PET 3322 Exam 2 study guide Chapter 12 Introduction to the nervous system Hypothalamus is a group of neurons that secretes hormones and controls the main hormonal gland system Sensory afferent then goes to the central nervous system then to peripheral nervous o So first it you sense what happens burning your hand this is sensed then travels along the afferent pathway to the central nervous system and then to through the efferent pathway to the effector organ Largest part of central nervous system are the brain and spinal cord Efferent organ will produce an effect The somatic Nervous system part will be the ONLY part of this diagram to be used for exam 2 The blue box is part of the peripheral nervous system o The blue box represents the sensory portion of the example the red box is the effector portion Overall theme Sensory Afferent Motor Efferent Neuron is the cell of the nervous system o Prolongations on the cell body are called the dendrites o These cells have specific functions very excitable Stimulate other cells in the soma these cells will produce a chemical substance Will produce an action potential which will travel along the axon and will cause the excitation of the neurotransmitter and will cause a contraction The only place in the neuron with receptors are dendrites and soma The axon terminal is the only place with neurotransmitters they travel here from the soma to eventually be released in the axon terminal Neurotransmitters are produced in the soma Not gonna ask about schwann cells Myelinated the only place in the neuron with myelin is the axon o conducts electrical impulses faster o Sometimes a signal needs to be sent faster than the other o Motor myelinated The larger the axon diameter the faster the impulse will travel Distribution of Gray and White matter o The more mass you have in a space a darker color o The Cortex is darker because it contains the soma o The white matter is white because it contains the axon Cortex o Action Potential is also known as the electrical signal Types of Ion Channels o Ligand gated channels the most important one is the sodium channel Don t worry about the word Ligand just remember gated channel Needs a neurotransmitter released from the axon terminal to open the o Voltage gated channels the most important is the potassium channel More positive charges on the outside and more negative charges on the inside sodium is attracted by the negativity in the inside as well as the high low concentration gradient The electrical charge inside the cell will start changing when sodium The positivity produced by sodium diffusion will open the potassium gate enters gate ACH is the most common neurotransmitter in the body and will be the main one discussed for exam purposes Resting Membrane Potential o When the cell is at rest it will measure around 70 Mv But this will vary o In normal conditions the proteins are trapped which causes more negativity inside the cell Leakage Channels are not important It is important to understand Action Potential o Ach neurotransmitter is released to open the sodium channel o Example of the action potential is the sodium potassium pumps o Depolarization lost the negative charge Sodium is positive When the ach binds to the receptor the sodium is released into the cell Inside of the cell is negative The cell becomes more positive as the sodium comes in o Repolarization electrical charge is returning The potassium gates now open to release the potassium outside of the cell o Around 55 we activate sodium potassium pump to create homeostasis pumps 3 sodium out but 2 potassium in which produces more negativity on the inside o Hyperpolarizing more negative than the resting value Propagation of an action potential o Propagation moving traveling of the action potential from the soma to the axon terminal o Action potential in the neuron is produced in the soma but it will not stay there it will propagate to the axon terminal and release the neurotransmitter o The main function of the neuron is to stimulate other cells which is why they have the long axon terminals Synapse o communication between two neurons o Communicate via the axon terminal of one neuron with the soma or the dendrites of another neuron axodendritic from axon to dendrite axosomatic from axon to cell body soma o Remember there are NO RECEPTORS in the axon terminal only neurotransmitters Chemical synapses o To release the neurotransmitters the action potential arriving will promote the production of calcium which will produce the release of the neurotransmitter Inside the vesicles is ACH produced in the soma they are waiting for the action potential which will release the calcium that will in turn release the ACH The ACH will travel and bind to the receptors in the sodium channel and sodium channel will open and sodium will diffuse and we will start depolarization ACH has to be deactivated after it binds to the sodium gate only stays there for a second o Acetylcholinesterase this is how the ACH is broken down or got rid of after it binds to the sodium gate EPSP will not be on the exam Review the IPSP o Taking potassium from inside of cell to outside of a cell causes more negativity or the diffusion of chloride into the cell Hyperpolarization o The cell will be inhibited because its moving away from the threshold Chapter 15 Sensory Motor and integrative system o Axon is the prolongation of one neuron o Each axon is covered with a endoneurium If a nerve is a part of the peripheral nerve then it will be called a nerve If a nerve is inside the Central nervous system it is not called a nerve but it is called a Tract Nociceptors pain receptors o They are found everywhere in the body except the brain If we feel chest pain if we feel pain the in the neck or in the arm it could be caused by iskemia lack of oxygen in the blood The back of the spinal cord is for sensory neurons o The somatic sensory pathways will start in the spinal cord and will be transmitted up to the somatosensory cortex First order neurons carry signals as far as the spinal cord or brainstem Second order neurons carry signals on to the thalamus Third order neurons travel from the thalamus to the cerebral cortex Sensory pathways o Once the action potential is released it can travel different ways The action potential is released o Posterior column pathways Spinocortical travels form the spinal cord to the cortex Corticalspino travels from the cortex to the spinal o Anterolateral pathways
View Full Document
Unlocking...