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Neural and Hormonal Systems. Neurons: The Building Blocks of the Nervous System. Nervous system – the body’s electrochemical system Brain, spinal cord and nerves are formed by NEURONS Neurons have 3 tasks: 1. receive information 2. carry information 3. pass information.
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Neurons: The Building Blocks of the Nervous System • Nervous system – the body’s electrochemical system • Brain, spinal cord and nerves are formed by NEURONS • Neurons have 3 tasks: • 1. receive information • 2. carry information • 3. pass information
Structure of a Neuron • Dendrite – branchy extensions that receive messages from other cells • Soma – cell body; contains nucleus and keeps cell healthy • Axon – passes messages away from cell body to other neurons, muscles, glands • Myelin Sheath – covers axon of neurons • Axon Terminals – points of departure; onto next neurons dendrites
Neural Communication • The Neural Impulse – What are the steps taken when a neuron “fires”? • 1. action potential – brief, electrical charge that travels down the axon • 2. refractory period – “recharging” phase of a neuron; cannot fire just yet • 3. resting potential – neuron is capable and ready to generate another action potential
How is neural impulse like flushing a toilet? • What is the action potential? • What is the refractory period? • What is the resting period? JUST LIKE A NEURON!!!!
Communication Between Neurons • Neurons communicate with each without actually touching one another! • Synapse – fluid-filled gap between axon terminal of one neuron and dendrite of another • Neurotransmitter – chemical messengers that travel across synapse from one neuron to the next • Reuptake – sending neuron reabsorbs excess neurotransmitter molecules
Other key terms: • Excitatory effect – neurotransmitter that likely generates an action potential • Inhibitory effect – neurotransmitter that likely does not generate an action potential • Sensory nerves – carry info to central nervous system • Motor nerves – carry info from central nervous system to muscles and glands
Key Neurotransmitters • Acetylcholine – enables muscle action, learning and memory; production decreases due to Alzheimer’s • Dopamine – influences movement, learning, attention and emotion; excess leads to schizophrenia; lack of cause Parkinson’s disease • Serotonin – affects mood, hunger, sleep and arousal; lack of causes depression • Norepinephrine – controls alertness and arousal; lack of affects mood
How Drugs Affect Neurotransmission • Agonists – molecule that is similar enough to bind to receptor and MIMIC its effects. • Antagonists – molecule that is similar enough to bind to receptor and INHIBIT its effect
Central Nervous System • Brain and spinal cord
Peripheral Nervous System • The CNS communicates with the body’s sensory receptors, muscles and glands via the peripheral nervous system (PNS). • Neurons travel in the PNS through nerves.
Somatic and Autonomic • PHS has two components: the somatic and autonomic nervous systems • Somatic – enables voluntary control of skeletal muscles • Autonomic – controls glands and muscles of internal organs; involuntary
Sympathetic and Parasympathetic • The autonomic system has two important, basic functions: • Sympathetic – arouses and expends energy • Parasympathetic – calmsand conserves energy
Endocrine System • Endocrine system – set of glands that produce hormones, chemical messengers that circulate in the blood stream • Hormone – chemical messengers • Pituitary gland – “master gland” in brain; controls the other glands • Thyroid gland – regulates energy levels • Adrenal glands – help to arouse body in times of stress