the nervous system anatomy & physiology ode to the brain
TRANSCRIPT
The Nervous System
Anatomy & Physiology
Ode To The Brain
http://www.wimp.com/brainautotuned/
The Basics:The Basics:The nervous system is your body's decision and
communication center.• The central
nervous system (CNS) is made of the brain and the spinal cord
• The peripheral nervous system (PNS) is made of nerves.
Neurons• A neuron is a nerve cell that is the basic building block of the
nervous system and are specialized to transmit information throughout the body.
• Job: communicating information in both chemical and electrical forms.
• 3 main types:
• 1. Sensory neurons (afferent) carry information from the sensory receptor cells throughout the body to the brain. 2. Motor neurons (efferent) transmit information from the
brain to the muscles of the body. 3. Interneurons are responsible for communicating information between different neurons in the body.
We’ll get back to these later…..
Do Now!
1. What are the two main parts of the nervous system?
2. What “organs” are these two parts made up of?
3. What is a neuron?
4. What are the 3 different kinds of neurons?
• axon - the long extension of a neuron that carries nerve impulses away from the body of the cell to other neurons.
• axon terminals - the hair-like ends of the axon • cell body - the cell body of the neuron; it contains the nucleus (also called the soma) • dendrites - the branching structure of a neuron that receives messages (attached to
the cell body) • myelin sheath - the fatty substance that surrounds and protects some nerve fibers
node of Ranvier - one of the many gaps in the myelin sheath - this is where the action potential occurs during saltatory conduction along the axon
• nucleus - the organelle in the cell body of the neuron that contains the genetic material of the cell
• Schwann's cells - cells that produce myelin - they are located within the myelin sheath.
Use the definitions below to correctly label this neuron
Neurons
Neuron Parts:• Soma: body of the cell (main space; contains nucleus/DNA)• Dendrites: receive messages from neurons• Axon: sends messages to other neurons
Anatomy of a nervehttp://www.youtube.com/watch?v=XgIaAs_ONG4&feature=related
Two parts of Nervous system & Neuron video clip
• The Nervous System:
• http://www.youtube.com/watch?v=xx--f9Y8wjg
The Teenage Brain on NOVA: http://www.pbs.org/wgbh/pages/frontline/video/flv/generic.html?s=frol02p392&continuous=1
How messages are sent and received
• Neurons send messages electrochemically. This means that chemicals cause an electrical signal.
• Chemicals in the body are "electrically-charged" -- when they have an electrical charge, they are called ions.
Watch Bill Nye’s Greatest Science Discoveries on Neutrotransmitters.
How messages are sent and received continued
• Resting Membrane Potential : At rest, there is an excess of negative ions inside the neuron compared to the outside.
•
How messages are sent and received continued
• Action Potential• When a message is incoming, the membrane opens at that point, and
positively charged ions flow in.• This process is repeated along the length of the membrane, creating the
neural impulse that travels down the axon, causing the neuron to fire.•
• Electrical changes during the action potential.The incoming message must be above a certain threshold to cause a neuron to fire. After it fires, the neuron is returned to its resting state. This process happens very quickly, and within a few thousandths of a second the neuron is ready to fire again.
http://www.teachertube.com/viewVideo.php?video_id=153535
Myelin and Nodes of Ranvier
• The axons of the nerve cells are sheathed in a smooth fatty protein called myelin which insulates the axon. It considerably increases the speed that nerve impulses travel along the axon.
• Without the myelin, the axons would have to be about one hundred times their volume to achieve the same speed of nerve transmissions. The myelin is wrapped around the axon in many thin layers. The myelin does not enclose the axon in one entire sheath, but has gaps at intervals called the nodes of Ranvier.
What causes the change in potential to occur?
1. A stimulus causes the sodium gates (channel) to open and, because there's more sodium on the outside than the inside of the membrane, sodium then diffuses rapidly into the nerve cell.
2. All these positively-charged sodium ions rushing in causes the membrane potential to become positive (the inside of the membrane is now positive relative to the outside). The sodium channels open only briefly, then close again.
3. The potassium channels then open, and, because there is more potassium inside the membrane than outside, positively-charged potassium ions diffuse out. As these positive ions go out, the inside of the membrane once again becomes negative with respect to the outside.
