* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download in the central nervous system
Donald O. Hebb wikipedia , lookup
Brain morphometry wikipedia , lookup
Selfish brain theory wikipedia , lookup
Brain Rules wikipedia , lookup
Aging brain wikipedia , lookup
Cognitive neuroscience wikipedia , lookup
Neuroplasticity wikipedia , lookup
Neuropsychology wikipedia , lookup
History of neuroimaging wikipedia , lookup
Haemodynamic response wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Activity-dependent plasticity wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Neural engineering wikipedia , lookup
Metastability in the brain wikipedia , lookup
End-plate potential wikipedia , lookup
Node of Ranvier wikipedia , lookup
Electrophysiology wikipedia , lookup
Evoked potential wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Development of the nervous system wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Microneurography wikipedia , lookup
Circumventricular organs wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Single-unit recording wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Synaptic gating wikipedia , lookup
Biological neuron model wikipedia , lookup
Neuroregeneration wikipedia , lookup
Neurotransmitter wikipedia , lookup
Chemical synapse wikipedia , lookup
Nervous system network models wikipedia , lookup
Synaptogenesis wikipedia , lookup
Stimulus (physiology) wikipedia , lookup
NERVOUS and CHEMICAL REGULATION 1. Organisms must respond to changes • • Changes outside the organism Changes inside the organism REGULATION 2. Organisms must respond in a coordinated way • • • Must be controlled and coordinated Homeostasis must be maintained Responses must be regulated (in the right order) REGULATION 3. Complex organisms control and regulate responses by • • The nervous system The endocrine system VOCAB • Irritability = the ability of a cell to respond to its environment • Regulation = all the activities that help to maintain an organism’s homeostasis ORGANISM PROTISTS (amoeba and paramecium) TYPE OF SYSTEM NONE But can respond to stimuli NERVE NET HYDRA EARTHWORM GRASSHOPPER No brain or nerve cord SIMPLE SYSTEM SIMPLE SYSTEM but more complex than the earthworm ADAPTATIONS OR SPECIALIZED STRUCTURES Fibers that control beating cilia Eyespots sensitive to certain stimuli Special receptor cells connected to muscle and gland cells Central nervous system (CNS) SENSE ORGANS NONE Coordinated movement of the tentacles Receptors in the skin brain and 2 ventral nerve cords sensitive to light, vibrations, chemicals, heat Peripheral nervous system (PNS) EYES ANTENNAE nerve branches muscles and glands (feelers) taste organs sound sensors (tympanium) Mechanisms of Nervous Regulation 1. Nerve cells = specialized cells that carry messages Impulses = the messages that nerve cells carry Receptor = (sense organ) specialized structures that are sensitive to certain changes 2. 3. Physical force Chemical changes inside or outside the organism May respond to heat, cold, light, sound, pressure, chemicals A stimulus to a receptor causes an impulse to be transmitted (carried) Mechanisms of Nervous Regulation 4. Effector = specialized structure that responds to the commands of the nervous system a) Gland – will increase or decrease activity b) Muscle – will contract 5. Stimulus = anything that causes a receptor to start an impulse a) It causes an electrical and chemical change →Stimulus activates a receptor →Impulses start across the nerve pathway →Effector responds to the impulse Mechanisms of Nervous Regulation 6. Brain = specialized group of nerve cells that control and coordinate the activities of the nervous system • • There are many interconnections along the nerve pathway – it is very complex The more complex the organism, the more complex the brain STRUCTURE OF NEURONS (bottom of page 6) Nerve cell = neuron = basic structure in nervous systems Neurons can send electrical and chemical impulses (electrochemical impulses) The sending of impulses is the property of the neuron’s cell membrane Transmission not through the cytoplasm, but along the cell membrane STRUCTURE OF A NEURON Where cell’s metabolic activity takes place CELL BODY Controls the cell’s growth NUCLEUS Receives impulses DENDRITES NODE OF RANVIER AXON TERMINAL BRANCHES Sends out impulses SCHWANN CELL NUCLEUS SCHWANN CELL MYELIN SHEETH Speeds transmission SYNAPTIC KNOBS STRUCTURE OF NEURONS SYNAPSE Synapse = microscopic gap at the end of the terminal branch of the neuron and the neighboring cell Each axon can have one or more synapses with as many as 1,000 other axons The many connections make the nervous system so complex SYNAPSE TYPES OF NEURONS SENSORY NEURON MOTOR NEURON INTERNEURON SENSORY NEURON Sensory nerves – receive impulses and send them along to other axons Carry information into the central nervous system MOTOR NEURON Motor neurons – carry impulses to effectors (ie: muscles) Carry information away from the central nervous system INTERNEURON Interneurons (associative neurons) – relay impulses neuron to neuron Found only in the central nervous system NERVES Nerves are