Nervous System II
Positive Charge Outside Negative Charge Inside: Polarized Positive Charge Outside Resting Potential: Difference in charge across a nerve cell membrane resulting from the negative charge on the inside and the positive charge on the outside.
Resting Potential: Polarized +++++++++++++++++++++++++ NA+ ++++++++++++++++++++++++ - - - - - - - - - - - - - - - - - K+ (less positive)
Action Potential The signal comes through the neuron…the sodium potassium pump is activated. Sodium ions go in and this is called depolarizing the neuron and when the sodium channels close and potassium channels open, this is called repolarization. The wave of activity that allows neurons to carry a signal over a certain distance is called an action potential.
Divisions of the Nervous System Central Nervous System -Brain -Spinal Cord Both covered by meninges (connective tissue) In between meninge and CNS is cerebrospinal fluid (protects CNS and acts as a shock absorber)
Spinal cord Function: The main function of the spinal cord is transmission of neural inputs between the periphery and the brain.
Brain Cerebrum (largest part): responsible for voluntary activities of the body. Site of intelligence, learning, memory and judgment. Cerebellum (2nd largest): Located in the back of the skull. Coordinates movement. Brain Stem: Connects brain and spinal cord. Contains the pons and medulla oblongata. Control center – controls vital functions such as blood pressure, heart rate, breathing and swallowing.
Brain Thalamus: Receives messages from sensory receptors and relays information to cerebrum for further processing. Hypothalamus: Controls hunger, thirst, fatigue, anger, body temperature.
Real Brain
Weight of human brain 3 pounds
Peripheral Nervous System Sensory Division (Sense Organs to CNS) Motor Division (Impulses from CNS to muscles or glands) - Somatic Nervous System (Conscious control) - Autonomic Nervous System (Unconscious control)