From One To The Next• A chemical message (called a neurotransmitter)
passes from the sending neuron to the receiving neuron.
• The neurotransmitters leave the sending neuron and enter the space between the sending and receiving neurons. This space is called the synapse or synaptic cleft.
• The neurotransmitters then hook up to a receptor on the receiving neuron to deliver their message.
• Once neurotransmitters have sent their message, they can be reabsorbed by the sending neuron in a process called reuptake.
• Reuptake allows the messengers to be reused.
•Two of these neurotransmitters are serotonin and norepinephrine
Reuptake of serotonin occurs when some of the serotonin that is passed from the presynaptic neuron is recycled back into that neuron (see upward arrows and F). SSRIs (P) block this reuptake by blocking the channels (B) which allow for this reuptake of the serotonin (C). This increases the amount of serotonin in the synaptic cleft that can bind with receptors on the postsynaptic terminal.
Antidepressant Meds• SSRI• Low levels of serotonin and norepinephrine in the synapse are associated with
depression and sadness. Some medications used to treat depression work by increasing the amount of certain neurotransmitters that are available to carry messages.
• Antidepressants, such as selective serotonin reuptake inhibitors, or SSRIs, work by slowing or blocking the sending neuron from taking back the released serotonin. In that way, more of this chemical is available in the synapse.
• The more of this neurotransmitter that is available, the more likely the message is received, and depression is reduced.
• MAO INHIBITORS:• The antidepressants known as MAO inhibitors, or MAOIs, affect
neurotransmitters differently. Monoamine oxidase (MAO) is a natural enzyme that breaks down neurotransmitters. The drug MAOI disrupts the action of the enzyme MAO. In that way, there is an increase in the amount of neurotransmitters in the synapse, making more messengers available to the receiving neuron, and thus reducing depression.
Neuron parts
http://garyfisk.com/anim/neuronparts.swf
Animated visual: http://www.classzone.com/cz/books/bio_07/get_chapter_group.htm?cin=9&rg=animated_biology&at=animated_biology&var=animated_biology
Quiz Time! Name the …..
1. Part of the neuron that releases neurotransmitters into the synaptic cleft. 2. Fatty material that surrounds some axons. 3. Part that takes information away from the cell body. 4. The gaps in the myelin sheath. 5. Part of neuron that contains the nucleus. 6. Part that takes information to the cell body. 7. Organelle in neuron that contains genetic material.
Answers are:
1. Axon terminal 4. Nodes of Ranvier 7. Nucleus
2. Myelin 5. Soma
3. Axon 6. Dendrites
The Central Nervous SystemThe Central Nervous SystemInteresting Facts!Interesting Facts!
The central nervous system is divided into two The central nervous system is divided into two parts: the parts: the brainbrain and the and the spinal cordspinal cord. .
The average adult human brain weighs 1.3 to 1.4 The average adult human brain weighs 1.3 to 1.4 kg (approximately 3 pounds).kg (approximately 3 pounds).
The brain contains about 100 billion nerve cells The brain contains about 100 billion nerve cells (neurons) and trillions of "support cells" called (neurons) and trillions of "support cells" called gila. gila.
The spinal cord is about 43 cm long in adult The spinal cord is about 43 cm long in adult women and 45 cm long in adult men and weighs women and 45 cm long in adult men and weighs about 35-40 grams.about 35-40 grams.
The vertebral column, the collection of bones The vertebral column, the collection of bones (back bone) that houses the spinal cord, is about (back bone) that houses the spinal cord, is about 70 cm long. Therefore, the spinal cord is much 70 cm long. Therefore, the spinal cord is much shorter than the vertebral column.shorter than the vertebral column.
young frankenstein part 1
The Brain: The Inside Story: http://watch.thirteen.org/video/1896942975/
The CNS: The Brain
• The cerebrum -- which is just Latin for "brain" -- is the newest (evolutionarily) and largest part of the brain as a whole. It is here that things like perception, imagination, thought, judgment, and decision occur.
• The surface of the cerebrum -- the cerebral cortex -- is composed of six thin layers of neurons (nerve cells) and is refered to as the grey matter. It sits on top of a large collection of white matter pathways.
