Biological Foundation [powerpoint]

Why explain human biology?

Aspects of human biology are directly relevant to understanding behavior (and mental processes)

In this case, the nervous system controls communication, behavior, and responses.

What are the biological “machines” psychological beings live in?

1. The Brain

2. The Nervous System

3. Endocrine Glands

4. Genetic mechanism

What would happen if the nervous system didn’t exist?

The body would be uncoordinated, unable to act, reason, or feel emotions → essentially no psychological life.

Why is the nervous system compared to a machine?

Because it’s built from specialized parts (neurons) that work together like components of an electronic machine

What is the nervous system’s main role?

It’s the biological control center—the body’s communication and computer network.

How does the brain communicate with the body?

Through the network of neurons that branch out to every part of the body.

The endocrine system

Endocrine glands secrete chemical messengers (hormones) that travel through the bloodstream.

Hormones regulate many functions of the body and influence our behavior and experience.

What are the main parts of the nervous system?

Brain, spinal cord, and nerves.

What functions does the brain handle

Thinking, calculating, feeling, and controlling motivation.

What are neurons?

Primary units of the nervous system that transmit messages.

Neuron length?

less than a millimeter —> more than a meter

What are the three parts of a neuron?

1. Cell body – contains the nucleus, maintains preservation & nourishment; keeps the cell alive

2. Dendrites – receive messages from other neurons

3. Axons – send messages to other neurons

What are the two steps of message transmission in neurons?

1. Neural transmission – message along a neuron
2. Synaptic transmission – message one neuron to the next

What does each neural membrane have?

A membrane potential or resting potential

What is the resting potential of a neuron?

The neuron is not firing and is said to be polarized.

What happens when there is enough change in electrical charge?

The neuron becomes depolarized, which triggers an action potential.

What is an action potential?

A brief electrical signal traveling down an axon.

• Nerve impulses are waves of action potentials

• Movement of ions in and out of the cell in a wave like pattern

• Begin at the dendrites and end at axon terminals

What is the all-or-none principle?

Once a neuron fires, its action potential is always the same magnitude.

What is the myelin sheath?

Insulating fatty layer around axons that speeds the transmission of neural messages and protects them.

The growth rate of the myelin sheath?

Continues to grow in thickness into late adulthood

Myelin Sheath interesting fact!

thickness of the myelin sheath is greater in females than in males in some areas of the brain (indicate more efficient neural processing of some kinds of information by females)

Multiple Sclerosis destroys the myelin sheath of many neurons, leaving them unable to operate at normal efficiency

Where are neurotransmitters stored?

Synapric vesicles located at the synaptic terminal [end of axon]

How do neurons communicate across the synaptic gap?

Using neurotransmitters released from synaptic vesicles at the axon terminal.

{Action potentials cannot travel down the synaptic gap = synapse]

What is the synaptic gap?

The small space between neurons where neurotransmitters carry messages.

What are glial cells?

Helper cells that nourish neurons, produce myelin sheath, and regulate message transmission.\ across the synaptic gap.

How do glial cells compare in number to neurons?

There are more glial cells than neurons.

What are the two main parts of the nervous system?

Central Nervous System (CNS) – brain and spinal cord

Peripheral Nervous System (PNS) – all other nerves branching from CNS

What are afferent and efferent neurons?

Afferent: carry messages from senses to CNS
Efferent: carry messages from CNS to muscles/organs

What are the two divisions of the PNS?

Somatic nervous system: voluntary
Autonomic nervous system: involuntary

What is the function of the Somatic Nervous System?

Carries messages from the CNS to the skeletal muscles that control movement.

Voluntary & Involuntary

receive and send messages from the sensory receptors to the CNS

What is the automatic nervous system composed of?

Nerves carrying messages to the glands and visceral organs (heart, stomach, intestine)

What are the two primary functions of the autonomic nervous system?

1. Essentisl body functions

2. Emotion

What are the two parts of the autonomic nervous system?

Sympathetic: arousal, energy expenditure (fight-or-flight)

Parasympathetic: supports activities that increase energy storage (rest-and-digest)