bundles of axons and dendrites bound together by connective tissue cell body nucleus dendrites INTERNEURON axon myelin sheath Schwann cell cell body node of Ranvier MOTOR NEURON synaptic knobs SENSORY NEURON THE NERVE IMPULSE The nerve impulse is the reversal of polarization Refractory period = a brief time (~3/1000 sec) when polarization of a neuron is returning to its normal (resting) state – the neuron can not be stimulated to carry an impulse during this period The sodium-potassium pump pumps Na+ out and can’t get back in! The membrane is impermeable to Na+ Na+ Na+ rushes in when the channels open to Na+ In Resting Cell: •Positive charge outside of the cell is caused by the increased concentration of Na+ outside the cell (negative charge inside the cell) •The cell membrane is said to be polarized In the area of impulse: •Positive charge inside the cell is caused by the permeability change in the cell membrane – it becomes permeable to the Na+ - this reverses the polarity •The cell membrane is said to be depolarized Impulse Transmission http://www.youtube.com/watch?v=yrsJ9HlnZ5s&feature=related http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html RATE OF IMPULSE CONDUCTION Depends upon: 1) Size of nerve fibers 2) Whether a neuron is myelinated or not a) Small non- myelinated neuron’s speed ~ 2 meters/sec b) Large myelinated neuron’s speed ~ 100 meters/sec Myelinated neurons are faster because the impulse “jumps” from one node of Ranvier to the next node of Ranvier This is called SALTATORY CONDUCTION SALTATORY CONDUCTION • Where the myelin is, depolarization is blocked • Depolarization only occurs at the nodes of Ranvier • The impulse “jumps” from node to node • Saltatory conduction is faster and uses less energy (less active transport) THRESHOLDS • Stimulus must have minimum strength to start an impulse • All or nothing response • On a particular axon, all impulses are the same “size” DISTINGUISHING SIZE AND TYPE OF STIMULUS The greater the strength of the stimulus, the more frequently the impulses are sent (increasing the rate of transmission) Particular types of stimulus (light, touch, sound) are only picked up by the specific receptor and travel to a specific place in the brain to be interpreted TRANSMISSION AT THE SYNAPSE TRANSMISSION AT THE SYNAPSE Axon of a neuron ends at the synaptic knob where the impulse must be carried to the axon (or dendrite) of the next neuron (across the synaptic gap) This occurs by a chemical process using chemicals known as neurotransmitters • Acetylcholine and norepinepherine TRANSMISSION AT THE SYNAPSE When the impulse reaches the synaptic knob, neurotransmitters are released Neurotransmitters diffuse across the synaptic gap Neurotransmitters change the permeability of the neighboring axon’s cell membrane (making it permeable to Na+) This initiates an impulse TURN TO PAGE 11 IN YOUR PACKET A. An impulse arrives at the synaptic knob of the pre-synaptic neuron B. Neurotransmitters are released from the synaptic vesicles C. Neurotransmitters diffuse across the synaptic gap D. The neurotransmitters change the permeability of the cell membrane of the postsynaptic neuron E. Depolarization occurs F. An impulse is initiated along the cell membrane of the post-synaptic axon …this initiates an impulse ** transmission across the synapse is a chemical process ** transmission across along the axon is an electrical process • chemical transmission is much slower than electrical transmission TRANSMISSION AT THE SYNAPSE The stronger the stimulus – the more neurotransmitter released – this increases the rate of impulse transmission in the postsynaptic neuron Neurotransmitters are broken down in the synaptic gap by specific enzymes after the postsynaptic neuron has responded • Acetylcholine’s enzyme is acetylcholinesterace and is one of the fastest reacting enzymes in the body Transmission Across the Synapse http://www.youtube.com/watch?v=z3F5dfmQ3hk&feature=related http://www.youtube.com/watch?v=HXx9qlJetSU&feature=related TRANSMISSION AT THE SYNAPSE Impulses flow from synaptic knobs to dendrites (one direction) Excitatory transmitters • acetylcholine, norepinephrine, histamine, glutamic acid Inhibitory transmitters • serotonin, epinephrine, glycine THE NEUROMUSCULAR JUNCTION Impulses pass from neurons to muscles Neurons end at the motor end plates Motor end plates contain neurotransmitters When impulses arrive, neurotransmitters are released and change the permeability of the muscle cells’ cell membrane (increasing the permeability to Na+) This starts an impulse along the cell membrane causing the muscle cell to contract THE NEUROMUSCULAR JUNCTION DRUGS AND SYNAPSE Poisons and drugs can affect chemical transmitters Curare (nerve gas) Botulin cause paralysis Stimulants • amphetamines “uppers” cause excitability followed by depression • caffeine causes sleeplessness and nervousness Depressants • Barbiturates “downers” block formation of norepinepherine Mind altering drugs • LSD • mescaline interfere with serotonin (inhibitory transmitter) DRUGS AND SYNAPSE http://learn.genetics.utah.edu/units/addiction/drugs/mouse.cfm THE