• The cortex is heavily convoluted with “ridges” called gyri and “valleys” called sulci. If you were to spread the cortex out, it would actually take up about 2 1/2 square feet (2500 sq cm). It includes about 10 billion neurons, with about 50 trillion synapses!
• The cerebral cortex is divided into four sections, called "lobes": the frontal lobe, parietal lobe, occipital lobe, and temporal lobe.
•
The BrainThe cerebral cortex is comprised of the:
frontal lobe, parietal lobe, occipital lobe, and temporal lobe.
What do each of these lobes do? • Frontal Lobe- associated with reasoning,
planning, parts of speech, movement, emotions, and problem solving
Functions associated with the frontal lobes:Conscious thought
Concentration Perseverance
Judgment Attention span
Impulse control - self monitoring and supervision
Problem solving Organization
Critical thinking Forward thinking
Ability to feel and express emotions Empathy
YouTube - NEURONS AND NEURO-TRANSMITTERS
What do each of these lobes do? • Frontal Lobe- associated with reasoning,
planning, parts of speech, movement, emotions, and problem solving
• Parietal Lobe- associated with movement, orientation, recognition, perception of stimuli
Parietal Lobe
• The parietal lobes can be divided into two functional regions.
• One involves sensation and perception and the other is concerned with integrating sensory input, primarily with the visual system.
What do each of these lobes do? • Frontal Lobe- associated with reasoning,
planning, parts of speech, movement, emotions, and problem solving
• Parietal Lobe- associated with movement, orientation, recognition, perception of stimuli
• Occipital Lobe- associated with visual processing
Occipital lobes
• The OC are the center of our visual perception system. They are not particularly vulnerable to injury because of their location at the back of the brain, although any significant trauma to the brain could produce subtle changes to our visual-perceptual system, such as visual field defects.
What do each of these lobes do? • Frontal Lobe- associated with reasoning, planning,
parts of speech, movement, emotions, and problem solving
• Parietal Lobe- associated with movement, orientation, recognition, perception of stimuli
• Occipital Lobe- associated with visual processing • Temporal Lobe- associated with perception and
recognition of auditory stimuli, memory, and speech
The senses of the body (speech, hearing, feelings, seeing and memory) and control of the muscles, are part of the grey matter’s function.
TEMPORAL LOBES: Located at sides of head above ears, the temporal lobes form the wings of
the soul of our living caduceus.Functions:
The dominant side is usually the left hand side and governs-
Hearing ability Understanding and processing language
Memory acquisition - particularly long term memory
Some visual perceptions Categorization of objects.
The no dominant side or right side governs-Recognition of facial expressions
Decoding vocal intonation Rhythm Music
Visual learning
How your memory works?
http://web-us.com/brain/braindominance.htmLeft vs. Right side brain test
• A deep furrow divides the cerebrum into two halves, known as the left and right hemispheres. Sometimes the right hemisphere is associated with creativity and the left hemispheres is associated with logic abilities.
• The corpus callosum is a bundle of axons which connects these two hemispheres.
The right hemisphere controls the left side of the body, and the left hemisphere controls the right side.
Do Now!1. What are the 4 parts of the cerebrum?2. The convolutions of the cerebrum are comprised of
ridges and valleys. What are the ridges called? The valleys?
3. What part of the brain is dedicated to visual perceptions?
4. What part of the brain is associated with reasoning, planning, parts of speech, movement, emotions, and problem solving?
5. What part of the brain is associated with movement, orientation, recognition, perception of stimuli?
6. What part of the brain is associated with perception and recognition of auditory stimuli, memory, and speech?
7. What is the deep furrow that divides the cerebrum into two halves known as?
The Cerebellum
The cerebellum, or "little brain", is similar to the cerebrum in that it has two hemispheres and has a highly folded surface or cortex.
CEREBELLUM: Located at the base of the skull, and attached to the rear of the brain stem.
Functions:Coordination of voluntary movement
posture Balance and equilibrium
Some memory for reflex motor acts.
Limbic SystemLimbic System:• The limbic system, often referred to as the "emotional
brain", is found buried within the cerebrum. Like the cerebellum, evolutionarily the structure is rather old.
