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Axon Terminal Fine ending/swelling of the axon Close to next dendrite Inside contains neurotransmitters that are contained inside a synaptic vesicle Synaptic Cleft Space between dendrite and axon terminal No action potential (nerve impulse) can be carried out here so communication is done through chemical synapse Presynaptic membrane Post synaptic membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. axon terminal synaptic vesicles enclose neurotransmitters synaptic cleft During an action potential the impulse travel along the axon until it reaches the axon terminal Here gated Ca+ channels open up and Ca+ enters the axon terminal Synaptic vesicles merge with presynaptic membrane and bind with a specific protein receptors Depending on the type of neurotransmitter and receptor the response of the postsynaptic neuron Excitation Action potential occurs Inhibition Action potential does not occur Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. neurotransmitter presynaptic membrane postsynaptic membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. neurotransmitter receptor Na+ postsynaptic neuron Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. axon terminal Ca2+ 1. After an action potential arrives at an axon terminal, Ca2+ enters, and synaptic vesicles fuse with the presynaptic membrane. synaptic vesicles enclose neurotransmitters synaptic cleft Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. Neurotransmitters are released and bind to receptors on the postsynaptic membrane. axon terminal Ca2+ 1. After an action potential arrives at an axon terminal, Ca2+ enters, and synaptic vesicles fuse with the presynaptic membrane. synaptic vesicles enclose neurotransmitters synaptic cleft neurotransmitter presynaptic membrane postsynaptic membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. Neurotransmitters are released and bind to receptors on the postsynaptic membrane. axon terminal Ca2+ 1. After an action potential arrives at an axon terminal, Ca2+ enters, and synaptic vesicles fuse with the presynaptic membrane. synaptic vesicles enclose neurotransmitters neurotransmitter postsynaptic membrane neurotransmitter receptor Na+ postsynaptic neuron synaptic cleft presynaptic membrane 3. When an excitatory neurotransmitter binds to a receptor, Na+ diffuses into the postsynaptic neuron, and an action potential begins. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. Neurotransmitters are released and bind to receptors on the postsynaptic membrane. axon terminal cell body of postsynaptic neuron Ca2+ 1. After an action potential arrives at an axon terminal, Ca2+ enters, and synaptic vesicles fuse with the presynaptic membrane. synaptic vesicles enclose neurotransmitters neurotransmitter postsynaptic membrane neurotransmitter receptor Na+ postsynaptic neuron synaptic cleft presynaptic membrane 3. When an excitatory neurotransmitter binds to a receptor, Na+ diffuses into the postsynaptic neuron, and an action potential begins. https://www.youtube.com/watch?v=rWrnz- CiM7A When neurotransmitter released into synaptic cleft it initiates a response and then is removed Removal of neurotransmitters prevents continues stimulation (or inhibition) of nerve impulse 2 types of neurotransmitters Excitatory Excitatory neurotransmitters are not necessarily exciting – they are what stimulate the brain. Inhibitory Those that calm the brain and help create balance are called inhibitory. balance mood and are easily depleted when the excitatory neurotransmitters are overactive. Acetylcholine excitatory neurotransmitter triggers muscle contraction In the central nervous system, it is involved in wakefulness, attentiveness, anger, aggression, sexuality, and thirst Alzheimer’s disease is associated with a lack of acetylcholine in certain regions of the brain Dopamine involved in controlling movement and posture It also modulates mood The loss of dopamine in certain parts of the brain causes the muscle rigidity typical of Parkinson’s disease GABA (gamma-aminobutyric acid) is an inhibitory neurotransmitter GABA contributes to motor control, vision, and many other cortical function Regulates anxiety https://www.youtube.com/watch?v=vkpz7xFTWJ o Norepinephrine is important for attentiveness, emotions, sleeping, dreaming, and learning Norepinephrine is also released as a hormone into the blood, where it causes blood vessels to contract and heart rate to increase. Serotonin contributes to various functions, such as regulating body temperature, sleep, mood, appetite, and pain Endorphins produced during exercise,excitement, pain, love and they resemble the opiates in their abilities to produce a feeling of well-being. The name “endorphin” comes from endo- and -orphin; intended to mean "a morphine-like substance originating from within the body. Curare - poison made from frog skin and causes paralysis by blocking Ach receptors at the neuromuscular junction. Strychnine poisoning can be fatal to humans and animals and can occur by inhalation, swallowing or absorption through eyes or mouth Strychnine is a neurotoxin which acts as an antagonist of acetylcholine receptors. It primarily affects the motor nerves in the spinal cord which control muscle contraction. An impulse is triggered at one end of a nerve by the binding of neurotransmitters to the receptors. Read about Strychnine Poisoning The neurotransmitter seretonin is vital in regulating many of our basic functions. Serotonin is, among other things, the feel good neurotransmitter and helps to regulate body temp. Our brain cells are constantly trying to bring some amount of serotonin back into the cells and out of the synapse using serotonin reuptake transporters. Ecstasy essentially takes these upkeep transporters and reverses their roles. This causes a massive flood of serotonin from the brain cells into the synapse. The most common cause of Ecstasy-related death is overheating (hyperthermia). MDMA interferes with the body's ability to regulate its own body temperature and to see other warning signs allowing the body to overheat without discomfort especially when dancing for hours in hot clubs. ●Zoloft is part of a class of drugs called selective serotonin reuptake inhibitors, or ● SSRIs for short. SSRIs act on a specific chemical within the brain known as serotonin. This is one of several chemicals used to send messages from one nerve cell to another. Brain and Spinal Cord make up the CNS CNS controls many bodily functions Breathing Heart rate Body temperature Blood pressure Emotions Memory Creativity The Spinal Cord The spinal cord extends from the base of the brain through a large opening in the skull and into the vertebral canal. Meninges protective membrane that surrounds spinal cord and brain Cerberospinal fluid found between meninges and brain or spinal cord Provides cushioning The spinal nerves project from the cord between the vertebrae. Fluid-filled intervertebral disks cushion and separate the vertebrae. A cross section of the spinal cord shows a central canal, gray matter, and white matter. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. spinal cord spinal nerve vertebra intervertebral disk a. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. dorsal white matter dorsal root gray matter dorsal root ganglion central canal ventral root spinal nerve meninges b. ventral Provides communication between the brain and the peripheral nerves Sends sensory information to brain Realays motor impulses from brain to muscles Center for thousands of arc reflexes Allow nerves and muscles to respond quickly to dangerous stimuli https://vimeo.com/93183048 https://www.youtube.com/watch?v=SgzRAAY 0wbA https://www.youtube.com/watch?v=rJ02HW _HDaE