Unit 2

The Nervous, Limbic, and Endocrine systems

Parts of the Nervous System

� Central Nervous System (CNS)� Brain and spinal cord

� Peripheral Nervous System (PNS)� Carries messages to and from CNS

Central nervous system

Peripheral nervous system

Sympathetic and parasympathetic divisions of the nervous system

Split brain operation—procedure used to reduce recurrent seizures of severe epilepsy

Corpus Callosum—thick band of axons that connects the two cerebral hemispheres

axon terminal

dendrite receptors

How Neurons Work

� Input comes in from/goes to part of the body� You want to move your arm

� An electrical impulse is sent down the axon to a nerve ending

� The electrical impulse stops at the synapse� Neurotransmitters (for movement) are released by

the axon terminal into the open space� Once in the open space the chemicals float to the

dendrite receptor for movement� The excited dendrite sends an electrical impulse to

the next cell and so on� The electrical impulse travels ends at muscle

receptors and your arm moves (120 yards / sec)

Neurotransmitters

� Acetylcholine� Regulates body processes such as movement� Memory � In Alzheimer’s disease patients it often is not working

properly� Dopamine

� Involved in the CONTROL of bodily movements� Parkinson’s disease patient have a shortage of it

� Endorphins� Relieve pain and increase our sense of well being� Creates the “runner’s high”

The Limbic System

� Hypothalamus� Amygdala� Hippocampus

� Contains structures involved in basic emotions, motivations, and memory

� Amygdala� Emotional responses like aggression, rage, and

fear

� Hippocampus � Enables us to form memories (not memory

storage)� If there’s damage to the hippocampus, we can’t

make new memories

The Limbic System

Hypothalamus� Contains nuclei involved in a variety

of behaviors� sexual behavior� hunger, thirst� sleep� water and salt balance� body temperature regulation� circadian rhythms� role in hormone secretion

Endocrine System: hormones

� Pituitary gland� Master gland� Growth hormones

� Thyroid� Regulates your metabolism (speed of body processes)

� Adrenal Glands� Secrete adrenaline. Prepares the body for emergencies

� Gonads: � sex glands make eggs or sperm for reproduction� Ovary in females (estrogen)� Testis in males (androgen)

Endocrine System