CENTRAL NERVOUS SYSTEM Made up of the brain and the spinal cord • Also interneurons and cell bodies of the motor neurons Protection Cranium – protects the brain The spinal column – protects the spinal cord Disks – between the vertebrae absorb shock Meninges – shock absorbers for the brain Three tough membranes filled with cerebrospinal fluid Ventricles –spaces in the brain filled with cerebrospinal fluid Cranium – protects the brain The spinal column – protects the spinal cord Disks – between the vertebrae absorb shock •Meninges – shock absorbers for the brain Three tough membranes filled with cerebrospinal fluid Ventricles –spaces in the brain filled with cerebrospinal fluid The Brain Blood Flow to the Brain • 20% blood from the heart goes to the brain • Greatest metabolizer of glucose Major parts of the brain CEREBRUM THALAMUS HYPOTHALAMUS PONS MEDULLA OBLONGATA CEREBELLUM Complete the right side of page 15 in your packet Identify the parts of the brain in the diagram numbered 1 - 5 PARTS AND FUNCTION OF THE BRAIN CEREBRUM A. 2/3 of the entire brain B. deep grooves separates 2 halves into the right and left hemispheres 1. right hemisphere – artistic and musical abilities 2. left hemisphere – mathematical abilities CEREBRUM D. outer most layer 1. gray matter cell bodies an unmyelinated interneurons many convolutions (folds) to increase surface area 2. white matter myelinated nerve fibers 1. sensory – receives and interprets impulses from sensory receptors (eyes, ears, taste buds, nose, touch, pain, pressure, heat, cold) 2. motor – all voluntary motion and position sense 3. associative – memory, learning, thought CEREBRUM E. Functions: CEREBRUM corpus callosum is the bridge between the two sides F. Nerve fibers cross on route from the brain to the spinal cord 1. the right side of the brain controls the left side of the body 2. the left side of the brain controls the right side of the body 1. Frontal lobe – personality, planning, higher level thoughts, emotional responses 2. Temporal lobe – speech 3. Occipital lobe – vision 4. Parietal lobe – language comprehension, spatial understanding (ie: depth perception), and tactile understanding CEREBRUM G. Lobes: A. located below the rear of the cerebrum B. controls all voluntary and some involuntary motions 1. receives input about body position, and muscle contractions 2. sends impulses to the cerebral cortex to correct and coordinate muscle movements 3. receives input from the inner ear to control balance 4. cerebellar damage results in a “drunken sailor gait” II. CEREBELLUM III. MEDULLA OBLONGATA A. Controls breathing, heart beat, blood flow, coughing IV SPINAL CORD A. Connects peripheral nerves with the brain (interneurons) B. Reflexes (automatic responses) Memory Not well understood Three types are • Momentary • Short term • Long term In what area of the brain is the function of memory? V. THALAMUS A. relay center between brain and spinal cord B. receives and changes all sensory impulses (except smell) before they travel to the cerebrum C. involved in pain and consciousness VI. HYPOTHALAMUS A. involved in controlling body temperature, blood pressure, sleep/wake cycles, emotions, and the endocrine system (hormones) VII. Pons A. relay center linking the spinal cord and the medulla oblongata, cerebellum, and cerebrum PONS Structure of the Brain 4. forebrain 1. thalamus 2.cerebrum 3. Hypothalamus 5. Corpus callosum 6. midbrain 10. hindbrain 7. Cerebellum 8. Pons 9. medulla 11. Spinal cord Area of the Brain Primary Function 2. CEREBRUM Voluntary motions Sensory input Motor output Personality / thoughts 7. CEREBELLUM Voluntary motions Coordinates muscle control Balance / equilibrium 9. MEDULLA OBLONGATA Involuntary responses (breathing ,heartbeat, blood flow, coughing, vomiting, sneezing, peristalsis) 1. THALAMUS Feeling pain / consciousness 3. HYPOTHALAMUS Involuntary responses (body temperature, blood pressure, sleep, emotion) Endocrine system 8. PONS Relay center THE PERIPHERAL NERVOUS SYSTEM Includes all nerve fibers outside the CNS (spinal cord and brain) Spinal nerves – nerves that exit the spinal cord (31 pair) Cranial nerves – nerves that exit the brain (12 pair) THE PERIPHERAL NERVOUS SYSTEM Includes all nerve fibers outside the CNS Cranial nerves exit the brain Spinal nerves exit the spinal cord The PNS is divided into Two Parts 1. Somatic nervous system 2. Autonomic nervous system Somatic Nervous System: • • • Nerves that are in voluntary control or there is conscious awareness of Made up of sensory and motor neurons Nerves that connect to muscles, sense organs, and skin Autonomic Nervous System: • • • • Made up of all motor neurons Nerves that serve internal organs of the body Heartbeat, blood flow, digestion, breathing, secretions of hormones Divided into two parts: – Sympathetic – Parasympathetic The Reflex Arc synapse sensory neuron synapse associative neuron effector sense receptor motor neuron Mechanism of Nervous Regulation A Reflex Arc sensory neuron sense receptor direction of impulse associative neuron or interneuron stimulus motor neuron response muscle cell effector (skeletal muscle)