The Nervous System

4 Functions of the Nervous System Receiving Specialized receptors located throughout body, allow signals to be received and then sent to processing centre. 2. Processing Information transmitted from the nerves to a processing centre (ex. brain) Decode meaning of message transmitted

4 Functions of the Nervous System 3. Storing Short-term Long-term 4. Transmitting Transmit information received from a processing centre through nerves to other parts of the body.

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 brain The spinal cord The nerves The senses

The Central Nervous System The Peripheral Nervous System Brain Spinal cord The Peripheral Nervous System The Nerves

The Neuron The nervous system functions with the help of neurons. They are specialized nerve cells in the nervous system that receive and transmit messages. The human body has an average of 100 billion neurons!!!

The Neuron Parts of the neuron Dendrites – receive message Cell body - contain nucleus Axon – transmit message Axon terminals – send message

Role of Neurons To pick up stimuli, transform them into nerve impulses and transmit these impulses.

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

Nerve Impulse An electrical signal transmitted by a neuron

Characteristics of the Neuron Can be stimulated – reacts to stimulus by changing it into nerve impulse Conductive – transmits nerve impulse from one neuron to another until reaches its target Consumes a lot of Oxygen and Glucose. Lives only a few minutes without oxygen Live more than 100 yrs. Cannot reproduce or be replaced if destroyed

Transmission of nerve impulses A nerve impulse travels from neuron to neuron until it reaches its target. It travels from dendrites to axon terminals

Transmission of nerve impulse Dendrites receive messages/stimuli and transform them into nerve impulses Nerve impulses are then transmitted along axons to axon terminals

Transmission of nerve impulses Nerve impulses travel from one to another by Neurotransmitters (chemical substances) secreted by axon terminals The transition zone between 2 neurons is called a synapse.

Nerve Impulses Nerve impulses move quickly from neuron to neuron and can reach up to speeds of 430km/h. Making sure there is rapid transmission of information to many parts of body.

Nerve Axons of neurons combine to form nerves. They are covered by protective tissue and blood vessels A nerve is a structure that helps transmit info between CNS and rest of body

Peripheral Nervous System Connects different parts of body to the CNS. Made up of all the nerves that run throughout the body.

Peripheral Nervous System Sensory Receptors Specialized nerves Pick up stimuli and transform it into nerve impulses Found throughout body Ex: receive information that let muscle know how much muscle should stretch

Peripheral Nervous System Sensory Nerves Transmit information picked up by the sensory receptors. Transmission in the form of nerve impulses. Ex: Optic nerve – sensory nerve Transmits information captured by the eye to the brain. Also pick up internal stimuli from vital organs.

Peripheral Nervous System Motor Nerves Transmit impulses from the CNS to the muscles in order to produce voluntary and involuntary movements. Ex: Cardiac and Respiratory rates increase when blood oxygen levels are too low… Ex: When we want to lift an arm, brain sends signal telling muscles to contract.

Central Nervous System The Brain The Spinal Cord

The Brain

The Brain Meninges – A membrane that covers the brain and spinal cord Protected by : The skull/cranium Meninges – A membrane that covers the brain and spinal cord

The Brain Communication 12 pairs of nerves known as cranial nerves

Parts of the Brain Cerebrum Cerebellum Brain Stem

Cerebrum Command Centre for: All voluntary movements Interpretation of senses Intelligence Centre of emotions

Cerebrum Divided into 4 lobes

Cerebrum Frontal: emotion, reasoning, planning, movement, speech Parietal: touch, pain, taste, pressure, temperature Temporal: hearing, memory, meaning, language Occipital: vision

Divided into 2 Hemispheres Right Hemisphere Controls left side of body Left Hemisphere Controls right side of body

Parts of the Cerebrum White matter Outer layer: Grey matter Cerebral Cortex – directs higher brain function like planning or reasoning Inner layer: White matter

5 Functions of Cerebrum Controls voluntary movements Interprets messages picked up by the senses Controls Intelligence Controls Emotion Regulates physiological functions (hunger, alertness, body temperature)

