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The nervous system

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icer215's version from 2016-08-17 02:02

Section 1

Question Answer
The nervous system consists ofBrain, Spinal cord, Sensory organs, Nerves
nervous system carries out various important functions, includingHigh-level, control Integration of body systems, Adaptive capability to external influences, Integrative and cognitive abilities
Sensory = Afferent Nerves carrying signal toward CNS.
Motor = EfferentNerves carry signal toward effector organs.
Somatic Nervous System = VoluntaryControls skeletal muscles.
Autonomic Nervous System = Involuntary Effects visceral organs.
Sympathetic divisionfight or flight response.
Parasympathetic division prepares body to rest.
Sensorsenses, carries sensory signals from the body to the CNS.
Effector causes an effect = carries motor signals from the CNS to the body.
SympatheticIncrease heart rate, blood pressure, More blood flow to muscles, less to digestive system. Pupil dilation. Break down glycogen to release glucose into blood.
ParasympatheticDecrease heart rate, blood pressure. Less blood to muscles, more to digestive system. Pupil constriction. Synthesizes glycogen for storage from glucose.
Brain is the primary control center in vertebrates and it is divided into forebrain, midbrain, and hindbrain
Spinal cord is responsible for carrying, coordinating, and controlling information and reflexes
Peripheral nervous system (PNS) is divided into two parts, which are autonomic (ANS) and somatic nervous system (SNS)
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Section 2

Question Answer
Sympathetic and parasympathetic nervous system are the two divisions of the autonomic nervous system (ANS). They are antagonistic (opposing) effects on the internal organs they innervate thus they are known to have antagonistic control
Reflexesare involuntary action
Feedback looppositive feedback , negative feedback , or reflex arc .
positive feedback uterine contraction lead to oxytocin release, which causes more uterine contraction. blood clotting platelets activated at wound site attract more platelet activation and clumping.
negative feedbackdrop in blood pressure causes ADH release, which increases it. Conversely increase in blood pressure causes a drop in ADH.
Reflex arc withdrawal from a painful stimulus = negative feedback. knee jerk = tapping the knee tendon causes sudden stretching of the muscle, which lead to contraction of that muscle that creates the knee jerk = negative feedback. receptor → sensory neuron → integration center → motor neuron → effector
receptor site of stimulus
sensory neuron carries impulse from receptor to integration center
integration center connects sensory to motor neuron via synapse inside the CNS
monosynaptic no interneuron, direct synapse of sensory to motor.
polysynapticinterneuron(s) present.
Golgi tendon reflexsudden contraction of the quads (extensor), causes a negative feedback that relaxes the quads and contracts the hamstrings (flexor).
Spinal cord provides the synapse (or synapses if it's polysynaptic) for the reflex arc.
Even though the reflex arc bypasses the brain, the brain is still aware of it happening.
Brain can overridespinal reflexes (eg. you don't jerk away from getting a vaccine shot)
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Section 3

Question Answer
Skin touch, heat and pain receptors close to the surface (dermis-epidermis boundary), pressure receptors deeper in the dermis.
proprioceptorsenses the position of a body part, located in muscle and connective tissue
mechanoreceptors touch, pressure
thermoreceptortemperature change (a warm object will feel warm if your hand is cool, but won't feel warm if your hand is already warm)
photoreceptorlight
chemoreceptor taste, smell
nocioreptors pain (extreme heat, cold, pressure, chemicals)
Olfaction Chemicals enter the nose via nostrils. Gets into the nasal cavity. Trapped in the mucus on top of the nasal cavity. Picked up by the membrane receptors on cilia (non-mobile, but they increase the surface area) of the olfactory receptor cell. Causes cell depolarization, and subsequent transduction of signal to the brain.
Taste Chemicals dissolve in saliva. Carried inside taste bud Hair-like microvilli of taste cells inside taste bud picks up chemicals. Releases neurotransmitters to send signal to brain.
Ear canal auditory canal.
Tympanic membrane eardrum
Ear bones malleus (hammer) → incus (anvil) → stapes (stirrup).
Vestibule contacts the oval window (where stirrup vibrates), is continuous with semicircular canals and cochlea.
Cochleaspiral = houses hair cells.
Semicircular canals 3 of them perpendicular to one another = senses position and movement of the head, help you balance.
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Section 4

Question Answer
mechanism of hearing Sound enters ear. Hits ear drum (tympanic membrane) Malleus (hammer) → Incus (anvil) → Stapes (stirrup) Vibrates fluid in Cochlea. Transmits to fluid in Cochlea. Cochlear hair cells excited by vibrations, and sends signal to brain.
light receptorsPhotoreceptor cells located on the back of the retina.
Rods senses light and dark (no color), more sensitive.
Cones senses color, less sensitive.
Rhodopsin chemical responsible for light reception = Retinal (chemical) + Opsin (transmembrane protein)
Light converts cis-retinal → trans-retinal.
trans-retinal then causes hyperpolarization of photoreceptor cell, which prompts the chain of events that sends signal to the brain.
Sends signal to brain via a bundle of nerves on the back of the retina (where the blind spot is)
eye structure Light first travels through the cornea Through the pupil (hole in the iris muscle) Lens = focuses light on retina. Vitreous humor = fluid. Retina = screen on the back of the eye = contains photorecept
visual image processingThe lens of the eye, just like a convex lens in physics, forms a real image on the retina. Real images are inverted. The brain processes this inverted image to make it seem upright in your mind. The brain combines the two images from each eye to make a 3D image, from which you can judge distance. Another reason for combining the two images from both eyes is that it gets rid of the blind spot in each eye.
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