of the Central Nervous System o Tracts bundle of axons in the CNS
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