1. 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

2. 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

3. 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

4. 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

5. 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
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6. 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

7. 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

8. 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
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9. 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
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10. 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
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11. 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

12. 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

13. 35-3 Divisions of the Nervous System
A Reflex is a quick, automatic response to stimulus

14. 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

15. 35-3 Divisions of the Nervous System
Reflex Arc
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16. 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

17. 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

18. 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

19. 35-4 The Senses
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20. 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

21. 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

22. 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

23. 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
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