• This system contains the:1. thalamus (almost all sensory information enters this structure
where neurons send that information to the overlying cortex ),2. hypothalamus (functions including homeostasis, emotion, thirst,
hunger, circadian rhythms, and control of the autonomic nervous system. In addition, it controls the pituitary )
3. amygdala (memory, emotion, and fear ),4. hippocampus (important for learning and memory, for
converting short term memory to more permanent memory, and for recalling spatial relationships in the world about us)
Sense of smell
BRAIN STEM: Located deep in the brain, leads to spinal cord. Often referred to as The 'Reptilian' or 'Primitive' Brain. The
majority of the cranial nerves exit from the brain stem at the pons.
Functions: Breathing Heart Rate Swallowing
Reflexes to seeing and hearing (Startle Response).
Controls sweating, blood pressure, digestion, temperature (Autonomic
Nervous System). Affects level of alertness.
Ability to sleep. Sense of balance (Vestibular Function).
• Grey matter – closely packed neuron cell bodies (making up the cerebral cortex) form the grey matter of the brain. The grey matter includes regions of the brain involved in muscle control, sensory perceptions, such as seeing and hearing, memory, emotions and speech.
• White matter – neuronal tissue containing mainly long, myelinated axons, is known as white matter or the diencephalon. It makes up the cerebrum. The color comes from the myelin.
• The nuclei of the white matter are involved in the relay of sensory information from the rest of the body to the cerebral cortex, as well as in the regulation of autonomic (unconscious) functions such as body temperature, heart rate and blood pressure.
• Certain nuclei within the white matter are involved in the expression of emotions, the release of hormones from the pituitary gland, and in the regulation of food and water intake. These nuclei are generally considered part of the limbic system.
Brain stem: 3 parts
• Lower animals have only a medulla.
• The brain stem controls the reflexes and automatic functions (heart rate, blood pressure), limb movements and visceral functions (digestion, urination).
• Corpus callosum
• Cerebellum
• Pituitary gland
• Pons
• Medulla
• Spinal cord
• Frontal
• Temporal
• Occipital
• Parietal
1.
3.
2.
7.
6.
9.
8.
5.
4.
10.
Put answers on back of fill-in page
12 Cranial Nerves
Fissure: any cleft or groove, normal or otherwise, especially a deep fold in the cerebral cortex involving its entire thickness.
Brains
Wild pig, dolphin, human
Chimpanzee
Sheep Brain Dissection Guide
http://www.wellesley.edu/Biology/Concepts/Html/sheepbrain.html
http://academic.scranton.edu/department/psych/sheep/
Dura materSuperior ID
After splitting the cerebral hemispheres
Part 1: Sheep brain dissection http://www.youtube.com/watch?v=y7gEWzPqm94
Ventral side of the brain
Part 2: Brain dissection
http://www.youtube.com/watch?v=jr3qSaUzc6Q
Here's the cerebellum pushed downward to expose the superior and inferior colliculi and
pineal gland The Superior colliculus (2 parts) and the inferior colliculus (2 parts) make up the corpora quadrigemina. They are the reflex centers involving hearing and vision.
The Nerves
The largest nerve in the body is the sciatic and it splits into the common tibial and fibular nerves that run down each leg.
How the messages
travel
PNS• As part of the Peripheral Nervous System, nerves reach from
your brain to your face, ears, eyes, nose, and spinal cord... and from the spinal cord to the rest of your body.
• Motor neurons (motoneurons) carry signals from the central nervous system to the outer parts (muscles, skin, glands) of your body.
• Sensory neurons carry signals from the outer parts of your body (periphery) into the central nervous system.
• Receptors sense the environment (chemicals, light, sound, touch) and encode this information into electrochemical messages that are transmitted by sensory neurons.
• Interneurons connect various neurons within the brain and spinal cord.
Reflex Pathways
• The simplest type of neural pathway is a monosynaptic (single connection) reflex pathway, like the knee-jerk reflex.
• 1. When the doctor taps the right spot on your knee with a rubber hammer, receptors send a signal into the spinal cord through a sensory neuron.
• 2. The sensory neuron passes the message to a motor neuron that controls your leg muscles. Nerve impulses travel down the motor neuron and stimulate the appropriate leg muscle to contract.
• 3. The response is a muscular jerk that happens quickly and does not involve your brain.
