Chapter 2 Nervous System

Brain

Vocabulary:• Phrenology- study of the

bumps on the skull in order to reveal mental ability and our character traits.

• Biological psychology- concerned with the links between biology and behavior– They have helped gain better

understanding of sleep and dreams, depression and schizophrenia, stress and disease.

You’ve got NERVE!!• Know your vocabulary

– Neuron– Dendrite– Axon– Myelin sheath– Action potential *– Threshold– Synapse– Neurotransmitters

• Dopamine• Serotonin• Norepinephrine• Acetylcholine (ACh)• endorphins

Nervous System• Again with the vocabulary!

– Central nervous system (brain and spinal cord)

– Peripheral nervous system • Autonomic (controls self-regulated

action of internal organs and glands)– Sympathetic (arousing)– Parasympathetic (calming)

• Somatic (controls voluntary movements of the skeletal muscles)

– Sensory neurons– Interneuron– billions and billions–

complexity lies in this internal communication system

– Motor neurons

How do neurons communicate?• Electrical impulses (action

potentials) travel from one neuron to another across the synapse. When axon reaches axon terminal, it stimulates the release of neurotransmitter molecules from sacs called vesicles. The molecules cross the synaptic gap and bind to the receptor sites on the receiving neuron. This allows electrically charged atoms to enter the receiving neuron and excite or inhibit a new action potential. The sending neuron reabsorbs excess neurotransmitter molecules, called reuptake.

Examples• If you touch a flame, the

messages are transmitted from your spinal cord to muscles in your hands which move it from the flame. This is all occurring in the _____ nervous system.

• Peripheral • When you later feel the pain–

its reached your brain! • Why do neurons network?

– So they have faster, shorter connections

How do you pick up a fork?• You central nervous system’s

hungry brain activates and guides the muscles of your arm and hand via your peripheral nervous system’s motor neurons.

• As you pick up the fork, your brain processes the information from your sensory nervous system, enabling it to continue to guide the fork to your mouth

• The functional circle starts with sensory input, continues with interneuron processing by the central nervous system, and finishes with motor output.

BRAIN• reticular activating system

: a part of the reticular formation that extends from the brain stem to the midbrain and thalamus with connections distributed throughout the cerebral cortex and that controls the degree of activity of the central nervous system (as in maintaining sleep and wakefulness and in making transitions between the two states)

Check this out!!

• http://science.nationalgeographic.com/science/health-and-human-body/human-body/brain-article.html?nav=A-Z

More stuff

• Glial cells– neuronal support cells that bind neurons. They insulate the myelin (covering) and aid in the speed of neural transmissions

• Aphasia– impaired language. If in Brocha’s area, patient will struggle to form words. If in Wernicke’s area, patient may speak meaningless words or be unable to comprehend what is said to them.

Neurotransmitters

Endorphins– natural opiates, released in response to pain and vigorous exercise.

Feedback linking nervous system and endocrine system

• The hypothalamus in the brain influences secretions by the pituitary gland. The pituitary regulates other endocrine glands, which release hormones that influence behavior. The hypothalamus monitors these changes in blood chemistry and thereby adjusts its inputs to the pituitary gland.

Neural Communication

Neurotransmitter molecule

Receiving cellmembrane

Receptor site onreceiving neuron

Agonist mimicsneurotransmitter

Antagonistblocksneurotransmitter

The Brain

CT (computed tomography) Scan a series of x-ray photographs taken from different angles and

combined by computer into a composite representation of a slice through the body; also called CAT scan

PET (positron emission tomography) Scan a visual display of brain activity that detects where a radioactive

form of glucose goes while the brain performs a given task MRI (magnetic resonance imaging)

a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain

CT Scans: An x-ray of the brain.

A CT scan is essentially a computerized assembly of several x-ray images taken from a series of different angles. With a CT, the resolution is much better than conventional x-rays, and the detail that can be seen is much greater. 

        MRI is a noninvasive imaging technique that does not use x-rays.   The process involves passing a strong magnetic field through the head.  The magnetic field used is 30,000 + times that of the earth's magnetic field.  It's effect on the body, however, is harmless and temporary.  The MRI scanner can detect radiation from certain molecules, which are present in different concentrations in different tissues. 

Tumor in Wernicke’s Area

PET measures the emission of positrons from the brain after a small amount of radioactive isotopes, or tracers,  have been injected into the blood stream.  A common example is a glucose-relative with embedded fluor-18.   With this molecule, the activity of different regions of the brain can be measured.  The result is a three-dimentional map with the brain activity represented by colors. 

PET

SCANS

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Dopamine

After Implant of Dopamine-secreting Tissue

Brain Development in First Year of Life

Normal Brain ADHD Brain