Ch 35 Nervous System 35-1 Human Body systems 35-2 The Nervous System 35-3 Divisions of The Nervous System 35-4 The Senses 35-5 Drugs and the Nervous System

35-1 Human Body Systems The levels of organization in a multicellular organism includes Cells Tissues Organs Organ systems Organism Specialized cells are uniquely suited to perform a particular function

35-1 Human Body Systems Four Basic types of Tissues Epithelial Tissue Glands and tissues that cover exterior and interior body surfaces Connective Tissue provides support for the body and connects its parts Nervous Tissue transmits nerve impulses throughout the body Muscle Tissue enable the body to move

35-1 Human Body Systems Homeostasis is the process by which organisms keep internal conditions relatively constant despite changes in external environments Maintained by feedback loops

35-1 Human Body Systems Feedback inhibition or negative feedback is the process in which a stimulus produces a response that opposes the original stimulus Pg 896 (1-5) Arts and Crafts Tomorrow

35-2 The Nervous System The nervous system controls and coordinates functions throughout the body and responds to internal and external stimuli Cells that transmit impulses are called Neurons The largest part of a typical neuron is the Cell Body

35-2 The Nervous System From the cell body are short, branched extensions called Dentrites The long fiber that carries impulses away from the cell body is called the Axon In some neurons, the axon is surrounded by an insulating membrane known as the Myelin Sheath

35-2 The Nervous System The electrical charge across the cell membrane of a neuron in its resting state is known as the Resting Potential ----- Meeting Notes (3/25/15 10:14) ----- heyyyyyy

35-2 The Nervous System An impulse begins when a neuron is stimulated by another neuron or by the environment The reversal of charges, from negative to positive, is called a nerve impulse or an Action potential The minimum level of a stimulus that is required to activate a neuron is called the Threshold ----- Meeting Notes (3/25/15 10:14) ----- loser

35-2 The Nervous System The location at which a neuron can transfer an impulse to another cell is called a Synapse Neurotransmitters are chemicals used by a neuron to transmit an impulse across a synapse to another Neuron Pg 900 (1-5) Coloring due tomorrow- Follow Directions ----- Meeting Notes (3/25/15 10:14) ----- LOSER

35-3 Divisions of the Nervous System The Central Nervous System (CNS) relays messages, processes information, and analyzes information The connective tissue around the brain and spinal cord is known as Meninges The fluid between the meninges and \ the CNS is called Cerebrospinal Fluid

35-3 Divisions of the Nervous System Parts of the Brain Cerebrum-largest, responsible for voluntary, or conscious activity, intelligence Cerebellum- Coordinates commands to the muscles and balance Brain Stem- Connects brain to spinal cord, includes pons and medulla oblongata which controls important functions- Blood Pressure, heart rate, breathing, and swallowing Thalamus- Receives messages from sensory receptors and relays the information to the cerebrum Hypothalamus- control center for hunger, thirst, fatigue, anger and body control

35-3 Divisions of the Nervous System A Reflex is a quick, automatic response to stimulus

35-3 Divisions of the Nervous System The sensory division of the peripheral nervous system (PNS) transmits impulses from the sense organs to the (CNS) The motor division transmits impulses from the central nervous system to the muscles or glands

35-3 Divisions of the Nervous System Reflex Arc Pg 905 (1-5)

35-4 The Senses Sensory Receptors, React to a specific stimulus such as light or sound by sending impulses to other neurons, and eventually to the CNS Five categories of sensory receptors Pain Receptors-Pain Thermoreceptors-Heat Mechanoreceptors-Touch Chemoreceptors-Chemicals Photoreceptors-Light

35-4 The Senses Vision Pupil- Opening to the Iris Lens- Attached to muscles that allow light to be focused to see near or distance objects Retina- Photoreceptors arranged to collect light here Rods-sensitive to light but don’t distinguish color Cones- respond to different colors

35-4 The Senses Vibrations in the air create pressure waves in the fluid- filled cochlea of the inner ear Three tiny canals at right angles from each other in the inner ear that help you with coordination and equilibrium are the Semicircular canals

35-4 The Senses Pg 909 ( 1-5 )

35-5 Drugs and the Nervous System A Drug is any substance, other than food, that changes the structure or function of the body Stimulants increase heart rate, blood pressure, and breathing rate In addition they also release neurotransmitters at some synapse in the brain Depressants slow down heart rate and breathing rate, lower blood pressure, relax muscles, and relieve tension

35-5 Drugs and the Nervous System Cocaine causes the sudden release in the brain of a neurotransmitter called dopamine Mimics feeling for pleasure and satisfaction Opiates mimic natural chemicals in the brain known as endorphins, which normally help to overcome sensations of pain Pain killers

35-5 Drugs and the Nervous System Alcohol is a depressant that slows down the rate in which the central nervous system functions Slows down reflexes Disrupts coordination Impairs judgement Fetal Alcohol Syndrome (FAS) is a group of birth defects caused by the effects of alcohol on the fetus 50,000 babies a year

35-5 Drugs and the Nervous System Drug abuse can be defined as the intentional misuse of any drug for nonmedical use An uncontrollable dependence on a drug is known as a drug Addiction Pg 914 (1-5)