Nervous Systems

Structure of a Vertebrate Neuron

Diversity of Nervous Systems Simple, slow moving animals like hydra have neurons arranged in a network of bipolar neurons called a nerve net.

Basic Tasks of the Nervous System Sensory Input: Monitor both external and internal environments. Integration: Process the information and often integrate it with stored information. Motor output: If necessary, signal effector organs to make an appropriate response.

The Nervous System

A system that controls all of the activities of the body. Nervous System A system that controls all of the activities of the body. The nervous system is made of: The spinal cord The brain The nerves The senses

The nervous system also allows you to react to a stimulus. A stimulus is a change in the environment. Example: A hot stove Or… tripping over a rock

Your reactions are automatic. Automatic Automatic means that you do not have to think about your reactions. Example: If a bug flies by your eye, you will blink.

Brain An organ that controls your emotions, your thoughts, and every movement you make.

Central Nervous System The Central Nervous System is made of the brain and the spinal cord. The Central Nervous System controls everything in the body.

The Outer Nervous System is made of the nerves and the sense organs.

Messages carried throughout the body by nerves. Nerve Impulse Messages carried throughout the body by nerves.

The “funny bone” is on the elbow. You have a nerve along your whole arm. "Funny Bone" The “funny bone” is the only place on the arm where the nerve is not protected. The “funny bone” is on the elbow.

Anatomy of a Neuron Cell body: functional portion Dendrites: short extensions that receive signals Axon: long extension that transmits impulses away

Nerve Impulse - The Action Potential Threshold potential will trigger an action potential or nerve impulse The action potential is an all-or-none response

Myelinated Neurons Many vertebrate peripheral neurons have an insulating sheath around the axon called myelin which is formed by Schwann cells. Myelin sheathing allows these neurons to conduct nerve impulses faster than in non-myelinated neurons.

Saltatory Conduction in Myelinated Axons Myelin sheathing has bare patches of axon called nodes of Ranvier Action potentials jump from node to node Fig. 48.11

How does a signal move from one neuron to another? A synape divides 2 neurons The action potential will not move across the synape Neuro transmitters Released by the signal cell to the receiver cell Move by diffusion

Types of chemical synapse Acetylcholine: neuromuscular junctions, glands, brain and spinal cord Norepinepherine: affects brain regions concerned with emotions, dreaming

The Central Nervous System The Nervous System The Central Nervous System

The Central Nervous System * The Central Nervous System controls all of the body’s activities. * The Central Nervous System is made of two main organs. 1. The brain 2. The spinal cord

The Spinal Cord * The spinal cord sends messages to the brain. * The spinal cord is the part of the nervous system that connects the brain to the rest of the nervous system.

The Brain * The brain controls everything in the body. * The brain is made of more than 10 billion nerves! * The brain is divided into three parts and is protected by the skull.

The Three Parts of the Brain * The Brain has three main parts… 1. The Cerebrum 2. The Cerebellum 3. The Brain Stem

* The Cerebrum is the largest part of the brain. 1. The cerebrum controls your thinking. 2. The cerebrum controls your memory. 3. The cerebrum controls your speaking. 4. The cerebrum controls your movement and identifies the information gathered by your sense organs.

* The cerebellum is below and to the back of the cerebrum. 1. The cerebellum controls you balance. 2. The cerebellum controls your posture.

The Brain Stem * The Brain Stem connects the brain to the spinal cord. * The nerves in the brain stem control your heartbeat, breathing, and blood pressure.

The Vertebrae * The vertebrae are the many bones that protect the nerves in the spinal cord.

The Outer Nervous System

Outer Nervous System * The outer nervous system carries messages between the central nervous system and the rest of the body. * The Outer Nervous System’s job is to connect the Central Nervous System to the rest of the body.

* The outer nervous system is made of the nerves and the sense organs. Eye Tongue Ear Nerves Skin

* An automatic reaction that happens without thinking about it. Reflex * An automatic reaction that happens without thinking about it. * A reflex happens quickly in less than a second.

Automatic Nervous System * The outer nervous system controls the body’s activities that you don’t think about. * The outer nervous system controls activities in your small intestine, your breathing, and your heartbeat. controls

The Senses

Sense Organs Sense organs carry messages about the environment to the central nervous system.

The eyes, ears, nose, tongue, and skin are examples of sense organs. The sense organs gather information (light, sound, heat, and pressure) from the environment.

The environment is everything outside the body. The sense organs gather information from outside the body, then send the messages to the brain.

