Chapter 31- Nervous System Big Idea: How does the structure of the nervous system allow it to regulate functions in every part of the body?

31.1 The Neuron F(x)s of Nervous System: Collect information Process information Respond to environment

Peripheral Nervous System (PNS): Central Nervous System (CNS): Consists of nerves and supporting cells Brain and spinal cord, takes info. and delivers it to appropriate part of PNS

Neuron f(x): Neurons transmit nervous system impulses. Types: Sensory- Carry messages from sense organs → CNS Motor-Info. from CNS → to muscles/glands Interneurons- Process/ send commands to other neurons

Cell body-contais nucleus +cytoplasm Neuron Structure: Cell body-contais nucleus +cytoplasm Dendrites- recieve impulses from other neurons, carries through cell body Axon- Long fiber carrying impulses away from cell body

Some axons are surrounded by myelin sheath, which speed impulse movement

The Nerve Impulse: Starts @ resting state, until large enough stimulus is received from environment or from another neuron. Travels quickly from: Dendrites → cell body → axon During impulse resting potential is reversed= nerve impulse= Action potential

Impulses move w/ a domino effect. Threshold= min. stimulus needed to start impulse. All or nothing. If signals are too weak nothing will happen. Synapse= point @ which impulse travels from one cell to another Nuerotransmitters= chemicals that carry signals from synapse → cell

31.2 Central Nervous System Control point of CNS= brain; 3 major areas: cerebrum, cerebellum, and brain stem Spinal cord connects brain → rest of body

Reflex= quick automatic response to a stimulus -Help protect us Cerebrum Largest area of brain. Controls voluntary movement, knowledge, and judgement Hemispheres connected by tissue called corpus callosum. Each hemisphere manages opposite side of body (=lateralization)

(Cerebrum continued) Outermost layer= cerebral cortex, composed of gray matter. Processes info. from senses, controls movement, thoughts, learning, etc. Folds in brain=greater surface area Inner layer= white matter. Bundles of axons, connect to diff. areas of brain

Parietal: Reading and speech Frontal: Decision making, forming plans Occipital: Vision Temporal: Hearing and smell

Limbic system- Deep region in brain (amygdala) associated w/ emotions, pleasure, long term memory, fight or flight response

Thalamus and Hypothalamus L: between brainstem and cerebrum f(x): (Thalamus) receives sensory info. and relays info. to proper region of brain (Hypothalamus) hunger, thirst, fatigue, anger, regulation of body temperature

Cerebellum: Controls coordination and balance. Familiarizes you w/ coordinated movements.

Brain Stem: -3 regions: midbrain, pons, medulla oblongata -f(x)s: regulates info. from brain → body. Controls breathing, swallowing, blood pressure, swallowing

Addiction and the Brain: Addictive substances cause change in a group of synapses that use the neurotransmitter (NT) dopamine Dopamine is associated w/ brain’s pleasure centers.

-When we find something pleasurable the brain releases dopamine -When we find something pleasurable the brain releases dopamine. Drugs overflow dopamine, or keep it in system longer. This overflow of dopamine causes a reduction in dopamine NT. Normal activities no longer produce pleasurable sensations they once did.

31.3 Peripheral Nervous System (PNS) Sensory portion of PNS transmits info. from sense organs → CNS

Type Responds to Chemoreceptor Chemicals Photoreceptor Light Mechanoreceptor Touch, pressure, vibrations, stretch Thermoreceptor Temperature changes Pain receptor Tissue injury

Somantic nervous system: Regulates movements under conscious control Reflex Arc (rapid response): Sensory receptors pick up stimulus (pick up) Sensory neurons relay info → spinal cord (relay) Interneuron processes info. (process) Motor neuron carries impulse → effector (carry) Effector (muscle moves) (response)

Autonomic nervous system: f(x): regulates involuntary activities (ex: heart rate, blood pressure (BP), sweat glands, digestion) Divisions: Sympathetic: Prepares body for intense activity “fight or flight” response, shuts/slows down activities not related to flee (slow digestion, increase in BP, and energy vs. Parasympathetic: “Rest and digest” response. Acts opposite of sympathetic, lowers heart rate and BP, stores food

31.4 Senses Different sensory receptors in the body respond to touch, temperature, and pain.

Sensations of taste and smell are the result of impulses sent to the brain by chemoreceptors. Much of what we taste is a result of smell. Taste buds detect taste.. Sweet, salty, bitter, sour, and “umami.” (Savory)

Hearing Mechanoreceptors in parts of ear transmit impulses to brain Main organ of hearing= cochlea -Cochlea structure= fluid filled portion of inner-ear - Cochlea f(x)=transmit vibrations to auditory nerve in brain, interpreted as sound

Balance Semicircular canals maintain balance Location: Above cochlea Structure= 3 tiny ½ circle canals. Fluid filled, lined w/ tiny hairs. Change in body position causes bend in hair cells F(x)= monitor body and head position in relation to gravity

outer ear tympanum auditory ossicles cochlea Mechanism of hearing: ______________ funnels sound to hit ___________, which causes the ______________ to vibrate, until it reaches the _______________ which transmits sound to the brain!

Vision -Photoreceptors in eyes transmit impulses to the brain, translates into images

Anterior (front) portion of eye Posterior (back) portion of eye Cornea:transparent, focuses light Lens: changes shape to focus Iris: colored portion, works w/ the pupil to adjust how much light gets in Retina: contains rods and cones Filled w/ aqueous humor Filled w/ vitreous humor

Cones: Differentiate colors In retina photoreceptors convert light into nerve impulses, that go to the brain through the optic nerve. Contain: Rods: Light sensitive Cones: Differentiate colors blue/black vs. white/gold dress can be explain by different distributions of rods and cones that vary between each individual.