BIOLOGY AND BEHAVIOR

CHAPTER 2

The mighty NEURON aka:the Naughty Neuron

• Nerve cell which transmits electrical and chemical information (via neurotransmitters) throughout the body. Each nerve cell is separate from another and is called a Neuron – a string of these is a nerve cell.

• Learning takes place by new dendrites actually sprouting to make connection with other neuron.

NEURONS

• Cell body – has the nucleus in it.

• Dendrite: means tree branches. It is the receiver of the messages from other neurons. It sends the message down it’s own axon.

• Axon: carries the messages from the cell to other neurons. At the end of the axon are terminals or bulbs .

Neurons continued

• Synapse: the space between the endings of the axon and the waiting dendrites.

• Vesicles: containers in the axon bulb of the neurotransmitters.

• Neurotransmitters: the chemicals that propel the message across the synapse from the end of the axon to the awaiting dendrite. Discovered 20 years ago. Die off in adulthood.

• Myelin: grease coating on the axon - speeds up message. Not much in the digestive track.

NEUROTRANSMITTERS

• Acetylcholine – Ach. Most and best understood NT. Memory, sleep. Deteriorates with Alzheimers.

• Dopamine – bodily movements – lack of causes Parkinson’s disease. Too much may cause schizophrenic episodes.

• Endorphins: relieve pain and increase our sense of well-being.

• Serotonin: our feel good NT

ACTION POTENTIAL

• Message breaks a threshold and goes to the awaiting dendrite, to the cell body, down the neuron’s axon surrounded by myelin to make it faster, to the axon bulbs vesicles where the appropriate NT is squeezed out of the vesicle to go across the synapse to the awaiting dendrite receptor.

SPINAL CORD

• Functions as an automatic brain…relays impulses to and from the higher brain.

• Central Nervous System:

the brain and the spinal cord

* The Peripheral Nervous system:

The Somatic and the Autonomic

Nervous systems: Autonomic =

Sympathetic – energizes. Parasympathetic – slows you down – back to homeostasis.

THE BRAIN

• Uses 20% of all our oxygen

• Eats most of our sugar intake

• Uses 20 watts of power

• MOST demanding organ in the body

• Has 2 hemispheres

• Has 4 Lobes

LOBES

• Frontal: contains the motor strip and frontal association area.– Motor strip – body movements, ear to ear

strip.– Elaborate associations, complex thinking.– Personality here– Damage here changes ones personality.– 30% of the brain

LOBES continued

• Parietal Lobe: area of the brain that contains the sensory strip.

• Occipital Lobe: interprets visual information. In the back of the brain.

• Temporal Lobe: area of the brain responsible for hearing. One each side of the brain (temples)

HEMISPHERES

• Doesn’t tend to be genetic.

• Ambidextrous: messages get stuck in the middle, possible brain trauma.

• Left brain: Logical and analytical, deals with verbal and speech material.

• Right brain: Artistic, creative, and emotional. Deals with space, art, music, emotions.

CEREBRAL CORTEX AND THE LOWER BRAIN

• Outermost layer of brain – the BARK

• Made up of hemispheres, lobes, frontal association

• Covers the lower brain

• Controls higher level thinking

• 2/3’s of the brain

• Macaroni like material – if we rolled it out – big as a bath towel.

LOWER BRAIN

• Basic animal unit

• Cortex fits over and around it – it’s the part that keeps you going– Thalamus: RELAY system. Takes in

messages and sends them out.– Cerebellum – coordinates and organizes

bodily movements for balance and accuracy. Looks like golf balls on the side of the spinal cord.

Lower Brain continued

– Hypothalamus: regulates basic needs: 4 F’s: fleeing, fighting, feeding, fornication and temperature. Size of a small pea under the thalamus.

– Reticular activating system: RAS: Sits at the base of the brain and regulates activity of the body. Makes us alert or tired. Drugs in surgery act on the RAS so it doesn’t notice pain.

Motor Cortex

Sensory Areas of the brain