Your Nervous System Peripheral Nervous System Explain Section 35-3 The Nervous System is divided into Central nervous system Peripheral nervous system Motor nerves which consists of that make up Somatic nervous system Autonomic nervous system which is divided into Sympathetic nervous system Parasympathetic nervous system Sensory nerves PNS 1. NERVES that connect the central nervous system to the rest of the body Motor Division – impulses from CNS to muscles or glands Two Parts: 2. Somatic Nervous System Autonomic Nervous System Sensory Division – transmits impulses from sense organs to CNS Motor Division PNS Somatic Nervous System Controls voluntary movement of the skeletal muscles Autonomic Nervous System Controls involuntary actions Subdivided into two system that have opposite effects on the same organs: 1. Parasympathetic – decreases heart rate 2. Controls internal organs during normal activity Sympathetic – increases heart rate Controls internal organs during high stress activity Sensory Division PNS 1. Pain Receptors Throughout body; except brain Respond to chemical released by damaged cells Important to recognize Danger Injury Disease 2. Thermoreceptors In skin, body core, hypothalamus Detect variations in body temperature 3. Mechanoreceptors Skin, skeletal muscle, and inner ears Sensitive to Touch Pressure Stretching of muscles Sound motion 4. Chemoreceptors Nose and Tongue Chemical in external environment Figure 35-14 The Eye Section 35-4 Vitreous humor Muscle Lens Fovea Aqueous humor Cornea Pupil Optic nerve Iris Blood vessels Ligaments Retina Choroid Sclera 5. Photoreceptors Eyes Sensitive to Light DO NOT WRITE NEXT INFO – IT IS ON YOUR SHEET Cornea Tiny muscles regulate the size Regulates amount of light Lens Back of cornea Colored part of eye Pupil Helps focus light Filled with aqueous humor Iris Vision Small muscles change its shape to focus on object near and far away Behind lens eye filled with vitreous humor Retina Has photoreceptors No photoreceptors where optic nerve passes through the back of the eye; blind spot Two types 1. 2. Rods – black and white Cones – color Pathway for Vision Reception Light cornea iris and pupil lens Retina to photoreceptors Rods Cones – Fovea Optic Nerve Brain Figure 35-15 The Ear Section 35-4 Anvil Stirrup Hammer Oval window Semicircular canals Cochlear nerve Cochlea Bone Auditory canal Tympanum Round window Eustachian tube Hearing and Balance Ear Two Functions Hearing Detecting Positional change to movement Hearing Sound – air vibrations Auditory canal – funnels air to tympanum (ear drum) Tymapnum – vibrates Hammer, Anvil, Stirrup- vibrate and transmit vibrations to oval window Cochlea – filled with fluid and vibrations create pressure waves in the inner ear Tiny hairs respond to waves and send messages to brain via the cochlear nerve Balance Semicircular Canals 3 canals that form half circles Filled with fluid and hairs that detect motion of head in relation to gravity Figure 35-15 The Ear Section 35-4 Anvil Stirrup Hammer Oval window Semicircular canals Cochlear nerve Cochlea Bone Auditory canal Tympanum Round window Eustachian tube Smell and Taste Chemoreceptors pick up chemical reception in nose and mouth Smell – olfactory bulb Taste – taste buds Salty Bitter Sour Sweet The Senses of Smell and Taste Section 35-4 Olfactory (smell) bulb Taste sensory area Olfactory nerve Thalamus Cerebral cortex Smell receptor Nasal cavity Smell sensory area Taste bud Taste pore Taste receptor Sensory nerve fibers Touch and Related Senses Largest sense organ? Sensory Receptors SKIN Temperature Touch Pain Greatest density of touch receptors Fingers Toes Face Concept Map Section 35-3 The Nervous System is divided into Central nervous system Peripheral nervous system Motor nerves which consists of that make up Somatic nervous system Autonomic nervous system which is divided into Sympathetic nervous system Parasympathetic nervous system Sensory nerves