Neural and Hormonal Systems

1. Neural and Hormonal Systems

2. 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

3. 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

5. 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

6. 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!!!!

7. 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

9. 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

10. 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

11. 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

12. Structure of the Nervous System

13. Central Nervous System • Brain and spinal cord

14. 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.

15. 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

16. Sympathetic and Parasympathetic • The autonomic system has two important, basic functions: • Sympathetic – arouses and expends energy • Parasympathetic – calmsand conserves energy

17. 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