Nervous System Control and Coordination Intro to Nervous System Movie

I.Functions A.Send and receive information B.Monitor and respond to stimuli 1.Stimuli – internal or external change that causes the body to respond (ex: heat, light, touch) C.Sensory input – vision, hearing, balance, smell, taste, and touch D.Motor output – muscle contraction and movement E.Memory and integration of information F.Maintain homeostasis 1.Homeostasis – maintaining constant conditions in the body despite changes in the internal/external environments

II.The Neuron (nerve cell) A.Neurons are specialized cells that carry information in the form of an electrical signal called an impulse 3 Types of Neurons: 1.Sensory – carry impulses from the sense organs to the spinal cord and brain 2.Interneurons – Connect sensory and motor neurons and carry impulses between them 3.Motor – carry impulses from brain and spinal cord to muscles and glands

B.Anatomy of a Neuron 1.Cell Body a.Controls all activities of the cell b.Contains nucleus Cell Body

2.Dendrites a.Carry impulses from the environment or from other neurons to the cell body Dendrite

3.Axon a.Long fiber that carries impulses away from the cell body b.Ends in small swellings called axon terminals Axon Axon terminals

4.Myelin Sheath a.Insulates the axon b.Increases impulse speed

Impulse Movement is One-Directional Dendrites Cell BodyAxon Axon terminals

Nervous Tissue (Neurons)

C.The Synapse 1.Gap between the axon of one neuron and the dendrites of the next neuron. 2.Neurons do not touch! 3.When the impulse reaches the end of the axon, chemicals called neurotransmitters are released and carry the signal to the next neuron. Vesicle Axon Axon terminal Synaptic cleft Neurotransmitter Receptor Dendrite of adjacent neuron Direction of Impulse

Synaptic Transmission

III.Organization of the Nervous System  Divided into two parts: A.Central N.S. - Control center of the body that relays messages, and processes and analyzes information 1.Brain 2.Spinal Cord B.Peripheral N.S. - made of all the nerves that receive information from the environment and relays to and from CNS and sensory, motor and gland cells 1.Somatic N.S. 2.Autonomic N.S.

IV.The Brain  The main control center of the human body

A. Cerebrum 1.Largest part of brain 2.Controls learning, intelligence, and judgment 3.Outer layer is cortex; many fold and wrinkles Why? 4.Left and right hemispheres are connected by corpus collosum Cerebrum

B.Cerebellum 1.Coordinates the actions of muscles & maintains balance Cerebellum

C. Brain Stem 1.Connects brain to spinal cord 2.Comprised of midbrain, pons, and medulla oblongata 3.Medulla oblongata controls involuntary activities like heartbeat, breathing, barfing, sneezing, etc. Medulla oblongata

D. Spinal Cord 1.Carries info between brain & body 2.Process simple responses called reflexes

V.Reflexes  Reflexes are an involuntary, automatic response to stimuli  Controlled by 5-part reflex arc: 1. Sensory receptors on finger reacts to stimulus (heat) 2. Impulse is carried to the spinal cord by a sensory neuron 3. In the spinal cord, the impulse is transferred by an interneuron to motor neuron 4. Motor neurons conducts the impulse to an effector (arm muscles) 5. Effector responds to the impulses by contracting (hand gets pulled away from the heat)

VI.Peripheral Nervous System  Receives information from the environment and relays to and from CNS and sensory, motor and gland cells

Two divisions: 1.Somatic NS (voluntary) responds to external stimuli. a.Made of nerves that go from the CNS to skeletal muscles b.Regulates activities that are under conscious control (e.g. picking your nose) c.Some reflex control 2.Autonomic (involuntary) NS respond to internal stimuli a.Controls heart rate, breathing, digestion, and glandular function

Autonomic Nervous System

VII. The Senses 5 General Sensory Receptors: pain, thermo-, mechano-, chemo- and photoreceptors. Where do you think these different types of receptors are found and what is their function? A.Vision B.Hearing and Balance C.Smell and Taste D.Temperature and pressure

VIII. Drugs and the Nervous System A.Stimulants 1. Accelerate HR, BP, and breathing rate 2. Increases the release of neurotransmitters; leads to release of energy and feeling of well-being 3. When effect wears off, brain’s supply is depleted leaving the user depressed and fatigued a. Caffeine – prevents binding of adenosine b. Cocaine – sudden release of dopamine c. Methamphetamines – same effect as cocaine

B.Depressants 1.Slow down HR, lower BP and breathing rate, relax muscles and relieves anxiety a.Alcohol – physical and mental impairment, depression, brain and liver damage b.Marijuana – more lung damage than cigarettes; memory loss, reduced levels of testosterone in males c.Sleeping Pills