• Humans have lots of hard-wired reflexes like this, but as tasks become more complex, the pathway "circuitry" gets more complicated and the brain gets involved.
Revisiting the Knee-Jerk Response
What is the stimulus?
• The hammer hits the tendon.
• The muscle contracts, causing the foot to jerk upward.
What is the response?
• The muscle contracts, causing
• the foot to jerk upward.
How is the Hammer Tap Detected?• The muscles in your leg have
stretch receptors.• They react to a change in length of
the muscle.• When the hammer hits the tendon
at the knee, it• makes a muscle in the front of your
thigh longer• (stretches it). • That stimulates the stretch
receptors in that muscle.
Other Reflexes:
Stimulus Response
An insect flying towards your eye Blinking
The aroma of your favorite food Salivation
A bright light shining in your eye Pupils get smaller
A nasty odor Nausea
What’s a Reflex?
• You need to detect a change in the environment (a stimulus) and react to the change (a response) in a way that maintains homeostasis.
• When you do this without thinking, it is called a reflex.
How is a Stimulus Detected?
• Some cells are specialized to react to a specific stimulus.
• These are called receptors (they receive a stimulus). The receptor cells of your eyes are stimulated by light.
The Response
• When the receptor is stimulated, it sends a message to a part of your body that effects the correct response.
• This is called the effector.
Reflex arc
How the Message Travels From the Receptor to the Effector.
• A sensory neuron carries the message from the receptor to the central nervous system (the spinal cord and brain).
• A motor neuron carries the message from the central nervous system to the effector.
• This is a reflex arc.
Motor (efferent) Neurons• Is divided into two groups:
– 1. Autonomic system– The ANS In most situations, we
are unaware of the workings of the ANS because it functions in an involuntary, reflexive manner.
2. Somatic system (back to this in a moment)
Name the Neurons
• Neuron 2 ?
• Sensory (Afferent) Neuron
Name the Neurons
• Neuron 3 ?
• Interneuron
Name the Neurons
• Neuron 4 ?
• Motor (Efferent) Neuron
1.In emergencies that cause stress and require us to"fight" or take "flight" (run away)
2.In non-emergencies that allow us to "rest" & "digest." .
The ANS is most important in two situations:
The ANS is divided into three parts: 1. The sympathetic nervous system 2. The parasympathetic nervous system 3. The enteric nervous system (is a meshwork of nerve fibers that innervate the viscera (gastrointestinal tract, pancreas, and gall bladder).
ANS• Sympathetic:• These are "Fight or
Flight" responses. In these types of situations, your sympathetic nervous system is called into action - it uses energy - your blood pressure increases, your heart beats faster, and digestion slows down.
• Parasympathetic• This calls for "Rest and
Digest" responses. Now is the time for the parasympathetic nervous to work to save energy - your blood pressure decreases, your heart beats slower, and digestion can start.
The Autonomic Nervous System
Structure Sympathetic Stimulation Parasympathetic Stimulation
Iris (eye muscle) Pupil dilation Pupil constriction
Salivary Glands Saliva production reduced Saliva production increased
Oral/Nasal Mucosa
Mucus production reduced Mucus production increased
HeartHeart rate and force increased
Heart rate and force decreased
Lung Bronchial muscle relaxed Bronchial muscle contracted
Stomach Peristalsis reducedGastric juice secreted; motility increased
Small Intestine Motility reduced Digestion increased
Large Intestine Motility reduced Secretions and motility increased
LiverIncreased conversion ofglycogen to glucose
Kidney Decreased urine secretion Increased urine secretion
Adrenal medullaNorepinephrine andepinephrine secreted
BladderWall relaxedSphincter closed
Wall contractedSphincter relaxed
• The inner part, the adrenal medulla, produces catecholamines, such as epinephrine.
• Also called adrenaline, epinephrine increases blood pressure and heart rate when the body experiences stress.
• These hormones are produced in response to stressors such as fright, anger, caffeine, or low blood sugar. (Epinephrine injections are often used to counteract a severe allergic reaction.)
Detailed epinephrine action :Fight or Flight:http://www.youtube.com/watch?v=ejq99wLEMTw&feature=related
Flight or Flight Response Video
• http://www.youtube.com/watch?v=4g25d7_Afmc&feature=related (from Discovery Channel: 6 min.)
