Class Notes (835,108)
Canada (508,934)
HSCI 100 (134)

week 8.docx

13 Pages
Unlock Document

Health Sciences
HSCI 100
Nienke Van Houten

CHAPTER 8 – NERVOUS SYSTEM Peripheral nervous system (PNS) - Peripheral nerves – sensory & motor, spinal nerves – sensory & motor - Somatic nervous system o Nerves that carry info to and from CNS = sensations + voluntary movement o Carry somatic nerves result in conscious sensations, light sound touch o Tells us about world around and within us - Autonomic nervous system o Governs involuntary, subconscious activates that keep body function (HR, breathing rate)  Sympathetic nervous system – stressful/emergency conditions  Parasympathetic nervous system – governs bodily activities during restful conditions Central nervous system (CNS) - Spinal cord, brain (Cranial nerves) protected by bony cases (skull and vertebral column), membranes (meninges), fluid cushion (cerebrospinal fluid) o Meninges – 3 connective tissues covering brain and spinal cord  Outer = dura mater, middle = arachnoid, inner = pia mater o Cerebrospinal fluid – fills space btwn meninges and internal cavities of brai (ventricles) & internal cavities of spinal (central canal)  Functions: shock absorption, support, nourishment/waste removal o Blood-brain barrier  Selects substances permitted to enter cerebrospinal fluid from blood - All voluntary/involuntary THE BRAIN - Cerebrum o Contains sensory areas for skin senses, vision, hearing, olfaction o Motor area for voluntary control of movement o Association areas for interpreting sensations, language, thinking, decision making, self-awareness, creativity, memory  Thin outer layer = cerebral cortex  Gray mater = unmyelinated axons  White matter = myelinated axons  Frontal, parietal, temporal, occipital lobes - Corpus callosum o Allows L&R cerebral hemispheres to communicate - Thalamus o Processes all sensory info except olfaction o Relays info to appropriate higher brain centers - Hypothalamus o Controls HR, bP, breathing rate, body temp, food intake o Center for emotions o “master biological clock” - Cerebellum o Coordinates sensory-motor voluntary movement o Stores memory of learned motor patterns - BRAINSTEM o Midbrain – relays info btwn cerebellum/spinal cord & cerebrum, integrates sensory input o Pons – bridge btwn higher/lower brain center o Medulla oblongata – contains autonomic ctrs for HR and digestive activities, relays sensory info thalamus LIMBIC SYSTEM – term for group of structures that help to produce emotions/memory - Feelings about thoughts - Short-term memory – holds small amt of info for few seconds/mins - Long term-memory – seemingly limitless amounts of info for hrs, days yrs, - Olfactory bulb transmits info about odors from nose to limbic system THE SPINAL CORD - Tube of neural tissue continuous with medulla at base of brain to below last rib - Function – transmit messages to and from brain, serve as reflex center - White matter found toward surface of spinal cord – grouped into tracts (ascending/descending tracts) - Reflex arc – receptor, sensory neuron, interneuron, motor neuron  effector o 1. Stimulus initiates a pain sensation o 2. Sensory messages are carried to spinal cord by sensory neuron o 3. Interneurons in the spinal cord integrates information from sensory neuron and stimulate appropriate motor neurons o 4. Motor neurons stimulate appropriate muscles o 5. Leg muscles contract, causing them to lift the foot off glass Reticular Activating System (RAS) – extensive network of neurons that runs through medulla and protects cerebral cortex - Activates cerebral cortex DISORDERS OF NERVOUS SYSTEM Headaches - Tension headache – response to stress most of us unconsciously contract muscles of our head, face, neck - Migraine headaches – confined to one side often centered behind one eye. Throbbing pain increases with each beat of heart. Experience an aura (visual disturbance, hallucinations, numbness) Strokes - Cerebrovascular accident – death of nerve cells caused by interruption of blood flow to a region of the brain - Neurons die b/c no oxygen and glucose - Causes? Blood clots, hemorrhage Coma - Person totally unresponsive to all sensory input and cannot be awakened - Cause? Trauma to neurons in regions of brain responsible for stimulating cerebrum, particular in RAS & thalamus - Can be caused by mechanical shock – blow to the head, tumors, infections, drug OD, failure of liver/kidney Spinal Cord Injury - Spinal cord = pathway that allows brain to communicate with rest of body o Damage to spinal cord = impair sensation & motor control below site of injury - Result? Damage, injury, paralysis, loss of sensation Mechanoreceptors – action potentials from physical formation and reformation Corpuscle – rounded globular mass of cells - Meissner’s (tactile) corpuscles o Light touch o Low frequency vibrations (<50Hz) o Concentrated in fingers, lips, palms, soles o Action potential from physical deformation o Adapt rapidly  Why you stop feeling your clothes - Pacinian (lamellar) corpuscles o Pressure o Vibration – 250 Hz o Silkiness of silk o Smoothness of finished wood o Roughness of concrete - Ruffini’s (bulbous) corpuscles o skin stretch o kinesthetic sense of finger position and movement o monitors slippage of objects on skin  grip modulation o sustained pressure with little adaptation  you do not feel the steering wheel - merkel’s discs o low frequency