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Nervous and Endocrine Systems Maintaining a stable internal environment. Regulation in organisms • Organisms use a communication network that involves a nervous system and endocrine system • The Nervous System consists of nerves, brain and spinal cord. Helps you respond to changes in the environment. Works very FAST!!! Neurons • The nervous system is made up of many nerves also known as neurons • Neurons are nerve cells that make pathways for impulses (messages) to travel. • You have billions of neurons What can neurons do? • Neurons can conduct and receive impulses. • It is composed of: • Dendrites- attached to the cell body RECEIVE impulses • Cell Body- contains the nucleus • Axon- carries impulses AWAY from the cell body • Myelin- protection for the axon Types of Neurons • Sensory Neurons carry impulses to the spinal cord and brain (attached to receptors) • Interneurons are located in between the cell bodies of sensory and motor neuron (it is a bridge between the two). • Motor Neuron carry impulses toward muscles (effectors) Reflexes • The three neurons are important in a reflex arc. • Your nervous system responds due to changes in the environment. • These changes are called stimuli • Ex: Touching a hot stove. • Hot stove is the stimulus and the response is to move your hand Parts to a reflex • Receptors, also known as sense organs. They are sensitive to changes in the environment. (ex: skin) – When receptors are stimulated impulses (messages) are sent along the sensory neuron to the brain to form a response. • The message travels along the sensory neuron to the brain and across the interneuron. • A response is made. The message then travels along a motor neuron and ends up at the effector (muscle or gland) 2 1 1 3 4 Sequence of a Reflex • Stimulus (Change in environment) • Receptor (Sensory Organ) Ex: Skin • Message travels (sensory, inter, motorneurons) • Effector (Muscle or Gland) Neurotransmitters • Chemicals of the nervous system that are released from vesicles in the terminal branches. • Allow messages to cross the synapse to the next neuron. • The synapse is the gap between two neurons. • Without neurotransmitters messages do not get sent or may not be received. Synapse clip • Toxins and Poisons such as drugs and alcohol can affect the function of neurotransmitters • They can interrupt the impulses from crossing the synapse. • If the impulses do not cross the message is not sent Nervous System Central Nervous (CNS) Brain and spinal cord Peripheral Nervous System(PNS) Motor Nerves Somatic Nervous System (voluntary actions) Sensory Nerves Autonomic Nervous System (involuntary actions Sympathetic Nervous System Parasympathetic Nervous System Central Nervous System • Consists of brain and spinal cord • Brain Facts: – Protected by 3 layers of tissue called meninges. – The space between meninges is filled with cerebrospinal fluid. – Meninges act as shock absorbers – Highly convoluted increases surface area. (Wavy) Parts of the Brain • Cerebrum- divided into 2 halves and contains the four lobes. • The four lobes are called: – Frontal – Parietal – Occipital – Temporal The Lobes • Frontal Lobe– Complex thought and motor function. • Parietal Lobe– Contains sensory cortex The Lobes • Occipital Lobe– Processes visual information • Temporal Lobe– Auditory and memory Parts of the Brain Cont. • Cerebellum- “little brain” – Plays a role in coordinating movements and posture. – Compares intention with actual performance. • Medulla/Pons- lower portion of brainstem. – Controls involuntary body functions like: • Breathing • Heart rate • Swallowing Endocrine System Endocrine System • The Endocrine System- consists of hormones and glands that work together with the Nervous system to maintain HOMEOSTASIS. – Endocrine glands produces chemical messengers (hormones) that are released into the blood. http://www.youtube.com/watch?v=VBwCBdd0ru8 Endo vs Exo • The two types of glands that exist are endocrine and exocrine glands. • Endocrine- Release hormones into the bloodstream. Ex Insulin and Estrogen • Exocrine glands- Release substances into ducts (tubes). Ex: Tears and Sweat How do hormones work? • Hormones work very much like enzymes and antibodies • They have specific cells that they TARGET!! • Target cells have receptors that hormones bind to and cause a response. Protein vs Steroid Hormones • Protein Hormones (nonsteroid) work by binding to the receptor on the cell membrane. • Steroid Hormones work by passing through the membrane and binding to the receptor inside the cell. • (see ditto Hormone Action) Feedback Mechanisms • Feedback mechanisms are necessary to maintain homeostasis in the body. • An example of feedback is a thermostat. • A feedback mechanism occurs when the level of one substance influences the level of another substance or activity of another organ. • There are two types positive and negative feedback. Negative Feedback • Examples of negative feedback that occur include: Sweating, Changes in sugar levels, guard cells and stomata, and thermostat. • It works by reversing the affect due to a change in your environment. • Get hotSweatCool downTemp Rises – The cycle then repeats to maintain homeostasis •Guard cells will open and close based on environmental conditions •Allows important materials to enter and leave the leaf at appropriate times. •The goal is to maintain HOMEOSTASIS!! Glands of Endocrine System • Pituitary Gland- “Master Gland” – Front side and back side located in the brain. – Controls many functions of other glands. – 8 hormones are released from the pituitary gland. • Thyroid Gland– Located in neck region. – Releases two important hormones. • Parathyroid Gland– Located on thyroid gland. – Releases 1 hormone. • Adrenal Gland– Located above kidneys – Release two hormones. – Cause “adrenaline rushes” • Pancreas– Located near stomach and liver – Releases two hormones that control sugar levels. • Gonads– Male gonads Testes – Female gonads Ovaries – Regulate reproductive system. Diseases • Goiter- disease of the thyroid gland. – Occurs when there is not enough iodine in the diet. – Iodine is needed for the production of thyroxin. • Diabetes- Malfunction of the pancreas – Too much insulin is made or not enough. GOITER Nervous vs. Endocrine • Nervous system • Fast response Endocrine Slow Response • Short Term Long Term • Use Neurotransmitters Use Hormones