• Adrenaline Rush: Standing on a cliff: http://www.youtube.com/watch?v=DplhL6mJhcQ&feature=related
• Adrenaline Rush: Shark cage: http://www.youtube.com/watch?v=50dVhd4dmp8&feature=fvwrel
Back to The Somatic Nervous System• Somatic Nervous System• The somatic nervous system consists of
peripheral nerve fibers that send sensory information to the central nervous system AND motor nerve fibers that project to skeletal muscle.
• The picture shows the somatic motor system. The cell body is located in either the brain or spinal cord and projects directly to a skeletal muscle.
This very strange creature in the Glasgow Science Centre is the Homunculus. The different parts of the body are sized according to the amount of nerves present in that part of the body.
Alzheimer’s disease:• progressive degenerative
brain disease that results in dementia associated with a shortage of acetylcholine (an important neurotransmitter) and structural changes in brain areas involving cognition and memory. Because nerve cells do not undergo mitosis, new cells can not be generated.
Cerebrovascular accident (CVA):• brain dysfunction
where blood supply to a region is blocked and vital brain tissues dies as by a blood clot or ruptured blood vessel. This is more commonly called a stroke.
http://www.webmd.com/stroke/ss/slideshow-stroke-overview?ecd=wnl_chl_100411
Stroke Test: Talk, Wave, Smile• The F.A.S.T. test helps spot symptoms. It
stands for:
• Face. Ask for a smile. Does one side droop?
• Arms. When raised, does one side drift down?
• Speech. Can the person repeat a simple sentence? Does he or she have trouble or slur words?
• Time. Time is critical. Call 911 immediately if any symptoms are present.
Parkinson’s Disease• Parkinson disease (PD) is characterized
by a slowing of voluntary movements, bradykinesia “stone face”, muscular rigidity and tremor at rest.
• These abnormalities result from a reduction of neurons that make dopamine.
Multiple sclerosis:• when the myelin
sheath around the axon deteriorates the electrical current is short circuited.
• The person may experience visual and speech disturbances and also lose muscle control.
M.S.
Tourette Syndrome• This syndrome begins in childhood and manifests itself
through various forms of tics. • These tics include frequent, irregular movements of the
head, neck, or shoulders. They also may be more complex motor behaviors such as snorting, sniffing, and involuntary vocalization.
• As the syndrome progresses repetitive behaviors such as touching others, obsessive compulsive symptoms, and explosive involuntary cursing can be more common.
• Aggressive behavior and improper sexual impulses are the rarest and most severe expressions of the syndrome.
• The cause of Tourette syndrome is not known, but it is believed to have a genetic component.
Famous People with Tourettes (OCD)
Wolfgang Amadeus Mozart - (1756-1791) It has also been documented that he was hyperactive, suffered from mood swings, had tics, and loved made-up words. Despite these behaviors, we will probably never know for certain whether Mozart had TS.
Dan Ackroyd was diagnosed with tourette's and asperger syndromes at an early age, but the symptoms seem to have disappeared when he was around 14. The diagnosis of Asperger syndrome did not exist in the 1960s, when Aykroyd was a preteen. It involved mostly grunting and physical tics through nervousness.
David suffers from OCD and it manifests itself through constant cleanliness and perfection of all that is around him. Anything out of order is enough to cause a conflict and must be attended to immediately. Examples of this complete order is that everything must be in pairs, if there are three books on a table one must be added, or one must be removed. Only 2% of the population suffer from this strong OCD.
Cerebral Edema• The brain reacts to severe head trauma by
retaining water. As a result, the brain swells. The pressure grows as the brain presses on the skull. This can be fatal or result in severe brain damage.
Famous People with Cerebral Edema
Actor Natasha Richardson
Video: The Secret Mind54 min
• http://video.google.com/videoplay?docid=2661634191857056612#
Nervous System TestNervous System TestComplete your study guide to Complete your study guide to
prepare for the test.prepare for the test.The test has….The test has….29 multiple choice (2 pts each)29 multiple choice (2 pts each)6 labeling neuron (2 points each)6 labeling neuron (2 points each)10 fill in the blanks (2 pts each)10 fill in the blanks (2 pts each)6 label parts of the brain6 label parts of the brain100 points100 points