The Cerebellum 2 Functions: Centre of balance and movement coordination Helps us to do many activities all at once

Cerebellum Helps us to: Run, speak, play piano, dance without falling down

Cerebellum Motion sickness and vertigo are disorders that occur when the cerebellum responds to contradictory signals

The Brain Stem Attached to spinal cord, cerebrum and cerebellum Also known as the MEDULLA

The Brain Stem 2 Functions: Controls internal stimuli Controls involuntary movement

The Brain Stem Example: Eating, swallowing,sneezing It will signal organs and glands to start working to help with proper digestion of food

The Spinal Cord 2 Functions: Carries information from different parts of the body to the brain The reflex centre

The Spinal Cord What is a reflex? A rapid involuntary reaction to a stimulus Allows for quick reaction time in an emergency Ex: Blinking, pulling arm away from sharp object

The Spinal Cord Reflex Arc The series of nerve impulses that occur during a reflex is known as a: Reflex Arc

The Reflex Arc Nerve Impulse travels much shorter distance Takes short cut and bypasses brain Occurs rapidly Automatically redirected to muscles

Staying Sharp! Physical activity Challenging your brain (mental activities) Interacting with people (social activities) Positive thinking (reduce stress factors) Healthy eating habits Getting enough sleep! Don't do drugs...

The End

Disorders

Stroke Symptoms: Deterioration in vision (double vision) Slurred speech Sudden weakness or loss of sensation in one limb or arm/leg (usually same side) Lack of coordination Severe symptoms: loss of consciousness Partial or complete paralysis

Stroke Causes: Blood supply to the brain is disrupted Nerve tissue affected by lack of oxygen loses ability to function and dies Could be due to : atherosclerosis, blood clot, cerebral hemorrhage, high blood pressure

Stroke Treatments: Depend on location and type of stroke Surgery (remove blood leak from hemorrhage) Medications Hospitalization, rehabilitation (physiotherapy)

Alzheimer’s Disease Symptoms: Gradual loss of memory Inability to learn new information Tendency to repeat oneself, misplace objects Increasing irritability, anxiety, depression Confusion

Alzheimer’s Disease Causes: Degeneration of brain Specific causes unknown Increased chance with age Course of disease can run from a few to 15 yrs or more…

Alzheimer’s Disease Treatments: 1. Some medications can treat behavior 2. Continue daily routine and activities 3. Home or hospital care to assist with living 4. Patience on the part of caregiver

Parkinson’s Disease Symptoms: Shaking at rest Reduction of facial expression Slowness of movements Shuffling walk Stiffness or rigidity of limbs Difficulty in speech, writing, swallowing and chewing Progresses slowly

Parkinson’s Disease Causes: Chemical necessary to transport signals from one nerve cell to the other is lost Specific cause is unknown

Parkinson’s Disease Treatments: Exercise and therapy Medications can help by restoring chemical needed for transfer of electrical impulses Surgery

Multiple Sclerosis (MS) Symptoms: numbness, weakness or paralysis in limbs Impaired vision Tremors, lack of coordination Symptoms can diminish or disappear (remission), but can recur (relapse)

Multiple Sclerosis (MS) Causes: usually between ages of 20-40 Disease of CNS Inflammation in area of nervous system resulting in destruction of outer coating of nerve cell, leaving areas of scarring (sclerosis) Specific cause unknown

Multiple Sclerosis (MS) Treatments: Medications can help control symptoms, reduce inflammation, provide temporary relief Physical therapy No cure

Meningitis Symptoms: Fever, sever headache, vomiting Confusion or drowsiness Stiff neck Sever cases: coma or seizures

Meningitis Causes: Bacterial infection and inflammation of the meninges and cerebrospinal fluid Caused by infections in other parts of body (respiratory, heart, bones, ear, sinus, nose, tooth) 3. Usually occurs in children but can strike at any age

Meningitis Treatments: Antibiotics depending on the type of bacteria Drainage of accumulated fluids may be necessary