Vision is your ability to see. Vision involves the eye and the brain.

Parts of the Eye Detectors on the Fovea Rods light intensity and motion sensitive Cones color sensitive The blind spot for the eye is cause by the optic nerve.

Myopia (Near-Sightedness) People with near-sightedness cannot see clearly at distance.

Hyperopia (Farsightedness) People with far-sightedness cannot see clearly up close

When a sound is made, the air around the sound vibrates. Hearing Hearing starts when some of the sound waves go into the ear.

Parts of the Ear There are nine main parts of the ear. 1. Pinna 5. Anvil 2. Ear canal 6. Stirrup 3. Ear drum 7. Cochlea 4. Hammer 8. Eustachian tube 9. Auditory nerve

The pinna is the part of the ear that you can see. Parts of the Ear The pinna is the part of the ear that you can see. The ear canal is the tube between the outside of the ear and the ear drum. The ear drum is in the middle ear. It vibrates when sound waves hit it.

The stirrup passes the vibrations to the inner ear. Parts of the Ear The three smallest bones in the body, the hammer, the anvil, and the stirrup, are in the middle ear. The hammer gets the vibrations from the eardrum, then sends them to the anvil. The anvil passes the vibrations to the stirrup. The stirrup passes the vibrations to the inner ear.

The inner ear is made of the cochlea and liquid. Parts of the Ear The Eustachian tube controls the amount of pressure in the ear. The inner ear is made of the cochlea and liquid. The cochlea is in the inner ear. The cochlea looks like a shell. The auditory nerve carries the hearing information to the brain and the brain tells us what we heard.

The ear works with the brain to control your balance. The Ear and Balance The ear works with the brain to control your balance. All of your movements are controlled by balance and muscles. The liquid in your inner ear is responsible for your balance. The liquid in your ear moves when we move. The liquid movement sends information to the brain to tell it how we are moving.

The sense of touch is located in the skin. The nerves in the skin allow us to feel texture, pressure, heat, cold, and pain. Texture is how something feels.

The nose is able to smell 80 different kinds of smells. The nose controls your sense of smell. Smell The nose is able to smell 80 different kinds of smells.

Your sense of taste comes from the taste buds in the tongue. Taste buds are the parts on the tongue that allow us to taste. The four kinds of taste buds are sweet, sour, bitter, and salty.

Tastes and smells work together to make flavors. Flavors are the tastes of food and drinks.

Addictive Drug Use: Tobacco, Alcohol, & Illicit Drugs Dr. Robert B. Coambs Psy333 November, 2002

Pharmacology of Addictive Drugs All addictive drugs produce: Short-term pleasure to some degree Long-term negative consequences Tolerance & physical dependence A withdrawal syndrome Activation of dopamine neurons in the Nucleus Accumbens

Transmission Across the Synapse Source: Gray

How Drugs Become Addictive

Detail of Axon Terminal

Detail of the Synapse Itself Neurotransmitter molecules (e.g., Acetylcholine or Dopamine) Postsynaptic membrane

How binding sites work Binding site

Neurotransmitter re-uptake helps keep binding sites clear

Cocaine inhibits the re-uptake of dopamine producing effects such as increased heart rate and blood pressure

Nicotine fills & activates acetylcholine binding sites producing effects such as increased heart rate and blood pressure

What is Addiction? All definitions describe behaviour which produces positive sensations in the short term, but negative consequences in the long term A straightforward definition: Compulsive use Loss of control Use despite harm * Portnoy

How People Start Using Drugs Genetics Predisposing risk factors: Age 11-22 for onset Primitive character structures Especially Conduct Disorder Peer influence Parental influence Smoking and alcohol use Constricted temporal focus?

Nicotine Use is Associated With Other Drug Use Kozlowski, Coambs, et al., 1989

Some People Never Start Factors which reduce risk: Age 35+ Nuanced character structures No Peer influence No Parental drug use history No other smoking or alcohol abuse E.G., the SISAP

Basic Treatment For Addiction Treat the urges directly, if possible Establish why the person uses the drug What needs are being fulfilled by that drug? Find methods to fulfil those needs without the drug

How People Quit Drug Abuse Most quit on their own (cold turkey) Most use no medication Probably those people who can quit easily do so Clinicians tend to see the difficult cases Ambivalence is normal Most quit by age 40

Relapse Prevention Plan for relapse: Abstinence Violation Effect Relapse is common: it is not failure! Repeated relapse is associated with success in quitting Learn from it in next attempt Find a way to control urges