vibration 5-15Hz o sustained response o sense very small displacement o high resolution tactile discrimination  braille, cotton vs burlap - free nerve endings = pain Medulla - autonomic functions o breathing – chemoreceptors o heart rate – sympathetic, parasympathetic o blood pressure – vasomotor baroreceptors o vomiting, coughing, sneezing, swallowing Pons - relay station: forebrain to cerebellum o sleep, respiration, swallowing, bladder control, hearing, taste, balance posture, facial expressions and sensation, eye movement Midbrain - substantia nigra o dopamine – motor control, motivation, habituation - relay of vision and hearing Thalamus - great relay station of the brain - all ascending tracks terminate here - thalamus  cortex, cortex  thalamus Cortical columns - basic computational element of the cortex - 6 neuron layers deep Cranial nerves - Special senses: smell (olfactory cortex), sight, hearing, taste (gustatory cortex). Facial motor After sensation comes response - Super fast response: reflexes - Fast response: limbic system - Slow response: cortical system Functions Amygdala - Positive/negative colouring of events - Memory modulation, sex, rage, social networks Cingulate gyrus - Links behavioural outcomes to motivation “it felt good when I learned to ride my bike” Nucleus accumbens - Pleasure dome: anticipates positive sensations. Euphoria in sex, drugs alcohol Insula - Integration of body’s emotional tone – craving, addiction, social violations, empathy, orgasms Cerebellum - Principal role in motor coordination - May be involved in fear/pleasure regulation - As many neurons as rest of brain Marshmallow test video – impulse (generated by limbic system) somehow being kept (or not) at the bay Frontal lobes - Executive function: o Regulation emotion o Impulse control o Interpersonal function o Planning Neuromodulation – shift overall +/- tone - Primary neurotransmitters = glutamate (excitatory +), GABA (inhibitory -) - Neuromodulators = dopamine, serotonin, norepinephrine, acetylcholine Dopamine: reward seeking behavior - Motivation to behave in certain ways o Reward from basic drive fulfillment: food, sex, drugs, learned stimuli - Craving and euphoria in addiction - Movement - Cognitive function - Social behavior - Dopaminergic drugs – Adderall, cocaine, crystal met, Dexedrine, Ritalin Serotonin – regulation of mood, appetite, sleep - Cognitive functions – memory/learning - Serotonergic drugs – turkey sandwiches, SSRI antidepressants, DMT, MDMA, LSD, mescaline Noradrenaline - Focuses attention = decision making - Fight or flight (sympathetic nervous stem) - Amygdala on-switch Acetylcholine - Memory - Muscle – neuromuscular junction - Parasympathetic system – rest & digest - Drugs = nicotine, acetyl cholinesterase inhibitors -  pharmacology o 1. Ach made from choline + acetyl CoA o 2. In synaptic clef, Ach rapidly broken down by enzyme acetyl cholinesterase o 3. Choline transported back into axon terminal and is used to make more ACh - Corpuscles – - Vesicles – acetylcholine - Motor cortex  pons  cerebellum (secondary input) - Dopamine – reward system - How many cortical columns are In the human brain -2 mil - Motor control – front , sensation in back == association cortex CHAPTER 8A – DRUGS & THE MIND DRUG DEPENDENCE - Tolerance: progressive decrease in effectiveness of a drug in a given person o Develops b/c body naturally steps up production of enzymes to break down drug, disabling it from having continued effect, o Also b/c changes in nerve cells - Cross tolerance: tolerance to one drug results in a lessened response to another - Dependence: state in which drug is necessary for physical/psychological well-being o Withdrawal symptoms Alcohol - Alcohol = ethanol. By-product of fermentation when yeast cells break down sugar to release energy for their own use - Absorption: o Absorbed from digestive system and into blood, delivered to brain o 20% absorbed in stomach, remaining = intestines - Distributed to all body tissues. Ethanol soluble in both fat & water - Elimination: o 95% that enters is metabolized and broken down before eliminated (in liver)  Converts alcohol to co2 & water o 5% eliminated unchanged through lungs/urine - Health related effects: o Nervous system – alcohol is a depressant  Slows activity o liver - fat accumulates  fat blocks blood flow == inflammation (hepatitis)  fibrous scar tissue forms (cirrhosis) == intestinal bleeding, kidney failure, fluid accumulation o cancer – tongue, mouth, esophagus o hearts & blood vessels – too much alcohol = reduce heart ability to pump blood, promote deposit of fat in blood vessels, higher bP  damage heart muscle, blood vessels clogged, high blood pressure == enlarge heart MARIJUANA THC receptors in brain - mimics anandamide – internal bliss – regulation of mood, memory, pain, appetite, movement - stimulates release of dopamine in reward pathways Health related effects of long term use - usually smoked, residual materials in smoke is harmful (not THC) - more tar buildup, carbon monoxide prevents RBC from carrying oxygen to cells of body - makes heart beat faster - interfere with reproductive functions STIMULANTS – excite CNS Heroin – acts in brain regions where neurons communicate using endorphins LSD & MDMA – act in brain regions where neurons communicate us
More Less

Related notes for HSCI 100

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.