Nervous System

Nervous System Brain Central Nervous System Spinal Cord Sensory Nerves Peripheral Nervous System Somatic Motor Nerves Automatic

Function of the nervous system: Controls and coordinates functions throughout the body

The Neuron – nerve cell Dendrite – reception of nerve impulses nucleus Axon terminals Dendrite – reception of nerve impulses from other cells Cell body – contains the cell nucleus Axon – carries the nerve impulse away from the cell body Myelin sheath – insulating membrane Cell body Myelin sheath nodes axon dendrites

Nerve Impulse Moves like the flow of electrons through a wire

Nerve Impulse 2 Phases: resting potential – the neuron membrane is positive outside and negative inside; the sodium-potassium pump moves sodium out while bringing in potassium action potential – negative outside and positive inside; as the nerve impulse moves along the neuron from the dendrites through the cell body to the axon, polarity changes across neuron membrane;

Practice A Label the indicated parts. B C

Synapse location where nerve impulse moves from one neuron to the next Tiny gap where the nerve impulse is transferred by chemical neurotransmitters

Divisions of the nervous system Central nervous system (CNS) – brain & spinal cord Peripheral nervous system (PNS) – nerves to other parts of the body Sensory – provides brain with information from the senses Motor – carries information from the CNS to the muscles & glands, divided into somatic nervous system (voluntary movement) and automatic nervous system (involuntary movement)

The Brain Controls and coordinate body activities Meninges – tough covering over the brain & spinal cord Cerebrum (gray matter) – controls voluntary activities, intelligence Cerebellum – back of skull; coordinates & balances actions of muscles & body

The Brain Brainstem – pons and medulla oblongata regulates the flow of information between the brain & body controls blood pressure, heart rate, breathing, & swallowing

The Brain Thalamus – receives messages from the senses & sends them to cerebrum Hypothalamus – control center that detects and analyzes hunger, thirst, fatigue, anger, & body temperature controls and coordinates nervous & endocrine systems

cerebrum cerebellum pons Medulla oblongata thalamus hypothalamus midbrain

Practice Which part of my brain…?

Reflex Arc Quick automatic response to stimulation like blinking or sneezing Nerve impulse goes to the spinal cord & back to muscles without passing through the brain

The Senses Eye – light passes though the cornea, pupil (opening at the front of the eye) & lens to the retina. Retina – consists of rods (sensitive to light) & cones (distinguishes color) Optic nerve – sends messages from the retina to the brain

Vitreous humor Muscle Lens Fovea Aqueous humor Cornea Optic nerve Pupil Iris Blood vessels Ligaments Retina Choroid Sclera

Ear Has 3 tiny bones - hammer, anvil, stirrup Conduct sound vibrations: tympanum, hammer, anvil, stirrup, oval window, cochlea Semicircular canals – three fluid-filled tiny canals, assist in balance

Stirrup Hammer Oval window Anvil Semicircular canals Cochlear nerve Cochlea Bone Auditory canal Tympanum Eustachian tube Round window

Taste buds – on the tongue, detect taste

Smell – detected by olfactory bulbs in nasal passages Touch – skin has sensory receptors to temperature, touch, and pain

Drugs that affect the nervous system: Stimulants – increase actions (heart rate, increase neurotransmitters in brain) Include: caffeine, nicotine, cocaine Depressants – decrease activity (heart rate) Include: marijuana, alcohol