The Nervous System

Opening Question What are the two main parts of the Nervous System?

The Brain and the Spinal Cord These two parts make up what is called the Central Nervous System

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Did you know? your brain uses approximately 20% of the total oxygen pumping around your body! Average number of neurons in the brain = 100 billion unconsciousness will occur after 8-10 seconds after loss of blood supply to the brain if you could harness the power used by your brain, you could power a 10-watt light bulb

Nervous System The Nervous System can be divided into two sub-systems: The Central Nervous System The Peripheral Nervous System

The Nervous System 1. Two main divisions a. Central Nervous System (CNS) – consists of brain and spinal cord b. Peripheral Nervous System (PNS) – includes nerves extending from brain and spinal cord c. The CNS receives messages from the PNS, interprets them, and then sends out a response.

Neurons 2. Neurons - nerve cells that transmit messages to and from the spinal cord and brain a. Sensory Neurons – carry messages FROM body TO CNS ex. Playing games in computer lab. When light switches to green, a sensory neuron transmits a message from your eye to your brain

Neurons b. Motor Neurons – carry message TO body FROM CNS ex. Your brain sends a signal through a motor neuron to tell your finger to click the mouse. c. Interneurons – connect neurons

What does a real neuron look like?

Neuron

3. Structure and Functions of Neurons 1. Dendrites – receive information and transmit impulses toward cell body 2. Cell Body – large area which contains cell nucleus or power plant 3. Nucleus – command center of the neuron

Neuron

4. Axon – transmit impulses away from cell body and toward axon terminal 5. Axon Terminals – branched structures at the ends of neurons. 6. Myelin Sheath – insulating coat which covers the axon. This helps messages relay faster.

The Central Nervous System 1. The brain a. Helps you think, remember, reason, feel emotion, and coordinate muscle movement b. Divided into three main parts: cerebrum, cerebellum, brain stem

The Brain

The Central Nervous System 2. The Cerebrum a. largest, most complex part of brain b. right and left sides communicate with each other to coordinate movement. Right controls left side and vice versa. c. left hemisphere is responsible for words, numbers, and logic. Controls the right side of your body d. right hemisphere is responsible for color, imagination, and daydreaming. Controls the left side of your body.

Lobes of the Brain

The Central Nervous System 3. Four lobes (parts) of the cerebrum a. Frontal Lobe –use of language b. Parietal Lobe – sensory information, including feelings of heat, cold, pain, touch c. Occipital Lobe – Controls sense of sight d. Temporal – sense of hearing and smell

The Central Nervous System 4. The Cerebellum a. second largest part of brain b. maintains body’s posture and balance c. coordinates complex muscle movements like serving a volleyball or playing violin

The Central Nervous System 5. The Brain Stem a. 3 inch long stalk of nerve cells that connect the spinal cord to the rest of the brain

The Central Nervous System b. five parts 1. Medulla Oblongata – regulates heartbeat, breathing rate 2. Pons – controls muscles of eyes and face. 3. Midbrain – controls pupil size 4. Thalamus – relays incoming information from the eyes, ears, and pressure receptors in skin 5. Hypothalamus – regulates body temp, appetite, sleep

Brain Stem

The Peripheral System 1. Broken into two parts a. Autonomic Nervous System – controls involuntary functions such as digestion and heart rate - you cannot control this; it is automatic! (autonomic) b. Somatic Nervous System – voluntary responses that are under your control - feeling and itch on your skin and scratching it, or giving someone a high five

The Peripheral System 2. Autonomic Nervous System a. Broken down into two smaller networks b. First part is the Sympathetic nervous system Watch these clips… qQbIiOtYM mUDknB2YWM

Sympathetic Nervous System - kicks in when you are startled. Your heart rate increases. Also, blood vessels dilate to allow for greater blood flow. - “Fight or flight response” - Rush of adrenaline

The Peripheral System c. The second part: Parasympathetic nervous system – opposite of sympathetic nervous system - slows heartbeat, relaxes blood vessels, lowers blood pressure

Problems of the Nervous System 1. Headaches – caused by muscle tension, eyestrain, sinus infection, dehydration, or food allergies 2. Head injuries a. concussion – a temporary loss of consciousness

Problems of the Nervous System 3. Spinal Injuries a. swelling of spinal cord tissue can result in temporary loss of nerve function b. if spinal cord is severed, you may become paralyzed.

Problems of the Nervous System 4. Meningitis – inflammation of the spinal and cranial meninges caused by a virus or bacteria a. symptoms include fever, headache, light and sound sensitivity, and neck stiffness. b. can result in death