The Nervous System Nervous Regulation – Allows you to respond to changes (STIMULI) in the environment (MAINTAIN HOMEOSTASIS)

Finally, you’re coming to your senses! 1.Pain Receptors 2.Thermoreceptors 3.Mechanoreceptors 4.Chemoreceptors 5. Photoreceptors A. Skin, skeletal muscles, inner ears; sensitive to touch, pressure, stretching of muscles, sound, and motion B.Located everywhere except the brain; respond to chemicals released by damaged cells C.Nose, taste buds; sensitive to chemicals in the outside environment D.Skin, body core, hypothalamus; detect variations in temperature E.Eyes; sensitive to light Sensory receptors: special neurons that react to a specific stimuli

How it works… 1.Stimulus – Any change in the environment 2.Receptors – detect change -5 Senses!!! 3.Impulse – Electric “message” sent through nerves 4.Effectors – Muscle or organ that responds to stimulus and message

Example – Hand on Hot Iron Stimulus – Receptor – Impulse – Effector - Hot iron Skin nerves  Thermoreceptors and pain receptors “Messages” through nerves “HOT!!!” Muscles to move arm and hand away

The Neuron (nerve cell) –receives, carries and sends electrochemical messages

Dendrites – Cell Body (Cyton) – Nucleus – Axon – Myelin Sheath – Terminal Branches –

The Synapse Space between neurons NEUROTRANSMITTERS: - chemical messages that “jump” synapse - neuron to neuron - SPECIFIC

Draw the sending of an impulse from one neuron to another Dendrite

Just another picture

Drugs that affect Neurotransmitters Anesthesia – Stimulants – Depressants – Block messages from being sent Examples: Surgery drugs, Novocain **Clip novacain baby Speed up messages Examples: Caffeine, cocaine, etc. Slow down messages Examples: Alcohol

Gallery of Neurons EnvironmentDendritesCell BodyAxon Terminal Branches

Classifying Neurons 1.Sensory neurons: From Receptors  To Spinal Cord 2.Interneurons: In Between Sensory and Motor neurons in SPINAL CORD 3.Motor neurons: From Spinal Cord  To Effectors (muscles and glands) According to the direction in which an impulse travels

Spinal Cord

Reflex Arc Stimulus  Receptor  Sensory Neuron  Inter Neuron  Also to Brain Spinal Cord Reflex Motor Neuron  Effector  To process

Divisions of the Nervous System Central Nervous System (CNS) Peripheral Nervous System (PNS) Brain and Spinal Cord Control center of the body Analyzes information Sensory neurons and Motor neurons Relays information from body to brain/ spinal cord and back to body

Brain and Spinal Cord Protected by: 1.Skull & Vertebrae 2.Meninges - membranes 3. CerebroSpinal Fluid

1 – Voluntary movements Thinking, reasoning, logical part 2 – Coordination and Balance –Muscle movement 3 – Controls involuntary actions –heart rate, breathing, swallowing, and digestion. 4 – Reflexes Connects body to brain

A mass of about 1.4 Kg (3 lbs) Cerebrum : the largest part of the brain FUNCTION Voluntary movements Thinking, reasoning, logical part

Outer layer consisting of gray matter Densely packed nerve cells Processes information from the sense organs and controls body movements A. White matter made up of bundles of axons with myelin sheaths B. Connects the cerebral cortex with the brain stem

More Cerebrum Right side controls left side of body Left side controls right side of body Are you Right or Left Brained? Creativity and artistic ability have been associated with the RIGHT hemisphere! Analytical and mathematical ability have been associated with the LEFT hemisphere!

At the back of the skull Coordination and Balance Cerebellum

Medulla – The Brain stem FUNCTION Controls innate involuntary actions –Blood pressure, heart rate, breathing, and swallowing Connects the brain and spinal cord Has two regions: –The pons –The medulla oblongata Funny Stuff

The Spinal Cord Spinal cord carries signals traveling between the brain and the body Kind of like a telephone line Why are reflexes important? Reaction without analyzing (brain)

Injury to spinal cord and brain? WhaWhat about Brain Injuries? Funny Nerve Clip What would have happened to his foot afterwards?

All the nerves and associated cells that are not part of the brain and spinal cord Divided into 2 parts

Body reactions, voluntary muscle Reflex Arc Regulates activities that are not voluntary (involuntary)

Let’s start with the Eye! Cow's Eye Dissection Optical Illusions The average human eye weighs about 1 ounce

Hear Me, Hear Ye, and Stay in Balance

Smell and Taste