FACT OF THE DAY: * Messages travel along the nerves as electrical impulses. They travel at speeds up to 248 miles per hour!

REGULATION Nervous System The nervous system maintains homeostasis by controlling and regulating all other parts of the body. http://faculty.washington.edu/chudler/stm0.html (short-term memory)

Functions of the Nervous System Sensory-uses receptors to gather information from all over the body 2. Interpretation-the brain then processes the information into possible responses 3. Response-sends messages back through the system of nerve cells to Control and coordinate functions throughout the body Respond to internal and external stimuli

Evolutionary Trends of the Nervous System Simple Complex Animal Taxon Aquatic Invertebrates Flatworms & Roundworms Segmented Worms & Arthropods Vertebrates Type of Nervous Tissue A simple system with interconnected neurons called nerve nets; contain specialized cells for touch and chemical detection Ganglia (a group of nerve cells) and nerve cords run along the body; can detect chemicals, touch, and some have eyespots Cephalization occurs which is the concentration of nerve cells in a head region to form a brain; intense senses in arthropods A well developed brain evolved from the spinal cord; the size and complexity increases from fish to mammals Picture of system   Examples sponges, jellyfish, hydra planaria, flukes, tapeworm, hookworm earthworm, ants, grasshopper, bees mammals, birds, reptiles, fish, amphibians

Structures of the Nervous System Neurons: the functional cell that transmits signals through the body; an individual nerve cell Parts of a Neuron cell body- the largest part of the neuron; contains the nucleus and organelles 2. dendrites- short, branching extensions spreading out from the cell body; receive and carry impulses to the cell body 3. axon- long, fibrous part of neuron; conducts nerve impulses away from cell body

TYPICAL MOTOR NEURON dendrite muscle tissue Axon cell body synapse Impulse in a Neuron muscle tissue TYPICAL MOTOR NEURON Axon dendrite synapse cell body cell body

Because neurons never touch, chemical signalers called neurotransmitters must travel through the space called synapse between two neurons. Neurotransmitters (pink spheres) The message is transferred when RECEPTORS receive neurotrans-mitters. Synapse (gap)

Neuron Nerve Impulse- an electrical signal is sent from the dendrite, along the axon, to the terminal. A chemical message, called a neurotransmitter is released from the axon terminals into the synapse, where it travels to the next cell.

Types of Neurons a. sensory neurons- carry impulses from sense organs to brain/spinal cord (CNS) b. motor neurons- carry impulses from brain/ spinal cord (CNS) to muscles/ organs c. interneurons- carry impulses between sensory and motor neurons (within CNS)

Reflexes Reflexes: They are involuntary They happen very quickly Take place without the brain receiving the message They protect you by triggering an involuntary response to stimuli (stepping on a tack)

Divisions of the Nervous System Central Nervous System (CNS) Peripheral Nervous System (PNS)

Central Nervous System (CNS) Brain- “control center”- receives and analyzes information; processes and sends back instructions

Parts of the Brain 1. Cerebrum Controls muscles Jobs that are voluntary It stores messages Studying/thought Language judgment

Lobes of the cerebrum Processes sensory impulses from the body Reasoning, logic, language, etc. Visual images Hearing, smell, memories

Logic/reasoning Speech

Language and Speech – strokes, tumors, injuries Wernicke’s Area: The posterior part of temporal lobe Damage to area means you can speak but unable to comprehend speech Responsible for hearing speech Broca’s Area: Primary motor cortex in the frontal lobe that controls muscles Damage to area means you can understand language but are unable to speak it Responsible for speech generation Ex – stroke patients http://www.hulu.com/#!watch/378989 (NY Med brocas area) 28:28- d section) http://www.hulu.com/watch/339577/greys-anatomy-one-step-too-far Go to 21 min mark

Parts of the Brain 2. Cerebellum: controls involuntary functions of muscles & maintains balance and posture ( hand-eye coordination)

Parts of the Brain 3. Hypothalamus: Controls homeostasis in body * body temperature, water balance, hunger, thirst, biological clock, flight or fight response)

Parts of the Brain Medulla Oblongata & Pons : 4. Brain stem Controls involuntary functions Medulla Oblongata & Pons : *breathing, heart rate, blood pressure, swallowing, vomiting, digestion

Peripheral Nervous System (PNS) Consists of nerves –ropelike bundles of neurons outside of the CNS Gathers information, delivers it to and from CNS C. PNS divided into two systems: Somatic (voluntary) Autonomic (involuntary)

Autonomic Nervous System Autonomic Nervous System - The involuntary branch of the nervous system Divided into two divisions: Sympathetic division Parasympathetic division

Autonomic Functioning Sympathetic – “Fight-or-flight” Response to unusual stimulus Takes over to increase activities Increases heart rate, blood pressure, blood glucose levels, dilates the bronchioles of the lungs, and dilates the pupils Remember as the “E” division = Exercise, excitement, emergency, and embarrassment

Autonomic Functioning Sympathetic – “Fight-or-flight” The effects of sympathetic nervous system activation continue for several minutes until its hormones are destroyed by the liver. Helps explain why we need time to “calm down” after an extremely stressful situation.

Autonomic Functioning Parasympathetic – Housekeeping activites “Resting and digesting” system Chiefly concerned with promoting normal digestion and elimination of feces and urine and with conserving body energy Heart rate, blood pressure, and respiratory rates are at low normal levels; pupils are constricted; skin is warm; digestive tract is actively digesting food Remember as the “D” division - Digestion, defecation, and diuresis (urination)

Levels of Organization Nerves Brain, spinal cord Nervous Neurons

Interaction with other systems for Regulation Bones of the skeletal system protect the spinal cord and brain. The brain controls heart rate, blood pressure, and breathing via the circulatory and respiratory systems. Glands in the brain control the release of hormones of the endocrine and reproductive systems. The brain controls muscles both in digestion and movement.

Diseases / Disorders of the Nervous System Polio- a virus that attacks the spinal cord; eventually causes paralysis Multiple Sclerosis (MS)- affects neurons; slows nerve impulses, causing muscle weakness, possibly paralysis. Alzheimer’s- brain tissue deteriorates; severe memory loss Stroke- a blockage in a blood vessel in the brain, causing brain damage Concussion- a bruise to the brain when the brain hits the inside of the skull

Fun Facts A human body contains more nerve cells than there are stars in the Milky Way Neurons are the largest cell in the body and do NOT undergo mitosis Nerve impulses move at 100 meters per second or more Longest axon of a neuron is 15 ft! (in the giraffe)

Reticular Formation – neurons in the core of the brainstem (midbrain -arousal, pons & medulla-sleep) Sleep & wakefulness produces patterns of electrical activity in the brain Recorded as an ElectoEncephaloGram (EEG) Most dreaming during REM (rapid eye movement sleep)

Did You Know… Bottlenose Dolphins swim while sleeping, rising to the surface to breathe air regularly! Their forebrain is divided into two halves. Since they sleep with one eye open and one closed they are able to sleep with one brain hemisphere at a time.

Lobotomy… Phineas Gage, 1848 – was a loving, caring father until the accident and then became detached, impatient & erratic Later in the 20th century, surgical procedures were done to remove portions of the frontal lobe in attempt to cure severe behavioral and psychiatric behaviors